Molecular richness in protostars: a paradise for astrochemists

Author: Ana, Lopez Sepulcre

Publisher: Zenodo

DOI: 10.5281/zenodo.17108748

Source: https://zenodo.org/records/17108748/files/Ana_Lopez-Sepulcre_ESO_TNF2025_Zenodo.pdf

Copy igh © 2009-2017 IRAM
Ana López Sepulc e
Ins i u de Plané ologie e d’As ophysique de G enoble (FR)
Ins i u de Radio As onomie Millimé ique (FR)
Ga ching, 11 Ma ch 2025
Molecula ichness in p o os a s
A pa adise o as ochemis s
sola -mass
T < 10 K
n > 105 cm-3
Molecula
en elope
~0.1 pc
~20000 au
CO eeze-ou
D-enhancemen
Collapse
En elope dissipa ion
G ain coagula ion
Plane o ma ion
~2000 au
Ske ches kindly p o ided by Ma a de Simone
~50 au
~1 au
P e-s ella co e P o os ella co e
P o oplane a y disk
Main sequence s a
Re iew by Podio
Re iew by Podio
1. Wha is he ypical molecula composi ion
in p o os a s?
2. P o os ella chemical di e si y: why, and
(how) does i depend on he en i onmen ?
3. Takeaway messages, open ques ions, and
s eps o wa d
P o os ella co e:
Onse o s a o ma ion
Ho co ino (?):
H2O ice sublima ion
“complex” o ganics
Ou line
Disclaime :
As a human being, I am limi ed and biased
Wha ollows is no exhaus i e!
2. P o os ella chemical di e si y: why, and
(how) does i depend on he en i onmen ?
3. Takeaway messages, open ques ions, and
s eps o wa d
P o os ella co e:
Onse o s a o ma ion
Ho co ino (?):
H2O ice sublima ion
“complex” o ganics
Ou line
1. Wha is he ypical molecula composi ion
in p o os a s? **
Spoile : The e is no such hing as “ ypical”, di e si y ules!
** Main ocus on o ganic chemical budge
IRAM 30-m
P o os ella o ganic ichness: IRAS 16293-2422
Cazaux e al. 2003 TIMASSS spec al su ey: Caux e al. 2011
SINGLE DISHINTERFEROMETRY
PILS spec al su ey: Jø gensen e al. 2016
ALMA
IRAM 30-m
Ex emely line- ich p o os ella spec a
Mos o he lines a e weak and emiKed by o ganic molecules

• Compac (< 100 au)
• Ho (T > 100 K) and dense (n > 107 cm-3)
• Rich in in e s ella Complex O ganic Molecules (iCOMs)
Ho co inos
HCOOH: o mic acid
CH3CHO: ace aldehyde
CH3OCHO: me hyl o ma e
CH3OCH3: dime hyl e he
CH3COCH3: ace one
CH2OHCHO: glycolaldehyde
C2H5OH: e hanol
CH3CN: me hyl cyanide
C2H5CN: e hyl cyanide
NH2CHO: o mamide
CH3OH: me hanol
iCOM dicYona y
CO
CO
H2O
H2O
HCOOCH3
Dus
g ain
CH3OH
H2CO
H2O
CO
CO
CO
H2O
H2O
H2O
Dus
g ain
HCO
H2CO
H2O
CO
Bianchi e al. 2019
Cecca elli e al. 2017
IRAS4A
ConYnuum @ 1.3mm
NOEMA
CLASS 0
CLASS 1
Resol ing iCOM emission in ho co inos
Lee e al. 2022 (see also Okoda e al. 2022)
CH3OH
HH212
NH2CHO
ALMA
• S aYﬁcaYon o iCOM emission in ho co inos eﬂec hei diﬀe en binding ene gies,
i.e. he diﬀe en empe a u es a which hey deso b om g ain su aces
Fe e o e al. 2020
(see also Wakelam e al. 2017, Das e al. 2018)
Resol ing iCOM emission in ho co inos
Lee e al. 2022 (see also Okoda e al. 2022)
CH3OH
HH212
NH2CHO
• S aYﬁcaYon o iCOM emission in ho co inos eﬂec hei diﬀe en binding ene gies,
i.e. he diﬀe en empe a u es a which hey deso b om g ain su aces
ALMA
F ediani e al. 2025
IRAS 4A2
CH2OHCHO
C2H5OH
CH3CHO
HCOOCH3
CH3OH
• MulY-line analysis and spaYal esoluYon o se e al s aYﬁed ho co ino iCOMs can help
cons ain he empe a u e p oﬁle
ALMA
• This s aYﬁcaYon s ongly sugges s ha iCOMs can be ound in solid o m a lowe T
Iden i ica ion o solid-s a e iCOMs in p o os a s
JWST is showing he ﬁ s p omising esul s o iCOMs on ices and much mo e
will be elucida ed in he coming yea s
Is his p oo ha iCOMs o m on he su ace o dus g ains?
Rocha e al. 2024
IRAS 2A
JWST
Sakai e al. 2008
IRAM PdBI
NRO 45-m & GBT
• Wa m p o os ella en elope ich in ca bon chains 10
o 100 Ymes mo e abundan han in ho co ino sou ces
• No e idence o sa u a ed iCOMs
• Icy man les con ain la ge amoun s o CH4
CH4
Dus
g ain
CO
T > 25K
CH4
CH4
CH4
CO
CH4
A chemically diﬀe en ype o p o os a :
Wa m Ca bon Chain Chemis y (WCCC) objec
Sakai e al. 2010
The “unsuccess ul” sea ch o iCOMs in L1527

