Rho2 Arietis

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For other star systems with this Bayer designation, see Rho Arietis.

Rho2 Arietis
Diagram showing star positions and boundaries of the Aries constellation and its surroundings
Cercle rouge 100%.svg
Location of ρ2 Arietis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Aries
Right ascension 02h 55m 48.49800s[1]
Declination +18° 19′ 53.9029″[1]
Apparent magnitude (V) 5.93[2] (5.62–6.01)[3]
Spectral type M6 III[4]
U−B color index +1.12[2]
B−V color index +1.51[2]
R−I color index 2.17[5]
Variable type SRB[3]
Radial velocity (Rv)+46.0[6] km/s
Proper motion (μ) RA: −7.78[1] mas/yr
Dec.: −14.98[1] mas/yr
Parallax (π)9.28 ± 0.30[1] mas
Distance350 ± 10 ly
(108 ± 3 pc)
Absolute magnitude (MV)+0.60[7]
Luminosity126[7] L
Surface gravity (log g)0.30[8] cgs
Temperature3,250[8] K
Metallicity [Fe/H]–0.24[8] dex
Other designations
ρ2 Ari, 45 Arietis, RZ Arietis, BD+17 457, HD 18191, HIP 13654, HR 867, SAO 93189.[9]
Database references

Rho2 Arietis is the Bayer designation for a M-type red giant star in the northern constellation of Aries. With an annual parallax shift of 9.28 mas,[1] it is approximately 350 light-years (110 parsecs) distant from the Earth. It is classified as a semiregular variable star with periods of 49.9 and 54.8 days,[10] while varying in visual magnitude between 5.62 and 6.01. This star is also known by its variable star designation, RZ Arietis.[3]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Lee, T. A. (October 1970), "Photometry of high-luminosity M-type stars", Astrophysical Journal, 162: 217, Bibcode:1970ApJ...162..217L, doi:10.1086/150648. 
  3. ^ a b c V* RZ Ari, entry, Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.), N. N. Samus, O. V. Durlevich, et al., CDS ID II/250.
  4. ^ Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics, 11: 29, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333. 
  5. ^ HR 867, entry, Bright Star Catalogue, 5th Revised Ed., D. Hoffleit and W. H. Warren, Jr., 1991, CDS ID V/50.
  6. ^ 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/0409579Freely accessible, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272. 
  7. ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971Freely accessible, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. 
  8. ^ a b c Prugniel, Ph.; Vauglin, I.; Koleva, M. (July 2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952Freely accessible, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769. 
  9. ^ "RZ Ari -- Semi-regular pulsating Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-08-08. 
  10. ^ Tabur, V.; et al. (December 2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society, 400 (4): 1945–1961, arXiv:0908.3228Freely accessible, Bibcode:2009MNRAS.400.1945T, doi:10.1111/j.1365-2966.2009.15588.x. 

Coordinates: Sky map 02h 55m 48.4978s, +18° 19′ 53.903″