Inferred orbits of 6 stars around supermassive black hole candidate Sagittarius A* at the Milky Way's center[1]
The Sagittarius A* cluster is the cluster of stars in close orbit around Sagittarius A*, the supermassive black hole at the center of the Milky Way (in the Galactic Center). The individual stars are often listed as "S-stars", but their names and IDs are not formalized, and stars can have different numbers in different catalogues.
One of the most studied stars is S2, a relatively bright star that also passes close by Sgr A*.
As of 2020[update], S4714 is the current record holder of closest approach to Sagittarius A*, at about 12.6 astronomical units (1.88×109 km), almost as close as Saturn gets to the Sun, traveling at about 8% of the speed of light. These figures given are approximate, the formal uncertainties being 12.6±9.3 au and 23928±8840 km/s. Its orbital period is 12 years, but an extreme eccentricity of 0.985 gives it the close approach and high velocity.[2]
List of stars
The inferred orbits of stars around supermassive black hole candidate Sagittarius A* at the Milky Way's center are according to Gillessen et al. 2017,[3] with the exception of S2 which is from GRAVITY 2019,[4] S62 which is from Peißker et al. Jan 2020,[5] and S4711 up to S4715, which are also from Peißker et al., Aug 2020.[2]
Here id1 is the star's name in the Gillessen catalog and id2 in the catalog of the University of California, Los Angeles. a, e, i, Ω and ω are standard orbital elements, with a measured in arcseconds. Tp is the epoch of pericenter passage, P is the orbital period in years and Kmag is the K-band apparent magnitude of the star. q and v are the pericenter distance in AU and pericenter speed in percent of the speed of light,[6] and Δ indicates the standard deviation of the associated quantities.
id1
id2
Other name
Spectral class
Mass (Solar masses)
Temperature (K)
a
Δa
e
Δe
i (°)
Δi
Ω (°)
ΔΩ
ω (°)
Δω
Tp (yr)
ΔTp
P (yr)
ΔP
Kmag
q (AU)
Δq
v (%c)
Δv
Radius (Solar radii)
S1
S0-1
B0-2 V
0.5950
0.0240
0.5560
0.0180
119.14
0.21
342.04
0.32
122.30
1.40
2001.800
0.150
166.0
5.8
14.70
2160.7
6.7
0.55
0.03
4.49
S2
S0-2
B0-2 V
14
0.1251
0.0001
0.8843
0.0001
133.91
0.05
228.07
0.04
66.25
0.04
2018.379
0.001
16.0518
0.0
13.95
118.4
0.2
2.56
0.00
6.36
S4
S0-3
B0-2 V
0.3570
0.0037
0.3905
0.0059
80.33
0.08
258.84
0.07
290.80
1.50
1957.400
1.200
77.0
1.0
14.40
1779.7
25.1
0.57
0.01
S6
S0-7
B0-2 V
0.6574
0.0006
0.8400
0.0003
87.24
0.06
85.07
0.12
116.23
0.07
2108.610
0.030
192.0
0.2
15.40
860.3
4.4
0.94
0.00
4.53
