Rho2 Arietis

For other stars with this Bayer designation, see ρ Arietis.
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]

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  9. ^ a b c Cite error: The named reference Georgiev2020 was invoked but never defined (see the help page).
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  11. ^ a b Cite error: The named reference mnras400_4_1945 was invoked but never defined (see the help page).
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