RR Centauri

Light curve of RR Cen.
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension 14h 16m 57.22s[1]
Declination −57° 51′ 15.6″[1]
Apparent magnitude (V) 7.29[2] (7.27 - 7.68[3])
Characteristics
Spectral type F0 V[4]
U−B color index +0.05[2]
B−V color index +0.36[2]
Variable type W Uma[3]
Astrometry
Radial velocity (Rv)-16.0 [5] km/s
Proper motion (μ) RA: -52.00[6] mas/yr
Dec.: -22.63[6] mas/yr
Parallax (π)10.16 ± 0.61 mas[6]
Distance320 ± 20 ly
(98 ± 6 pc)
Absolute magnitude (MV)+1.882[4]
Orbit[7]
PrimaryRR Cen1
CompanionRR Cen2
Period (P)0.60569 days
Semi-major axis (a)3.92 ± 0.19 R☉
Eccentricity (e)0
Inclination (i)81.00 ± 0.44°
Details[7]
RR Cen1
Mass1.82 ± 0.26 M☉
Radius2.1 ± 0.01 R☉
Luminosity8.89 L☉
Temperature6,912 K
RR Cen2
Mass0.38 ± 0.06 M☉
Radius1.05 ± 0.03 R☉
Luminosity2.2 L☉
Temperature6,891 ± 13 K
Other designations
RR Cen, 2MASS J14165721-5751156, HD 124689, HIP 69779, SAO 241587, TYC 8686-210-1, Cordoba Durchmusterung CD-57 5498[1]
Database references
SIMBADdata

RR Centauri is a variable star of apparent magnitude maximum +7.29. It is located in the constellation of Centaurus, approximately 320 light years distant from the solar system.[6]

The system is a contact binary of the W UMa type - two stars in physical contact whose two components share a gaseous envelope — with a variation in brightness of 0.41 magnitude.[7] Its spectral type is A9V or F0V.[1] The binary nature of the star was discovered in 1896 by the Scottish-South African astronomer Alexander Roberts, so the system has been well observed for over a century.[8] The primary component has a mass of 1.82 solar masses, an effective temperature of around 6900 K, and a radius somewhat larger than twice the solar radius.[7] The secondary component is 0.39 solar masses, giving a mass ratio of the system (q) of 0.210. the secondary has a temperature of about 6890 K and a radius is almost equal to the solar radius.

The orbital period of this system is 0.6057 days (14.54 h). Calculations by astronomers from the Chinese Academy of Sciences show a possible cyclic variation in orbital period over 65.1±0.4 years whose amplitude is 0.0124±0.0007 d.[7] The origin of this periodic variation could be due to the gravitational influence of a third object yet observed. Superimposed on this variation seems to be a secular increase in the period of 1.21×10−7 d/a, suggesting that there is transfer of stellar mass from secondary to primary component. If this increase is confirmed, RR Centauri may evolve into a single rapidly rotating star.

References

  1. ^ a b c d "V* RR Cen -- Eclipsing binary of W UMa type (contact binary)". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2016-02-27.
  2. ^ a b c Loden, L.O. (1979). "Continued studies of loose clusterings in the Southern Milky Way". Astronomy and Astrophysics Supplement. 38: 355. Bibcode:1979A&AS...38..355L.
  3. ^ a b 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. Bibcode:2009yCat....102025S.
  4. ^ a b Eker, Z.; Bilir, S.; Yaz, E.; Demircan, O.; Helvaci, M. (2009). "New absolute magnitude calibrations for W Ursa Majoris type binaries". Astronomische Nachrichten. 330 (1): 68–76. arXiv:0807.4989. Bibcode:2009AN....330...68E. doi:10.1002/asna.200811041. S2CID 15071352.
  5. ^ Bilir, S; Karatas, Y; Demircan, O; Eker, Z (2005). "Kinematics of W Ursae Majoris type binaries and evidence of the two types of formation". Monthly Notices of the Royal Astronomical Society. 357 (2): 497–517. arXiv:astro-ph/0411291. Bibcode:2005MNRAS.357..497B. doi:10.1111/j.1365-2966.2005.08609.x. S2CID 16274339.
  6. ^ a b c d van Leeuwen, F. (November 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.
  7. ^ a b c d e Yuan-Gui, Y.; Sheng-Bang, Q.; Li-Ying, Z.; Jia-Jia, H.; Jin-Zhao, Y (2005). "Photometric Investigations of Three Short-Period Binary Systems: GSC 0763–0572, RR Centauri, and Epsilon Coronae Australis". Publications of the Astronomical Society of Japan. 57 (6): 983–993. Bibcode:2005PASJ...57..983Y. doi:10.1093/pasj/57.6.983.
  8. ^ Roberts, Alexander (1903). "Determination of the Orbital Elements of RR Centauri from the Observed Light Curve". Monthly Notices of the Royal Astronomical Society. 63 (8): 540–549. Bibcode:1903MNRAS..63..536R. doi:10.1093/mnras/63.8.527.
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