2005A&A...435..177J


C.D.S. - SIMBAD4 rel 1.7 - 2021.02.24CET19:23:44

2005A&A...435..177J - Astronomy and Astrophysics, volume 435, 177-182 (2005/5-3)

Molecular freeze-out as a tracer of the thermal and dynamical evolution of pre- and protostellar cores.

JORGENSEN J.K., SCHOEIER F.L. and VAN DISHOECK E.F.

Abstract (from CDS):

Radiative transfer models of multi-transition observations are used to determine molecular abundances as functions of position in pre- and protostellar cores. The data require a ``drop'' abundance profile with radius, with high abundances in the outermost regions probed by low excitation 3mm lines, and much lower abundances at intermediate zones probed by higher frequency lines. The results are illustrated by detailed analysis of CO and HCO+ lines for a subset of objects. We propose a scenario in which the molecules are frozen out in a region of the envelope where the temperature is low enough (≲40K) to prevent immediate desorption, but where the density is high enough (>104-105cm–3) that the freeze-out timescales are shorter than the lifetime of the core. The size of the freeze-out zone is thereby a record of the thermal and dynamical evolution of the cores. Fits to CO data for a sample of 16 objects indicate that the size of the freeze-out zone decreases significantly between class 0 and I objects, explaining the variations in, for example, CO abundances with envelope masses. However, the corresponding timescales are 105±0.5-years, with no significant difference between class 0 and I objects. These timescales suggest that the dense pre-stellar phase with heavy depletions lasts only a short time, of the order of 105yr, in agreement with recent chemical-dynamical models.

Abstract Copyright:

Journal keyword(s): stars: formation - ISM: molecules - ISM: abundances

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 - 2021
#notes
1 IRAS 03222+3034 Y*O 03 25 22.32 +30 45 13.9           ~ 126 0
2 [SDA2014] West4 Y*O 03 25 38.83 +30 44 06.2           ~ 244 1
3 IRAS F03226+3033 Y*O 03 25 38.83 +30 44 06.2           ~ 313 0
4 IRAS 03258+3104 Y*O 03 28 55.30 +31 14 27.8           ~ 160 1
5 [JCC87] IRAS 2A Y*O 03 28 55.55 +31 14 36.7           ~ 407 3
6 [JCC87] IRAS 4A Y*O 03 29 10.49 +31 13 30.8           ~ 622 1
7 [JCC87] IRAS 4 FIR 03 29 10.9 +31 13 26           ~ 469 0
8 [JCC87] IRAS 4B Y*O 03 29 12.058 +31 13 02.05           ~ 568 0
9 LDN 1489 DNe 04 04 47.5 +26 19 42           ~ 198 0
10 IRAS 04361+2547 Y*O 04 39 13.89288 +25 53 20.8788           ~ 187 1
11 LDN 1527 DNe 04 39 53 +25 45.0           ~ 518 0
12 LDN 1544 DNe 05 04 16.6 +25 10 48           ~ 715 0
13 NAME [BM89] L1544 cor 05 04 22.5 +25 11 36           ~ 435 1
14 NAME VLA 1623-243 Y*O 16 26 26.42 -24 24 30.0           ~ 379 0
15 [SSG2006] MMS002 smm 16 26 26.50 -24 24 30.9           ~ 241 0
16 IRAS 16293-2422 cor 16 32 22.56 -24 28 31.8           ~ 1076 1
17 LDN 1689B DNe 16 34 42.1 -24 36 11           ~ 143 0
18 LDN 483 DNe 18 17 35 -04 39.8           ~ 220 0
19 LDN 723 DNe 19 18 12 +19 13.6           ~ 153 0
20 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 500 0
21 LDN 1262 MoC 23 25 47 +74 17.6           ~ 130 0

    Equat.    Gal    SGal    Ecl

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2021.02.24-19:23:44

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