HD 83953 (I Hydrae) is a single,[9] blue-white hued star in the equatorial constellation of Hydra. It is visible to the naked eye, having an apparent visual magnitude of 4.76.[2] Based upon an annual parallax shift of 6.6 mas,[1] the distance to this star is estimated as 500 light years. It is moving further from Earth with a heliocentric radial velocity of +16 km/s.[4]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 09h 41m 17.00785s[1] |
| Declination | −23° 35′ 29.4325″[1] |
| Apparent magnitude (V) | 4.76[2] |
| Characteristics | |
| Spectral type | B5 V[3] |
| B−V color index | −0.117±0.015[2] |
| Astrometry | |
| Radial velocity (Rv) | +16.05±1.5[4] km/s |
| Proper motion (μ) | RA: −29.969[1] mas/yr Dec.: +1.914[1] mas/yr |
| Parallax (π) | 6.5733 ± 0.2851 mas[1] |
| Distance | 500 ± 20 ly (152 ± 7 pc) |
| Absolute magnitude (MV) | −1.19[2] |
| Details | |
| Mass | 4.57±0.08[5] M☉ |
| Radius | 4.00±0.08[6] R☉ |
| Luminosity | 708+60 −55[5] L☉ |
| Surface gravity (log g) | 2.54±0.03[6] cgs |
| Temperature | 15,000±150[6] K |
| Rotational velocity (v sin i) | 315[5][7] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a B-type main-sequence star with a stellar classification of B5 V.[3] It has been known to be a Be star since 1926, when an Hβ emission line was discovered in the stellar spectrum by Mount Wilson Observatory.[10] This energy is coming from a circumstellar envelope of heated gas that has been expelled from the central star and formed a thin orbiting disk.[11] HD 83953 is spinning rapidly with a projected rotational velocity of 315 km/s, giving the star an oblate shape with an equatorial bulge that is 18% larger than the polar radius.[7]
HD 83953 has 4.6[5] times the mass of the Sun and 4.0[6] times the Sun's radius. It is radiating 708[5] times the Sun's luminosity from its photosphere at an effective temperature of 15,000 K.[6]
References
edit- ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
- ^ a b c d 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.
- ^ a b Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
- ^ a b Becker, Juliette C.; et al. (April 2015), "Extracting Radial Velocities of A- and B-type Stars from Echelle Spectrograph Calibration Spectra", The Astrophysical Journal Supplement Series, 217 (2): 13, arXiv:1503.03874, Bibcode:2015ApJS..217...29B, doi:10.1088/0067-0049/217/2/29, S2CID 33968873, 29.
- ^ a b c d e 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.
- ^ a b c d e Arcos, C.; et al. (March 2018), "Stellar parameters and H α line profile variability of Be stars in the BeSOS survey", Monthly Notices of the Royal Astronomical Society, 474 (4): 5287–5299, arXiv:1711.08675, Bibcode:2018MNRAS.474.5287A, doi:10.1093/mnras/stx3075.
- ^ a b Belle, G. T. (2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.
- ^ "HD 83953". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-25.
- ^ Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
- ^ Merrill, Paul W.; Burwell, Cora G. (September 1933), "Catalogue and Bibliography of Stars of Classes B and A whose Spectra have Bright Hydrogen Lines", Astrophysical Journal, 78: 87, Bibcode:1933ApJ....78...87M, doi:10.1086/143490.
- ^ Arcos, C.; et al. (June 2017), "Evidence for Different Disk Mass Distributions Between Early and Late-Type Be Stars in the BeSOS Survey", The Astrophysical Journal, 842 (1): 18, arXiv:1704.08133, Bibcode:2017ApJ...842...48A, doi:10.3847/1538-4357/aa6f5f, S2CID 119418279, 48.