AKARI near-infrared spectroscopy: Detection of H2O and CO 2 ices toward young stellar objects in the Large Magellanic Cloud

Takashi Shimonishi, Takashi Onaka, Daisuke Kato, Itsuki Sakon, Yoshifusa Ita, Akiko Kawamura, Hidehiro Kaneda

Research output: Contribution to journalArticlepeer-review

Abstract

We present the first results of the AKARI Infrared Camera near-infrared spectro-scopic survey of the Large Magellanic Cloud (LMC). The circumstellar material of young stellar objects (YSOs) are affected by galactic environments such as a metallicity or radiation field. Ices control the chemical balance of circumstellar environments of embedded YSOs. We detected absorption features of the H2O ice 3.05 μm and the CO2 ice 4.27 μm stretching mode toward seven massive YSOs in the LMC. This is the first detection of the 4.27 μm CO2 ice feature toward extragalactic YSOs. The present samples are for the first time spectroscopically confirmed to be YSOs. We used a curve-of-growth method to evaluate the column densities of the ices and derived the CO2/H2O ratio to be 0.45±0.17. This is clearly higher than that seen in Galactic massive YSOs (0.17±0.03). We suggest that the strong ultraviolet radiation field and/or the high dust temperature in the LMC may be responsible for the observed high CO2 ice abundance.

Original languageEnglish
Pages (from-to)233-238
Number of pages6
JournalProceedings of the International Astronomical Union
Volume4
Issue numberS256
DOIs
Publication statusPublished - 2008 Jul 1
Externally publishedYes

Keywords

  • Circumstellar matter
  • Galaxies: individual (LMC)
  • ISM: molecules
  • Magellanic Clouds
  • Stars: pre-main-sequence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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