J/ApJ/681/1254 Radial velocities of stars in the Galactic Center (Zhu+, 2008)
Radial velocities of stars in the Galactic center.
Zhu Q., Kudritzki R.P., Figer D.F., Najarro F., Merritt D.
<Astrophys. J., 681, 1254-1278 (2008)>
=2008ApJ...681.1254Z 2008ApJ...681.1254Z (SIMBAD/NED BibCode)
ADC_Keywords: Stars, late-type ; Radial velocities ; Spectral types ;
Spectroscopy ; Stars, early-type ; Equivalent widths ;
Stars, nearby
Keywords: Galaxy: center - stars: kinematics - techniques: spectroscopic
Abstract:
We present results from K-band slit scan observations of a ∼20"x20"
region of the Galactic center (GC) in two separate epochs more than 5
years apart. The high-resolution (R={lamda}/Δλ≥14000)
observations allow the most accurate radial velocity and acceleration
measurements of the stars in the central parsec of the Galaxy.
Detected stars can be divided into three groups based on the CO
absorption band heads at ∼2.2935um and the HeII lines at ∼2.0581 and
∼2.112, 2.113um: cool, narrow-line hot, and broad-line hot. The radial
velocities of the cool, late-type stars have approximately a
symmetrical distribution with its center at ~-7.8±10.3km/s and a
standard deviation ∼113.7±10.3km/s. Although our statistics are
dominated by the brightest stars, we estimate a central black hole
mass of (3.9±1.1)x106M☉, consistent with current estimates
from complete orbits of individual stars. Our surface density profile
and the velocity dispersion of the late-type stars support the
existence of a low-density region at the Galactic center suggested by
earlier observations.
Description:
Four slit scan observations were conducted over a ∼20"x20" region in
the GC with the near-infrared spectrometer (NIRSPEC) on the Keck II
Telescope during 1999 June 4, 1999 July 4, 2005 April 13, and 2005
April 14.
Objects:
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RA (2000) DE Designation(s)
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17 45 40.04 -29 00 28.11 NAME Sgr A*
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 81 123 Cool star velocity
table5.dat 119 20 Radial velocities of narrow HeI line stars
table6.dat 117 9 Radial velocities of broad HeI line stars
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See also:
J/A+A/499/483 : NIR observations of sources in galactic center (Buchholz+,
2009)
J/ApJ/670/1115 : IRS spectra at 38 positions in Galactic center (Simpson+,
2007)
J/A+A/426/81 : Kinematic analysis of the Minispiral (Paumard+, 2004)
J/ApJ/597/323 : Cool stars at the Galactic Center (Blum+, 2003)
J/ApJ/523/248 : Variable stars in the Galactic center (Ott+, 1999)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Source identification (1)
12- 17 F6.2 arcsec oRA Right ascension offset from Sagittarius A*
19- 24 F6.2 arcsec oDE Declination offset from Sagittarius A*
26- 31 F6.1 km/s RV99 ? Radial velocity; epoch 1999 (2)
33- 35 F3.1 km/s e_RV99 ? RV99 uncertainty
37- 42 F6.1 km/s RV05 ? Radial velocity; epoch 2005 (2)
44- 46 F3.1 km/s e_RV05 ? RV05 uncertainty
48- 53 F6.1 km/s Mean radial velocity
55- 57 F3.1 km/s e_ uncertainty
59- 62 I4 K Teff Effective temperature (3)
64 A1 --- l_SpT Limit flag on SpType
65- 70 A6 --- SpT MK spectral type (3)
72- 77 F6.1 km/s RVf ? Radial velocity from Figer et al.
(2003ApJ...599.1139F 2003ApJ...599.1139F) (4)
79- 81 F3.1 km/s e_RVf ? RVFig uncertainty (4)
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Note (1): Designations of the stars are taken from Figer et al.,
2003ApJ...599.1139F 2003ApJ...599.1139F and Tanner et al., 2006ApJ...641..891T 2006ApJ...641..891T. For those
objects which were not included in the previous works, we use their
coordinates as the designation (they are <[ZKF2008] +XX.xx+YY.yy> in
Simbad).
Note (2): Radial velocity of individual cool stars derived from the Dopplor
shift of the CO(2-1) band-head feature. Velocity measurements in two
epochs 1999 and 2005 are listed when available.
Note (3): The temperatures and spectral types are calculated with measured
average equivalent widths of the CO feature using the method describe
in Tanner et al. (2006ApJ...641..891T 2006ApJ...641..891T).
Note (4): Values are taken from Figer et al. (2003ApJ...599.1139F 2003ApJ...599.1139F), which was
based on the same two data sets obtained in 1999.
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Byte-by-byte Description of file: table5.dat table6.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Star designation
15 A1 --- r_Name [ab] Name reference (1)
17- 21 F5.2 arcsec oRA Right ascension offset from Sagittarius A*
23- 27 F5.2 arcsec oDE Declination offset from Sagittarius A*
29- 34 F6.1 km/s RV1 ? Radial velocity 1 (2)
36- 40 F5.1 km/s e_RV1 ? RV1 uncertainty
42- 47 F6.1 km/s RV2 ? Radial velocity 2 (2)
49- 53 F5.1 km/s e_RV2 ? RV2 uncertainty
55- 60 F6.1 km/s RV3 ? Radial velocity 3 (2)
62- 66 F5.1 km/s e_RV3 ? RV3 uncertainty
68- 73 F6.1 km/s RV4 ? Radial velocity 4 (2)
75- 78 F4.1 km/s e_RV4 ? RV4 uncertainty
80- 85 F6.1 km/s Mean radial velocity
87- 91 F5.1 km/s e_ uncertainty
93- 97 F5.1 km/s DRV ? Radial velocity difference between 1999 and
2005
99-102 F4.1 km/s e_DRV ? DRV uncertainty
104-109 F6.2 0.1nm EW Equivalent width (3)
111-119 A9 --- Ref Previous reference(s) (4)
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Note (1): Source name as follows:
a = Figer et al. (2003ApJ...599.1139F 2003ApJ...599.1139F, <[FGK2003] NNN> or
<[GPE2000] NN.NNA> in Simbad.)
b = Ott et al. (1999, Cat. J/ApJ/523/248, <[OEG99] NNN> in Simbad)
IRS sources are in Simbad.
Note (2): Radial velocity measurements of narrow or broad type HeI stars
from four data sets. Unlike the cool star cases, radial velocities of
some hot stars are quite uncertain due to the variation of extracted
line profiles from night to night within one epoch. Big uncertainties
are expected for the measurements.
Note (3): The equivalent width for each narrow type HeI star is calculated
from the average width of the fitted Gaussian components. The
equivalent width for each broad type HeI star is calculated by
integrating the area below the normalized spectrum within the
±1000km/s wavelength range of the corresponding spectral line
emission peak.
Note (4): References as follows:
1 = Genzel et al., 2000MNRAS.317..348G 2000MNRAS.317..348G
2 = Paumard et al., 2001A&A...366..466P 2001A&A...366..466P
3 = Tanner et al., 2006ApJ...641..891T 2006ApJ...641..891T
4 = Paumard et al., 2006ApJ...643.1011P 2006ApJ...643.1011P
5 = Paumard et al., 2003ANS...324..303P 2003ANS...324..303P
6 = Paumard et al., 2004, Cat. J/A+A/426/81
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 28-Oct-2010