| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius |
| Right ascension | 17 48 10.47559 |
| Declination | −31° 42′ 11.5636″ |
| Apparent magnitude (V) | 4.79 |
| Characteristics | |
| Spectral type | B8 Ib/II |
| B−V color index | −0.028±0.023 |
| Astrometry | |
| Radial velocity (Rv) | −13.3±2.8 km/s |
| Proper motion (μ) | RA: +6.845 mas/yr Dec.: −8.161 mas/yr |
| Parallax (π) | 6.5831 ± 0.3618 mas |
| Distance | 500 ± 30 ly (152 ± 8 pc) |
| Absolute magnitude (MV) | −1.37 |
| Details | |
| Mass | 3.93±0.08 M☉ |
| Radius | 3.2 R☉ |
| Luminosity | 565+59 −53 L☉ |
| Surface gravity (log g) | 3.38 cgs |
| Temperature | 11066+77 −76 K |
| Rotational velocity (v sin i) | 24 km/s |
| Other designations | |
| CD−31° 14609, HD 161840, HIP 87220, HR 6628, SAO 209303 | |
| Database references | |
| SIMBAD | data |
HD 161840 is a single, blue-white hued star in the southern zodiac constellation of Scorpius. It is faintly visible to the naked eye with an apparent visual magnitude of 4.79. With an annual parallax shift of 6.5 mas it is located roughly 500 light years from the Sun. It is moving closer with a heliocentric radial velocity of −13 km/s.
There has been some uncertainty as to the classification of this stage. Houk (1979) lists a stellar class of B8 Ib/II for HD 161840, which corresponds to a B-type bright giant/lesser supergiant mix. Multiple studies still use an older classification of B8 V, suggesting instead this is a B-type main-sequence star. Garrison and Gray (1994) assigned it a class of B8 III-IV, which would put it on the subgiant/giant star track. It has an estimated 3.93 times the mass of the Sun and 3.2 times the Sun's radius. The star is radiating 565 times the Sun's luminosity from its photosphere at an effective temperature of 11,066 K.
References
- ^ 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.
- ^ 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.
- ^ Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H.
- ^ 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.
- ^ Pasinetti Fracassini, L. E.; et al. (2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy & Astrophysics, 367 (3rd ed.): 521–24, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
- ^ Hempel, M.; Holweger, H. (September 2003), "Abundance analysis of late B stars. Evidence for diffusion and against weak stellar winds", Astronomy and Astrophysics, 408: 1065–1076, Bibcode:2003A&A...408.1065H, doi:10.1051/0004-6361:20030889.
- "HD 161840". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-08-04.
- ^ 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.
- Garrison, R. F.; Gray, R. O (1994), "The late B-type stars: Refined MK classification, confrontation with stromgren photometry, and the effects of rotation", The Astronomical Journal, 107: 1556, Bibcode:1994AJ....107.1556G, doi:10.1086/116967.
