7 Arietis

7 Arietis
Observation data
Epoch J2000      Equinox J2000
Constellation Aries
Right ascension 01h 55m 51.03905s[1]
Declination +23° 34′ 38.3509″[1]
Apparent magnitude (V) 5.76[2]
Characteristics
Spectral type K1 III[3]
U−B color index +1.04[4]
B−V color index +1.185[4]
Variable type Eclipsing binary[5]
(disputed)[6][7]
Astrometry
Radial velocity (Rv)+15.95[8] km/s
Proper motion (μ) RA: +11.050[1] mas/yr
Dec.: −9.513[1] mas/yr
Parallax (π)5.3941 ± 0.1720 mas[1]
Distance600 ± 20 ly
(185 ± 6 pc)
Details
Radius25.0+0.9
−1.4[1] R☉
Luminosity231.3±8.5[1] L☉
Temperature4500+130
−78[1] K
Rotational velocity (v sin i)1.8±1.0[9] km/s
Other designations
7 Ari, RR Arietis, BD+22 284, FK5 2130, HD 11763, HIP 8993, HR 559, SAO 75030[4]
Database references
SIMBADdata

7 Arietis is a binary star[3] system in the northern constellation of Aries. 7 Arietis is the Flamsteed designation. The pair have a combined apparent visual magnitude of 5.76,[2] making it faintly visible to the naked eye from dark suburban skies. Based upon an annual parallax shift of 5.39 mas,[1] it is approximately 600 light-years (180 parsecs) distant from the Earth, give or take a 30 light-year margin of error. It is drifting further away from the Sun with a radial velocity of +16 km/s.[8]

This is listed as an eclipsing binary system with a period of 47.9 days (although the star does not appear to be variable in the General Catalogue of Photometric Data, the Hipparcos data, and a study done in 1979-1980)[6][7] It has the variable star designation RR Arietis. During each eclipse of the primary star, the magnitude of the system decreases by 0.40. The eclipse of the secondary reduces the magnitude by 0.35.[5] The primary component of the system is an evolved giant star with a stellar classification of K1 III.[3] It is about 25 times the size of the Sun and is radiating 231 times the Sun's luminosity from its photosphere at an eeffective temperature of 4,500 K.[1]

The eclipsing binary nature of this star has been disputed by Italian astronomer Ennio Poretti.[10] Observations made as part of the British Astronomical Association eclipsing binaries program by Tristram Brelstaff were also unable to confirm eclipses.[11]

References

  1. ^ a b c d e f g h i j 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. ^ a b Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
  3. ^ a b c Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  4. ^ a b c "7 Ari". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-18.
  5. ^ a b Malkov, O. Yu.; et al. (February 2006), "A catalogue of eclipsing variables", Astronomy and Astrophysics, 446 (2): 785–789, Bibcode:2006A&A...446..785M, doi:10.1051/0004-6361:20053137, hdl:10995/73280.
  6. ^ a b "RR Ari". The International Variable Star Index. AAVSO. Retrieved 27 November 2024.
  7. ^ a b Isles, J. E. (December 1985). "Eclipsing Binaries, Andromeda To Camelopardalis, in 1972-1983". Journal of the British Astronomical Association. 96: 27–32. Bibcode:1985JBAA...96...27I. Retrieved 27 November 2024.
  8. ^ a b Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430 (1): 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272, S2CID 17804304.
  9. ^ De Medeiros, J. R.; et al. (November 2002), "A catalog of rotational and radial velocities for evolved stars. II. Ib supergiant stars", Astronomy and Astrophysics, 395: 97–98, arXiv:1312.3474, Bibcode:2002A&A...395...97D, doi:10.1051/0004-6361:20021214.
  10. ^ Poretti, Ennio (1984). "RR Ari: Not a variable star". Astrophysics and Space Science. 106 (1): 201–203. Bibcode:1984Ap&SS.106..201P. doi:10.1007/BF00653927. S2CID 120037068.
  11. ^ Isles, J. E. (1985). "Eclipsing Binaries, Andromeda To Camelopardalis, in 1972-1983". Journal of the British Astronomical Association. 96: 27–32. Bibcode:1985JBAA...96...27I.