Omicron Herculis

Short description: Variable star in the constellation Hercules

o Herculis

Location of o Herculis (circled)

Observation data
Equinox J2000.0]] (ICRS)
Constellation | Hercules
Right ascension |  18h 07m 32.55073s[1]
Declination | +28° 45′ 44.9679″[1]
Apparent magnitude (V) | 3.83[2]
Characteristics
Spectral type | B9.5III[3]
U−B color index | −0.07[2]
B−V color index | −0.02[2]
Variable type | γ Cas[4]
Astrometry
Radial velocity (Rv)| −29.5[5] km/s
Proper motion (μ)|  RA: −0.02[1] mas/yr
Dec.: +8.55[1] mas/yr
Parallax (π)| 9.65 ± 0.16[1] mas
Distance| 338 ± 6 ly
(104 ± 2 pc)
Absolute magnitude (MV)| −1.24[6]
Details
Mass| 3.49±0.04[7] M☉
Radius| 6.3[8] R☉
Luminosity| 355 L☉
Surface gravity (log g)| 2.86[9] cgs
Temperature| 9,484[8] K
Metallicity [Fe/H]| −0.06[6] dex
Rotational velocity (v sin i)| 194[10] km/s
Other designations

o Her, 103 Herculis, BD+28 2925, FK5 681, HD 166014, HIP 88794, HR 6779, SAO 85750

Database references
SIMBAD| data

Omicron Herculis, Latinized from o Herculis, is a star in the constellation Hercules.

## Contents

* 1 Nomenclature
* 2 Properties
* 3 References
* 4 External links

## Nomenclature

This star used to be called Masym (from Arabic for "the wrist"), but this name was transferred to Lambda Herculis.[11][12]

In Chinese astronomy, this is the fourth star of the asterism Tiān Shì Zuǒ Yuán (天市左垣, Left Wall of Heavenly Market Enclosure), representing the state Zhongshan (中山).[13] In R. H. Allen's book Star Names this name, transliterated as Chung Shan with the meaning "the Middle Mountain", was instead attributed to ν Her, ξ Her, and 99 (b) Her.[12]

## Properties

Omicron Herculis is a B9.5III star approximately 106 pc from the Earth. It has an apparent magnitude of 3.83. The star radiates with a bluish-white hue, and has a luminosity approximately 355 times as bright as the Sun. Omicron Herculis is 3.49 solar masses.[7] Stellar evolutionary caclulations show that it has just left the main sequence.[7]

Omicron Herculis is an eruptive variable of the Gamma Cassiopeiae class,[4] which are rapidly rotating B-class stars with mass outflow. It has a projected rotational velocity of 194 km/s.[10]

Some sources list Omicron Herculis as being both spectroscopic and an interferometric binary star with a separation of about 60 milliarcseconds, although the companion star has not been confirmed.[14]

Omicron Hercules is notable for residing close to the coordinates of the solar apex, the direction towards which the Sun is moving. This was first noticed by William Herschel in 1783,[15] although in his first calculation he identified this point with Lambda Herculis.[16] It will eventually become the brightest star in the night sky in approximately 3.47 million years from today, at –0.63,[17] slightly less bright than Canopus today.[17]

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
2. ↑ 2.0 2.1 2.2 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode: 1966CoLPL...4...99J.
3. ↑ Slettebak, A. (1982), "Spectral types and rotational velocities of the brighter Be stars and A-F type shell stars", Astrophysical Journal Supplement Series 50: 55, doi:10.1086/190820, Bibcode: 1982ApJS...50...55S.
4. ↑ 4.0 4.1 Samus, N. N. et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1 61 (1): 80–88, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S.
5. ↑ Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication (Washington: Carnegie Institution of Washington), Bibcode: 1953GCRV..C......0W.
6. ↑ 6.0 6.1 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
7. ↑ 7.0 7.1 7.2 Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics 537: A120, doi:10.1051/0004-6361/201117691, Bibcode: 2012A&A...537A.120Z.
8. ↑ 8.0 8.1 Stassun K.G. (October 2019), "The revised TESS Input Catalog and Candidate Target List", The Astronomical Journal 158 (4): 138, doi:10.3847/1538-3881/ab3467, Bibcode: 2019AJ....158..138S.
9. ↑ Anders, F. et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics 628: A94. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode: 2019A&A...628A..94A.
10. ↑ 10.0 10.1 Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics 463 (2): 671–682, doi:10.1051/0004-6361:20065224, Bibcode: 2007A&A...463..671R.
11. ↑ Kaler, Jim. "Omicron Herculis". http://stars.astro.illinois.edu/sow/omiher.html.
12. ↑ 12.0 12.1 Allen, R. H. (1899), Star Names: Their Lore and Meaning, p. 245, https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Hercules*.html
13. ↑ "AEEA 天文教育資訊網" (in zh). http://aeea.nmns.edu.tw/2006/0606/ap060623.html.
14. ↑ Hutter, D. J.; Tycner, C.; Zavala, R. T.; Benson, J. A.; Hummel, C. A.; Zirm, H. (2021). "Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical Be Stars". The Astrophysical Journal Supplement Series 257 (2): 69. doi:10.3847/1538-4365/ac23cb. Bibcode: 2021ApJS..257...69H.
15. ↑ Lankford, John (1997), History of astronomy: an encyclopedia, Garland encyclopedias in the history of science, 1, Taylor & Francis, p. 258, ISBN 0-8153-0322-X, https://archive.org/details/historyofastrono00john/page/258.
16. ↑ Herschel, William (1783). "On the Proper Motion of the Sun and Solar System; With an Account of Several Changes That Have Happened among the Fixed Stars since the Time of Mr. Flamstead [sic]". Philosophical Transactions of the Royal Society of London 73: 247–83. doi:10.1098/rstl.1783.0017.
17. ↑ 17.0 17.1 Tomkin, Jocelyn (April 1998). "Once and Future Celestial Kings". Sky and Telescope 95 (4): 59–63. Bibcode: 1998S&T....95d..59T. – based on computations from HIPPARCOS data. (The calculations exclude stars whose distance or proper motion is uncertain.) PDF

