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Rho2 Arietis

Coordinates: Sky map 02h 55m 48.4978s, +18° 19′ 53.903″
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ρ2 Arietis
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] (5.45–6.01)[3]
Characteristics
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]
Astrometry
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 mas[1]
Distance350 ± 10 ly
(108 ± 3 pc)
Absolute magnitude (MV)+0.60[7]
Details
Mass1.21[8] M
Radius107.9±6.2[8] R
Luminosity1,390[8] L
Surface gravity (log g)0.5[9] cgs
Temperature3,400[9] K
Metallicity [Fe/H]–0.25[8] dex
Rotation<909[8] days
Rotational velocity (v sin i)6.0±0.5[9] km/s
Other designations
ρ2 Ari, 45 Arietis, RZ Arietis, BD+17 457, HD 18191, HIP 13654, HR 867, SAO 93189.[10]
Database references
SIMBADdata

Rho2 Arietis is an 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.

A visual band light curve for Rho2 Arietis, plotted from data presented in Tabur et al. (2009)[11]

Rho2 Arietis is classified as a semiregular variable star with periods of 49.9 and 54.8 days.[11] It varies in visual magnitude between 5.45 and 6.01. It has the variable star designation, RZ Arietis.[3] It is more likely be an asymptotic giant branch star, having exhausted its core helium.[12][8] It is predicted to have started its life with 1.5 solar masses. At its current evolutionary stage, Rho2 Arietis has expanded to 108 times the Sun's radius and is radiating 1,400 times the Sun's luminosity.[8]

This star possesses a strong magnetic field, one of the strongest for M-type giants. It also possesses a high lithium abundance, higher than expected from evolutionary models. The strong magnetic field, rapid rotation and unusual lithium abundance might be explained by a planet engulfment, when the star was on the red-giant branch.[8]

References

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  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:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  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/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272, S2CID 17804304.
  7. ^ 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, S2CID 119257644.
  8. ^ a b c d e f g h Konstantinova-Antova, R.; Georgiev, S.; Lèbre, A.; Palacios, A.; Morin, J.; Bogdanovski, R.; Abbott, C.; Baron, F.; Aurière, M.; Drake, N. A.; Tsvetkova, S.; Josselin, E.; Paladini, C.; Mathias, P.; Zamanov, R. (2024-01-01). "A long-term study of the magnetic field and activity in the M giant RZ Ari - Magnetism and planet engulfment in a fairly evolved star?". Astronomy & Astrophysics. 681: A36. arXiv:2312.12549. doi:10.1051/0004-6361/202346949. ISSN 0004-6361.
  9. ^ a b c Georgiev, Stefan; Lèbre, Agnès; Josselin, Eric; Konstantinova-Antova, Renada; Morin, Julien (June 2020). "Determining rotational and macroturbulent velocities of cool magnetic giant stars". Astronomische Nachrichten. 341 (5): 486–492. arXiv:2202.00971. doi:10.1002/asna.202013725. ISSN 0004-6337.
  10. ^ "RZ Ari -- Semi-regular pulsating Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-08-08.
  11. ^ a b 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:0908.3228, Bibcode:2009MNRAS.400.1945T, doi:10.1111/j.1365-2966.2009.15588.x, S2CID 15358380.
  12. ^ Eggen, Olin J. (1992). "Asymptotic Giant Branch Stars Near the Sun". The Astronomical Journal. 104: 275. Bibcode:1992AJ....104..275E. doi:10.1086/116239.