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Chemistry and Physics of a Low-metallicity Hot Core in the Large Magellanic Cloud

Shimonishi, Takashi ; Das, Ankan ; Sakai, Nami ; Tanaka, Kei E. I. ; Aikawa, Yuri ; Onaka, Takashi ; Watanabe, Yoshimasa ; Nishimura, Yuri

The Astrophysical journal, 2020-03, Vol.891 (2), p.164 [Periódico revisado por pares]

Philadelphia: The American Astronomical Society

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Título:
Chemistry and Physics of a Low-metallicity Hot Core in the Large Magellanic Cloud
Autor: Shimonishi, Takashi ; Das, Ankan ; Sakai, Nami ; Tanaka, Kei E. I. ; Aikawa, Yuri ; Onaka, Takashi ; Watanabe, Yoshimasa ; Nishimura, Yuri
Assuntos: Abundance ; Astrochemistry ; Astrophysics ; Chemical composition ; Cores ; Dust continuum emission ; Galactic rotation ; Galaxies ; Ice formation ; Interstellar line emission ; Interstellar molecules ; Isotopic abundances ; Large Magellanic Cloud ; Magellanic clouds ; Metallicity ; Milky Way ; Nitrogen ; Organic chemistry ; Protostars ; Radio telescopes ; Star formation ; Submillimeter astronomy ; Sulfur ; Sulfur dioxide
É parte de: The Astrophysical journal, 2020-03, Vol.891 (2), p.164
Notas: AAS21630
Interstellar Matter and the Local Universe
Descrição: We here present the results of 0.1 pc scale observations in 250 and 350 GHz toward a newly-discovered hot molecular core in a nearby low-metallicity galaxy, the Large Magellanic Cloud (LMC), with the Atacama Large Millimeter/submillimeter Array. A variety of C/N/O/Si/S-bearing molecules are detected toward the high-mass young stellar object, ST16. A rotating protostellar envelope is for the first time detected outside our Galaxy by SO2 and 34SO lines. An outflow cavity is traced by CCH and CN. The isotope abundance of sulfur in the source is estimated to be 32S/34S = 17 and 32S/33S = 53 based on SO, SO2, and CS isotopologues, suggesting that both 34S and 33S are overabundant in the LMC. Rotation diagram analyses show that the source is associated with hot gas (>100 K) traced by high-excitation lines of CH3OH and SO2, as well as warm gas (∼50 K) traced by CH3OH, SO2, 34SO, OCS, and CH3CN lines. A comparison of molecular abundances between LMC and Galactic hot cores suggests that organic molecules (e.g., CH3OH, a classical hot core tracer) show a large abundance variation in low metallicity, where the present source is classified into an organic-poor hot core. Our astrochemical simulations suggest that different grain temperatures during the initial ice-forming stage would contribute to the chemical differentiation. In contrast, SO2 shows similar abundances within all of the known LMC hot cores, and the typical abundance roughly scales with the LMC's metallicity. Nitrogen-bearing molecules are generally less abundant in the LMC hot cores, except for NO. The present results suggest that chemical compositions of hot cores do not always simply scale with the metallicity.
Editor: Philadelphia: The American Astronomical Society
Idioma: Inglês

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Chemistry and Physics of a Low-metallicity Hot Core in the Large Magellanic Cloud

Shimonishi, Takashi ; Das, Ankan ; Sakai, Nami ; Tanaka, Kei E. I. ; Aikawa, Yuri ; Onaka, Takashi ; Watanabe, Yoshimasa ; Nishimura, Yuri

Philadelphia: The American Astronomical Society

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