## External links

* http://www.alcyone.de/SIT/bsc/HR6779.html

* v
* t
* e

Hercules constellation

Stars (list)|

| Bayer|

* α (Rasalgethi)
* β (Kornephoros)
* γ
* δ (Sarin)
* ε
* ζ
* η
* θ
* ι
* κ (Marsic)
* λ (Maasym)
* μ
* ν
* ξ
* ο
* π
* ρ
* σ
* τ
* υ
* φ
* χ
* ω (Cujam)

|

Flamsteed|

* 2
* 4
* 5 (r)
* 8
* 9
* 10
* 12
* 13
* 14
* 15
* 16
* 17
* 18
* 19
* 21 (o)
* 25
* 26
* 28 (n)
* 29 (h)
* 30 (g)
* 31
* 32
* 33
* 34
* 36
* 37 (m)
* 38
* 39
* 41
* 42
* 43 (i)
* 45 (l)
* 46
* 47 (k)
* 48
* 49
* 50
* 51
* 52
* 53
* 54
* 56
* 57
* 59 (d)
* 60
* 61
* 62
* 63
* 68 (u)
* 69 (e)
* 70
* 72 (w)
* 73
* 74
* 77 (x)
* 78
* 79
* 82 (y)
* 83
* 84
* 87
* 88 (z)
* 89
* 90 (f)
* 93
* 95
* 96
* 97
* 98
* 99 (b)
* 100
* 101
* 102
* 104 (A)
* 105
* 106
* 107 (t)
* 108
* 109
* 110
* 111
* 112
* 113
* 32 Oph
* 33 Oph
* 34 Oph
* 48 Ser (q)
* 49 Ser

Variable|

* U
* X
* Z
* RS
* RU
* RX
* SS
* ST
* SY
* SZ
* TT
* TU
* TW
* TX
* UU
* UX
* VX
* VZ
* YY
* AC
* AD
* AH
* AK
* AM
* AP
* AR
* AW
* BB
* BL
* CC
* CT
* DI
* DQ
* DY
* HS
* LQ
* LT
* MM
* OP
* PW
* V338
* V443
* V446
* V451
* V533
* V535
* V600
* V624
* V636
* V640
* V642
* V644
* V656
* V728
* V771
* V772
* V773
* V775
* V777
* V792
* V795
* V814
* V815
* V819
* V822
* V827
* V829
* V831
* V835
* V838
* V842
* V844
* V857
* V884
* V899
* V934
* V959
* V974

HR|

* 5950
* 5964
* 6050
* 6057
* 6087
* 6090
* 6091
* 6121
* 6152 (s)
* 6154
* 6157
* 6162
* 6169
* 6181
* 6183
* 6203
* 6208
* 6222
* 6227
* 6230
* 6239
* 6246
* 6256
* 6259
* 6264
* 6286
* 6287
* 6301
* 6307
* 6313
* 6325
* 6333
* 6336
* 6343
* 6351
* 6352
* 6362
* 6363
* 6364
* 6376
* 6377 (c)
* 6388
* 6399
* 6419
* 6430
* 6432
* 6443
* 6444
* 6455
* 6463
* 6466
* 6467
* 6481
* 6482
* 6488
* 6491
* 6499
* 6502
* 6506
* 6528
* 6531
* 6541
* 6542
* 6550
* 6959
* 6563
* 6564
* 6570
* 6584
* 6589
* 6591
* 6592
* 6594
* 6599
* 6604
* 6612
* 6619
* 6627
* 6638
* 6641
* 6642
* 6654
* 6655
* 6665
* 6669
* 6673
* 6674
* 6687
* 6697
* 6711
* 6722
* 6726
* 6728
* 6737
* 6744
* 6753
* 6763
* 6767
* 6768
* 6791
* 6792
* 6793
* 6799
* 6803
* 6806
* 6807
* 6814
* 6820
* 6824
* 6826
* 6852
* 6854
* 6867
* 6882
* 6885
* 6887
* 6904
* 6906
* 6917
* 6924
* 6943
* 6950
* 6955
* 6966
* 6977
* 6980
* 6981
* 6995
* 7047
* 7067
* 7079
* 7086
* 7148

