2015A&A...574A.107K


Query : 2015A&A...574A.107K

2015A&A...574A.107K - Astronomy and Astrophysics, volume 574A, 107-107 (2015/2-1)

Depletion of chlorine into HCl ice in a protostellar core. The CHESS spectral survey of OMC-2 FIR 4.

KAMA M., CAUX E., LOPEZ-SEPULCRE A., WAKELAM V., DOMINIK C., CECCARELLI C., LANZA M., LIQUE F., OCHSENDORF B.B., LIS D.C., CABALLERO R.N. and TIELENS A.G.G.M.

Abstract (from CDS):

The freezeout of gas-phase species onto cold dust grains can drastically alter the chemistry and the heating-cooling balance of protostellar material. In contrast to well-known species such as carbon monoxide (CO), the freezeout of various carriers of elements with abundances <10–5 has not yet been well studied. Our aim here is to study the depletion of chlorine in the protostellar core, OMC-2 FIR 4. We observed transitions of HCl and H2Cl+ towards OMC-2 FIR 4 using the Herschel Space Observatory and Caltech Submillimeter Observatory facilities. Our analysis makes use of state of the art chlorine gas-grain chemical models and newly calculated HCl-H2 hyperfine collisional excitation rate coefficients. A narrow emission component in the HCl lines traces the extended envelope, and a broad one traces a more compact central region. The gas-phase HCl abundance in FIR 4 is 9x10–11, a factor of only 10–3 that of volatile elemental chlorine. The H2Cl+ lines are detected in absorption and trace a tenuous foreground cloud, where we find no depletion of volatile chlorine. Gas-phase HCl is the tip of the chlorine iceberg in protostellar cores. Using a gas-grain chemical model, we show that the hydrogenation of atomic chlorine on grain surfaces in the dark cloud stage sequesters at least 90% of the volatile chlorine into HCl ice, where it remains in the protostellar stage. About 10% of chlorine is in gaseous atomic form. Gas-phase HCl is a minor, but diagnostically key reservoir, with an abundance of ≲10–10 in most of the protostellar core. We find the 35Cl/37Cl ratio in OMC-2 FIR 4 to be 3.2±0.1, consistent with the solar system value.

Abstract Copyright:

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

Simbad objects: 10

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Number of rows : 10
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NAME OMC-1 MoC 05 35 14 -05 22.4           ~ 1112 2
2 NAME Trapezium Cluster As* 05 35 16.5 -05 23 14           ~ 1549 1
3 NAME Ori Region reg 05 35 17.30 -05 23 28.0           ~ 538 0
4 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 805 0
5 V* V2457 Ori Or* 05 35 26.97000 -05 09 54.4644         18.858 ~ 140 0
6 OMC 2 MoC 05 35 27 -05 10.1           ~ 432 1
7 2MASS J05352762-0509337 Y*O 05 35 27.622 -05 09 33.78           ~ 88 0
8 NAME NGC 6334-I Cl* 17 20 53.35 -35 47 01.5           ~ 310 0
9 NAME Sgr B2 (South) HII 17 47 20.430 -28 23 45.06           ~ 94 0
10 [DE95] LDN 1157 B1 out 20 39 11 +68 01.3           ~ 225 0

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2022.08.10-18:54:27

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