Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Sub-millimeter Detection of a Galactic Center Cool Star IRS 7 by ALMA   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.

5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom