EXOHOST conference Abstract book

Project: 101079231 — EXOHOST — HORIZON-WIDERA-2021-ACCESS-03 14-17 October 2025 Tartu, Estonia EXPLORING STAR-PLANET-DISK CONNECTIONS CONFERENCE ABSTRACT BOOK Edited by Laurits Leedjärv and Alexandra Lehtmets Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 2 Table of Contents Introduction ......................................................................................................................... 6 Session 1: Fundamental Stellar Properties ........................................................................ 7 Invited Speaker: Camilla Danielski - The Star Sets the Stage: Understanding Exoplanets Through Their Hosts ..................................................................................... 7 Alix Freckelton - The Gr8stars Catalogue: a Public Library of FGKM Dwarf Spectra and Their Homogeneously Derived Parameters. ............................................................. 8 Lara Piscarreta - Accretion Makes Young Stars Look Old: Lessons from Orion ......... 8 Matthias Ammler-von Eiff - How to Improve the Characterization of Distant Stars with Transiting Exoplanets? ............................................................................................ 9 Nicola Miller - Eclipsing Binaries as Benchmark Stars: Addressing the “Effective Temperature” Elephant in the Room ............................................................................. 10 Andreas Quirrenbach - Terrestrial Planets Orbiting Low-mass Stars ..................... 11 Tõnis Eenmäe - Enhancing Northern Sky Monitoring: Upgrades to Tartu Observatory’s 1.5 m Telescope for High ‑ Resolution Spectroscopy and Multi ‑ Band Photometry ..................................................................................................................... 11 Session 2: Stellar Activity ................................................................................................. 13 Invited Speaker: Savita Mathur - Magnetic Lives of Solar-like Stars: Implications for Exoplanet Study ............................................................................................................. 13 Telmo Monteiro - Analysis of NIR Activity Indices for Exoplanet Detection and Characterization ............................................................................................................ 14 Eike Wolf Guenther - The First Spectroscopic Screening of Exoplanet Host Stars of PLATO ............................................................................................................................ 15 Hala Alqubelat - Accretion Variability and Binarity in Young Stars: Insights from DQ Tau and Transition Disks ....................................................................................... 16 Fatemeh Zahra Majidi - Mauve: a Three-year UV-Vis Survey Dedicated to Monitor Stellar Activity and Variability ..................................................................................... 17 Simranpreet Kaur - Polarized Radio Emission from Scallop-shell Stars: The Case of J0508-21 and DG Cvn.................................................................................................... 17 Gloria Canocchi - Challenging Na Detections in the Atmospheres of Giant Exoplanets with 3D Non-LTE Stellar Spectra ................................................................................. 18 Bertram Bitsch - Introduction of the COST Action CA22133 PLANETS .................. 19 Session 3: Stellar Chemical Composition ......................................................................... 20 Invited Speaker: Elisa Delgado Mena - The Impact of Stellar Composition: from Galactic Chemical Evolution to Planet Formation ........................................................ 20 Edita Stonkute - Chemical Signatures of Planet-Hosting Stars ................................ 21 Masanobu Kunitomo - New-Generation Solar and Stellar Models Including Accretion ......................................................................................................................... 22 Neda Hejazi - A New Method to Measure the Detailed Chemical Abundances of Cool Dwarfs and Its Application to Star-Planet Chemical Connection Studies ................... 23 Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 3 Jiayue Zhang - Unveiling the Chemical Abundance Pattern of Solar Analogues Hosting Debris Disks ...................................................................................................... 24 Sandipan Borthakur - Stellar Photospheric Contamination in Early-Type Stars - from Protoplanetary to Debris Disks.............................................................................. 24 Veronika Mitrokhina - Detectability of Deuterium in the Spectra of A-type Stars ... 25 Karolina Szewczyk - Disk Caught at the Transition from Protoplanetary to Debris Stage ............................................................................................................................... 26 Andrea Perdomo García - Most Planet-Hosts Have Sub-Solar Metallicities, But Solar or Super-Solar Iron .............................................................................................. 27 Session 4: Elemental Abundances in Planet Formation .................................................. 28 Invited Speaker: Diego Turrini - Genetic Links and Compositional Connections between Stars, Their Circumstellar Disks and Their Planets ....................................... 28 Bertram Bitsch - The Limits of Planetesimal Formation at Low Metallicity ............ 29 Daisy Turner - Investigating Star-Planet Compositional Ties for Systems with Host Stars of Varying Composition ........................................................................................ 30 Giulia Ricciardi - Compact or Large? CO Observations of the Faintest PlanetForming Disks ................................................................................................................ 30 Heather Johnston - The Rise and Fall of the Giant Planet Occurrence Rate............ 31 Jason Ran - Bayesian Constraints on Planet Formation Models with Population Synthesis and Simulation Based Inference ................................................................... 32 Nidhi Rohit Bangera - Unpacking Disequilibrium Chemistry in Exoplanet Atmospheres: From C/O Constraints to Sulphur Photochemistry ................................ 33 Anna Thomas - Population Synthesis to Investigate the Effect of Volatile to Refractory Sulphur Conversion on the Production of Hot and Cold Gas Giants ............................ 34 Sébastien Paine - Photoevaporated Dust Disk Models and Synthetic Observations . 34 Luke Keyte - The Chemical Composition of Externally Irradiated Disks .................. 35 Session 5: Stellar Abundances & Planet Composition ..................................................... 36 Invited Speaker: Vardan Adibekyan - From Stellar Atmospheres to Planetary Interiors .......................................................................................................................... 36 Yoshi Eschen - Chemical Fingerprints: Decoding Stellar Abundance Influence on Planetary Composition ................................................................................................... 37 Maria Tsantaki - The Exoplanet Population in the Galactic Context from the Ariel Mission Candidate Sample ............................................................................................ 38 Kevin Schlaufman - Terrestrial Exoplanet Internal Structure Constraints on Planet Formation Enabled by Comprehensive Host Star Characterization ............................. 39 Alexandra Lehtmets - Stellar Abundance Anomalies in A–F Type Stars and the Role of Planetary Contamination ........................................................................................... 40 Subsession on Disks .......................................................................................................... 41 Antonio Garufi - 300 Disks Imaged, and Counting… ................................................ 41 Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 4 Karina Mauco - Characterization of Protoplanetary Disks Near and Far: a Complementary Perspective ........................................................................................... 41 Mari-Liis Aru - Studying the Effect of the Environment on Disk Evolution with MUSE ............................................................................................................................. 42 Daniel Daza Valdebenito - Hydrodynamical Simulations of Planet-Disk Interactions in PDS 70 ................................................................................................... 43 Thi My Hanh Tran - Exploration of the Inner Region of the System HD 142527 ...... 44 Zuzanna Jonczyk - Gone with the Wind: CO Depletion in Magnetically-Driven Protoplanetary Disks ...................................................................................................... 44 Yinuo Han - High-Resolution ALMA Imaging of Extrasolar Planetesimal Belts ....... 