HD|

* 146389
* 147506
* 149026 (Ogma)
* 149908
* 151044
* 154345
* 155061
* 155358
* 156074
* 156668
* 158038
* 161817
* 164595
* 164922

Gliese|

* 623
* 638
* 649
* 669
* 686
* 3991

Other|

* ADS 10075
* BD +13° 3324
* BD +17° 3248
* BD +22° 3406
* Furuhjelm 46
* GD 362
* HAT-P-14
* HAT-P-18
* Hercules X-1
* GSC 02620-00648
* GSC 03089-00929
* IRAS 18062+2410
* PG 1654+160
* PG 1658+441
* PG 1707+427
* PG 1716+426
* Ross 640
* WISE 1738+2732
* WISE 1741+2553
* WISE 1804+3117

Star clusters|

| Globular|

* Messier 13
* Messier 92
* NGC 6229

|

Nebulae|

| Planetary|

* Abell 39
* IC 4593
* NGC 6058
* NGC 6210

|

Galaxies|

| NGC|

* 6013
* 6028
* 6030
* 6032
* 6034
* 6035
* 6039
* 6040
* 6041
* 6042
* 6043
* 6044
* 6045
* 6046
* 6047
* 6052
* 6053
* 6054
* 6055
* 6056
* 6057
* 6060
* 6061
* 6062
* 6073
* 6074
* 6075
* 6078
* 6081
* 6083
* 6084
* 6098
* 6099
* 6106
* 6113
* 6132
* 6138
* 6141
* 6145
* 6146
* 6147
* 6148
* 6149
* 6150
* 6154
* 6155
* 6158
* 6159
* 6160
* 6161
* 6162
* 6163
* 6166
* 6168
* 6173
* 6174
* 6175
* 6177
* 6179
* 6180
* 6181
* 6184
* 6185
* 6186
* 6194
* 6195
* 6196
* 6197
* 6201
* 6203
* 6207
* 6212
* 6219
* 6224
* 6225
* 6228
* 6230
* 6233
* 6239
* 6241
* 6243
* 6255
* 6257
* 6261
* 6263
* 6264
* 6265
* 6267
* 6269
* 6270
* 6271
* 6272
* 6274
* 6276
* 6278
* 6279
* 6282
* 6283
* 6301
* 6308
* 6311
* 6312
* 6313
* 6314
* 6315
* 6320
* 6321
* 6323
* 6327
* 6329
* 6330
* 6332
* 6336
* 6339
* 6343
* 6347
* 6348
* 6349
* 6350
* 6351
* 6363
* 6364
* 6367
* 6371
* 6372
* 6375
* 6379
* 6389
* 6408
* 6417
* 6427
* 6429
* 6430
* 6431
* 6433
* 6442
* 6443
* 6446
* 6447
* 6452
* 6458
* 6460
* 6467
* 6468
* 6482
* 6484
* 6485
* 6486
* 6487
* 6490
* 6495
* 6500
* 6501
* 6504
* 6513
* 6518
* 6524
* 6527
* 6547
* 6548
* 6549
* 6550
* 6555
* 6560
* 6571
* 6574
* 6575
* 6576
* 6577
* 6579
* 6580
* 6581
* 6582
* 6585
* 6586
* 6587
* 6591
* 6593
* 6599
* 6600
* 6602
* 6610
* 6616
* 6619
* 6623
* 6627
* 6628
* 6632
* 6635
* 6641
* 6658
* 6660
* 6661
* 6674
* 6680
* 6697

|

Other|

* A2261-BCG
* Arp 272 (NGC 6050 and IC 1179)
* AT2018cow
* IC 1182
* Hercules (dwarf galaxy)
* Hercules A
* MCG+07-33-027
* PGC 214560
* QSR J1819+3845

Galaxy clusters|

* Abell 2152
* Abell 2199
* Hercules Cluster
* Hercules Superclusters
* Zwicky's Triplet

Other|

* Hercules–Corona Borealis Great Wall
* LBG-2377

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