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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 (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). 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) 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 ; (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). Other authors wishing to use the data presented here are invited to contact the authors of this work at <ste{at}>
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 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
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