2010A&A...514A..12S


Query : 2010A&A...514A..12S

2010A&A...514A..12S - Astronomy and Astrophysics, volume 514, A12-12 (2010/5-1)

Spectroscopic observations of ices around embedded young stellar objects in the Large Magellanic Cloud with AKARI.

SHIMONISHI T., ONAKA T., KATO D., SAKON I., ITA Y., KAWAMURA A. and KANEDA H.

Abstract (from CDS):

The aim of this study is to understand the chemical conditions of ices around embedded young stellar objects (YSOs) in the metal-poor Large Magellanic Cloud (LMC). We performed near-infrared (2.5-5µm) spectroscopic observations toward 12 massive embedded YSOs and their candidates in the LMC using the infrared camera (IRC) onboard AKARI. We estimated the column densities of the H2O, CO2, and CO ices based on their 3.05, 4.27, and 4.67µm absorption features, and we investigated the correlation between ice abundances and physical properties of YSOs. The ice absorption features of H2O, CO2, 13CO2, CO, CH3OH, and possibly XCN are detected in the spectra. In addition, hydrogen recombination lines and PAH emission bands are detected toward the majority of the targets. The derived typical CO2/H2O ice ratio of our samples (∼0.36±0.09) is greater than that of Galactic massive YSOs (∼0.17±0.03), while the CO/H2O ice ratio is comparable. It is shown that the CO2 ice abundance does not correlate with the observed characteristics of YSOs: the strength of hydrogen recombination line and the total luminosity. Likewise, clear correlation is not seen between the CO ice abundance and YSO characteristics, but it is suggested that the CO ice abundance of luminous samples is significantly lower than in other samples. The systematic difference in the CO2 ice abundance around the LMC's massive YSOs, which was suggested by previous studies, is confirmed with the new near-IR data. We suggest that the strong ultraviolet radiation field and/or the high dust temperature in the LMC are responsible for the observed high abundance of the CO2 ice. It is suggested that the internal stellar radiation does not play an important role in the evolution of the CO2 ice around a massive YSO, while more volatile molecules like CO are susceptible to the effect of the stellar radiation.

Abstract Copyright:

Journal keyword(s): astrochemistry - circumstellar matter - ISM: abundances - ISM: molecules - Magellanic Clouds - infrared: ISM

Nomenclature: Table 1: [SOK2008] STNN (Nos 8-12) added.

Simbad objects: 23

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Number of rows : 23
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 SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10204 1
2 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6285 1
3 2MASS J04564078-6632307 Y*O 04 56 40.784 -66 32 30.79           ~ 10 0
4 2MASS J05144939-6712216 Y*O 05 14 49.5386182632 -67 12 21.470285340 21.299 21.145 20.652   18.771 ~ 14 0
5 IC 2127 EmO 05 22 12.532 -67 58 31.92     11.60     ~ 93 1
6 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16002 1
7 IRAS 05237-6755 AB? 05 23 35.558 -67 52 35.68 16.58 17.19 16.95 16.870 16.60 ~ 9 0
8 2MASS J05235115-6807122 Y*O 05 23 51.150 -68 07 12.23   19.426 16.657 14.930   ~ 14 0
9 2MASS J05254650-6614113 Y*O 05 25 46.509 -66 14 11.33           ~ 9 0
10 2MASS J05264658-6848469 Y*O 05 26 46.586 -68 48 46.98           ~ 16 0
11 IRAS 05311-6836 Y*O 05 30 54.4212026496 -68 34 27.763705812           ~ 13 0
12 2MASS J05323858-6825221 Y*O 05 32 38.588 -68 25 22.18           ~ 20 0
13 [RLK73] IRc 2 IR 05 35 14.51548 -05 22 30.5943           ~ 608 1
14 2MASS J05372806-6908479 Y*O 05 37 28.067 -69 08 47.98           ~ 10 0
15 IRAS 05400-7013 Y*O 05 39 31.172 -70 12 16.63           ~ 16 0
16 2MASS J05394112-6929166 Y*O 05 39 41.125 -69 29 16.68           ~ 7 0
17 NGC 2170 RNe 06 07 48 -06 23.1           ~ 40 0
18 Elia 2-29 Y*O 16 27 09.43032 -24 37 18.7716           ~ 276 1
19 W 33a Y*O 18 14 39.0 -17 52 03           ~ 608 0
20 RAFGL 2136 Y*O 18 22 26.52888 -13 30 14.0400           ~ 267 0
21 SH 2-140 OpC 22 19 07.8 +63 17 07           ~ 645 2
22 IRAS 22176+6303 Y*O 22 19 17.978 +63 18 52.92           ~ 590 0
23 IRAS 23118+6110 Y*O 23 14 01.63 +61 27 20.2           ~ 360 0

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2022.05.25-19:56:18

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