45 Session 6: Future Instrumentation ................................................................................... 47 Invited Speaker: Giovanna Tinetti - Ariel Space Mission ......................................... 47 Invited Speaker: Heike Rauer, Juan Cabrera, and the PLATO Team - PLATO ....... 48 Invited Speaker: Ana Ines Gomez de Castro - The Unique Capabilities of the Habitable Worlds Observatory for the Investigation of the Evolution of Young Planetary Systems .......................................................................................................... 49 Invited Speaker: Daniel Angerhausen - LIFE Looks for Life - Characterizing Rocky Worlds with the Large Interferometer For Exoplanets Concept .................................... 50 Invited Speaker: Marica Valentini - The Milky Way in the 4MOST era ................... 51 Invited Speaker: Enric Palle - Probing the Cradle of Planets: How ANDES@ELT will Unravel the Link between Protoplanetary Disks and Exoplanetary Systems ............... 52 Poster session .................................................................................................................... 54 Colin Folsom - Chemical Traces of Selective Accretion in the HD 135344 Binary System ............................................................................................................................ 54 Timothy Rawle - ESA Ariel Science Archive .............................................................. 54 Tomoyuki Kudo - Low Water Ice Abundance in the Disk Surface of AB Aur: Insights from Polarimetric Observations ..................................................................................... 55 Alexandra Lehtmets - Investing Circumstellar Atomic Radiation-driven Dynamics56 Anna Maria Weiß - The New Exoplanet TOI 1147b: a Hot Jupiter Orbiting Its Subgiant-Class Star in a Highly Elliptical Orbit ......................................................... 56 Prateek Boga - Characterizing Atmospheres of Ultra Hot Jupiters with the 2m Wendelstein Telescope. ................................................................................................... 57 Ugnė Jonauskaitė - Chemical Analysis of Solar Twin and Analogue Stars ............. 58 Heleri Ramler - Hot Stars in the Ariel Mission Sample: Intermediate-Mass Star and Planet Correlations ........................................................................................................ 59 Nicola Miller - Towards a Homogeneous Sample of M-dwarf Properties and Abundances for the PLATO Mission .............................................................................. 59 Mohamad Ali-Dib - Protoplanetary cores drove chondrule formation ....................... 60 Scientific Organising Committee ...................................................................................... 61 Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 5 Local Organising Committee ............................................................................................. 61 Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 6 Introduction The study of the star-planet-disk connections is crucial for understanding the formation and evolution of planetary systems, including our own. Stars, disks, and planets are not isolated entities, but are intrinsically linked by their formation processes and shared chemical environments. By examining how these components interact, we can gain insight into the initial conditions that govern planet formation, the evolution of planetary atmospheres, and the potential habitability of exoplanets. In an era of rapid advances in exoplanet detection and characterization, this field is more relevant than ever for unveiling the diversity of planetary systems and understanding the forces that shape them. The scope of the conference “Exploring Star-Planet-Disk Connections” will span a wide array of topics, including methods to study stellar atmospheres, the challenges of stellar characterization in the era of large-scale space missions, and the chemical processes within disks that influence planet formation and composition, providing a holistic view of planetary system formation and evolution. This timely meeting offers a platform for researchers to share their latest findings and collaborate on solutions to some of the most pressing challenges in the field. This is the final conference of the EXOHOST project being coordinated by the Tartu Observatory, University of Tartu from 2023 to 2025. EXOHOST is a Twinning project with the main goal to build excellence in spectral characterization of exoplanet hosts and other stars at Tartu Observatory. Our partners in the project are Uppsala University, Space Research Institute of the Austrian Academy of Sciences, and University College London. This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No. 101079231 (EXOHOST), and from UK Research and Innovation (UKRI) under the UK government’s Horizon Europe funding guarantee (grant number 10051045). Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 7 Session 1: Fundamental Stellar Properties Understanding the key physical properties of stars — such as mass, radius, age, and temperature — that are crucial for interpreting exoplanet observations and evolution. Invited Speaker: Camilla Danielski - The Star Sets the Stage: Understanding Exoplanets Through Their Hosts (University of Valencia, Spain) To understand the nature of exoplanets, we must move beyond studying them in isolation and instead characterize entire planetary systems. The fundamental, chemical and dynamical properties of host stars set the scale for planetary parameters and shape their evolution, while the Galactic environment in which a system forms can influence the diversity of planetary architectures and atmospheres. Ensuring consistency in stellar characterization is also crucial, so that observed correlations reflect genuine astrophysical trends rather than analysis artefacts. In this talk, I will give an overview of these themes and discuss how expanding our target selection across a wide range of chemical and dynamical environments—from local overdensities to the Galactic halo, and across different stellar evolutionary phases—will be key to uncovering how planets form and evolve under diverse conditions. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 8 Alix Freckelton - The Gr8stars Catalogue: a Public Library of FGKM Dwarf Spectra and Their Homogeneously Derived Parameters. (University of Birmingham) Advances in instrumentation and techniques are leading us into a new era of stellar and exoplanetary studies. A homogeneous, precise, and accurate source of stellar parameters for bright stars is crucial for many studies, including, but not limited to, designing radial velocity exoplanet surveys, performing precision stellar abundance analyses, and planning future direct imaging surveys. I introduce the Gr8stars catalogue, which currently provides uniformly formatted spectra and homogeneous atmospheric parameters, determined using the PAWS pipeline, for 1715 FGKM main sequence stars in the solar neighbourhood. Ongoing expansions to the catalogue will ultimately result in the classification of nearly 6000 main sequence stars with G < 8, further improving the usefulness of Gr8stars in studying stellar composition, host-star characterization, and evolutionary trends. Future plans for the Gr8stars collaboration include the comparison of atmospheric parameters determined by varying spectroscopic methods across parameter space, stellar activity investigations, and detailed stellar abundances studies. In this talk I will present the Gr8stars catalogue, detail the PAWS spectroscopic pipeline and present the resulting homogeneous properties of these bright nearby stars. Lara Piscarreta - Accretion Makes Young Stars Look Old: Lessons from Orion (European Southern Observatory (ESO)) The observed decline in protoplanetary disk frequency with increasing age in nearby star-forming regions implies typical disk lifetimes of a few Myr, setting constraints on the timescales of planet formation and disk dispersal. However, in the Orion Nebula, some pre-main sequence (PMS) stars exhibiting infrared excess and strong H-alpha emission (signatures of ongoing accretion) appear anomalously old (≳10 Myr) in optical colour-magnitude diagrams (CMDs). Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 9 To investigate this discrepancy, we conducted a spectroscopic analysis of PMS stars located in the Orion Nebula using VLT/X-Shooter. We derived stellar parameters (effective temperature, extinction, stellar luminosity), accretion diagnostics (accretion luminosity, mass accretion rate), and lithium equivalentwidths across a sample of 40 PMS with isochronal ages spanning from ~1 to >30 Myr. After accounting for extinction and excess continuum emission coming from the accretion process, we find that most of the seemingly old stars occupy positions in the HR diagram consistent with a younger population (1–5 Myr). Strong lithium absorption and typical accretion-to-stellar luminosity ratios further support their youth. Moreover, these seemingly old stars typically show some of the highest accretion luminosities in the sample. This study highlights how accretion affects the photometry of PMS stars and the importance of accounting for this effect to obtain reliable age estimates. In this talk, I will explore how ongoing accretion can shift stars in optical CMDs, and how this impacts our understanding of stellar ages and disk evolution in young clusters. Matthias Ammler-von Eiff - How to Improve the Characterization of Distant Stars with Transiting Exoplanets? (MPI for Solar System Research) The accurate determination of the host star parameters is essential to characterize their orbiting planets. In the PLATO mission, the target sample consists of stars with V <= 13 mag, many of which may be too faint for the full characterization via asteroseismology and ground-based spectroscopy, as is planned for the brighter targets. Additionally, these stars tend to be distant, making interstellar extinction a more significant factor compared to other PLATO targets. To assess the limitations of the stellar characterization and to explore possible solutions in preparation for PLATO, we reviewed the stellar parameters of all 36 CoRoT planet hosts. These are typically faint (V=12-16 mag) and can be as distant as 1 kpc and more. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 16 Hala Alqubelat - Accretion Variability and Binarity in Young Stars: Insights from DQ Tau and Transition Disks (European Southern Observatory (ESO)) Accreting binary systems interact dynamically with their circumstellar and circumbinary environments, producing variability across multiple wavelengths and timescales. Understanding these variations is crucial for constraining accretion physics and disk structures. DQ Tau is a short-period (15.698 days), highly eccentric (e = 0.6), equal-mass binary exhibiting sharp accretion bursts near periastron. The orbital motion clears the inner region, enabling the formation of multiple accretion disks. The circumbinary accretion streams are strongly influenced by the system's orbital parameters. Using VLT/UVES and VLT/X-Shooter, we applied the broadening function (BF) technique to calculate radial velocities (RVs) across multiple epochs. The BF analysis reveals two distinct RV signatures, confirming the equal-mass components. Over time, we observe changes in BF peak heights (flux ratios) tied to orbital phase, offering insights into veiling on each star. I will present results from spectral disentangling of DQ Tau, deriving accretion rates for both stars, and show how pulsed accretion affects measured RVs over 10 orbits from a recent JWST, LCO, X-Shooter, and UVES campaign. DQ Tau has shaped our understanding of young binaries, but how far can we push binarity studies in variable accretors? I will highlight disks with large, dust-free cavities seen in ALMA continuum images, proposing they are carved by stellar or substellar companions. I will discuss RV variations observed with ESPRESSO/VLT over 3 years for 12 transition disks, and the possible binary configurations responsible for the observed cavities. Finally, I will address how to disentangle RV variations caused by stellar activity versus planetary companions. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 17 Fatemeh Zahra Majidi - Mauve: a Three-year UV-Vis Survey Dedicated to Monitor Stellar Activity and Variability (Blue Skies Space) Mauve is a satellite equipped with a 13 cm telescope and a UV-Visible spectrometer (with an operative wavelength range of 200-700 nm) conceived to measure the stellar magnetic activity and variability. The science programme will be delivered via a multi-year collaborative survey programme, with thousands of hours each year available for long baseline observations of hundreds of stars, unlocking a significant time domain astronomy opportunity. Mauve’s mission lifetime is 3 years with the ambition of 5 years, and it will cover a broad field in the sky (–46.4 to 31.8 degrees in ICRS) during this period. Booked to launch in October 2025, Mauve’s science team will form prior to the launch date, defining the observation strategy and targets. This facility was conceived to support pilot studies and new ideas in science and is fully dedicated to time-domain astronomy. The main surveys to be executed by Mauve are long baseline observations of flare stars (eruptive Wolf–Rayet stars, UV Ceti stars, etc.), RS CVn variables, eclipsing binaries, Herbig Ae/Be stars, exoplanet hosts, hot stars, etc. Besides these major science themes, the spectrometer’s data can be utilized to support and complement existing and upcoming facilities as a pathfinder, or conduct simultaneous/follow-up observations. Simranpreet Kaur - Polarized Radio Emission from Scallop-shell Stars: The Case of J0508-21 and DG Cvn (Institute of Space Sciences (ICE-CSIC), Barcelona) Scallop-shell stars (SSSs) or Complex Periodic Variables (CPVs) are a recently discovered class of young M dwarfs, which show quasi-periodic dips in their optical light curves that are stable over tens to hundreds of rotation cycles. The origin of these dips is not well understood, however the most promising scenarios involve the presence of gas trapped in huge prominences or dust from the debris disk or a Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 18 disrupting rocky planet at the co-rotation radius. The talk will focus on the radio observations of two of the radio loud SSSs: J0508-21 and DG CVn. J0508-21 was observed at 575–720 MHz with the uGMRT in two epochs of 7 hours each. We detected ~mJy level fluxes with high circular polarization, along with an ~hourlong helicity reversal in both epochs, happening at a similar rotational phase. This suggests presence of two emission components: a persistent gyro-synchrotron emission and a short-duration, auroral like emission, likely powered by the ECM mechanism, possibly resulting from a Jupiter-Io like interaction between the star and the occulting material. On the other hand, DG CVn displays a weakly polarized, quiescent component along with ~100% polarized bursts lasting from minutes to over half an hour during its 14 hours of VLA observations at 1.5 GHz. Some of these bursts also show a drift in frequency and time, which could be caused due to beaming effects or the motion of the source and are consistent with plasma or ECM mechanisms. Overall, these observations reveal that the SSSs are no longer constrained to optical observations only, and how the radio observations can help reveal the underlying processes, highlighting the need to have more contemporaneous/simultaneous multi-wavelength observations of such systems. Gloria Canocchi - Challenging Na Detections in the Atmospheres of Giant Exoplanets with 3D Non-LTE Stellar Spectra (Stockholm University) Transmission spectroscopy from high-resolution ground-based spectrographs is one of the most powerful techniques for characterizing the atmospheres of giant exoplanets. Previous studies have highlighted the importance of correcting the transmission spectra for the center-to-limb variation (CLV) and the RossiterMcLaughlin (RM) effect arising as the planet transits the stellar disk. If not properly corrected, these effects can indeed resemble or cancel out planetary absorption in certain cases, thus affecting the determination of elemental abundances in the planetary atmospheres, as shown by Yan et al. (2017). Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 19 However, commonly used 1D plane-parallel LTE atmosphere models fail to reproduce spatially resolved observations of the solar disk. 3D radiation hydrodynamic models and non-local thermodynamic equilibrium (non-LTE) line formation are required for an accurate modelling of the CLV effect. Sodium is by far the most detected species in transmission spectra, through the analysis of the Na I D lines, which are affected by strong 3D non-LTE effects. In this talk, I will present new results regarding the analysis of these lines in ESPRESSO data of several benchmark gas giants, by modelling their CLV and RM effect using 3D non-LTE radiative transfer. These kinds of studies will be fundamental in preparation for the ELT in order to be able to fully exploit its capabilities in the near future. Bertram Bitsch - Introduction of the COST Action CA22133 PLANETS (University College Cork) COST Actions are projects funded by the European Union to bring scientists working on similar topics together. In particular the COST Action CA22133 PLANETS is designed to advance our understanding of planet formation by focusing on different aspects from laboratory experiments to simulations. The COST Action also organizes (online) presentations and workshops, meetings and allows members to apply for funding to visit conferences as well as to visit collaborators. In this talk I will introduce the scientific goals of the COST Action CA22133 PLANETS, how you can become a member of the COST Action, and how you can benefit from joining. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 20 Session 3: Stellar Chemical Composition Characterizing the elemental abundances of stars to understand their formation history and the chemical environment where planets emerge. Invited Speaker: Elisa Delgado Mena - The Impact of Stellar Composition: from Galactic Chemical Evolution to Planet Formation (CAB, Spain) The characterization of solar-type stars is fundamental for various fields in astrophysics, including exoplanet detection and the chemical evolution of our Galaxy. In particular, the determination of chemical abundances for stars at different metallicities and ages provides us with a key insight on how and when the various chemical elements were formed within the Galaxy. The chemical trends observed in different parts of the Galaxy (thin disk, thick disk, bulge and halo) also serve to understand how those different populations were formed. On the other hand, knowing the particular characteristics of a given star is essential to be able to detect its hosted planets as well as to characterize their mass, radius, structure and bulk internal composition. The probability of finding planets is clearly related to the chemical makeup of the stars and these planets in turn can have an influence on the stellar composition. In this talk I will review some of the important advances in these topics. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 21 Edita Stonkute - Chemical Signatures of Planet-Hosting Stars (Institute of Theoretical Physics and Astronomy, Vilnius University) With the recent discovery of numerous exoplanets, our observational studies aim to understand the relationship between stars and their planets by analysing the elemental compositions of stars that host these planets. Accurate and consistent determinations of stellar atmospheric parameters and chemical compositions across various Galactic components are essential for advancing our understanding of exoplanet formation and evolution. To achieve this, we require homogeneous abundance measurements for a statistically significant number of planet-hosting stars, along with a substantial comparison sample. Our follow-up programme employs the high-resolution Vilnius University Echelle Spectrograph at the Moletai Observatory's 1.65 m telescope to study these stars. This state-of-the-art spectrograph allows us to perform detailed and precise analyses, making it an invaluable tool for our research. We have determined the atmospheric parameters, kinematics, ages, and abundances of elements such as C, N, O, Mg, Si, and neutron-capture elements. In this presentation, I will share our findings from the analysis of 160 stars with planets, highlighting the potential connections between stars and their planetary companions. Our work showcases the capabilities of the advanced instrumentation available in Lithuania, emphasising the significant contributions that can be made to the field of exoplanetary science using the Vilnius University Echelle Spectrograph. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 22 Masanobu Kunitomo - New-Generation Solar and Stellar Models Including Accretion (Kurume University) We present our theoretical models of the Sun and other stars, including accretion processes. Traditionally, star formation and planet formation have been studied independently. However, we now know that the first phase of stellar evolution is affected by the accretion from protoplanetary disks. Planet formation theory predicts that the composition of the gas accreted by the star must have been variable: the growth and inward drift of dust in the disk leads to a "pebble wave" of increased metallicity, followed by a phase in which the exhaustion of the pebbles and the formation of planets leads to the accretion of metal-poor gas. Our solar models show that the low-metallicity protosolar accretion is imprinted onto our Sun's core, which has a higher metallicity by up to 5% and consequently, a higher temperature than predicted by standard models. Our model with accretion simultaneously reproduces the observations of solar neutrino fluxes and the lowmetallicity surface (Asplund et al. 2021). In addition to the Sun, the metal-poor protostellar accretion has a stronger impact on A-type stars, which have a thin or no surface convective zone. We argue that the accretion is a strong candidate for the origin of λ Boo stars. In the main sequence, dynamical instability of planetary systems leads to planet(esimal) accretion, which increases the stellar surface metallicity. Again, the accretion signature is expected to be stronger in A-type stars. However, in this scenario, one should also pay attention to the effect of radiative levitation, in which radiation pressure pushes heavy elements upward in the stellar interior. From the comparison between the models of A-type stars and a large sample of stellar abundances from GALAH and Gaia surveys, we found ~30 stars that exhibit accretion signatures. We suggest that these stars would be prime targets investigated in detail by PLATO. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 23 Neda Hejazi - A New Method to Measure the Detailed Chemical Abundances of Cool Dwarfs and Its Application to Star-Planet Chemical Connection Studies (University of Kansas / Universidad de Tarapaca) JWST has opened up new vistas to precisely determine the chemical composition of exoplanets around low-mass stars. Searching for chemical links between stars and their planets thus demands abundance measurements of JWST planet hosts. We present a new methodology to reliably measure the detailed abundances of different key (up to 15) elements in cool dwarfs with 3100<Teff<4900 K using an in-depth high-resolution spectroscopy. We develop an automatic, line-by-line, synthetic model-fitting code, AutoSpecFit, which performs a series of minimization processes along with a meticulous routine to locally normalize the observed flux, and accounts for the complex correlations between the abundances of different elements via an iterative procedure. Using the high-resolution (R=45,000), NIR IGRINS spectra, we measure the abundances of the K dwarf WASP-107 (Hejazi et al. 2023) hosting a super-Neptune planet and the M dwarf K2-18 (Hejazi et al. 2024) hosting a sub-Neptune planet; both planets have been targeted by JWST observations. Using our inferred C/O ratios, we trace the formation location of these planets relative to the ice lines within the protoplanetary disk, and along with Mg/Si, we constrain the proportion of rockforming silicates in their rocky cores. By measuring the C/O ratio of a young Mtype T Tauri star, DH Tau A, using its IGRINS spectra, we reveal a chemical homogeneity between the star and its super-gas giant companion, suggesting a direct and fast gravitational collapse, rather than a slow core accretion process for the formation of the companion (Hejazi et al. 2025). We further measure the abundances of the M dwarf GJ 341 using its IGRINS spectra, which are then used to estimate the core mass fraction, iron mass fraction, and bulk molar ratios of the orbiting small rocky planet (also targeted by JWST) through interior models. We are currently measuring the abundances of 8 rocky-planet cool dwarfs and the relevant results are discussed in this presentation. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 24 Jiayue Zhang - Unveiling the Chemical Abundance Pattern of Solar Analogues Hosting Debris Disks (Tsinghua University) The peculiar depletion of refractory elements in the solar photosphere compared to nearby solar twins remains a mystery in stellar astrophysics and star-planet connection. Recent studies suggest possible links to planet formation or diskrelated processes. However, debris disks, tracers of planet formation, have been largely unexplored in this context. We propose the first systematic observations of the chemical abundances of 69 solar analogues with confirmed debris disks using high-resolution spectroscopy. By comparing their detailed abundance patterns, especially the [X/Fe] versus condensation temperature (Tc) slope, with a large control sample of over 17,000 solar-analogue stars, we aim to identify potential chemical signatures imprinted by disk-related evolution. Our results will provide crucial insights into the origin of the solar abundance anomaly and constrain the chemical evolution pathways of planetary systems. Sandipan Borthakur - Stellar Photospheric Contamination in EarlyType Stars - from Protoplanetary to Debris Disks (OeAW Space Research Institute) Young stars accrete material from their protoplanetary disks, which can contaminate the stellar photosphere. This is especially noticeable in hot stars with radiative envelopes, where slower mixing in the photosphere preserves these contamination signatures over longer timescales. The accreted material carries a chemical imprint, particularly in disks with gaps, where dust is trapped at the outer edge while gas moves inward. This results in the accretion of dust-poor material, leading to a photospheric abundance pattern with depletion of