R Arae

R Arae is an Algol-type eclipsing binary in the constellation Ara. Located approximately 298 parsecs (970 ly) distant, it normally shines at magnitude 6.17, but during eclipses can fall as low as magnitude 7.32.[2] It has been suggested by multiple studies that mass transfer is occurring between the two stars of this system,[6][7] and the period of eclipses seems to be increasing over time.[7] The primary is a blue-white main sequence star of spectral type B5V that is 5 times as massive as the Sun, while the secondary is a yellow-white star of spectral type F1IV that is 1.5 times as massive as the Sun. Stellar material is being stripped off the secondary and accreting on the primary.[4]

R Arae
Observation data
Epoch J2000      Equinox J2000
Constellation Ara
Right ascension 16h 39m 44.726s[1]
Declination −56° 59′ 39.92″[1]
Apparent magnitude (V) 6.17 (- 6.20) - 7.32[2]
Characteristics
Spectral type B9Vp[3] (B5V + F1IV[4])
B−V color index 0.10[4]
Variable type Algol[3]
Astrometry
Radial velocity (Rv)+5.5[4] km/s
Proper motion (μ) RA: −4.991[5] mas/yr
Dec.: −17.810[5] mas/yr
Parallax (π)3.3603 ± 0.0647[5] mas
Distance970 ± 20 ly
(298 ± 6 pc)
Absolute magnitude (MV)−0.48 + 0.00[4]
Orbit[4]
Period (P)4.425 d
Eccentricity (e)0
Inclination (i)78.0°
Semi-amplitude (K1)
(primary)		55.3 km/s
Semi-amplitude (K2)
(secondary)		181.6 km/s
Details[4]
A
Mass5.0 M☉
Radius3.41 R☉
Luminosity257 L☉
Surface gravity (log g)4.07 cgs
Temperature12,500 K
Rotational velocity (v sin i)202[4] km/s
B
Mass1.5 M☉
Radius5.97 R☉
Luminosity78 L☉
Surface gravity (log g)3.07 cgs
Temperature7,000 K
Rotational velocity (v sin i)73 km/s
Other designations
HIP 81589, CD-56°6482, SAO 244037, HD 149730
Database references
SIMBADdata

R Arae has an 8th-magnitude companion 3″ away.[4] The companion star is at a similar distance.[8]

References
  1. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. VSX (25 October 2010). "R Arae". AAVSO Website. American Association of Variable Star Observers. Retrieved 30 June 2014.
  3. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  4. Bakıș, H.; Bakıș, V.; Eker, Z.; Demircan, O. (2016). "Active binary R Arae revisited: Bringing the secondary component to light and physical modelling of the circumstellar material". Monthly Notices of the Royal Astronomical Society. 458 (1): 508–516. Bibcode:2016MNRAS.458..508B. doi:10.1093/mnras/stw320.
  5. 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.
  6. Nield, K. M. (1991). "Observations and analysis of the Southern binary R Arae". Astrophysics and Space Science. 180 (2): 233–252. Bibcode:1991Ap&SS.180..233N. doi:10.1007/BF00648180. S2CID 122896654.
  7. Reed, P. A.; McCluskey Jr., G. E.; Kondo, Y.; Sahade, J.; Guinan, E. F.; GiméNez, A.; Caton, D. B.; Reichart, D. E.; Ivarsen, K. M.; Nysewander, M. C. (2010). "Ultraviolet study of the active interacting binary star R Arae using archivalIUEdata". Monthly Notices of the Royal Astronomical Society. 401 (2): 913. arXiv:0909.4047. Bibcode:2010MNRAS.401..913R. doi:10.1111/j.1365-2966.2009.15741.x. S2CID 15237238.
  8. 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.
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