Omicron Herculis

Last updated
o Herculis
Hercules constellation map.svg
Red circle.svg
Location of o Herculis (circled)
Observation data
Epoch J2000       Equinox J2000
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  mas [1]
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. It used to be called Masym ("the wrist"), but this name was transferred to Lambda Herculis. [11]

Contents

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. [12]

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, [13] although in his first calculation he identified this point with Lambda Herculis. [14] It will eventually become the brightest star in the night sky in approximately 3.47 million years from today, at –0.63, [15] slightly less bright than Canopus today. [15]

Related Research Articles

Sigma Serpentis, Latinized from σ Serpentis, is a star in the equatorial constellation Serpens. It is faintly visible to the naked eye with an apparent visual magnitude of +4.82. Based upon an annual parallax shift of 36.67 mas as seen from Earth, it is located 89 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −49 km/s.

<span class="mw-page-title-main">Gamma Trianguli Australis</span> Star in the constellation Triangulum Australe

Gamma Trianguli Australis, Latinized from γ Trianguli Australis, is a single, white-hued star in the southern constellation of Triangulum Australe. Along with Alpha and Beta Trianguli Australis it forms a prominent triangular asterism that gives the constellation its name. It is the third-brightest member of this constellation with an apparent visual magnitude of +2.87. Based upon parallax measurements, Gamma Trianguli Australis is located at a distance of about 184 light-years from Earth.

Omicron Arietis, Latinised from ο Arietis, is the Bayer designation for a single, blue-white-hued star in the northern constellation of Aries. It has an apparent visual magnitude of +5.78, which means it is dimly visible to the naked eye. Based upon an annual parallax shift of 5.49 mas as seen from Earth, it is located roughly 590 light-years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.22 due to interstellar dust.

47 Boötis is a binary star system in the northern constellation of Boötes, located 261 light years away from the Sun. It has the Bayer designation k Boötis; 47 Boötis is the Flamsteed designation. The system is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of 5.58. It is moving closer to the Earth with a heliocentric radial velocity of −13 km/s.

Lambda Herculis, formally named Maasym, is a star in the constellation of Hercules. From parallax measurements taken during the Gaia mission, it is approximately 393 light-years from the Sun.

<span class="mw-page-title-main">Omicron Capricorni</span> Star in the constellation Capricornus

Omicron Capricorni is a wide binary star system in the constellation Capricornus. The brighter component has an apparent visual magnitude of +5.94, which is near the lower limit on stellar brightness that still can be seen with the naked eye. Based upon an annual parallax shift of 15.07 mas as seen from Earth, this system is located roughly 220 light-years from the Sun. Large but uncertain discrepancies in the parallax measurements from Hipparcos may indicate, weakly, that there is a third, unseen companion in the system.

<span class="mw-page-title-main">Nu Cassiopeiae</span> B-type star in the constellation Cassiopeia

Nu Cassiopeiae, Latinized from ν Cassiopeiae, is a solitary star in the northern constellation of Cassiopeia. With an apparent visual magnitude of +4.89, it is a faint star but visible to the naked eye. Based upon an annual parallax shift of 7.92 mas as seen from Earth, this star is located around 410 light years from the Sun. Cowley et al. (1969) catalogued this star with a stellar classification of B9 III, indicating it has the spectrum of an evolved B-type giant star. However, Palmer et al. (1968) assigned it a class of B8 V, which would instead suggest it is an ordinary B-type main-sequence star.

HD 152010 is a solitary star in the southern circumpolar constellation Apus. It has an apparent magnitude of 6.48, placing it near the max visibility for the naked eye. Located 1,006 light yearsaway, the object is approaching the Solar System with a heliocentric radial velocity of −15 km/s.

Omega Aurigae, Latinized from ω Aurigae, is the Bayer designation for a double star in the northern constellation of Auriga. Its apparent magnitude is 4.95, which is bright enough to be seen with the naked eye. The distance to this system, as determined using parallax measurements, is approximately 162 light-years. The system is a member of the Columba group of co-moving stars.

16 Camelopardalis is a single star in the northern circumpolar constellation Camelopardalis, located 348 light years away from the Sun as determined from parallax measurements. It is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 5.28. This object is moving further from the Earth with a heliocentric radial velocity of around 12 km/s.

<span class="mw-page-title-main">Epsilon Herculis</span> Multiple star systen in the constellation Hercules

Epsilon Herculis, Latinized from ε Herculis, is a fourth-magnitude multiple star system in the northern constellation of Hercules. The combined apparent visual magnitude of 3.9111 is bright enough to make this system visible to the naked eye. Based upon an annual parallax shift of 21.04 mas as seen from Earth, it is located 155 light years from the Sun. The system is moving closer to the Sun with a radial velocity of −25 km/s.

<span class="mw-page-title-main">4 Scorpii</span> A-type main sequence star in the constellation Scorpius

4 Scorpii is a single star in the southern zodiac constellation of Scorpius. With an apparent visual magnitude of +5.6, it is dimly visible to the naked eye under good viewing conditions. The distance to this star can be estimated from its annual parallax shift of 7.99±0.77 mas, which yields a value of around 410 light years. It is moving closer to the Sun with a heliocentric radial velocity of −29 km/s and will reach perihelion in about two million years at an estimated distance of 280 ly (86 pc).