refractory elements (e.g., Fe, Mg), while volatile elements (e.g., C, O) remain unchanged. These chemically peculiar stars are known as lambda Bootis type stars. These contamination signatures in the stellar photosphere give us valuable insights into Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 25 the elemental composition of the inner disk since the accreted material comes from this region. In this talk, I will present our study of the photospheric composition of young Atype stars hosting debris disks, a later stage in protoplanetary disk evolution. While debris disks have low accretion rates that don't significantly affect the stellar photosphere, there has been little work on abundance anomalies in these stars. We analysed the high-resolution spectra of six such stars and identified two that exhibit lambda Bootis type peculiarities. This talk will discuss the origins of these peculiarities in these two stars and compare young debris disk-hosting stars with their protoplanetary disk-hosting counterparts. Understanding these anomalies may provide insights into similar lambda Bootis type stars over 100 million years old, where accretion from a circumstellar disk is not expected. Veronika Mitrokhina - Detectability of Deuterium in the Spectra of A-type Stars (Tartu Observatory, University of Tartu) Deuterium (D) was primarily produced during Big Bang Nucleosynthesis, with a primordial abundance of [D/H] = (2.58 ± 0.13) × 10⁻⁵ (Cyburt et al. 2016). Deuterium is easily destroyed in stellar interiors through astration (Epstein et al. 1976) making its detection in stellar atmospheres unlikely unless external processes, such as planetary engulfment, temporarily enhance surface abundances. A-type stars, with radiative envelopes, provide a favourable environment for the survival of accreted deuterium. In this study, we explore the detectability of deuterium in A-type stars, which possess radiative envelopes that can delay the mixing and destruction of accreted material. We generated synthetic spectra for stars with effective temperatures between 7500 and 12500 K and a surface gravity of log g = 4.0 using the ZEEMAN spectrum synthesis code and a grid of ATLAS9 model atmospheres. The linelist was modified by manually inserting the deuterium lines, focusing on the optical wavelength region. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 32 Jason Ran - Bayesian Constraints on Planet Formation Models with Population Synthesis and Simulation Based Inference (University College London) The discovery of thousands of exoplanets has enabled extensive statistical analyses of exoplanet demographics. Further, advancements in spatially resolved, multi-wavelength observations of protoplanetary disks have revealed rich details about the dynamics, structure, and chemistry of planet-forming environments. Large-scale catalogues of such disk observations, combined with host star information, have opened new pathways for demographic studies that are critical to the development of self-consistent planet formation theories. One powerful approach to bridging disk and exoplanet demographics is exoplanet population synthesis, which provides a framework for testing planet formation models. However, even the simplest such models are highly nonlinear, involving complex, high-dimensional parameter spaces that are typically addressed using numerical simulations. This complexity introduces significant challenges in constraining model parameters and comparing competing formation theories due to potential degeneracies. In this talk, I will introduce a novel Bayesian method for constraining planet formation parameters using normalizing flows and simulation-based inference. This machine learning technique models the probability density of planet formation outcomes conditioned on formation parameters. By leveraging this probabilistic approach, we can robustly quantify uncertainties, disentangle model degeneracies, and enable principled comparisons between competing theories in a natural Bayesian framework. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 33 Nidhi Rohit Bangera - Unpacking Disequilibrium Chemistry in Exoplanet Atmospheres: From C/O Constraints to Sulphur Photochemistry (Institut für Weltraumforschung) The interpretation of exoplanetary spectra is often complicated by atmospheric disequilibrium processes that alter the expected chemical concentrations. 1D kinetic-photochemical models offer a framework to quantify these effects and to constrain elemental ratios, such as the carbon-to-oxygen (C/O) ratio, which are believed to serve as tracers of planet formation histories. We apply such a 1D model to the atmosphere of WASP-69b, exploring variations in C/O, vertical eddy diffusion strength (Kzz), and gas temperature. The resulting parameter space exploration reveals strong degeneracies among these parameters, with multiple combinations producing equally viable fits to highresolution spectral data. This analysis highlights the sensitivity of retrieved atmospheric properties to prior assumptions and model configurations. Another key result indicates that the concentrations of photochemically produced species (e.g. C2H2 and HCN) are inversely related to the strength of vertical mixing, suggesting a potential diagnostic for constraining Kzz. The chemical network used in the model is further extended to include sulphurion species, allowing for a more complete treatment of sulphur photochemistry under various atmospheric conditions. With this we aim to assess the sulphur-tonitrogen (S/N) ratio as a complementary tracer of planetary formation histories, particularly in scenarios with enriched metallicity and non-solar elemental abundances. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 34 Anna Thomas - Population Synthesis to Investigate the Effect of Volatile to Refractory Sulphur Conversion on the Production of Hot and Cold Gas Giants (University College London) Planet population synthesis is an integral useful tool for linking the currently observed exoplanet population to formation environments (protoplanetary disks). We present the first individual planet growth tracks and example planet populations from the code. Furthermore, we explore their composition. Most studies attempting to link giant planet composition to their formation history have focussed on the carbon-to-oxygen ratio (C/O) in gas or solids. Sulphur has always been assumed to be 100% refractory in such models, thus making its abundance a tracer of accreted rocky solids. However, sulphur also has a volatile reservoir that is known to be dominant at the onset of star and planet formation. We have applied a novel gas-grain conversion of sulphur to study how the formation trajectories of giant planets relate to the final composition of their cores and gas envelopes. Sébastien Paine - Photoevaporated Dust Disk Models and Synthetic Observations (Queen Mary University of London) The environment in which circumstellar disks evolve plays a crucial role in their evolution and the formation of planets. In stellar clusters, nearby large stars will irradiate gas and dust: heating the disk and entraining planet-forming solids. An important, but under-studied aspect of this is what sizes of dust get entrained in the disk wind. This affects the amount and position of planet-forming solids, as well as dust shielding the disk from UV radiation. We have developed a particle solver to track the entrainment of dust in multi-dimensional simulations of photoevaporating disks. Dust entrainment varies significantly depending on where from the disk surface the dust is launched into the wind: from sub-micron above the disk up to 100 µm near the disk outer edge. However, we also find that the dust opacity is mostly uniform from all directions. This has implications for the Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 35 structure of gas mass loss and observational characteristics of proplyds. Here, we present synthetic images and SEDs of these evaporated disk models at various wavelengths, including optical, IR and mm and discuss what can be learned from them. Luke Keyte - The Chemical Composition of Externally Irradiated Disks (Queen Mary University of London) Most stars form within dense clusters, where protoplanetary disks are exposed to intense ultraviolet radiation from nearby massive stars. Despite the prevalence of these environments, our understanding of how such radiation influences disk composition remains surprisingly limited. In this talk, I will share recent insights into how external UV irradiation affects disk chemistry and shapes planet formation pathways. Our studies uncover complex effects that challenge conventional models. Although UV radiation is quickly attenuated near the disk surface, reprocessed radiation can penetrate deeper, altering temperature profiles and changing volatile abundances. Photoevaporative winds induced by external UV radiation can significantly enhance molecular emission, producing observational signatures that could be mistakenly interpreted as evidence of altered disk chemistry. I will contextualize these findings with respect to recent ALMA and JWST observations, and discuss their implications for interpreting chemical inventories across diverse star-forming regions — from isolated disks to dense clusters where most planetary systems originate. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 36 Session 5: Stellar Abundances & Planet Composition Connecting stellar elemental abundances to the composition of exoplanets. Invited Speaker: Vardan Adibekyan - From Stellar Atmospheres to Planetary Interiors (IA, Portugal) Stars and planets emerge together from the same primordial material, shaping and reshaping one another through a variety of interconnected processes. Stellar radiation governs the evolution of protoplanetary disks and thereby planet formation, while, conversely, processes such as planet engulfment can leave measurable chemical fingerprints on stellar atmospheres. Because protoplanetary disks dissipate within just a few million years—well before most planets can be detected—stellar atmospheres provide the only long-lived record of the disk’s original chemistry. In this talk, I will review the compositional link between stars and planets, emphasizing how stellar abundances inform our understanding of planetary formation, system architecture, and interior chemistry. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 37 Yoshi Eschen - Chemical Fingerprints: Decoding Stellar Abundance Influence on Planetary Composition (University of Warwick) Planets and stars form from the same proto-stellar material. Hence the stellar refractory elemental abundances are assumed to be strongly linked to rocky planet interiors. This is also found for the refractory elemental abundances of the Sun and Earth. For exoplanets, this compositional link has been recently suggested and explored in small demographic studies. However, the sample of rocky planets around metal-poor, alpha-enhanced stars is limited. This makes it challenging to find and validate potentially vital chemical trends. We present a novel machine learning approach to identify planet hosting stars of interest to fill in the lack of well-characterised small planets around metal-poor stars. This algorithm leverages stellar abundances from the large stellar surveys of APOGEE and GALAH to classify host stars chemically. We then searched for planets around these golden targets. We present newly characterized systems containing super-Earths and subNeptunes around metal-poor, alpha-enhanced stars of the thick disk. These planetary systems were observed with transit photometry and radial velocity allowing us to measure their radius and masses precisely. We used our obtained planet properties to model their interior structures using specialized tools which output the core and mantle mass fractions. These give insights into the elemental abundance ratios of the planets. Hence, we directly study the connection between the planet and host star abundances. These new discoveries significantly add to the sample of rocky planets around thick disk stars and will be followed by further detections and characterizations from our machine learning algorithm. Placing our new and upcoming systems in demographic context, we are now able to further explore the link between stellar refractory elemental abundances and their impact on small planets in a larger and more diverse sample. This enables insights into planet formation across the Galaxy. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 38 Maria Tsantaki - The Exoplanet Population in the Galactic Context from the Ariel Mission Candidate Sample (Osservatorio Astrofisico di Arcetri - INAF) Stellar populations differ significantly across the Galaxy in terms of chemistry, kinematics, and age, which is likely to affect planet demographics. Our neighbourhood is occupied by young, metal-rich stars located in the thin disk, whereas the halo and thick disk host older and metal-poor stars. In this talk, I will present our results on the role of the Galactic environment in shaping planetary systems based on the candidate sample from the Ariel space mission in collaboration with the Ariel stellar characterization working group. We first derived precise stellar parameters from high-resolution spectra and homogeneous stellar masses from isochrone fitting for 358 planet hosts. We then investigated the connection of planetary properties with the different Galactic disk populations. In particular, we find that giant planets are more frequent around more metal-rich stars that belong to the Galactic thin disk, while lower-mass planets are found in more metal-poor environments and are more frequent in the thick disk, thus orbiting older stars. Additionally, our analysis reveals a close relationship between stellar mass and giant planet radius, with more inflated planets at lower metallicities. We also investigate the correlations between stellar and planetary masses and planet multiplicity. Our results highlight the importance of Galactic chemical evolution, although often overlooked, on the current distribution of planet populations. Understanding planet formation across the Galaxy can shed light on the habitability in the Galactic context. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 39 Kevin Schlaufman - Terrestrial Exoplanet Internal Structure Constraints on Planet Formation Enabled by Comprehensive Host Star Characterization (Johns Hopkins University) Exoplanet mass and radius inferences fundamentally rely on host star mass and radius inferences. Despite the importance of host star mass, radius, and elemental abundance inferences for the derivation of exoplanet internal structure constraints, published constraints have often been based on inferences that are not self-consistent. For 24 dwarf stars hosting terrestrial exoplanets, we use astrometric and photometric data plus high-resolution spectroscopy to infer accurate, precise, homogeneous, and physically self-consistent photospheric and fundamental stellar parameters as well as elemental abundances. We infer updated planetary masses and radii using these data plus Doppler and transit observables, then use the complete data set to derive constraints on the core-mass fractions of these terrestrial exoplanets. We find that the population of resonant or plausibly resonant terrestrial exoplanets represented by Kepler-36 b and Kepler-105 c has a significantly lower mean core-mass fraction than the rest of the terrestrial exoplanets in our sample. Their resonant configurations suggest that they migrated inwards from more distant formation locations, and we attribute their low densities to the incorporation and retention of significant amounts of water during their formation. We confirm that the ultra-short-period exoplanets 55 Cnc e and WASP-47 e have densities inconsistent with pure rock compositions. We propose that they are both the stripped cores of mini-Neptunes and associate their low densities with the presence of significant amounts of hydrogen, helium, water, and/or other volatiles in their interiors. Contrary to previous studies, we find no evidence for a significant population of dense, super-Mercury type planets. Likewise, we fail to recover the recently identified relationship between host star age and terrestrial planet core-mass fraction. We show that the latter relationship is a consequence of observational biases. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 40 Alexandra Lehtmets - Stellar Abundance Anomalies in A–F Type Stars and the Role of Planetary Contamination (Tartu Observatory, University of Tartu) Close-in giant exoplanets around A–F type stars are subject to intense stellar irradiation, leading to atmospheric evaporation and possible mass transfer towards the host star. If a fraction of this planetary material is accreted, it could modify the stellar photospheric composition, producing subtle abundance of anomalies indicative of stellar contamination. This mechanism was proposed by Jermyn & Kama (2018) as a potential indirect pathway for probing exoplanetary atmospheric composition. In this preliminary study, we investigate whether such contamination could contribute to the observed chemical peculiarities in A–F type stars hosting closein gas giants. We are currently identifying suitable systems and compiling stellar abundance data from literature and spectroscopic catalogues. The stellar sample will be divided into two groups based on estimated extreme-ultraviolet (EUV) flux: stars with strong EUV radiation, where contamination is expected to be suppressed due to efficient ionisation and dispersal of planetary material, and stars with weaker EUV flux, where accretion may be more likely. A reference “zero-line” will be constructed to represent baseline stellar abundances, allowing comparison with systems showing potential contamination signatures. The goal is to determine whether abundance deviations correlate with conditions favorable for planetary material accretion, providing population-level constraints on how often and under what circumstances stellar photospheric contamination may occur. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 41 Subsession on Disks Antonio Garufi - 300 Disks Imaged, and Counting… (INAF, Istituto di Radioastronomia, Bologna) The extensive sample of high-resolution images from near-IR high-contrast instruments and ALMA has now reached a level of maturity that allows for comprehensive demographic studies of planet-forming disks. I present the current state of disk evolution characterization, examining how various stellar and environmental factors influence this process based on a dataset of over 300 disks observed over the past decade. Karina Mauco - Characterization of Protoplanetary Disks Near and Far: a Complementary Perspective (European Southern Observatory (ESO)) Given the variety of properties found in planetary systems in our Galaxy, to understand disk evolution and planet formation, we must analyse general disk and host star properties measured in a large statistical sample of systems at different evolutionary stages and environments. Disks in nearby regions, without the presence of massive stars, evolve differently than disks in highly irradiated environments, where the far-UV radiation fields from OB-type stars disperse the closest protoplanetary disks from the outside in. Since the majority of (exo)planet host stars (including our Solar System) form in dense and massive stellar clusters in which the presence of OB-type stars dominates the radiation field, disk evolution studies must consider internal as well as external factors shaping the evolutionary path of protoplanetary disks in a complementary way. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 48 Invited Speaker: Heike Rauer, Juan Cabrera, and the PLATO Team - PLATO (DLR, Germany) PLATO, the 3rd Medium class ESA’s mission, is being built to detect and characterize extrasolar planets by photometrically monitoring a large number of stars. PLATO will detect small planets around bright stars, including terrestrial planets in the habitable zone of Sun-like stars. PLATO will also study the (host) stars using asteroseismology, allowing us to determine the stellar properties with high accuracy (radius, mass, age), substantially enhancing our knowledge of stellar structure and evolution. Radial velocity observations from ground will allow characterizing planets for their radius and mass (hence density), and age with high accuracy. The mission will provide a catalogue of well-characterized exoplanets up to intermediate orbital periods, relevant for a meaningful comparison to planet formation theories and to better understand planet evolution. In addition, PLATO´s Guest Observer programme will allow for a large number of complementary science cases, based on proposals from the community. PLATO is scheduled for a launch date at the end 2026 on an Ariane 6 rocket. The payload instrument consists of 26 cameras with 12 cm aperture each. For at least four years, the mission will perform high-precision photometric measurements of about 150,000 stars per field, with 2 long pointings foreseen. The payload and the spacecraft have recently arrived in a cleanroom in the ESA facilities in the Netherlands for further testing. In this talk we will present the current status of the mission and review the expected science performance for the project, resulting in the key scientific results that can be achieved by the mission. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 49 Invited Speaker: Ana Ines Gomez de Castro - The Unique Capabilities of the Habitable Worlds Observatory for the Investigation of the Evolution of Young Planetary Systems (UCM, Spain) The Habitable Worlds Observatory (HWO) is the next NASA flagship mission. This large telescope will be equipped with instrumentation to image and analyse the radiation from Earth-like planets orbiting nearby stars. In this talk, I will present a short summary of the current status of the mission and the European participation in it. I will also present the current status of our understanding of the star-disk interaction during the evolution of young planetary disks and the contribution of future HWO instrumentation to the study of this process. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 50 Invited Speaker: Daniel Angerhausen - LIFE Looks for Life - Characterizing Rocky Worlds with the Large Interferometer For Exoplanets Concept (ETH Zürich, Switzerland) The detection and atmospheric characterization of a significant number of temperate and rocky exoplanets, including the search for habitable and potentially inhabited planets, is arguably the major goal of exoplanetary science and one of the most challenging questions in 21st century astrophysics. In this contribution we present an update on the LIFE (Large Interferometer For Exoplanets) mission, which addresses this challenge by investigating the scientific potential and technological viability of an ambitious mission employing a formation-flying nulling interferometer in space working at mid-infrared wavelengths. LIFE, in synergy with other planned future missions, will for the first time in human history enable us to conduct studies in “Comparative Exobiology” – understanding life and habitability in the context of the diversity of planetary systems that might host it. Progress in our understanding of the exoplanet population as well as significant breakthroughs in relevant technologies justify the need, but also the feasibility for future life detecting missions to investigate some of the most fundamental questions of humankind. LIFE directly engages with the scientific theme of identifying and characterizing temperate exoplanets in the mid-infrared (MIR), a topic accorded 'highest scientific priority' by ESA’s Voyage 2050 Senior Committee report as a potential focus for a future L-class mission within the ESA Science Programme. We will present the unique discovery space for a mid-infrared mission, in particular for the detection of atmospheric biosignatures in exoplanets and summarize additional relevant LIFE related work. We will discuss the international scope of the initiative (including contributions from the US, Japan and Australia) and will highlight synergies between LIFE and NASA's future Habitable Worlds Observatory mission. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 51 Invited Speaker: Marica Valentini - The Milky Way in the 4MOST era (AIP, Germany) 4MOST is a new survey facility that will be available at the ESO's 4m-VISTA telescope at Paranal, Chile. 4MOST uniquely combines a large field of view (4.4 square degrees) with a high multiplex fibre positioner. Of the 2436 fibres available for science, 1624 fibres will feed two low-resolution optical spectrographs (R = λ/Δλ ~ 6500) while 812 fibres will feed the high-resolution optical spectrograph (R ~ 20,000). At the end of October 2025, the first scientific light is planned, and this means that the crucial scientific verification phase will start soon after, with the first data and results from 4MOST data foreseen for mid-2026. I will give an overview of the status of the instrument and of the planned galactic science projects that will be pursued through the Consortium and the Community programs that constitutes the unique operational scheme implemented by 4MOST. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 52 Invited Speaker: Enric Palle - Probing the Cradle of Planets: How ANDES@ELT will Unravel the Link between Protoplanetary Disks and Exoplanetary Systems (IAC, Spain) The chemical and dynamical properties of protoplanetary disks set the initial conditions for planet formation and ultimately dictate the diversity of observed exoplanets. However, a critical gap remains in our understanding of the inner disk regions (<20 au), where the majority of planets are believed to form. Characterizing the gas properties, accretion processes, and angular momentum extraction mechanisms in this unresolved region is essential for connecting disk evolution to the final architectures and atmospheric compositions of planetary systems. The ANDES spectrograph on the Extremely Large Telescope (ELT) will be a transformative instrument for this field. Its unique combination of high spectral resolution (R ~ 100,000) and high spatial resolution (via an AO-assisted Integral Field Unit) will allow us to spatially and spectrally resolve the inner regions of nearby protoplanetary disks. ANDES will directly probe the physics of disk winds and jets—the primary mechanisms for disk dispersal and angular momentum transport—by measuring kinematics in key forbidden lines like [O I] 630 nm and [Fe II] 1.64 µm. Furthermore, its possible extension to cover the K-band (currently a goal) would enable studies of molecular winds (e.g., H₂ at 2.12 µm) and hot molecular gas (e.g., CO rovibrational bands), providing a complete picture of the disk's thermochemical structure. This detailed characterization of the initial conditions will be directly linked to ANDES's groundbreaking studies of the exoplanet populations these disks produce. The instrument will conduct atmospheric reconnaissance of everything from young, accreting giant planets to the atmospheres of terrestrial planets in the habitable zones of M-dwarfs. By measuring atmospheric compositions, dynamics, and isotopic ratios, ANDES will provide the empirical data needed to test planet formation and migration models. