Astronomy:HD 77258
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Vela |
| Right ascension | 09h 00m 05.4104s[1] |
| Declination | −41° 15′ 12.9734″[1] |
| Apparent magnitude (V) | 4.45[2] |
| Characteristics | |
| Spectral type | G8-K1III[3] + A7[4] |
| B−V color index | 0.75±0.02[2] |
| Variable type | Constant[3] |
| Astrometry | |
| Radial velocity (Rv) | −7.4±4.1[2] km/s |
| Proper motion (μ) | RA: −42.227[1] mas/yr Dec.: 50.599[1] mas/yr |
| Parallax (π) | 14.9687 ± 0.2155[1] mas |
| Distance | 218 ± 3 ly (66.8 ± 1.0 pc) |
| Absolute magnitude (MV) | 0.40[2] |
| Orbit[3] | |
| Period (P) | 74.13715±0.00073 d |
| Semi-major axis (a) | ≥ (2.0057±0.0004)×107 km |
| Eccentricity (e) | 0.00085±0.00019 |
| Periastron epoch (T) | 2453625.5112±0.0017 HJD |
| Argument of periastron (ω) (secondary) | 106±13° |
| Semi-amplitude (K1) (primary) | 19.6744±0.0041 km/s |
| Details | |
| A | |
| Radius | 7.97+0.66 −1.42[1] R☉ |
| Luminosity | 68.769±1.152[1] L☉ |
| Temperature | 5889+607 −232[1] K |
| Metallicity [Fe/H] | 0.72±0.15[5] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 77258 is a binary star system in the southern constellation of Vela. It has the Bayer designation w Velorum, while HD 77258 is the identifier from the Henry Draper Catalogue. The system is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.45.[2] It is located at a distance of approximately 218 light years from the Sun based on parallax.[1] The radial velocity of the system barycenter is poorly constrained, but it appears to be drifting away at a rate of ~7 km/s.[2]
The radial velocity variation of this system was first reported by H. K. Palmer in 1904. It is a single-lined spectroscopic binary with an orbital period of 74.14 days and an eccentricity (ovalness) of 0.00085, indicating the orbit is essentially circular.[3] The visible component has a stellar classification of G8-K1III,[3] matching a late G-type giant star. This is an evolved star that has exhausted the supply of hydrogen at its core, then cooled and expanded away from the main sequence. In 1975, S. Maladora flagged the spectrum as peculiar.[7]
The level of ultraviolet flux coming from this system suggests the companion is a hot A-type star of class A6.5 or A7.[4] The system is a source of X-ray emission.[8]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 3.0 3.1 3.2 3.3 3.4 Hearnshaw, J. B. et al. (2012). "A study of non-Keplerian velocities in observations of spectroscopic binary stars". Monthly Notices of the Royal Astronomical Society 427 (1): 298–310. doi:10.1111/j.1365-2966.2012.21802.x. Bibcode: 2012MNRAS.427..298H.
- ↑ 4.0 4.1 Parsons, Sidney B.; Ake, Thomas B. (November 1998). "Ultraviolet and Optical Studies of Binaries with Luminous Cool Primaries and Hot Companions. V. The Entire IUE Sample". The Astrophysical Journal Supplement Series 119 (1): 83–104. doi:10.1086/313152. Bibcode: 1998ApJS..119...83P.
- ↑ Gáspár, András et al. (2016). "The Correlation between Metallicity and Debris Disk Mass". The Astrophysical Journal 826 (2): 171. doi:10.3847/0004-637X/826/2/171. Bibcode: 2016ApJ...826..171G.
- ↑ "HD 77258". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+77258.
- ↑ Malaroda, S. (August 1975). "Study of the F-type stars. I. MK spectral types.". Astronomical Journal 80: 637–641. doi:10.1086/111786. Bibcode: 1975AJ.....80..637M.
- ↑ Pizzolato, N. et al. (1998). Donahue, R. A.; Bookbinder, J. A.. eds. "Evolution of X-ray Activity of 1-3 M_odot Late-Type Stars in Early Post-Main-Sequence Phases". The Tenth Cambridge Workshop on Cool Stars, Stellar Systems and the Sun. ASP Conference Series 154: 1146. Bibcode: 1998ASPC..154.1146P.
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