S8
S0-4
B0-2 V
0.4047
0.0014
0.8031
0.0075
74.37
0.30
315.43
0.19
346.70
0.41
1983.640
0.240
92.9
0.4
14.50
651.7
22.5
1.07
0.01
4.47
S9
S0-5
B0-2 V
0.2724
0.0041
0.6440
0.0200
82.41
0.24
156.60
0.10
150.60
1.00
1976.710
0.920
51.3
0.7
15.10
793.2
36.9
0.93
0.02
S10
S0-6
[CRG2004] 12
K5 III
14.26
S12
S0-19
B4-9 V
0.2987
0.0018
0.8883
0.0017
33.56
0.49
230.10
1.80
317.90
1.50
1995.590
0.040
58.9
0.2
15.50
272.9
2.0
1.69
0.01
S13
S0-20
B4-9 V
0.2641
0.0016
0.4250
0.0023
24.70
0.48
74.50
1.70
245.20
2.40
2004.860
0.040
49.0
0.1
15.80
1242.0
2.4
0.69
0.01
S14
S0-16
B4-9 V
0.2863
0.0036
0.9761
0.0037
100.59
0.87
226.38
0.64
334.59
0.87
2000.120
0.060
55.3
0.5
15.70
56.0
3.8
3.83
0.06
3.1789
S17
K0 III
5,000
0.3559
0.0096
0.3970
0.0110
96.83
0.11
191.62
0.21
326.00
1.90
1991.190
0.410
76.6
1.0
15.30
1755.3
16.4
0.57
0.02
9
S18
S0-18
0.2379
0.0015
0.4710
0.0120
110.67
0.18
49.11
0.18
349.46
0.66
1993.860
0.160
41.9
0.2
16.70
1029.3
3.8
0.77
0.01
S19
S0-28
K-M
0.5200
0.0940
0.7500
0.0430
71.96
0.35
344.60
0.62
155.20
2.30
2005.390
0.160
135.0
14.0
16.00
1063.3
4.5
0.83
0.20
S21
0.2190
0.0017
0.7640
0.0140
58.80
1.00
259.64
0.62
166.40
1.10
2027.400
0.170
37.0
0.3
16.90
422.7
3.6
1.32
0.02
S22
1.3100
0.2800
0.4490
0.0880
105.76
0.95
291.70
1.40
95.00
20.00
1996.900
10.200
540.0
63.0
16.60
5903.7
9.7
0.32
0.10
S23
0.2530
0.0120
0.5600
0.1400
48.00
7.10
249.00
13.00
39.00
6.70
2024.700
3.700
45.8
1.6
17.80
910.5
1.6
0.85
0.06
S24
S0-26
0.9440
0.0480
0.8970
0.0049
103.67
0.42
7.93
0.37
290.00
15.00
2024.500
0.030
331.0
16.0
15.60
795.3
30.8
0.99
0.07
S27
S0-27
K3 III
15.74
S29
0.4280
0.0190
0.7280
0.0520
105.80
1.70
161.96
0.80
346.50
5.90
2025.960
0.940
101.0
2.0
16.70
952.2
67.4
0.87
0.05
S31
S0-8
B4-9 V
0.4490
0.0100
0.5497
0.0025
109.03
0.27
137.16
0.30
308.00
3.00
2018.070
0.140
108.0
1.2
15.70
1653.7
14.6
0.63
0.02
S33
S0-33
0.6570
0.0260
0.6080
0.0640
60.50
2.50
100.10
5.50
303.70
1.60
1928.000
12.000
192.0
5.2
16.00
2106.5
179.7
0.56
0.03
S38
S0-38
M III
5.9713
3,330
0.1416
0.0002
0.8201
0.0007
171.10
2.10
101.06
0.24
17.99
0.25
2003.190
0.010
19.2
0.0
17.00
208.4
1.5
1.91
0.01
185.84
S39
0.3700
0.0150
0.9236
0.0021
89.36
0.73
159.03
0.10
23.30
3.80
2000.060
0.060
81.1
1.5
16.80
231.2
3.3
1.86
0.09
S42
0.9500
0.1800
0.5670
0.0830
67.16
0.66
196.14
0.75
35.80
3.20
2008.240
0.750
335.0
58.0
17.50
3364.4
24.8
0.44
0.13
S54
1.2000
0.8700
0.8930
0.0780
62.20
1.40
288.35
0.70
140.80
2.30
2004.460
0.070
477.0
199.0
17.50
1050.2
1.9
0.86
0.78
S55
S0-102
B0-2 V
0.1078
0.0010
0.7209
0.0077
150.10
2.20
325.50
