Rho2 Arietis is an M-type red giant star in the northern constellation of Aries. Its brightness varies from magnitude 5.45 to 6.01,[11] making it faintly visible to the naked eye under good observing conditions. With an annual parallax shift of 9.28 mas,[1] it is approximately 350 light-years (110 parsecs) distant from the Earth.
  | |
| 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] |
| Distance | 350 ± 10 ly (108 ± 3 pc) |
| Absolute magnitude (MV) | +0.60[7] |
| Details | |
| Mass | 1.21[8] M☉ |
| Radius | 107.9±6.2[8] R☉ |
| Luminosity | 1,390[8] L☉ |
| Surface gravity (log g) | 0.5[9] cgs |
| Temperature | 3,400[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 | |
| Database references | |
| SIMBAD | data |
Rho2 Arietis is classified as a semiregular variable star with periods of 49.9 and 54.8 days.[12] It has the variable star designation, RZ Arietis.[3] It is probably an asymptotic giant branch star, having exhausted its core helium.[13][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
edit- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ HR 867, entry, Bright Star Catalogue, 5th Revised Ed., D. Hoffleit and W. H. Warren, Jr., 1991, CDS ID V/50.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ "RZ Ari -- Semi-regular pulsating Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-08-08.
- ^ "RZ Ari". The International Variable Star Index. AAVSO. Retrieved 27 November 2024.
- ^ 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.
- ^ Eggen, Olin J. (1992). "Asymptotic Giant Branch Stars Near the Sun". The Astronomical Journal. 104: 275. Bibcode:1992AJ....104..275E. doi:10.1086/116239.