J/MNRAS/494/396 Metallicity distribution in GC (Feldmeier-Krause+, 2020)
Asymmetric spatial distribution of subsolar metallicity stars in the
Milky Way nuclear star cluster.
Feldmeier-Krause A., Kerzendorf W., Do T., Nogueras-Lara F., Neumayer N.,
Walcher C.J., Seth A., Schodel R., De Zeeuw P.T., Hilker M.,
Lutzgendorf N., Kuntschner H., Kissler-Patig M.
<Mon. Not. R. Astron. Soc., 494, 396-410 (2020)>
=2020MNRAS.494..396F 2020MNRAS.494..396F (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Galactic center ; Stars, late-type ;
Radial velocities ; Photometry, infrared
Keywords: stars: late-type - Galaxy: centre - infrared: stars
Abstract:
We present stellar metallicity measurements of more than 600 late-type
stars in the central 10pc of the Galactic Centre. Together with our
previously published KMOS data, this data set allows us to
investigate, for the first time, spatial variations of the nuclear
star cluster's metallicity distribution. Using the integral-field
spectrograph KMOS (VLT), we observed almost half of the area enclosed
by the nuclear star cluster's effective radius. We extract spectra at
medium spectral resolution and apply full spectral fitting utilizing
the PHOENIX library of synthetic stellar spectra. The stellar
metallicities range from [M/H]=-1.25dex to [M/H]>+0.3dex, with
most of the stars having supersolar metallicity. We are able to
measure an anisotropy of the stellar metallicity distribution. In the
Galactic north, the portion of subsolar metallicity stars with
[M/H]<0.0dex is more than twice as high as in the Galactic south. One
possible explanation for different fractions of subsolar metallicity
stars in different parts of the cluster is a recent merger event. We
propose to test this hypothesis with high- resolution spectroscopy and
by combining the metallicity information with kinematic data.
Description:
We obtained near-infrared K-band spectra of more than 600 late-type
stars in the central 10pc2 of the Galactic Center, using the
integral-field spectrograph KMOS (VLT). We analysed the medium-
resolution spectra using the full-spectral fitting code "starkit",
employing the Goettingen Spectral library of synthetic PHOENIX
spectra.
We derived the effective temperature, overall metallicity [M/H],
surface gravity log(g) and radial velocity vz.
Here we present the full table A.1 from Appendix A.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 100 648 Table of stellar parameters
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 7 I7 --- Id Identifation number
9- 17 F9.5 deg RAdeg Right ascension (J2000)
19- 28 F10.6 deg DEdeg Declination (J2000)
30- 33 I4 K Teff Effective temperature
36- 38 I3 K e_Teff Lower uncertainty of effective temperature
41- 43 I3 K E_Teff Upper uncertainty of effective temperature
45- 49 F5.2 --- [M/H] Metallicity
52- 55 F4.2 --- e_[M/H] Lower uncertainty of metallicity
58- 61 F4.2 --- E_[M/H] Upper uncertainty of metallicity
63- 65 F3.1 [cm/s2] logg Surface gravity
67- 69 F3.1 [cm/s2] e_logg Lower uncertainty of surface gravity
71- 73 F3.1 [cm/s2] E_logg Upper uncertainty of surface gravity
75- 80 F6.1 km/s RV Radial velocity in local standard of rest
84- 87 F4.1 km/s e_RV Lower uncertainty of radial velocity
91- 94 F4.1 km/s E_RV Upper uncertainty of radial velocity
96-100 F5.2 mag Kmag Ks-band magnitude (1)
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Note (1): extinction corrected with map from Nogueras-Lara et al.
2018A&A..620A..83N.
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Acknowledgements:
Anja Feldmeier-Krause, afeldmei(at)uchicago.edu
(End) Anja Feldmeier-Krause [Chicago Univ.], Patricia Vannier [CDS] 25-Jun-2020