HD 199942

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]

HD 199942
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[1] mas
Distance184 ± 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
Mass1.65[7] M
Radius1.97+0.07
−0.09
[1] R
Luminosity10.2±0.3[1] L
Surface gravity (log g)3.94[7] cgs
Temperature7342+181
−115
[1] K
Rotational velocity (v sin i)159[4] km/s
Age1.016[7] Gyr
Other designations
5 G. Equulei, KUI 102, BD+06°4718, HD 199942, HIP 103652, HR 8038, SAO 126447, WDS J21001+0731AB[8]
Database references
SIMBADdata

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

  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. Gaia DR2 record for this source at VizieR.
  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.
  3. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920
  4. 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.
  5. Abt, H. A. (1981), "Visual multiples. VII - MK classifications", The Astrophysical Journal Supplement Series, 45: 437, Bibcode:1981ApJS...45..437A, doi:10.1086/190719.
  6. Hartkopf, W. I.; et al. (June 30, 2006), Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory, retrieved 2020-02-11.
  7. 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.
  8. "HD 199942". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-02-10.
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