4.00
331.50
3.90
2009.340
0.040
12.8
0.1
17.50
246.1
4.1
1.70
0.02
S60
0.3877
0.0070
0.7179
0.0051
126.87
0.30
170.54
0.85
29.37
0.29
2023.890
0.090
87.1
1.4
16.30
894.5
1.7
0.89
0.02
S62
B0-2 V
6.1
0.0897
0.00005
0.9760
0.0020
72.76
4.58
122.61
0.57
42.62
0.40
2003.330
0.010
9.9
0.0
16.10
16.4
1.5
7.03
0.04
3.8
S66
S1-2
[RGH2007] GEN-0.06-1.01
O-B
1.5020
0.0950
0.1280
0.0430
128.50
1.60
92.30
3.20
134.00
17.00
1771.000
38.000
664.0
37.0
14.80
10712.4
620.5
0.21
0.02
S67
S1-3
O-B
1.1260
0.0260
0.2930
0.0570
136.00
1.10
96.50
6.40
213.50
1.60
1705.000
22.000
431.0
10.0
12.10
6511.2
360.6
0.29
0.01
S71
S0-71
0.9730
0.0400
0.8990
0.0130
74.00
1.30
35.16
0.86
337.80
4.90
1695.000
21.000
346.0
11.0
16.10
803.8
1.4
0.99
0.06
S83
S0-15
[GEO97] W5
O9-9.5 V
33,000
1.4900
0.1900
0.3650
0.0750
127.20
1.40
87.70
1.20
203.60
6.00
2046.800
6.300
656.0
69.0
13.60
7738.6
22.5
0.27
0.05
7.5
S85
M0 III
9.178
3,800
4.6000
3.3000
0.7800
0.1500
84.78
0.29
107.36
0.43
156.30
6.80
1930.200
9.800
3580.0
2550.0
15.60
8277.1
29.6
0.30
0.33
51.008
S87
S1-12
2.7400
0.1600
0.2240
0.0270
119.54
0.87
106.32
0.99
336.10
7.70
611.000
154.000
1640.0
105.0
13.60
17390.5
2572.9
0.17
0.02
S89
1.0810
0.0550
0.6390
0.0380
87.61
0.16
238.99
0.18
126.40
4.00
1783.000
26.000
406.0
27.0
15.30
3191.8
407.2
0.46
0.04
S91
1.9170
0.0890
0.3030
0.0340
114.49
0.32
105.35
0.74
356.40
1.60
1108.000
69.000
958.0
50.0
12.20
10928.4
74.5
0.22
0.02
S96
S0-96
GCIRS 16C
Ofpe/WN9
1.4990
0.0570
0.1740
0.0220
126.36
0.96
115.66
0.59
233.60
2.40
1646.000
16.000
662.0
29.0
10.00
10127.0
530.0
0.22
0.02
S97 A
S1-16
GCIRS 16SW
Ofpe/WN9
50
24,400
2.3200
0.4600
0.3500
0.1100
113.00
1.30
113.20
1.40
28.00
14.00
2132.000
29.000
1270.0
309.0
10.30
12333.9
305.9
0.21
0.08
54.5 × 58.2 × 62.7
S97 B
S1-16
GCIRS 16SW
Ofpe/WN9
50
23,500
2.3200
0.4600
0.3500
0.1100
113.00
1.30
113.20
1.40
28.00
14.00
2132.000
29.000
1270.0
309.0
10.30
12333.9
305.9
0.21
0.08
54.5 × 58.2 × 62.7
S145
M III
5.1216
3,330
1.1200
0.1800
0.5000
0.2500
83.70
1.60
263.92
0.94
185.00
16.00
1808.000
58.000
426.0
71.0
17.50
4580.2
1471.2
0.37
0.10
179.46
S175
0.4140
0.0390
0.9867
0.0018
88.53
0.60
326.83
0.78
68.52
0.40
2009.510
0.010
96.2
5.0
17.50
45.0
0.8
4.27
0.47
S4711
B8-9 V
2.2
11,587.84
0.0751
0.0015
0.768
0.030
114.71
2.92
20.10
3.72
131.59
3.09
2010.85
0.06
7.6
0.3
18.4
143.7
7.4
2.2
0.2
2.59
S4712
B9-A0 V
2.2
10,000
0.451
0.0025
0.365
0.032
117.28
1.31
166.38
3.20
238.08
3.43
2007.12
0.08
112.0
2.9
18.4
2366
120
0.48
0.02
S4713
2.1
0.2
0.095
0.351
0.059
111.07
1.66
95.06
5.15
301.97
