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Massive Young Stellar Objects in the Galactic Center. II. Seeing Through the Ice-rich Envelopes
- Title
- Massive Young Stellar Objects in the Galactic Center. II. Seeing Through the Ice-rich Envelopes
- Authors
- Jang D.; An D.; Sellgren K.; Ramírez S.V.; Boogert A.C.A.; Schultheis M.
- Ewha Authors
- 안덕근
- SCOPUS Author ID
- 안덕근
![scopus](/images/layout/icon2.png)
- Issue Date
- 2022
- Journal Title
- Astrophysical Journal
- ISSN
- 0004-637X
- Citation
- Astrophysical Journal vol. 930, no. 1
- Publisher
- Institute of Physics
- Indexed
- SCIE; SCOPUS
![scopus](/images/layout/scopus2.gif)
- Document Type
- Article
- Abstract
- To study the demographics of interstellar ices in the Central Molecular Zone (CMZ) of the Milky Way, we obtain near-infrared spectra of 109 red point sources using NASA IRTF/SpeX at Maunakea. We select the sample from near-and mid-infrared photometry, including 12 objects in the previous paper of this series, to ensure that these sources trace a large amount of absorption through clouds in each line of sight. We find that most of the sample (100 objects) show CO band-head absorption at 2.3 μm, tagging them as red (super-) giants. Despite the photospheric signature, however, a fraction of the sample with L-band spectra (9/82 = 0.11) exhibit large H2O ice column densities (N > 2 × 1018 cm-2), and six of them also reveal CH3OH ice absorption. As one of such objects is identified as a young stellar object (YSO) in our previous work, these ice-rich sight lines are likely associated with background stars in projection to an extended envelope of a YSO or a dense cloud core. The low frequency of such objects in the early stage of stellar evolution implies a low star-formation rate (â‰20.02 M yr-1), reinforcing the previous claim on the suppressed star-formation activity in the CMZ. Our data also indicate that the strong "shoulder"CO2 ice absorption at 15.4 μm observed in YSO candidates in the previous paper arises from CH3OH-rich ice grains having a large CO2 concentration [N(CO2)/N(CH3OH) ≈ 1/3]. © 2022. The Author(s). Published by the American Astronomical Society.
- DOI
- 10.3847/1538-4357/ac5d51
- Appears in Collections:
- 사범대학 > 과학교육과 > Journal papers
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