J/A+A/549/A57 Young, massive star candidates in Sgr A* (Nishiyama+, 2013)
Young, massive star candidates detected throughout the nuclear star cluster of
the Milky Way.
Nishiyama S., Schoedel R.
<Astron. Astrophys. 549, A57 (2013)>
=2013A&A...549A..57N 2013A&A...549A..57N
ADC_Keywords: Stars, nearby ; Stars, early-type ; Stars, distances ; Photometry
Keywords: Galaxy: center - stars: formation - stars: early-type
Abstract:
Nuclear star clusters (NSCs) are ubiquitous at the centers of
galaxies. They show mixed stellar populations and the spectra of many
NSCs indicate recent events of star formation. However, it is
impossible to resolve external NSCs in order to examine the relevant
processes. The Milky Way NSC, on the other hand, is close enough to be
resolved into its individual stars and presents therefore a unique
template for NSCs in general.
Young, massive stars have been found by systematic spectroscopic
studies at projected distances R≲0.5pc from the supermassive black
hole, Sagittarius A* (Sgr A*). In recent years, increasing evidence
has been found for the presence of young, massive stars also at
R>0.5pc. Our goal in this work is a systematic search for young,
massive star candidates throughout the entire region within R∼2.5pc of
the black hole.
Description:
The main criterion for the photometric identification of young,
massive early-type stars is the lack of CO-absorption in the spectra.
We used narrow-band imaging with the near-infrared camera ISAAC at the
ESO VLT under excellent seeing conditions to search for young, massive
stars within ∼2.5pc of Sgr A*.
Fits mosaic images used in our analysis are presented. The filter and
day of observation are given in the titles of the images. Imaging
observations were acquired through various narrow-band filters with
ISAAC at the ESO VLT. The FOV is 2.5'x2.5' with a pixel scale of
0.15". Details of the observations are listed in Table 1 of the paper.
A standard image reduction procedure (sky subtraction, bad pixel
correction, and flat-fielding) was carried out for the images, but
the images are not astrometrically aligned and not photometrically
calibrated. A non-standard part of the image reduction is included
in the bias correction. See sec. 2 of the paper for more detail.
The raw data are available from the ESO data archive.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 89 63 Early-type star candidates in the Galactic Center
list.dat 57 7 List of FITS images
fits/* . 7 FITS images
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See also:
J/ApJ/597/323 : Cool stars at the Galactic Center (Blum+, 2003)
J/ApJ/643/1011 : Early-type stars in the center of the Galaxy (Paumard+, 2006)
J/A+A/499/483 : Galactci center sources NIR observations (Buchholz+, 2009)
J/ApJ/697/1741 : Warped disks of YSOs in Galactic center (Bartko+, 2009)
J/MNRAS/417/114 : HST/NICMOS Galactic Center survey catalogue (Dong+, 2011)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/63] Sequential number
4- 5 I2 h RAh Right ascension (J2000) (1)
7- 8 I2 min RAm Right ascension (J2000) (1)
10- 15 F6.3 s RAs Right ascension (J2000) (1)
17 A1 --- DE- Declination sign (J2000) (1)
18- 19 I2 deg DEd Declination (J2000) (1)
21- 22 I2 arcmin DEm Declination (J2000) (1)
24- 28 F5.2 arcsec DEs Declination (J2000) (1)
30- 34 F5.2 arcsec R.A* Distance from Sgr A*
36- 39 F4.2 mag [1.71]-[2.25] ? Magnitude difference between [1.71] and
[2.25], after the color correction
41- 45 F5.2 mag [2.25]-[2.34] Magnitude difference between [2.25] and
[2.34], after the color correction and
the relative extinction correction
47- 56 A10 --- Name Name of counterparts (2)
58- 67 A10 --- SpType MK spectral type from Paumard et al. -2006,
Cat. J/ApJ/643/1011) if no reference
70- 71 A2 --- r_SpType Reference for spectral type (3)
74- 89 A16 --- Ctp Counterparts (4)
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Note (1): Typical positional uncertainty is 0.1"-0.3".
Note (2): Names of counterparts in Paumard et al. (2006, Cat. J/ApJ/643/1011)
and Lu et al. (2009ApJ...690.1463L 2009ApJ...690.1463L). The source # 53 is probably a foreground
star, because of its very blue color in [1.71] - [2.25].
Note (3): References for spectral type as follows:
Ba = Bartko et al. (2010, Cat. J/ApJ/697/1741)
Ta = Tanner et al. (2005ApJ...624..742T 2005ApJ...624..742T)
Bl = Blum et al. (2003, Cat. J/ApJ/597/323)
Note (4): Counterpart from
* Blum et al. (2003, Cat. J/ApJ/597/323), Bl NNN, <[BSD96] NNN> in Simbad
* Buchholz et al. (2009, Cat. J/A+A/499/483), Bu NNN
* Dong et al. (2011, Cat. J/MNRAS/417/114), Do NNN, <[DWC2011] NNN> in Simbad.
* Letters in parentheses denotes quality flags from Buchholz et al.
(2009. Cat. J/A+A/499/483), as:
E1 = quality 1 early-type candidates
E3 = quality 3 early-type candidates
L1 = quality 1 late-type candidates
L2 = quality 2 late-type candidates
N = sources with noisy SED
R = strongly reddened sources
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Filt ISAAC narrow-band filter name
(NB171, NB209, NB225, or NB234)
7- 17 A11 "DD/MMM/YYYY" Date Observation date
19- 22 I4 pix Nx Number of pixels along X-axis
23 A1 --- --- [x]
24- 27 I4 pix Ny Number of pixels along Y-axis
29- 57 A29 --- FileName Name of FITS file in subdirectory fits
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Acknowledgements:
Shogo Nishiyama, shogo.nishiyama (at)nao.ac.jp
(End) Patricia Vannier [CDS] 23-Nov-2012