2020年3月9日
Sub-millimeter detection of a Galactic center cool star IRS 7 by ALMA
Publications of the Astronomical Society of Japan
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- 記述言語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1093/pasj/psaa013
- 出版者・発行元
- Oxford University Press ({OUP})
IRS 7 is an M red supergiant star which is located at $5".5$ north of
Sagittarius A$^\ast$. We detected firstly the continuum emission at 340 GHz of
IRS 7 using ALMA. The total flux density of IRS 7 is $S_\nu=448\pm45 \mu$Jy.
The flux density indicates that IRS 7 has a photosphere radius of $R=1170\pm60
~R_\odot$, which is roughly consistent with the previous VLTI measurement. We
also detected a shell like feature with north extension in the H30$\alpha$
recombination line by ALMA. The electron temperature and electron density of
the shell like structure are estimated to be $\bar{T}^\ast_{\mathrm
e}=4650\pm500$ K and $\bar{n}_{\mathrm e}=(6.1\pm0.6)\times10^4$ cm$^{-3}$,
respectively. The mass loss rate is estimated to be $\dot{m} \sim 1\times
10^{-4} M_\odot$ yr$^{-1}$, which is consistent with a typical mass loss rate
of a pulsating red supergiant star with $M=20-25 M_\odot$. The kinematics of
the ionized gas would support the hypothesis that the shell like structure made
by the mass loss of IRS 7 is supersonically traveling in the ambient matter
toward the south. The brightened southern half of the structure and the north
extension would be a bow shock and a cometary-like tail structure,
respectively.
Sagittarius A$^\ast$. We detected firstly the continuum emission at 340 GHz of
IRS 7 using ALMA. The total flux density of IRS 7 is $S_\nu=448\pm45 \mu$Jy.
The flux density indicates that IRS 7 has a photosphere radius of $R=1170\pm60
~R_\odot$, which is roughly consistent with the previous VLTI measurement. We
also detected a shell like feature with north extension in the H30$\alpha$
recombination line by ALMA. The electron temperature and electron density of
the shell like structure are estimated to be $\bar{T}^\ast_{\mathrm
e}=4650\pm500$ K and $\bar{n}_{\mathrm e}=(6.1\pm0.6)\times10^4$ cm$^{-3}$,
respectively. The mass loss rate is estimated to be $\dot{m} \sim 1\times
10^{-4} M_\odot$ yr$^{-1}$, which is consistent with a typical mass loss rate
of a pulsating red supergiant star with $M=20-25 M_\odot$. The kinematics of
the ionized gas would support the hypothesis that the shell like structure made
by the mass loss of IRS 7 is supersonically traveling in the ambient matter
toward the south. The brightened southern half of the structure and the north
extension would be a bow shock and a cometary-like tail structure,
respectively.
- リンク情報
-
- DOI
- https://doi.org/10.1093/pasj/psaa013
- arXiv
- http://arxiv.org/abs/arXiv:2002.01620
- Arxiv Url
- http://arxiv.org/abs/2002.01620v1
- Arxiv Url
- http://arxiv.org/pdf/2002.01620v1 本文へのリンクあり
- ID情報
-
- DOI : 10.1093/pasj/psaa013
- ORCIDのPut Code : 70265021
- arXiv ID : arXiv:2002.01620