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HD 83953 (I Hydrae) is a single, 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. Based upon an annual parallax shift of 6.6 mas, 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.

This is a B-type main-sequence star with a stellar classification of B5 V. 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. 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. 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.

HD 83953 has 4.6 times the mass of the Sun and 4.0 times the Sun's radius. It is radiating 708 times the Sun's luminosity from its photosphere at an effective temperature of 15,000 K.

References

1. ^ 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.
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.
3. ^ 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.
4. ^ 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.
5. ^ 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.
6. ^ 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.
7. ^ 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.
8. "HD 83953". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-25.
9. 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.
10. 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.
11. 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.

• B-type main-sequence stars
• Be stars
• Hydra (constellation)
• Bayer objects
• Durchmusterung objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects