HR 6384

HR 6384 is a binary star system in the southern constellation of Ara, the Altar. The system is faintly visible to the naked eye with a combined apparent visual magnitude that fluctuates around 6.153,[2] and it is located at a distance of approximately 1,300 light-years (400 parsecs) from the Sun.[1] It is drifting closer with a radial velocity of around −34 km/s.[5]

HR 6384
Observation data
Epoch J2000      Equinox J2000
Constellation Ara
Right ascension  17h 14m 13.40536s[1]
Declination –56° 53′ 18.6897″[1]
Apparent magnitude (V) 6.153[2]
Characteristics
Spectral type M1/M2II/III + A[3]
U−B color index +1.340[2]
B−V color index +1.787[2]
Variable type ellipsoidal variable[4]
Astrometry
Radial velocity (Rv)−34.0±4.0[5] km/s
Proper motion (μ) RA: 2.760[1] mas/yr
Dec.: –7.033[1] mas/yr
Parallax (π)2.2407 ± 0.1939[1] mas
Distance1,500 ± 100 ly
(450 ± 40 pc)
Absolute magnitude (MV)−2.20[5]
Details
Radius160.39+9.31
−23.02[1] R☉
Luminosity3,732±368[1] L☉
Temperature3,562+287
−99[1] K
Other designations
V829 Ara, CD–56°6744, HD 155341, HIP 84311, HR 6384, SAO 244539[6]
Database references
SIMBADdata

The system appears to be a close, interacting binary with a hot secondary component of class A or hotter.[7] It forms a suspected ellipsoidal variable[4] with a period of 80 days and an amplitude variation of 0.08 in magnitude.[8] The primary component is an aging red giant/bright giant with a stellar classification of M1/M2II/III,[3] currently on the asymptotic giant branch.[9] With the supply of hydrigen at its core exhausted, it has expanded to 160 times the girth of the Sun. It is radiating 3,562 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 3,562 K.[1]

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. Walker, W. S. G.; Marino, B. F.; Herdman, G. (August 1985), "Photometry of HR 6384 - an 80 Day Ellipsoidal Binary?", Information Bulletin on Variable Stars, 2775: 1, Bibcode:1985IBVS.2775....1W.
  3. Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  4. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085.
  5. 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.
  6. "V829 Ara". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-12-07.
  7. Ake, T. B.; Parsons, S. B. (March 1985), "HR 6384: a Probable Interacting Binary", Information Bulletin on Variable Stars, 2686: 1, Bibcode:1985IBVS.2686....1A.
  8. Hoffleit, Dorrit (1996), "A Catalogue of Correlations Between Eclipsing Binaries and Other Categories of Double Stars", The Journal of the American Association of Variable Star Observers, 24 (2): 105–116, Bibcode:1996JAVSO..24..105H.
  9. Eggen, Olin J. (July 1992), "Asymptotic giant branch stars near the sun", Astronomical Journal, 104 (1): 275–313, Bibcode:1992AJ....104..275E, doi:10.1086/116239.
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