Ho co inos e sus WCCC p o os a s
• Ho co inos:
Complex O ganic Molecules (iCOMs)
e.g. HCOOCH3, CH3OCH3, C2H5CN
Abundances ~100x hose in WCCCs
Sizes < 100 au
Example: IRAS 4A
• WCCC p o os a s:
Unsa u a ed (long) ca bon chains
e.g. C4H2, HC5N, C4H, C6H
Abundances ~10-100x hose in ho co inos
Sizes ~2000 au
Example: L1527
see e.g. Yoshida e al. 2019 o an abundance
compa ison be ween ho co inos and WCCC objec s
WCCC s uc u e
~2000-3000 au
Inne egion
T>100 K
H2O sublima ion
iCOMs de iciency
WCCC zone (CH4- ich)
T > 25 K
CH4 sublima ion
en iched in Hyd oca bons
(e.g. CCH, C4H, c-C3H2)
Su ounding
molecula cloud
Ho co ino s uc u e
~150 au
Ho co ino egion
T>100 K
H2O sublima ion
en iched in iCOMs
(e.g. CH3OH, CH3CHO, CH3OCH3)
En elope (CH4-poo )
Hyd oca bons de iciency
Su ounding
molecula cloud
Cou esy o M. Bou ie
Cou esy o M. Bou ie
© NASA, ESA, CSA, and STScI. (JWST)
1. Wha is he ypical molecula composi ion
in p o os a s?
2. P o os ella chemical di e si y: why, and
(how) does i depend on he en i onmen ?
3. Takeaway messages, open ques ions, and
s eps o wa d
P o os ella co e:
Onse o s a o ma ion
Ho co ino (?):
H2O ice sublima ion
“complex” o ganics
Ou line
WCCC (?):
CH4 ice sublima ion
C-chains
Chemical di e si y explained (?)
WCCC
(C-chains)
C —> ice: CH4
P e-s ella du aRon Rmescale
Sho (~105 y )
Ho co ino
(iCOMs)
CO —> ice: CH3OH
Long (~106 y )
(Sakai & Yamamo o 2013)
P e-s ella en i onmen al eﬀec s
En i onmen al ac o s ha may aﬀec he g ain man le composiYon inhe i ed by he
p o os ella phase a e densi y, empe a u e, and UV/cosmic- ay i adiaYon
(e.g. Spezzano e al. 2016, 2020, Aikawa e al. 2020, Kal ans 2021)
CH4
g ain
CO
T > 25K
CH4
CH4
CH4
CO
CH4
CO
H2O
H2O
CH3OH
g ain
CH3OH
H2CO
H2O
CO
T > 100K
C
C
H2O
H2O
g ain
CO
H2O
CO
CH4
CH4
CH4
CO
CO
H2O
H2O
g ain
H2CO
H2O
CH3OH
CH3OH
CH3OH
As ochemical modelling ﬁnds ha WCCC is a ou ed by a long p e-s ella cold phase
(Aikawa e al. 2020)
Hyb id p o os a s, p esenYng bo h ho
co ino and WCCC beha iou s, we e
in uiY ely p edic ed ~10 y s ago
Oya e al. 2017
HOWEVER:
• Only 4 hyb id p o os a s “solidly” idenYﬁed o da e (Oya e al. 2017, Imai e al. 2022, Okoda e al. 2023)
• C-chains/ ings no ye well cha ac e ised chemically
The middle poin : hyb id p o os a s
G aninge e al. 2016
B335
ALMA
Imai e al. 2016
Fi s hyb id p o os a
conﬁ med in 2016, in a
Bok Globule
Bok Globules/isola ed p o os a s end o show hyb id beha iou
Wha abou o he en i onmen s?
O ion e sus Pe seus: en i onmen ma e s
ORION
PERSEUS
VS
Analogue o he Sola
Sys em’s na al
en i onmen
(see Adams e al.
2010, P alzne e al.
2015, P alzne &
Vincke 2020)
Pe seus Molecula
Cloud
Loose p o o-clus e !
Less UV-illumina ed
PEACHES
50 sola -mass p o os a s
ORANGES
19 sola -mass p o os a s
OMC-2/3
Dense p o oclus e !
Highly UV-illumina ed
31%
ho co inos a e sca ce
56%
ho co inos a e abundan
Yang e al. 2021
See also Higuchi e al. 2018
C edi : ESO
C edi : Ge ha d
Bachmaye
Bou ie e al. 2022
Bu see also Hsu e al. 2022

