| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 02m 27.376s[2] |
| Declination | +30° 04′ 25.49″[2] |
| Apparent magnitude (V) | 8.6-9.6[1] |
| Characteristics | |
| Evolutionary stage | Yellow supergiant |
| Spectral type | G7Ia[3] |
| U−Bcolor index | +1.9 – +2.8[1] |
| B−Vcolor index | +2.1 – +2.5[1] |
| Variable type | L[4] |
| Astrometry | |
| Proper motion (μ) | RA: −2.936[2]mas/yr Dec.: −5.55[2]mas/yr |
| Parallax (π) | 0.2390±0.0178 mas[2] |
| Distance | 14,000 ± 1,000 ly (4,200 ± 300 pc) |
| Absolute magnitude (MV) | −7.956[3] |
| Details | |
| Radius | 559[3][a] R☉ |
| Luminosity | 176,200[3] L☉ |
| Surface gravity (log g) | −0.81[5] cgs |
| Temperature | 5,000[3] K |
| Other designations | |
| HD 333385, TYC 2670-4475-1,2MASS J20022738+3004252 | |
| Database references | |
| SIMBAD | data |
V1027 Cygni is a luminousyellow supergiant star located in the constellation ofCygnus, about 14,000light years away. For a time, it was thought that it could be a low-masspost-AGB star, however recentparallax measurements published inGaia DR3 have shown this to likely not be the case, and instead it is likely a massive yellow supergiant star.[3]
V1027 Cygni has asurface temperature about5,000 K, which has been found in many studies. However, studies before Gaia DR3 generally used a distance around1,280 pc, which led to low luminosity estimates, hence a tentative post-AGB star status.[1] Recent Gaia DR3 data shows that V1027 Cygni is likely much further away, over4,000 pc away, which implies a much higher luminosity (about 176,000 L☉) which would place it firmly outside the post-AGB star luminosity range and in that of the more massive, younger yellow supergiants.[3]Spectral indicators of luminosity also suggest a supergiant status.[1]
Assuming a temperature of5,000 K and a luminosity of about 176,200 L☉ for V1027 Cygni leads to a size of about 560 times that of the Sun.[a]
When V1027 Cygni was first noticed as avariable star, it was thought to be anirregular variable, dimming and brightening erratically with no discernible period. However, in 2009, a small-amplitude period of 237 days was observed in long-termphotometry of the star.[1]
