J/ApJ/837/30 25yrs monitoring of stellar orbits in the GC (Gillessen+, 2017)
An update on monitoring stellar orbits in the Galactic Center.
Gillessen S., Plewa P.M., Eisenhauer F., Sari R., Waisberg I., Habibi M.,
Pfuhl O., George E., Dexter J., von Fellenberg S., Ott T., Genzel R.
<Astrophys. J., 837, 30-30 (2017)>
=2017ApJ...837...30G 2017ApJ...837...30G (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Radial velocities ; Photometry, infrared
Keywords: astrometry; black hole physics; Galaxy: center;
Galaxy: fundamental parameters; techniques: high angular resolution
Abstract:
Using 25 years of data from uninterrupted monitoring of stellar orbits
in the Galactic Center (GC), we present an update of the main results
from this unique data set: a measurement of mass and distance to
SgrA*. Our progress is not only due to the eight-year increase in time
base, but also to the improved definition of the coordinate system.
The star S2 continues to yield the best constraints on the mass of and
distance to Sgr A*; the statistical errors of 0.13x106M☉ and
0.12kpc have halved compared to the previous study. The S2 orbit fit
is robust and does not need any prior information. Using coordinate
system priors, the star S1 also yields tight constraints on mass and
distance. For a combined orbit fit, we use 17 stars, which yields our
current best estimates for mass and distance:
M=4.28±0.10|stat.±0.21|sysx106M☉ and
R0=8.32±0.07|stat.±0.14|syskpc. These numbers are in
agreement with the recent determination of R0 from the statistical
cluster parallax. The positions of the mass, of the near-infrared
flares from Sgr A*, and of the radio source Sgr A* agree to within
1mas. In total, we have determined orbits for 40 stars so far, a
sample which consists of 32 stars with randomly oriented orbits and a
thermal eccentricity distribution, plus eight stars that we can
explicitly show are members of the clockwise disk of young stars, and
which have lower-eccentricity orbits.
Description:
This work is an update and improvement over our previous orbital study
(Gillessen+ 2009ApJ...692.1075G 2009ApJ...692.1075G).
Since the previous work we have added eight more years of data, using
the adaptive optics (AO) imager NACO on the VLT and the AO-assisted
integral field spectrograph SINFONI. This extends our time base from
17 to 25 years for the imaging and from five to 13 years for the
spectroscopy. We add (in the best cases) 78 epochs of imaging and 19
epochs of spectroscopy.
Our imaging data set contains an interruption. During 2014 and in
spring 2015, NACO was not available at the VLT, resulting in
significant gaps in our time series.
The first high-resolution imaging data of the GC region were obtained
in 1992 with the SHARP camera at ESO's 3.5m NTT in Chile. The first AO
imaging data available to us of the GC region were obtained in 2002
with the Naos-Conica (NACO) system mounted at the fourth unit
telescope Yepun of the VLT (see Gillessen+ 2009ApJ...692.1075G 2009ApJ...692.1075G) for
more details.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 118 40 Orbital parameters of the 40 stars for which
we were able to determine orbits
table5.dat 557 216 *Orbital data used in this work
--------------------------------------------------------------------------------
Note on table5.dat: The astrometric data presented here will change in future
publications on monitoring stellar orbits, since they refer to the
current definition of the reference system, which will improve in the
future. Using these data requires some care concerning the coordinate
system. The position and the velocity of the origin of the coordinate
system in which these data are given do not correspond directly to the
central point mass, but only to our best estimate where the radio source
Sgr A* is located in the coordinate system (Plewa+ 2015MNRAS.453.3234P 2015MNRAS.453.3234P ;
(α ,δ)=(0,0)±(0.2,0.2)mas at our reference epoch 2009.0).
