V1027 Cygni

V1027 Cygni

A visual band light curve for V1027 Cygni, adapted from Arkhipova et al. (2016) [1]
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−B color index	+1.9 –+2.8 [1]
B−V color 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 luminous yellow supergiant star located in the constellation of Cygnus, about 14,000 light years away. For a time, it was thought that it could be a low-mass post-AGB star, however recent parallax measurements published in Gaia DR3 have shown this to likely not be the case, and instead it is likely a massive yellow supergiant star. ^[3]

Properties

V1027 Cygni has a surface temperature about 5,000 K, which has been found in many studies. However, studies before Gaia DR3 generally used a distance around 1,280  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, over 4,000 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 of 5,000 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]

Variability

When V1027 Cygni was first noticed as a variable star, it was thought to be an irregular variable, dimming and brightening erratically with no discernible period. However, in 2009, a small-amplitude period of 237 days was observed in long-term photometry of the star. ^[1]

Notes

1. Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772  K:

   ${\displaystyle {\sqrt {(5772/5000)^{4}*176,197.605}}=559.387\ R\odot }$

References

1. Arkhipova, V. P.; Taranova, O. G.; Ikonnikova, N. P.; Esipov, V. F.; Komissarova, G. V.; Shenavrin, V. I.; Burlak, M. A. (2016-11-01). "Photometric and spectroscopic study of the supergiant with an infrared excess V1027 Cygni". Astronomy Letters. 42 (11): 756–773. arXiv: 1609.09279 . Bibcode:2016AstL...42..756A. doi:10.1134/S1063773716100017. ISSN   1063-7737. S2CID   119185536.
2. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
3. Parthasarathy, M.; Kounkel, Marina; Stassun, Keivan G. (2022-10-01). "Evolutionary Status of Selected Post-AGB Stars Based on Gaia DR3". Research Notes of the American Astronomical Society. 6 (10): 210. arXiv: 2210.00890 . Bibcode:2022RNAAS...6..210P. doi: 10.3847/2515-5172/ac99dd . ISSN   2515-5172. S2CID   252683050.
4. Samus', N. N; et al. (2017). "General catalogue of variable stars". Astronomy Reports. GCVS 5.1. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID   125853869.
5. Fouesneau, M.; Andrae, R.; Dharmawardena, T.; Rybizki, J.; Bailer-Jones, C. A. L.; Demleitner, M. (2022). "Astrophysical parameters from Gaia DR2, 2MASS, and AllWISE". Astronomy and Astrophysics. 662: A125. arXiv: 2201.03252 . Bibcode:2022A&A...662A.125F. doi:10.1051/0004-6361/202141828. S2CID   245837778.