Y Cygni

Not to be confused with Upsilon Cygni.

Y Cyg

A light curve for Y Cygni, plotted from TESS data [1]
Observation data Epoch J2000       Equinox J2000
Constellation	Cygnus
Right ascension	20h 52m 3.57718s [2]
Declination	+34° 39′ 27.4861″ [2]
Apparent magnitude  (V)	7.3 - 7.9 [3]
Characteristics
Primary
Spectral type	O9.5V [4]
Apparent magnitude  (U)	5.91[ citation needed ]
Apparent magnitude  (B)	6.996[ citation needed ]
Apparent magnitude  (V)	7.287 [4]
U−B color index	−1.086 [4]
B−V color index	−0.291 [4]
Secondary
Spectral type	O9.5V [4]
Apparent magnitude  (U)	5.883[ citation needed ]
Apparent magnitude  (B)	6.974[ citation needed ]
Apparent magnitude  (V)	7.265 [4]
U−B color index	−1.091 [4]
B−V color index	−0.291 [4]
Variable type	Algol [3]
Astrometry
Proper motion (μ)	RA: +2.763 [2] mas/yr Dec.: −15.981 [2] mas/yr
Parallax (π)	0.6759±0.0338  mas [2]
Distance	4,900  ly (1,500 [4]   pc)
Absolute magnitude  (MV)	−3.59/−3.62 [4]
Absolute bolometric magnitude  (Mbol)	−6.65±0.04/−6.7±0.04 [4]
Orbit [4]
Primary	Y Cyg A
Companion	Y Cyg B
Period (P)	2.99633210±0.00000031  d
Semi-major axis (a)	28.72 R☉
Eccentricity (e)	0.14508
Inclination (i)	86.474±0.019°
Periastron epoch (T)	2,446,308.66407±0.0001
Argument of periastron (ω) (secondary)	312.514°
Argument of periastron (ω) (primary)	132.514±0.052°
Details [4]
Primary
Mass	17.72±0.35  M☉
Radius	5.785±0.091  R☉
Luminosity	36,000  L☉
Surface gravity (log g)	4.161±0.014  cgs
Temperature	33,200±200  K
Rotational velocity (v sin i)	132 km/s
Age	2  Myr
Secondary
Mass	17.73±0.3  M☉
Radius	5.816±0.063  R☉
Luminosity	37,700  L☉
Surface gravity (log g)	4.157±0.01  cgs
Temperature	33,521±40  K
Rotational velocity (v sin i)	132 km/s
Age	2  Myr
Other designations
Y Cyg, HD 198846, HIP 102999
Database references
SIMBAD	data

Y Cygni is an eclipsing and double-lined spectroscopic binary star system in the constellation of Cygnus. It is located about 4,900 light-years from Earth. The system was one of the first binaries with a convincing detection of the apsidal precession. ^[4]

The two stars, being O-type main-sequence stars, orbit each other with a period of nearly 3 days. ^[4]

Observation history

The early type of Y Cyg made it a popular target for astronomers in the past, and spectroscopic orbits have been historically computed numerous times. ^[5] The first of these studies was published in 1920 by John Stanley Plaskett. ^[6] Extensive spectroscopic studies of Y Cyg were carried out as early as 1930. ^[7] Several follow-ups to these have been published in 1959, ^[8] 1971, ^{[9] [10]} and 1980. ^[11] The latter of these contained an estimate of the period of apsidal precession.

References

1. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
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. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/GCVS. Bibcode:2009yCat....102025S.
4. Harmanec, P.; Holmgren, D. E.; Wolf, M.; Božić, H.; Guinan, E. F.; Kang, Y. W.; Mayer, P.; McCook, G. P.; Nemravová, J.; Yang, S.; Šlechta, M.; Ruždjak, D.; Sudar, D.; Svoboda, P. (March 2014). "Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni". Astronomy and Astrophysics . 563: A120. arXiv: 1403.0721 . Bibcode:2014A&A...563A.120H. doi:10.1051/0004-6361/201323230. ISSN   0004-6361. S2CID   118651473.
5. Hill, G.; Holmgren, D. E. (May 1995). "Studies of early-type variable stars. IX. Y Cygni". Astronomy and Astrophysics. 297: 127–134. Bibcode:1995A&A...297..127H.
6. Jones, Harold Spencer (1 November 1942). "John Stanley Plaskett, 1865-1941". Obituary Notices of Fellows of the Royal Society. 4 (11): 67–82. doi: 10.1098/rsbm.1942.0007 .
7. Redman, R. O. (August 1930). "Y Cygni". Publications of the Astronomical Society of the Pacific. 42: 250. Bibcode:1930PASP...42..250R. doi: 10.1086/124047 . S2CID   250785748.
8. Struve, O.; Sahade, J.; Zabergs, V. (January 1959). "Y Cygni". Astrophysical Journal. 129: 59. Bibcode:1959ApJ...129...59S. doi:10.1086/146595.
9. Vitrichenko, E. A. (1971). "The improvement of the Spectroscopic orbit of Y Cyg". Società Astronomia Italiana. 43: 71. Bibcode:1972MmSAI..43...71V.
10. Vitrichenko, E. A. (1971). "The improvement of the Spectroscopic orbit of Y Cyg". Izv. Krym. Astrofiz. Obs. 43: 71–75. Bibcode:1971IzKry..43...71V.
11. Gimenez, A.; Costa, V. (December 1980). "Y CYG : photometry and apsidal motion". Publications of the Astronomical Society of the Pacific. 92: 782–784. Bibcode:1980PASP...92..782G. doi:10.1086/130747. S2CID   120757652.