Astronomy:HD 20104

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Short description: Visual binary in the constellation Camelopardalis
HD 20104
Observation data
{{#ifeq:J2000.0 (ICRS)|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| [[History:Epoch|Epoch J2000.0 (ICRS)]]      [[Astronomy:Equinox (celestial coordinates)|Equinox J2000.0 (ICRS)}}
Constellation Camelopardalis
A
Right ascension  03h 17m 31.527s[1]
Declination +65° 39′ 30.11″[1]
Apparent magnitude (V) 7.05±0.01[1]
B
Right ascension  03h 17m 31.593s[1]
Declination +65° 39′ 30.26″[1]
Apparent magnitude (V) 7.39±0.01[1]
Characteristics
A
Spectral type A2 V[2]
U−B color index +0.06[3]
B−V color index +0.08[3]
B
Spectral type A4V[2]
Astrometry
Radial velocity (Rv)−6±2[4] km/s
Proper motion (μ) RA: −10.54[5] mas/yr
Dec.: +5.84[5] mas/yr
Parallax (π)5.92 ± 0.65[5] mas
Distanceapprox. 550 ly
(approx. 170 pc)
Absolute magnitude (MV)+0.3[6]
Orbit[7]
PrimaryHD 20104 A
CompanionHD 20104 B
Period (P)350 yr
Semi-major axis (a)0.46″
Eccentricity (e)0.4
Inclination (i)135°
Longitude of the node (Ω)58°
Periastron epoch (T)2055.0
Argument of periastron (ω)
(secondary)		100°
Details
A
Mass2.46[8] M☉
B
Mass2.27[8] M☉
Other designations
Database references
SIMBADThe system
A
B

HD 20104 (HR 967) is a visual binary in the northern circumpolar constellation Camelopardalis. The system has a combined apparent magnitude of 6.41,[9] making it near naked eye visibility. When resolved in a large telescope, HD 20104 appears to be a pair of 7th magnitude A-type main-sequence stars with a separation of about 0.5″.[10] Located approximately 550 light years away,[5] the system is approaching the Sun with a heliocentric radial velocity of −6 km/s.[4]

The system's stars have masses twice that of the Sun[8] and effective temperatures ranging from 8,100 to 8,700 K,[9][11] typical of stars their type. The primary radiates at 71.3 solar luminosity[11] − over luminous for its class − and spins with a projected rotational velocity of 159 km/s.[12] HD 20104 has an age of 313 million years.[11]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Fabricius, C.; Høg, E.; Makarov, V. V.; Mason, B. D.; Wycoff, G. L.; Urban, S. E. (March 2002). "The Tycho double star catalogue". Astronomy & Astrophysics 384 (1): 180–189. doi:10.1051/0004-6361:20011822. ISSN 0004-6361. Bibcode: 2002A&A...384..180F. 
  2. ↑ 2.0 2.1 Edwards, T. W. (April 1976). "MK classification for visual binary components". The Astronomical Journal 81: 245. doi:10.1086/111879. ISSN 0004-6256. Bibcode: 1976AJ.....81..245E. 
  3. ↑ 3.0 3.1 Haupt, H. F.; Schroll, A. (1974). "Photoelektrische Photometrie von Shell-Sternen.". Astronomy and Astrophysics Supplement Series 15: 311–319. ISSN 0365-0138. Bibcode: 1974A&AS...15..311H. 
  4. ↑ 4.0 4.1 Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities.". Carnegie Institute Washington D.C. Publication: 0. Bibcode: 1953GCRV..C......0W. 
  5. ↑ 5.0 5.1 5.2 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy & Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. ISSN 0004-6361. Bibcode: 2007A&A...474..653V. 
  6. ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation" (in en). Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  7. ↑ Heintz, W. D. (July 1998). "Observations of Double Stars. XVIII.". The Astrophysical Journal Supplement Series 117 (2): 587–598. doi:10.1086/313127. Bibcode: 1998ApJS..117..587H. 
  8. ↑ 8.0 8.1 8.2 Cvetkovic, Zorica; Ninkovic, S. (2010). "On the component masses of visual binaries". Serbian Astronomical Journal 180 (180): 71–80. doi:10.2298/SAJ1080071C. Bibcode: 2010SerAJ.180...71C. 
  9. ↑ 9.0 9.1 Anders, F.; Khalatyan, A.; Chiappini, C.; Queiroz, A. B.; Santiago, B. X.; Jordi, C.; Girardi, L.; Brown, A. G. A. et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics 628: A94. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode: 2019A&A...628A..94A. 
  10. ↑ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal 122 (6): 3466–3471. doi:10.1086/323920. ISSN 0004-6256. Bibcode: 2001AJ....122.3466M. 
  11. ↑ 11.0 11.1 11.2 Zorec, J.; Royer, F. (January 2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics 537: A120. doi:10.1051/0004-6361/201117691. ISSN 0004-6361. Bibcode: 2012A&A...537A.120Z. 
  12. ↑ Royer, F.; Zorec, J.; Gómez, A. E. (February 2007). "Rotational velocities of A-type stars: III. Velocity distributions". Astronomy & Astrophysics 463 (2): 671–682. doi:10.1051/0004-6361:20065224. ISSN 0004-6361. Bibcode: 2007A&A...463..671R. 



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