SU Persei
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  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Perseus[1] |
| Right ascension | 02h 22m 06.89s[2] |
| Declination | +56° 36′ 14.9″[2] |
| Apparent magnitude (V) | 7.2 - 8.7[3] |
| Characteristics | |
| Evolutionary stage | red supergiant[4] |
| Spectral type | M3.5Iab[3] |
| Variable type | SRc[3] |
| Astrometry | |
| Radial velocity (Rv) | −44.8±0.3[4] km/s |
| Proper motion (μ) | RA: −0.765[2] mas/yr Dec.: −1.204[2] mas/yr |
| Parallax (π) | 0.4168±0.0279 mas[2] |
| Distance | 7,800 ± 500 ly (2,400 ± 200 pc) |
| Absolute magnitude (MV) | −5.78[5] |
| Details | |
| Mass | 13±4[6] M☉ |
| Radius | 1,044+31 −21 – 1,139+34 −23[6] R☉ |
| Luminosity | 91,201[5] L☉ |
| Surface gravity (log g) | −0.1[7] cgs |
| Temperature | 3,650±50[6] K |
| Other designations | |
| SU Persei, BD+55°597, HD 14469,[8] ASASSN-V J022206.86+563614.8[3] | |
| Database references | |
| SIMBAD | data |
SU Persei is a red supergiant star located in the constellation of Perseus. It is located within the Double Cluster, 7,250+470
−420 light-years away.[10] It is a semiregular variable star[3] that ranges in brightness from magnitude 7.2 to 8.7,[3] which makes it too faint to be seen with the naked eye, but can be seen with binoculars or a telescope.
SU Persei was imaged by the CHARA array in 2015, 2016, 2019, 2020, and 2021.[11] Observations during 2015 and 2016 with CHARA show that the star has an angular diameter between 3.51 and 3.68 milliarcseconds. Considering its large distance from Earth, this results in a radius between 1,044 and 1,139 times that of the Sun, making it one of the largest stars known.[6]
SU Persei is losing mass at a rate of 1.62+0.72
−0.63×10−6 M☉ per year, via a stellar wind.[12]
In 1907, Henrietta Swan Leavitt discovered that the star's brightness varies by examining photographic plates.[13] It was given its variable star designation, SU Persei in 1908.[14]