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 53 In this talk, I will present the capabilities of ANDES and demonstrate how its observations of disks, planets, and their host stars will provide an unprecedented, holistic view of the life cycle of planetary systems. Operating in synergy with contemporaneous facilities like JWST, ALMA, and Ariel, ANDES will fundamentally advance our understanding of the intricate relationships between stars, their disks, and the planets they nurture. Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 54 Poster session Colin Folsom - Chemical Traces of Selective Accretion in the HD 135344 Binary System (Tartu Observatory, University of Tartu) The chemical fingerprints of recent accretion can be found in spectra of some Aand B-type stars. These stars have radiative atmospheres, where mixing is slow, and thus can build up a layer of recently accreted material at their surface. When there is a dust trap in the disk around a star, such as a gap in the disk due to planet formation, this can lead to an inner disk depleted in refractory elements. This refractory depletion can then be detectable in the surface chemical abundances of the star. The HD 135344 binary system, with an A-type primary and an F-type secondary, is a particularly interesting case. The primary displays a clear refractory depletion, while the secondary is chemically normal. In the primary, accretion has halted and the current depletions appear to be a relic of earlier accretion. In the secondary, accretion is ongoing, although the star has a significant amount of surface convection, potentially washing out any traces of accreted abundances. In order to more fully characterize our uncertainties, and thus understand the differences between these stars, we used a novel MCMC based approach to deriving chemical abundances from observed spectra. Timothy Rawle - ESA Ariel Science Archive (European Space Agency) ESA's Ariel (Atmospheric Remote-sensing Infrared Exoplanet Large survey) aims to characterize the atmospheres of more than 500 diverse exoplanets during a 3.5year mission launching in 2029. A combination of optical-to-mid-infrared spectroscopic and photometric time series, covering transits, eclipses and, in some cases, entire orbital phase curves, will enable analysis of the atmospheric structure, elemental composition and variation, including cloud properties and Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 55 distribution, as well as further investigation into the impact of stellar host activity. The ESA Ariel Science Archive, hosted by the ESAC Science Data Centre (ESDC) near Madrid in Spain, will serve the broad community with all levels of scientific product generated at the ESA Science Operations Centre using the official Ariel Mission Consortium data processing pipeline. In this presentation, we introduce the concept for the Ariel Archive and solicit community input to ensure it meets the demands of modern European research into exoplanetary systems. Tomoyuki Kudo - Low Water Ice Abundance in the Disk Surface of AB Aur: Insights from Polarimetric Observations (Subaru telescope / National Astronomical Observatory of Japan) Water (H2O) ice grains play an important role in planet formation and related matters. Therefore, revealing water ice distribution within a protoplanetary disk is a critical work for understanding planet formation. Polarimetric observations are a powerful technique for tracing scattered light from dust grains at the disk surface. We deployed thermal infrared (TIR) polarization capabilities on the existing IRCS+AO at the Subaru Telescope, Hawaii. Water ice has a strong spectral feature at a wavelength of 3 μm. A comparison of high-resolution polarized images obtained at 3 μm and its adjacent wavelengths allows us to probe the presence of H2O ice grains in disks. We carried out polarization imaging observations of AB Aur in the K, H2O ice and L'-bands. The disk structure has been clearly detected in all bands. Compared to the radiative transfer models, our results are consistent with a water-ice mass fraction less than ∼ 5%. We cannot rule out the presence of ice-rich grains in the disk surface if a carbonaceous material exists as a highly absorptive form. However, if the ice-poor scenario is the case, the inferred water-ice abundance is lower than what has been found in other studies, such as disk observations and solar system observations, suggesting an efficient removal of water ice from the near-infrared scattering surface. Adding polarized imaging data in the J-, H-, and Ks-bands from Subaru/HiCIAO, we also found that the polarized disk-scattered light colour is better explained by porous Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 56 grains than non-porous grains. In this poster, we report detailed results on the presence of H2O ice and the dust properties in the disk surface around AB Aur. Alexandra Lehtmets - Investing Circumstellar Atomic Radiationdriven Dynamics (Tartu Observatory, University of Tartu) In our study, we investigate how early-type stars influence the gases escaping from exoplanet atmospheres into space. We focus on two key aspects: how the star's radiation force and gravity affect the path of these gases, and how fast neutral atoms speed up before changing into ions. By combining theories and models, we aim to understand these processes better. Our research not only deepens our understanding of exoplanets but also sheds light on their relationship with the stars they orbit. Additionally, our models could help predict which chemical elements end up accreting onto the host star. For early-type stars, our predictions might even show up as observable patterns in their spectra, because one of the unique features of early-type stars is that material accreting onto them can easily “pollute” the photosphere. Anna Maria Weiß - The New Exoplanet TOI 1147b: a Hot Jupiter Orbiting Its Subgiant-Class Star in a Highly Elliptical Orbit (Leibniz-Institute for Astrophysics Potsdam) This study aims to identify and characterize a novel extrasolar planetary system. To achieve this, periodic transit events were analysed within the light curves obtained from the Transiting Exoplanet Survey Satellite (TESS). To determine the nature of the transiting object, its mass was estimated using radial velocity measurements. TOI 1147 was subsequently observed utilizing the STELLA Échelle Spectrograph at the Izaña Observatory, Tenerife. The light curves of TOI 1147 exhibit a periodic dimming event occurring every 10.9 days. Over approximately 280 days of Exploring Star-Planet-Disk Connections conference, 14-17 October 2025 Page | 57 observational data, the same periodicity detected in TESS data was confirmed. These measurements facilitated the determination of the system’s architecture and the assessment of additional planetary bodies. The newly discovered exoplanet, TOI 1147b, has a derived mass of 1.3 𝑀𝐽 and a radius of 2.3 𝑅𝐽, classifying it as a ""puffy"" exoplanet. Moreover, its orbit is highly elliptical, with an eccentricity of 𝑒 = 0.64. Spectroscopic analysis using STELLA Échelle Spectrograph provided insights into the host star, particularly through the evaluation of the H𝛼-Index. The results indicate that TOI 1147 is a Sun-like, lowactivity star undergoing stellar evolution. Additionally, radial velocity data revealed the presence of a third, long-period companion in the system, which was not detected via transit observations. This object also exhibits a high eccentricity, warranting further investigation. These findings contribute to the broader understanding of planetary system diversity and formation mechanisms. The ongoing observational campaign at the Izaña Observatory aims to refine the orbital and physical parameters of the system through additional spectroscopic data collection. Future studies will focus on characterizing the long-period companion and its dynamical influence on the planetary system. Prateek Boga - Characterizing Atmospheres of Ultra Hot Jupiters with the 2m Wendelstein Telescope. (Ludwig Maximilian University / Universitat Sternwarte München) Ultra Hot Jupiters (UHJs) are gas giant exoplanets located close to their host stars, making them some of the brightest targets for exoplanet studies. Their extreme exposure to stellar radiation results in strong spectral features, enabling detailed investigations into their chemical makeup, thermal profiles, and atmospheric dynamics. While large-aperture telescopes have typically been used for atmospheric studies, this project aims to showcase the capabilities of mediumaperture facilities, specifically the Wendelstein 2m telescope with the FOCES high-resolution (HR) spectrograph, to achieve comparable results.