RS Persei
Star in the constellation Perseus
From Wikipedia, the free encyclopedia
RS Persei is a red supergiant variable star located in the Double Cluster in Perseus. The star's apparent magnitude varies from 7.82 to 10.0, meaning it is never visible to the naked eye. It is a member of the cluster NGC 884, χ Persei, one half of the famous Double Cluster.[7]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Perseus |
| Right ascension | 02h 22m 24.296s[1] |
| Declination | +57° 06′ 34.10″[1] |
| Apparent magnitude (V) | 7.82 – 10.0[2] |
| Characteristics | |
| Evolutionary stage | Red supergiant |
| Spectral type | M4Iab[3] |
| Variable type | SRc[2] |
| Astrometry | |
| Radial velocity (Rv) | −38.0±2[4] km/s |
| Proper motion (μ) | RA: −0.602[1] mas/yr Dec.: −1.107[1] mas/yr |
| Parallax (π) | 0.3874±0.0450 mas[1] |
| Distance | 7,650±180 ly (2,345±55 pc)[5] |
| Absolute magnitude (MV) | −6.18[6] |
| Details[5] | |
| Mass | 12 – 15 M☉ |
| Radius | 770±30 R☉ |
| Luminosity | 77,600+9,500 −8,400 L☉ |
| Surface gravity (log g) | −0.2±0.05 cgs |
| Temperature | 3,470±90 K |
| Other designations | |
| RS Per, HD 14488, BD+56°583, 2MASS J02222428+5706340, AAVSO 0215+56A | |
| Database references | |
| SIMBAD | data |
Variability
In March of 1904, Lidiya Tseraskaya discovered that the star, then referred to as BD+56°583, is a variable star.[9] It was listed with its variable star designation, RS Persei, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars.[10] RS Persei is classified as a semiregular variable star, with its brightness varying from magnitude 7.82 to 10.0 over 245 days,[2] Detailed studies show that it also pulsates with a long secondary period of 4,200±1,500 days.[11]
Properties
RS Persei is a large cool star with a temperature of 3,500 K. Its size makes it luminous, although much of its radiation is emitted in the infrared. In 2005, RS Per was calculated to have a bolometric luminosity of 145,000 L☉ and a radius around 1,000 R☉.[6] More recently, across all wavelengths gives the star a lower luminosity of 77,600+9,500
−8,400 L☉, and a radius of 770±30 R☉ based on the distance and the measured angular diameter by the CHARA array.[5] A 2023 paper gives an even smaller luminosity of 59,000 L☉.[12] Estimates based on measured angular diameters and distances estimated by the Gaia DR2 and Gaia DR3 give radii of 547+9
−7 R☉[13] and 775+110
−85 R☉.[14]
RS Persei has sometimes been considered to be a highly evolved low mass Asymptotic Giant Branch (AGB) star,[15] but calculations of its current mass suggest that it is a true red supergiant. NGC 244 is also too young to host AGB stars.[5]