J/ApJ/707/L114 The orbit of S2 star around Sgr A* (Gillessen+, 2009)
The orbit of the star S2 around Sgr A* from Very Large Telescope and Keck data.
Gillessen S., Eisenhauer F., Fritz T.K., Bartko H., Dodds-Eden K.,
Pfuhl O., Ott T., Genzel R.
<Astrophys. J., 707, L114-L117 (2009)>
=2009ApJ...707L.114G 2009ApJ...707L.114G
ADC_Keywords: Positional data ; Radial velocities ; Milky Way ;
Stars, double and multiple
Keywords: astrometry - black hole physics - Galaxy: center - infrared: stars
Abstract:
Two recent papers (Ghez et al. 2008ApJ...689.1044G 2008ApJ...689.1044G; Gillessen et al.
2009ApJ...692.1075G 2009ApJ...692.1075G) have estimated the mass of and the distance to
the massive black hole (MBH) in the center of the Milky Way using
stellar orbits. The two astrometric data sets are independent and
yielded consistent results, even though the measured positions do not
match when simply overplotting the two sets. In this Letter, we show
that the two sets can be brought to excellent agreement with each
other when we allow for a small offset in the definition of the
reference frame of the two data sets. The required offsets in the
coordinates and velocities of the origin of the reference frames are
consistent with the uncertainties given in Ghez et al. The so-combined
data set allows for a moderate improvement of the statistical errors
of the mass of and the distance to Sgr A*, but the overall accuracies
of these numbers are dominated by systematic errors and the long-term
calibration of the reference frame.
Description:
The astrometric data from the NTT/VLT we are using are identical to
the data from Gillessen et al. (2009ApJ...692.1075G 2009ApJ...692.1075G) up to 2008
August. Since then, one more epoch has been observed in 2008 and 11
more epochs in 2009. In total, the NTT/VLT data set contains 70 epochs
from 1992 March to 2009 August. In their Table 3 Ghez et al.
(2008ApJ...689.1044G 2008ApJ...689.1044G) presented the measured positions for all Keck
epochs. We use the given 26 epochs, ranging between 1995 and 2008.
Objects:
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RA (2000) DE Designation(s)
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17 45 40.0 -29 00 28 S2 = [EG97] S2
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 61 96 Orbital data for S2 used in this work
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See also:
V/55 : A catalogue of high-velocity stars (Roman, 1955)
J/ApJ/699/186 : VLA observations of the Galactic center (Zhao+, 2009)
J/ApJ/697/1741 : Warped disks of YSOs in Galactic center (Bartko+, 2009)
J/ApJ/681/1254 : Radial velocities of stars in the Galactic Center (Zhu+, 2008)
J/ApJ/659/1241 : Stellar variability in Galactic Center (Rafelski+, 2007)
J/AJ/127/3399 : Sgr A* variability at cm wavelengths (Herrnstein+, 2004)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 yr Ep.A Year of the astrometric observation
10- 14 F5.1 mas oRA Offset in Right Ascension relative to SgrA*
16- 19 F4.1 mas e_oRA Uncertainty in oRA
21- 25 F5.1 mas oDE Offset in Declination relative to SgrA*
27- 30 F4.1 mas e_oDE Uncertainty in oDE
32- 37 A6 --- Tel.A Telescope used in astrometric observation
39- 46 F8.3 yr Ep.V ? Year of the radial velocity observation
48- 52 I5 km/s VLSR ? Local Standard of Rest Velocity
54- 56 I3 km/s e_VLSR ? Uncertainty in VLSR
58- 61 A4 --- Tel.V Telescope used in radial velocity observation
(VLT or Keck)
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 06-Jan-2012