2020A&A...643A..48P


Query : 2020A&A...643A..48P

2020A&A...643A..48P - Astronomy and Astrophysics, volume 643A, 48-48 (2020/11-1)

Linking ice and gas in the Serpens low-mass star-forming region.

PEROTTI G., ROCHA W.R.M., JORGENSEN J.K., KRISTENSEN L.E., FRASER H.J. and PONTOPPIDAN K.M.

Abstract (from CDS):


Context. The interaction between dust, ice, and gas during the formation of stars produces complex organic molecules. While observations indicate that several species are formed on ice-covered dust grains and are released into the gas phase, the exact chemical interplay between solid and gas phases and their relative importance remain unclear.
Aims. Our goal is to study the interplay between dust, ice, and gas in regions of low-mass star formation through ice- and gas-mapping and by directly measuring gas-to-ice ratios. This provides constraints on the routes that lead to the chemical complexity that is observed in solid and gas phases.
Methods. We present observations of gas-phase methanol (CH3OH) and carbon monoxide (13CO and C18O) at 1.3mm towards ten low-mass young protostars in the Serpens SVS 4 cluster from the SubMillimeter Array (SMA) and the Atacama Pathfinder EXperiment (APEX) telescope. We used archival data from the Very Large Telescope (VLT) to derive abundances of ice H2O, CO, and CH3OH towards the same region. Finally, we constructed gas-ice maps of SVS 4 and directly measured CO and CH3OH gas-to-ice ratios.
Results. The SVS 4 cluster is characterised by a global temperature of 15±5K. At this temperature, the chemical behaviours of CH3OH and CO are anti-correlated: larger variations are observed for CH3OH gas than for CH3OH ice, whereas the opposite is seen for CO. The gas-to-ice ratios (Ngas/Nice) range from 1-6 for CO and 1.4x10–4-3.7x10–3 for CH3OH. The CO gas-maps trace an extended gaseous component that is not sensitive to the effect of freeze-out. Because of temperature variations and dust heating around 20K, the frozen CO is efficiently desorbed. The CH3OH gas-maps, in contrast, probe regions where methanol is predominantly formed and present in ices and is released into the gas phase through non-thermal desorption mechanisms.
Conclusions. Combining gas- and ice-mapping techniques, we measure gas-to-ice ratios of CO and CH3OH in the SVS 4 cluster. The CH3OH gas-to-ice ratio agrees with values that were previously reported for embedded Class 0/I low-mass protostars. We find that there is no straightforward correlation between CO and CH3OH gas with their ice counterparts in the cluster. This is likely related to the complex morphology of SVS 4: the Class 0 protostar SMM 4 and its envelope lie in the vicinity, and the outflow associated with SMM 4 intersects the cluster. This study serves as a pathfinder for future observations with ALMA and the James Webb Space Telescope (JWST) that will provide high-sensitivity gas-ice maps of molecules more complex than methanol. Such comparative maps will be essential to constrain the chemical routes that regulate the chemical complexity in star-forming regions.

Abstract Copyright: © ESO 2020

Journal keyword(s): ISM: molecules - stars: protostars - astrochemistry - molecular processes - stars: low-mass - ISM: individual objects: Serpens

VizieR on-line data: <Available at CDS (J/A+A/643/A48): sources.dat sp/* list.dat fits/*>

Simbad objects: 21

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Number of rows : 21
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 JCMTSF J054429.8+090856 DNe 05 44 30 +09 08.8           ~ 21 0
2 3C 279 Bla 12 56 11.16657958 -05 47 21.5251510   18.01 17.75 15.87   ~ 2923 2
3 * gam Oph PM* 17 47 53.5597327 +02 42 26.199985 3.83 3.80 3.75 3.71 3.71 A1VnkA0mA0 381 0
4 4C 09.57 BLL 17 51 32.81857326 +09 39 00.7284066   17.46 16.78 15.57   ~ 902 1
5 NAME Serpens Cloud SFR 18 29 49 +01 14.8           ~ 1049 2
6 [AHA2018] Serpens SMM4B Y*O 18 29 56.50 +01 13 11.0           ~ 7 0
7 2MASS J18295655+0112596 Y*O 18 29 56.553 +01 12 59.65           ~ 22 0
8 2MASS J18295667+0112393 Y*O 18 29 56.674 +01 12 39.32           ~ 19 0
9 [AHA2018] Serpens SMM4A Y*O 18 29 56.70 +01 13 15.0           ~ 11 0
10 2MASS J18295696+0112478 Y*O 18 29 56.967 +01 12 47.83           M3.0 25 0
11 NAME Serpens SMM 4 cor 18 29 57.1 +01 13 15           ~ 134 0
12 [EC89] SVS 4-12 * 18 29 57.22 +01 12 58.4           ~ 2 0
13 [EC89] SVS 4-5 Y*O 18 29 57.59 +01 13 00.6           ~ 33 1
14 2MASS J18295760+0113004 Y*O 18 29 57.602 +01 13 00.42           ~ 35 3
15 2MASS J18295781+0112280 Y*O 18 29 57.819 +01 12 28.05           ~ 20 0
16 NAME Serpens SVS 4 IR Cluster Cl* 18 29 57.84 +01 12 48.1           ~ 40 1
17 2MASS J18295784+0112379 Y*O 18 29 57.849 +01 12 37.90           ~ 23 0
18 2MASS J18295785+0112514 Y*O 18 29 57.858 +01 12 51.40           ~ 60 3
19 [EC92] 95 Y*O 18 29 57.893 +01 12 46.25           K1.0 73 3
20 ICRF J183005.9+061915 QSO 18 30 05.93984953 +06 19 15.9522412       19.5   ~ 93 1
21 * lam Aql PM* 19 06 14.9386542192 -04 52 57.225885348 3.07 3.34 3.43 3.46 3.55 B8.5V 220 0

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2023.02.06-07:23:36

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