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Title: THE DETECTION OF A HOT MOLECULAR CORE IN THE LARGE MAGELLANIC CLOUD WITH ALMA

Abstract

We report the first detection of a hot molecular core outside our Galaxy based on radio observations with ALMA toward a high-mass young stellar object (YSO) in a nearby low metallicity galaxy, the Large Magellanic Cloud (LMC). Molecular emission lines of CO, C{sup 17}O, HCO{sup +}, H{sup 13}CO{sup +}, H{sub 2}CO, NO, SiO, H{sub 2}CS, {sup 33}SO, {sup 32}SO{sub 2}, {sup 34}SO{sub 2}, and {sup 33}SO{sub 2} are detected from a compact region (∼0.1 pc) associated with a high-mass YSO, ST11. The temperature of molecular gas is estimated to be higher than 100 K based on rotation diagram analysis of SO{sub 2} and {sup 34}SO{sub 2} lines. The compact source size, warm gas temperature, high density, and rich molecular lines around a high-mass protostar suggest that ST11 is associated with a hot molecular core. We find that the molecular abundances of the LMC hot core are significantly different from those of Galactic hot cores. The abundances of CH{sub 3}OH, H{sub 2}CO, and HNCO are remarkably lower compared to Galactic hot cores by at least 1–3 orders of magnitude. We suggest that these abundances are characterized by the deficiency of molecules whose formation requires the hydrogenation of CO on grain surfaces.more » In contrast, NO shows a high abundance in ST11 despite the notably low abundance of nitrogen in the LMC. A multitude of SO{sub 2} and its isotopologue line detections in ST11 imply that SO{sub 2} can be a key molecular tracer of hot core chemistry in metal-poor environments. Furthermore, we find molecular outflows around the hot core, which is the second detection of an extragalactic protostellar outflow. In this paper, we discuss the physical and chemical characteristics of a hot molecular core in the low metallicity environment.« less

Authors:
 [1];  [2];  [3];  [4]
  1. Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Aramakiazaaoba 6-3, Aoba-ku, Sendai, Miyagi, 980-8578 (Japan)
  2. Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
  3. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 (Japan)
  4. Center for Computational Sciences, The University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8577 (Japan)
Publication Date:
OSTI Identifier:
22679526
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 827; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; CARBON MONOXIDE; COMPARATIVE EVALUATIONS; COSMIC GASES; DETECTION; EMISSION; HYDROGEN; HYDROGENATION; MAGELLANIC CLOUDS; MASS; METALLICITY; METALS; METHANOL; MOLECULES; NITRIC OXIDE; NITROGEN; PROTOSTARS; SILICON OXIDES; SULFUR DIOXIDE; SURFACES

Citation Formats

Shimonishi, Takashi, Onaka, Takashi, Kawamura, Akiko, and Aikawa, Yuri. THE DETECTION OF A HOT MOLECULAR CORE IN THE LARGE MAGELLANIC CLOUD WITH ALMA. United States: N. p., 2016. Web. doi:10.3847/0004-637X/827/1/72.
Shimonishi, Takashi, Onaka, Takashi, Kawamura, Akiko, & Aikawa, Yuri. THE DETECTION OF A HOT MOLECULAR CORE IN THE LARGE MAGELLANIC CLOUD WITH ALMA. United States. https://doi.org/10.3847/0004-637X/827/1/72
Shimonishi, Takashi, Onaka, Takashi, Kawamura, Akiko, and Aikawa, Yuri. 2016. "THE DETECTION OF A HOT MOLECULAR CORE IN THE LARGE MAGELLANIC CLOUD WITH ALMA". United States. https://doi.org/10.3847/0004-637X/827/1/72.
@article{osti_22679526,
title = {THE DETECTION OF A HOT MOLECULAR CORE IN THE LARGE MAGELLANIC CLOUD WITH ALMA},
author = {Shimonishi, Takashi and Onaka, Takashi and Kawamura, Akiko and Aikawa, Yuri},
abstractNote = {We report the first detection of a hot molecular core outside our Galaxy based on radio observations with ALMA toward a high-mass young stellar object (YSO) in a nearby low metallicity galaxy, the Large Magellanic Cloud (LMC). Molecular emission lines of CO, C{sup 17}O, HCO{sup +}, H{sup 13}CO{sup +}, H{sub 2}CO, NO, SiO, H{sub 2}CS, {sup 33}SO, {sup 32}SO{sub 2}, {sup 34}SO{sub 2}, and {sup 33}SO{sub 2} are detected from a compact region (∼0.1 pc) associated with a high-mass YSO, ST11. The temperature of molecular gas is estimated to be higher than 100 K based on rotation diagram analysis of SO{sub 2} and {sup 34}SO{sub 2} lines. The compact source size, warm gas temperature, high density, and rich molecular lines around a high-mass protostar suggest that ST11 is associated with a hot molecular core. We find that the molecular abundances of the LMC hot core are significantly different from those of Galactic hot cores. The abundances of CH{sub 3}OH, H{sub 2}CO, and HNCO are remarkably lower compared to Galactic hot cores by at least 1–3 orders of magnitude. We suggest that these abundances are characterized by the deficiency of molecules whose formation requires the hydrogenation of CO on grain surfaces. In contrast, NO shows a high abundance in ST11 despite the notably low abundance of nitrogen in the LMC. A multitude of SO{sub 2} and its isotopologue line detections in ST11 imply that SO{sub 2} can be a key molecular tracer of hot core chemistry in metal-poor environments. Furthermore, we find molecular outflows around the hot core, which is the second detection of an extragalactic protostellar outflow. In this paper, we discuss the physical and chemical characteristics of a hot molecular core in the low metallicity environment.},
doi = {10.3847/0004-637X/827/1/72},
url = {https://www.osti.gov/biblio/22679526}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 827,
place = {United States},
year = {Wed Aug 10 00:00:00 EDT 2016},
month = {Wed Aug 10 00:00:00 EDT 2016}
}