8.02
2000.03
0.22
33.2
2.5
18.5
1073
110
0.71
0.05
S4714
2
0.102
0.0003
0.985
0.011
127.7
0.28
129.28
0.63
357.25
0.08
2017.29
0.02
12.0
0.3
17.7
12.6
9.3
8.0
3
S4715
B9 V
2.8
0.1439
0.011
0.247
0.040
129.8
3.72
282.15
2.92
359.99
5.38
2008.05
0.3
20.2
2.4
17.8
894
83
0.75
0.04
2.37
S4716
B7-8 V
12,417.07
1.9300
0.756
161.24
151.54
0.073
4.0
2.45
R34
1.8100
0.1500
0.6410
0.0980
136.00
8.30
330.00
19.00
57.00
8.00
1522.000
52.000
877.0
83.0
14.00
5314.6
856.3
0.36
0.05
R44
3.9000
1.4000
0.2700
0.2700
131.00
5.20
80.50
7.10
217.00
24.00
1963.000
85.000
2730.0
1350.0
14.00
23285.6
901.5
0.15
0.11
id1
id2
a
Δa
e
Δe
i (°)
Δi
Ω (°)
ΔΩ
ω (°)
Δω
Tp (yr)
ΔTp
P (yr)
ΔP
Kmag
q (AU)
Δq
v (%c)
Δv
References
^Eisenhauer, F.; et al. (July 20, 2005). "SINFONI in the Galactic Center: Young Stars and Infrared Flares in the Central Light-Month". The Astrophysical Journal. 628 (1): 246–259. arXiv:astro-ph/0502129. Bibcode:2005ApJ...628..246E. doi:10.1086/430667. S2CID 122485461.
^ abPeißker, Florian; Eckart, Andreas; Zajaček, Michal; Basel, Ali; Parsa, Marzieh (August 2020). "S62 and S4711: Indications of a Population of Faint Fast-moving Stars inside the S2 Orbit—S4711 on a 7.6 yr Orbit around Sgr A*". The Astrophysical Journal. 889 (50): 5. arXiv:2008.04764. Bibcode:2020ApJ...899...50P. doi:10.3847/1538-4357/ab9c1c. S2CID 221095771.
^Gillessen, S.; et al. (February 2017). "An Update on Monitoring Stellar Orbits in the Galactic Center". The Astrophysical Journal. 837 (1): 30. arXiv:1611.09144. Bibcode:2017ApJ...837...30G. doi:10.3847/1538-4357/aa5c41. S2CID 119087402.
^Abuter, R.; Amorim, A.; Bauböck, M.; Berger, J. P.; Bonnet, H.; Brandner, W.; Clénet, Y.; Coudé Du Foresto, V.; De Zeeuw, P. T.; Dexter, J.; Duvert, G.; Eckart, A.; Eisenhauer, F.; Förster Schreiber, N. M.; Garcia, P.; Gao, F.; Gendron, E.; Genzel, R.; Gerhard, O.; Gillessen, S.; Habibi, M.; Haubois, X.; Henning, T.; Hippler, S.; Horrobin, M.; Jiménez-Rosales, A.; Jocou, L.; Kervella, P.; Lacour, S.; et al. (April 2019). "A geometric distance measurement to the Galactic center black hole with 0.3% uncertainty". Astronomy & Astrophysics. 625: L10. arXiv:1904.05721. Bibcode:2019A&A...625L..10G. doi:10.1051/0004-6361/201935656. S2CID 119190574.
^Peißker, Florian; Eckart, Andreas; Parsa, Marzieh (January 2020). "S62 on a 9.9 year orbit around SgrA*". The Astrophysical Journal. 889 (1): 61. arXiv:2002.02341. Bibcode:2020ApJ...889...61P. doi:10.3847/1538-4357/ab5afd. S2CID 211043784.
^Næss, S. (October 4, 2019). "Galactic center S-star orbital parameters".