<span class="mw-page-title-main">Nu Cygni</span> Star in the constellation Cygnus

Nu Cygni, Latinized from ν Cygni, is a binary star system in the constellation Cygnus. Its apparent magnitude is 3.94 and it is approximately 374 light years away based on parallax. The brighter component is a magnitude 4.07 A-type giant star with a stellar classification of A0III n, where the 'n' indicates broad "nebulous" absorption lines due to rapid rotation. This white-hued star has an estimated 3.6 times the mass of the Sun and about 1.9 times the Sun's radius. It is radiating 412 times the Sun's luminosity from its photosphere at an effective temperature of 9,462 K. The magnitude 6.4 companion has an angular separation of 0.24" from the primary.

<span class="mw-page-title-main">27 Vulpeculae</span> Star in the constellation Vulpecula

27 Vulpeculae is a single, blue-white star in the northern constellation of Vulpecula. It is a dim star, visible to the naked eye, with an apparent visual magnitude of 5.59. An annual parallax shift of 10.6692±0.0483 mas provides a distance estimate of about 306 light-years. It is moving closer with a heliocentric radial velocity of −22 km/s, and will make perihelion passage at a distance of around 119 ly (36.56 pc) in 3.75 million years.

60 Herculis is a single star located 134 light years away from the Sun in the northern constellation of Hercules, and is positioned just seven degrees away from Rasalgethi. It is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.871. This star is moving closer to the Earth with a heliocentric radial velocity of −4 km/s.

Rho Herculis is a double star in the constellation of Hercules. The apparent magnitudes of the components are 4.510 and 5.398, respectively. Parallax measurements published in Gaia Data Release 2 put the system at some 360-390 light-years away.

HD 3322 is a binary star system in the northern constellation of Andromeda. With an apparent visual magnitude of 6.51, it lies below the nominal brightness limit for visibility with the normal naked eye, but it is still possible to see the star with excellent vision under ideal seeing conditions. An annual parallax shift of 4.59±0.65 mas provides a distance estimate of roughly 700 light years.

<span class="mw-page-title-main">HD 93905</span> Star in the constellation Antlia

HD 93905 is a solitary star located in the southern constellation Antlia. The star has an absolute magnitude of 0 and an apparent magnitude of 5.61, making it faintly visible to the naked eye under ideal conditions. The star is located 371 light years away based on its parallax shift and is drifting closer with a helocentric radial velocity of −9.6 km/s.

HD 34868 is a solitary star located in the southern constellation Columba. With an apparent magnitude of 5.97, it's barely visible to the unaided eye. The star is located 410 light years away based on parallax, but is drifting away with a heliocentric radial velocity of 18 km/s.

<span class="mw-page-title-main">HD 31134</span> Star in the constellation of Camelopardalis

HD 31134, also designated as HR 1561, is a solitary star located in the northern circumpolar constellation Camelopardalis, the giraffe. It is faintly visible to the naked eye as a white-hued star with an apparent magnitude of 5.74. Gaia DR3 parallax measurements place it 473 light years away. It appears to be approaching the Solar System with a heliocentric radial velocity of −15.1 km/s. At its current distance, HD 31134's brightness is diminished by 0.35 magnitudes due to interstellar dust. It has an absolute magnitude of +0.19.

References

  1. 1 2 3 4 5 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv: 0708.1752 , Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID   18759600.
  2. 1 2 3 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, Bibcode:1982ApJS...50...55S, doi: 10.1086/190820 .
  4. 1 2 Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID   125853869.
  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. 1 2 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv: 1108.4971 , Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID   119257644.
  7. 1 2 3 Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv: 1201.2052 , Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID   55586789.
  8. 1 2 Stassun K.G.; et al. (October 2019), "The revised TESS Input Catalog and Candidate Target List", The Astronomical Journal , 158 (4): 138, arXiv: 1905.10694 , Bibcode:2019AJ....158..138S, doi:10.3847/1538-3881/ab3467, S2CID   166227927.
  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. arXiv: 1904.11302 . Bibcode:2019A&A...628A..94A. doi: 10.1051/0004-6361/201935765 . ISSN   0004-6361.
  10. 1 2 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, arXiv: astro-ph/0610785 , Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID   18475298.
  11. ↑ Kaler, Jim. "Omicron Herculis" . Retrieved 2016-05-13.
  12. ↑ 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. arXiv: 2109.06839 . Bibcode:2021ApJS..257...69H. doi:10.3847/1538-4365/ac23cb. S2CID   237503492.
  13. ↑ Lankford, John (1997), History of astronomy: an encyclopedia , Garland encyclopedias in the history of science, vol. 1, Taylor & Francis, p.  258, ISBN   0-8153-0322-X.
  14. ↑ 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. JSTOR   106492. S2CID   186213288.
  15. 1 2 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 [ permanent dead link ]
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