Abundant Methanol Ice toward a Massive Young Stellar Object in the Central Molecular Zone
- 주제(키워드) astrochemistry , Galaxy: nucleus , ISM: abundances , stars: massive , stars: protostars
- 등재 SCIE, SCOPUS
- 발행기관 IOP PUBLISHING LTD
- 발행년도 2017
- URI http://www.dcollection.net/handler/ewha/000000147096
- 본문언어 영어
- Published As http://dx.doi.org/10.3847/2041-8213/aa7cfe
초록/요약
Previous radio observations revealed widespread gas-phase methanol (CH3OH) in the Central Molecular Zone (CMZ) at the Galactic center (GC), but its origin remains unclear. Here, we report the discovery of CH3OH ice toward a star in the CMZ, based on a Subaru 3.4-4.0 mu m spectrum, aided by NASA/IRTF L' imaging and 2-4 mu m spectra. The star lies similar to 8000 au away in projection from a massive young stellar object (MYSO). Its observed high CH3OH ice abundance (17%. 3% relative to H2O ice) suggests that the 3.535 mu m CH3OH ice absorption likely arises in the MYSO's extended envelope. However, it is also possible that CH3OH ice forms with a higher abundance in dense clouds within the CMZ, compared to within the disk. Either way, our result implies that gasphase CH3OH in the CMZ can be largely produced by desorption from icy grains. The high solid CH3OH abundance confirms the prominent 15.4 mu m shoulder absorption observed toward GC MYSOs arises from CO2 ice mixed with CH3OH.
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