XX Persei
Star in the constellation Perseus
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XX Persei (IRC +50052 / HIP 9582 / BD+54°444) is a semiregular variable red supergiant star in the constellation Perseus, between the Double Cluster and the border with Andromeda.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Perseus |
| Right ascension | 02h 03m 09.35854s[1] |
| Declination | 55° 13′ 56.6229″[1] |
| Apparent magnitude (V) | 7.9 - 9.0[2] |
| Characteristics | |
| Evolutionary stage | Red supergiant |
| Spectral type | M4Ib + B7V[3] |
| Variable type | SRc[4] |
| Astrometry | |
| Proper motion (μ) | RA: −1.263[1] mas/yr Dec.: −1.819[1] mas/yr |
| Parallax (π) | 0.3980±0.0316 mas[1] |
| Distance | 6,614+1,060 −812 ly (2,029+325 −249 pc)[5] |
| Absolute magnitude (MV) | −4.6[6] |
| Details | |
| Mass | 16[6] M☉ |
| Radius | 718+80 −56[7] R☉ |
| Luminosity | 42,000[8] L☉ |
| Temperature | 3,339[5] K |
| Other designations | |
| XX Per, BD+54°444, GSC 03689-01837, HD 12401, HIP 9582, IRC+50052, 2MASS J02030935+5513566, HV 3414, SAO 22875, AAVSO 0156+54 | |
| Database references | |
| SIMBAD | data |
Variability
In 1917 it was announced that Ida E. Woods had discovered that this star is a variable star, by examining 520 photographs taken from December 1, 1887 through February 4, 1913.[10] It was given its variable star designation in 1921.[11] XX Persei is a semiregular variable star of sub-type SRc, indicating a cool supergiant. The General Catalogue of Variable Stars gives the period as 415 days.[4] It also shows a long secondary period which was originally given at 4,100 days.[6] A more recent study shows only slow variations with a period of 3,150 ± 1,000 days.[2] Another study failed to find any long period up to 10,000 days.[12]
Distance
The most likely distance of XX Per is 2,290 pc, from assumed membership of the Perseus OB1 association.[13] Gaia Data Release 3 includes a parallax of 0.3980±0.0316 mas, corresponding to a distance of around 2,500 pc.[1]
Characteristics
XX Per is a red supergiant of spectral type M4Ib with an effective temperature below 4,000 K. It has a large infrared excess, indicating surrounding dust at a temperature of 900 K, but no masers have been detected.[14][15]
XX Persei has a mass of 16 solar masses, above the limit beyond which stars end their lives as supernovae.[6] This makes XX Persei similar to the more well-known red supergiant Antares.[16]
Companions
XX Persei is listed in multiple star catalogues with a companion of magnitude 9.8 223″ away.[17] This star is BD+54°445 and it is an unrelated foreground object. In addition, the spectrum of XX Persei shows absorption lines of a hot companion too close to be resolved. The combined spectral type has been given as M4Ib + B7V,[3] while the UV spectrum of the companion has been used to derive a spectral classification of A.[18]