Even Keplerian orbits therefore are expected to yield non-closing orbit
figures, see figure 2 and table 1. Non-closing orbits do thus not mean
automatically that post-Newtonian effects have been detected, or that the
mass distribution is extended. Due to the uncertainty in the reference
frame, it is also non-trivial to add to these data other astrometric
measurements, see Gillessen+ (2009ApJ...692.1075G 2009ApJ...692.1075G). Other authors wishing
to use the data presented here are invited to contact the authors of this
work at <ste{at}mpe.mpg.de>
--------------------------------------------------------------------------------
See also:
J/ApJ/697/1741 : Warped disks of YSOs in Galactic center (Bartko+, 2009)
J/ApJ/707/L114 : The orbit of S2 star around Sgr A* (Gillessen+, 2009)
J/ApJ/737/73 : Infrared extinction toward the Galactic Centre (Fritz+, 2011)
J/ApJ/783/131 : Kinematic of stars in Galactic center (Yelda+, 2014)
J/A+A/570/A2 : Spectra & RVs of nuclear stars (Feldmeier+, 2014)
J/ApJ/821/44 : Star motions in the nuclear cluster of the MW (Fritz+, 2016)
J/ApJ/830/17 : GC secondary IR astrometric standards (Boehle+, 2016)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Star Star Name
6 A1 --- f_Star [a] Flag on Object S111 (1)
8- 15 F8.4 arcsec a [-12.3/4.6] Semi-major axis of the orbit,
from Sag A*
17- 22 F6.4 arcsec e_a [0.0002/8.4] Uncertainty in a
24- 29 F6.4 --- e [0.1/1.1] Eccentricity
31- 36 F6.4 --- e_e [0.0003/0.3] Uncertainty in e
38- 43 F6.2 deg i [24.7/171.1] Inclination
45- 48 F4.2 deg e_i [0.06/8.3] Uncertainty in i
50- 55 F6.2 deg Omega [7.9/345] Position angle of the ascending node
57- 61 F5.2 deg e_Omega [0.07/19] Uncertainty in Ω
63- 68 F6.2 deg w [17.9/357] Longitude of the pericenter
70- 74 F5.2 deg e_w [0.07/24] Uncertainty in w
76- 82 F7.2 yr Tp [611/2132] Epoch of pericenter passage,
fractional year (G1)
84- 89 F6.2 yr e_Tp [0.01/154] Uncertainty in Tp
91- 97 F7.2 yr Per [12.8/3580]? Orbital period (G1)
99-105 F7.2 yr e_Per [0.02/2550]? Uncertainty in Per
107-107 A1 --- SpT [el] Spectral type: e=early-type stars,
l=late-type stars
109-113 F5.2 mag Kmag [10/18] K-band magnitude
115-118 F4.2 --- r [0.9/3.4] Global rescaling factor
--------------------------------------------------------------------------------
Note (1):
a = Object S111 formally has a negative semi major axis, indicative for
a hyperbolic orbit with e>1 and no solution for an orbital period.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.3 yr Date Observation date, fractional year (G1)
10- 11 A2 --- Flag [a rv] Observation flag (a=astrometric data;
rv=radial velocity data)
13- 18 F6.1 mas oRA-S1 ? Offset in Right Ascension, S1 relative to SgrA*
20- 23 F4.1 mas e_oRA-S1 ? Uncertainty in oRA-S1
25- 30 F6.1 mas oDE-S1 ? Offset in Declination, S1 relative to SgrA*
32- 35 F4.1 mas e_oDE-S1 ? Uncertainty in oDE-S1
37- 41 I5 km/s RV-S1 [-1192/-917]? Radial Velocity for S1
43- 45 I3 km/s e_RV-S1 [35/175]? Uncertainty in RVel-S1
47- 51 F5.1 mas oRA-S2 ? Offset in Right Ascension, S2 relative to SgrA*
