XX Persei
02h03m 09.35854s[1]
55° 13′ 56.6229″[1]
7.9 - 9.0[2]
Characteristics
M4Ib + B7V[3]
Proper motion (μ)
RA: −1.263[1] mas/yr
Dec.: −1.819[1] mas/yr
Parallax (π)
6,614+1,060
−812 ly
(2,029+325
−249 pc)[5]
Absolute magnitude (MV)
−4.6[6]
Details
Database references
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.
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.[10]
The most likely distance of XX Per is 2,290 pc, from assumed membership of the Perseus OB1 association.[11] Gaia Data Release 3 includes a parallax of 0.3980±0.0316 mas, corresponding to a distance of around 2,500 pc.[1]
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.[12][13]
XX Persei has a mass of 16 solar masses, above the limit beyond which stars end their lives as supernovae.[6]
XX Persei is listed in multiple star catalogues with a companion of magnitude 9.8 223″ away.[14] 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.[15]
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