Wha abou WCCC s a is ics?
• Nei he PEACHES no ORANGES we e designed o adequa ely p obe WCCC ace s
and spaYal scales.
2017
2025
# ho co inos
9
~50
# WCCC objec s
5
6
This is a cell memb ane, whose composiYon
includes long hyd oca bon chains
A comple e pic u e o o ganics in p o os a s
should include WCCC s udies
• Obse aYons ha e so a been hea ily biased owa ds ho co inos due o hei
en ichmen in iCOMs and hei in e es as building blocks o p ebioYc molecules
No es o cau ion on WCCC su eys
The de ecYon o small C-chains/ ings such as CCH and c-C3H2 in p o os a s canno be
au omaYcally aK ibu ed o WCCC, which is igge ed by wa m (>25 K), sublima ed CH4.
These species can also be eﬃcien ly syn hesised in pho o-dissociaYon egions (PDRs).
1. Single-dish su eys using CCH o c-C3H2 o idenY y WCCC p o os a s should be
a oided. Ins ead, in e e ome ic maps should be p i ileged o assess hei spaYal
dis ibuYon concen a ed in inne wa m en elope a ound he p o os ella objec .
(see Bou ie e al. 2022)
2. A secu e WCCC idenYﬁcaYon equi es he
de ecYon o se e al, hea ie C-chains such as C4H,
C4H2, HC5N…, and he cha ac e isaYon o he
emiung gas ia mulY-line adiaY e ans e analysis.
Imai e al. 2016
B335
WCCC does no exis ,
we a e jus seeing UV-
illumina ed ou low
ca i y walls!
(some people in he communi y)
ALMA
Towa ds imp o ing WCCC s a is ics
• Follow up o he ho co ino hun ca ied ou wi h he ORANGES
su ey using bo h ALMA (3mm and 7mm) and NOEMA (3mm)
Main a ge ed species: C3H, C4H, C4H2, C3H2,
CH3CCH, HC3N, HC5N
WCCC s uc u e
~2000-3000 au
Inne egion
T>100 K
H2O sublima ion
iCOMs de iciency
WCCC zone (CH4- ich)
T > 25 K
CH4 sublima ion
en iched in Hyd oca bons
(e.g. CCH, C4H, c-C3H2)
Su ounding
molecula cloud
Analogue o he Sola
Sys em’s na al
en i onmen
• O he egions and pa Ycula ly isola ed p o os a s a e e y p omising
candida es o WCCC/ho co ino s udies: a e hey all hyb ids?
• Compa ison wi h CH4/CH3OH solid abundance aYos?
JWST/ALMA+NOEMA+JVLA…
1. Wha is he ypical molecula composi ion
in p o os a s?
2. P o os ella chemical di e si y: why, and
(how) does i depend on he en i onmen ?
3. Takeaway messages, open ques ions, and
s eps o wa d
P o os ella co e:
Onse o s a o ma ion
Ho co ino (?):
H2O ice sublima ion
“complex” o ganics
Ou line
WCCC (?):
CH4 ice sublima ion
C-chains

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