HD 161840 is a single,[8] 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.[2] With an annual parallax shift of 6.5 mas[1] it is located roughly 500 light years from the Sun. It is moving closer with a heliocentric radial velocity of −13 km/s.[2]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius |
| Right ascension | 17h 48m 10.47559s[1] |
| Declination | −31° 42′ 11.5636″[1] |
| Apparent magnitude (V) | 4.79[2] |
| Characteristics | |
| Spectral type | B8 Ib/II[3] |
| B−V color index | −0.028±0.023[2] |
| Astrometry | |
| Radial velocity (Rv) | −13.3±2.8[2] km/s |
| Proper motion (μ) | RA: +6.845[1] mas/yr Dec.: −8.161[1] mas/yr |
| Parallax (π) | 6.5831 ± 0.3618 mas[1] |
| Distance | 500 ± 30 ly (152 ± 8 pc) |
| Absolute magnitude (MV) | −1.37[2] |
| Details | |
| Mass | 3.93±0.08[4] M☉ |
| Radius | 3.2[5] R☉ |
| Luminosity | 565+59 −53[4] L☉ |
| Surface gravity (log g) | 3.38[6] cgs |
| Temperature | 11066+77 −76[4] K |
| Rotational velocity (v sin i) | 24[4] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
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,[3] which corresponds to a B-type bright giant/lesser supergiant mix. Multiple studies still use an older classification of B8 V,[8][6][4] suggesting instead this is a B-type main-sequence star. Garrison and Gray (1994) assigned it a class of B8 III-IV,[9] which would put it on the subgiant/giant star track. It has an estimated 3.93[4] times the mass of the Sun and 3.2[5] times the Sun's radius. The star is radiating 565[4] times the Sun's luminosity from its photosphere at an effective temperature of 11,066 K.[4]
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 e f 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 (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.
- ^ a b c d e f g 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.
- ^ a b 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.
- ^ a b 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.
- ^ a b 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.