53- 55 F3.1 mas e_oRA-S2 ? Uncertainty in oRA-S2
57- 61 F5.1 mas oDE-S2 ? Offset in Declination, S2 relative to SgrA*
63- 65 F3.1 mas e_oDE-S2 ? Uncertainty in oDE-S2
67- 71 I5 km/s RV-S2 [-1571/1199]? Radial Velocity for S2
73- 75 I3 km/s e_RV-S2 [17/113]? Uncertainty in RVel-S2
77- 81 F5.1 mas oRA-S4 ? Offset in Right Ascension, S4 relative to SgrA*
83- 85 F3.1 mas e_oRA-S4 ? Uncertainty in oRA-S4
87- 91 F5.1 mas oDE-S4 ? Offset in Declination, S4 relative to SgrA*
93- 95 F3.1 mas e_oDE-S4 ? Uncertainty in oDE-S4
97-101 I5 km/s RV-S4 [-1015/-525]? Radial Velocity for S4
103-105 I3 km/s e_RV-S4 [25/125]? Uncertainty in RVel-S4
107-111 F5.1 mas oRA-S8 ? Offset in Right Ascension, S8 relative to SgrA*
113-115 F3.1 mas e_oRA-S8 ? Uncertainty in oRA-S8
117-122 F6.1 mas oDE-S8 ? Offset in Declination, S8 relative to SgrA*
124-126 F3.1 mas e_oDE-S8 ? Uncertainty in oDE-S8
128-131 I4 km/s RV-S8 [-306/26]? Radial Velocity for S8
133-135 I3 km/s e_RV-S8 [30/118]? Uncertainty in RVel-S8
137-141 F5.1 mas oRA-S9 ? Offset in Right Ascension, S9 relative to SgrA*
143-146 F4.1 mas e_oRA-S9 ? Uncertainty in oRA-S9
148-153 F6.1 mas oDE-S9 ? Offset in Declination, S9 relative to SgrA*
155-158 F4.1 mas e_oDE-S9 ? Uncertainty in oDE-S9
160-162 I3 km/s RV-S9 [390/805]? Radial Velocity for S9
164-166 I3 km/s e_RV-S9 [41/165]? Uncertainty in RVel-S9
168-172 F5.1 mas oRA-S12 ? Offset in RA, S12 relative to SgrA*
174-177 F4.1 mas e_oRA-S12 ? Uncertainty in oRA-S12
179-183 F5.1 mas oDE-S12 ? Offset in Declination, S12 relative to SgrA*
185-188 F4.1 mas e_oDE-S12 ? Uncertainty in oDE-S12
190-192 I3 km/s RV-S12 [-90/349]? Radial Velocity for S12
194-196 I3 km/s e_RV-S12 [71/272]? Uncertainty in RVel-S12
198-203 F6.1 mas oRA-S13 ? Offset in RA, S13 relative to SgrA*
205-208 F4.1 mas e_oRA-S13 ? Uncertainty in oRA-S13
210-215 F6.1 mas oDE-S13 ? Offset in Declination, S13 relative to SgrA*
217-220 F4.1 mas e_oDE-S13 ? Uncertainty in oDE-S13
222-225 I4 km/s RV-S13 [-409/602]? Radial Velocity for S13
227-229 I3 km/s e_RV-S13 [130/375]? Uncertainty in RVel-S13
231-235 F5.1 mas oRA-S14 ? Offset in RA, S14 relative to SgrA*
237-240 F4.1 mas e_oRA-S14 ? Uncertainty in oRA-S14
242-246 F5.1 mas oDE-S14 ? Offset in Declination, S14 relative to SgrA*
248-251 F4.1 mas e_oDE-S14 ? Uncertainty in oDE-S14
253-255 I3 km/s RV-S14 [131/765]? Radial Velocity for S14
257-259 I3 km/s e_RV-S14 [108/259]? Uncertainty in RVel-S14
261-265 F5.1 mas oRA-S17 ? Offset in RA, S17 relative to SgrA*
267-270 F4.1 mas e_oRA-S17 ? Uncertainty in oRA-S17
272-277 F6.1 mas oDE-S17 ? Offset in Declination, S17 relative to SgrA*
279-282 F4.1 mas e_oDE-S17 ? Uncertainty in oDE-S17
284-287 I4 km/s RV-S17 [-165/864]? Radial Velocity for S17
289-291 I3 km/s e_RV-S17 [68/242]? Uncertainty in RVel-S17
293-298 F6.1 mas oRA-S18 ? Offset in RA, S18 relative to SgrA*
300-303 F4.1 mas e_oRA-S18 ? Uncertainty in oRA-S18
305-310 F6.1 mas oDE-S18 ? Offset in Declination, S18 relative to SgrA*
312-315 F4.1 mas e_oDE-S18 ? Uncertainty in oDE-S18
317-320 I4 km/s RV-S18 [-605/-190]? Radial Velocity for S18
322-324 I3 km/s e_RV-S18 [114/342]? Uncertainty in RVel-S18
326-331 F6.1 mas oRA-S19 ? Offset in RA, S19 relative to SgrA*
333-336 F4.1 mas e_oRA-S19 ? Uncertainty in oRA-S19
338-343 F6.1 mas oDE-S19 ? Offset in Declination, S19 relative to SgrA*
345-348 F4.1 mas e_oDE-S19 ? Uncertainty in oDE-S19
350-354 I5 km/s RV-S19 [-2326/-724]? Radial Velocity for S19
356-358 I3 km/s e_RV-S19 [128/385]? Uncertainty in RVel-S19
360-365 F6.1 mas oRA-S21 ? Offset in RA, S21 relative to SgrA*
367-369 F3.1 mas e_oRA-S21 ? Uncertainty in oRA-S21
371-376 F6.1 mas oDE-S21 ? Offset in Declination, S21 relative to SgrA*
378-380 F3.1 mas e_oDE-S21 ? Uncertainty in oDE-S21
382-384 I3 km/s RV-S21 [373/523]? Radial Velocity for S21
386-388 I3 km/s e_RV-S21 [48/112]? Uncertainty in RVel-S21
390-395 F6.1 mas oRA-S24 ? Offset in RA, S24 relative to SgrA*
397-400 F4.1 mas e_oRA-S24 ? Uncertainty in oRA-S24
402-407 F6.1 mas oDE-S24 ? Offset in Declination, S24 relative to SgrA*
409-412 F4.1 mas e_oDE-S24 ? Uncertainty in oDE-S24
414-417 I4 km/s RV-S24 [-987/-771]? Radial Velocity for S24
419-421 I3 km/s e_RV-S24 [39/154]? Uncertainty in RVel-S24
423-428 F6.1 mas oRA-S31 ? Offset in RA, S31 relative to SgrA*
430-433 F4.1 mas e_oRA-S31 ? Uncertainty in oRA-S31
435-439 F5.1 mas oDE-S31 ? Offset in Declination, S31 relative to SgrA*
441-444 F4.1 mas e_oDE-S31 ? Uncertainty in oDE-S31
446-449 I4 km/s RV-S31 [-480/1020]? Radial Velocity for S31
451-453 I3 km/s e_RV-S31 [79/473]? Uncertainty in RVel-S31
455-460 F6.1 mas oRA-S38 ? Offset in RA, S38 relative to SgrA*
462-465 F4.1 mas e_oRA-S38 ? Uncertainty in oRA-S38
467-471 F5.1 mas oDE-S38 ? Offset in Declination, S38 relative to SgrA*
473-476 F4.1 mas e_oDE-S38 ? Uncertainty in oDE-S38
478-481 I4 km/s RV-S38 [-189/-2]? Radial Velocity for S38
483-485 I3 km/s e_RV-S38 [173/248]? Uncertainty in RVel-S38
487-491 F5.1 mas oRA-S54 ? Offset in RA, S54 relative to SgrA*
493-496 F4.1 mas e_oRA-S54 ? Uncertainty in oRA-S54
498-503 F6.1 mas oDE-S54 ? Offset in Declination, S54 relative to SgrA*
505-508 F4.1 mas e_oDE-S54 ? Uncertainty in oDE-S54
510-514 I5 km/s RV-S54 [-1790/-1046]? Radial Velocity for S54
516-518 I3 km/s e_RV-S54 [182/467]? Uncertainty in RVel-S54
520-524 F5.1 mas oRA-S55 ? Offset in RA, S55 relative to SgrA*
526-529 F4.1 mas e_oRA-S55 ? Uncertainty in oRA-S55
531-536 F6.1 mas oDE-S55 ? Offset in Declination, S55 relative to SgrA*
538-541 F4.1 mas e_oDE-S55 ? Uncertainty in oDE-S55
543-546 I4 km/s RV-S55 [-732/-400]? Radial Velocity for S55
548-550 I3 km/s e_RV-S55 [145/210]? Uncertainty in RVel-S55
552-557 A6 --- Inst Observation Source (VLT (201 occurrences),
NTT (11 occurrences), Keck (3 occurrences) or
GEMINI)
--------------------------------------------------------------------------------
Global notes:
Note (G1): Time is measured in Julian years of 365.25 days since J2000.0.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Oct-2017