Summary
HD 199942 is a binary star system in the northern constellation of Equuleus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.98.[2] The system is located at a distance of approximately 184 light years based on parallax, and it has an absolute magnitude of 1.59.[2] It is drifting closer with a radial velocity of −26 km/s.[2]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Equuleus |
| Right ascension | 21h 00m 03.99267s[1] |
| Declination | +07° 30′ 58.3018″[1] |
| Apparent magnitude (V) | 5.98[2] (6.23 + 8.13)[3] |
| Characteristics | |
| Evolutionary stage | Main sequence[4] |
| Spectral type | F1Vp[3] or F1VgF1mA8[5] |
| B−V color index | 0.283±0.006[2] |
| Astrometry | |
| Radial velocity (Rv) | −26.2[2] km/s |
| Proper motion (μ) | RA: +40.810[1] mas/yr Dec.: +30.445[1] mas/yr |
| Parallax (π) | 17.7360 ± 0.4820 mas[1] |
| Distance | 184 ± 5 ly (56 ± 2 pc) |
| Absolute magnitude (MV) | 1.59[2] |
| Orbit[6] | |
| Period (P) | 58.40 yr |
| Semi-major axis (a) | 0.295″ |
| Eccentricity (e) | 0.295 |
| Inclination (i) | 130.8° |
| Longitude of the node (Ω) | 192.0° |
| Periastron epoch (T) | 1959.09 |
| Argument of periastron (ω) (secondary) | 318.1° |
| Details | |
| A | |
| Mass | 1.65[7] M☉ |
| Radius | 1.97+0.07 −0.09[1] R☉ |
| Luminosity | 10.2±0.3[1] L☉ |
| Surface gravity (log g) | 3.94[7] cgs |
| Temperature | 7342+181 −115[1] K |
| Rotational velocity (v sin i) | 159[4] km/s |
| Age | 1.016[7] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This system is moving through the galaxy at a velocity of 30.3 km/s relative to the Sun. Its galactic orbit carry it somewhere between 25100-22000 light years from the galactic core, and it'll come at its closest to the Sun 2.1 million years from now, at a distance of 124.0 light-years.[2]
The binary nature of this system was discovered in 1934 by G. P. Kuiper, who found the pair had an angular separation of 0.3″.[3] The pair orbit each other with a period of 58.4 years and an eccentricity of 0.295.[6] The primary component is of visual magnitude 6.23 and is a chemically-peculiar F-type main-sequence star with a class of F1Vp.[3] The companion is of magnitude 8.13.[3]
References edit
- ^ a b c d e f g h 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. Gaia DR2 record for this source at VizieR.
- ^ a b c d e f g h 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 c d e Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920
- ^ a b 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.
- ^ Abt, H. A. (1981), "Visual multiples. VII - MK classifications", The Astrophysical Journal Supplement Series, 45: 437, Bibcode:1981ApJS...45..437A, doi:10.1086/190719.
- ^ a b Hartkopf, W. I.; et al. (June 30, 2006), Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory, retrieved 2020-02-11.
- ^ a b c David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
- ^ "HD 199942". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-02-10.