55 Cygni

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55 Cygni
Cygnus constellation map.svg
Red circle.svg
Location of 55 Cyg (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Cygnus
Right ascension  20h 48m 56.29119s [1]
Declination +46° 06 50.8824 [1]
Apparent magnitude  (V)4.86 [2] (4.81 - 4.87 [3] )
Characteristics
Spectral type B2.5Ia [4] - B4Ia [5]
U−B color index 0.45 [2]
B−V color index +0.42 [2]
Variable type L [3] or α Cyg [6]
Astrometry
Radial velocity (Rv)7.2 [7]  km/s
Proper motion (μ)RA: 2.65 [1]   mas/yr
Dec.: 2.84 [1]   mas/yr
Parallax (π)1.40 ± 0.17 [1]   mas
Distance 830 [8]   pc
Absolute magnitude  (MV)6.93 [8] - 7.26 [9]
Details [6]
Mass 23 [9]   M
Radius 54 - 65  R
Luminosity 324,000 - 478,000  L
Surface gravity (log g)2.35 - 2.50  cgs
Temperature 18,600 - 19,000  K
Rotational velocity (v sin i)61 [9]  km/s
Other designations
55  Cyg, V1661  Cyg, HR  7977, BD+45°3291, HD  198478, SAO  50099, HIP  102724, AAVSO  2045+45
Database references
SIMBAD data

55 Cygni (55 Cyg) is a blue supergiant star in the constellation Cygnus. It is thought to be a member of the Cygnus OB7 stellar association at about 2,700 light years.

Its apparent magnitude is 4.86, but this is slightly variable and the star is also called V1661 Cyg. When first analysed, it was classified as an irregular supergiant variable, [10] but subsequent studies have treated it as an Alpha Cygni variable. It shows pulsations with multiple periods from a few hours to 22 days, and both p- and g-modes. [6] Apart from p- and g-modes, strange mode and associated instabilities have also been found in models of this star. [11] The spectrum also shows variation, leading to different classifications being given for the star. [12]

The exact properties of 55 Cygni are not known precisely and are also variable. It is a hot luminous supergiant several hundred thousand times as luminous as the sun. This star was originally a standard for the B3 Ia spectral type. [13]

The type of pulsations that 55 Cyg exhibits suggest that it was previously a red supergiant that has shed its outer layers. The most massive red supergiants are expected to pass through a blue supergiant phase before becoming a Wolf-Rayet star and eventually exploding as a type Ib or Ic supernova. [6]

Related Research Articles

Deneb Star in the constellation Cygnus

Deneb is a first-magnitude star in the constellation of Cygnus, the swan. Deneb is one of the vertices of the asterism known as the Summer Triangle and the "head" of the Northern Cross. It is the brightest star in Cygnus and the 19th brightest star in the night sky, with an average apparent magnitude of +1.25. A blue-white supergiant, Deneb rivals Rigel as the most luminous first magnitude star. However its distance, and hence luminosity, is poorly known; its luminosity is somewhere between 55,000 and 196,000 times that of the Sun. Its Bayer designation is α Cygni which is Latinised to Alpha Cygni, abbreviated to Alpha Cyg or α Cyg.

KY Cygni star in the constellation Cygnus

KY Cygni is a red supergiant of spectral class M3.5Ia located in the constellation Cygnus. It is one of the largest stars known, with a radius about 672 times that of the Sun. It is approximately 3,600 light-years away.

Alpha Cygni variables are variable stars which exhibit non-radial pulsations, meaning that some portions of the stellar surface are contracting at the same time other parts expand. They are supergiant stars of spectral types B or A. Variations in brightness on the order of 0.1 magnitudes are associated with the pulsations, which often seem irregular, due to beating of multiple pulsation periods. The pulsations typically have periods of several days to several weeks.

32 Cygni Star in the constellation Cygnus

32 Cygni is the Flamsteed designation for a binary star system in the Cygnus constellation. It is a 4th magnitude star, which can be seen with the naked eye under suitably dark skies. Parallax measurements give an estimated distance of 1,100 light-years (320 parsecs) from the Earth. However, Schröder et al. (2007) suggest the actual value, after correcting for Malmquist bias, may be closer to 1,174 light-years (360 parsecs). Although it is a spectrsocopic binary with components that cannot be separated visually, it has two entries in the Henry Draper Catalogue, with identical magnitudes and positions, but showing the spectral types of the two components.

Cygnus OB2 #8A is a double-lined spectroscopic binary located near the centre of the Cygnus OB2 association located 5,500 light years away.

6 Cassiopeiae Star in the constellation Cassiopeia

6 Cassiopeiae is a double star in the constellation Cassiopeia.

Sigma Cygni star in the constellation Cygnus

Sigma Cygni, Latinised from σ Cygni, is a blue supergiant star in the constellation Cygnus. Its apparent magnitude is 4.2. It belongs to the Cygnus OB4 stellar association and is located approximately 3,300 light years away from Earth.

Omega1 Cygni, Latinized from ω1 Cygni, is the Bayer designation for a solitary star in the northern constellation of Cygnus. It is visible to the naked eye with an apparent visual magnitude of 4.94. Based upon an annual parallax shift of 2.59 mas, it is estimated to lie roughly 1,260 light years from the Sun. Relative to its neighbors, this star has a peculiar velocity of 25.7±2.2 km/s.

63 Cygni is a single star in the northern constellation of Cygnus, located around 1,030 light years away from Sun. It is visible to the naked eye as an orange-hued star with an apparent visual magnitude of 4.56. 63 Cyg is moving closer to the Earth with a heliocentric radial velocity of −26 km/s.

29 Cygni is a single star in the northern constellation of Cygnus. It is dimly visible to the naked eye as a white-hued star with an apparent visual magnitude of 4.93. The distance to 29 Cyg, as estimated from an annual parallax shift of 24.9 mas, is 131 light years. The star is moving closer to the Earth with a heliocentric radial velocity of −17 km/s. It is a member of the 30–50 million year old Argus Association of co-moving stars.

V1073 Scorpii star

V1073 Scorpii is a variable star in the constellation Scorpius. It also has a non-Greek Bayer designation of k Scorpii.

UY Scuti (BD-12°5055) is a red supergiant star in the constellation Scutum. It was formerly considered one of the largest known stars by radius and is also a pulsating variable star, with a maximum brightness of magnitude 8.29 and a minimum of magnitude 10.56.

9 Persei star in the constellation Perseus

9 Persei is a single variable star in the northern constellation Perseus, located around 4,300 light years away from the Sun. It has the Bayer designation i Persei; 9 Persei is the Flamsteed designation. This body is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 5.17. It is moving closer to the Sun with a heliocentric radial velocity of −15.2 km/s. The star is a member of the Perseus OB1 association of co-moving stars.

W Cygni semi-regular variable star

W Cygni is a semi-regular variable star in the constellation Cygnus, located 570 light-years from Earth. It lies less than half a degree southeast of ρ Cygni.

R Cygni star in the constellation Cygnus

R Cygni is a variable star of the Mira type in the constellation Cygnus, less than 4' from θ Cygni. This is a red giant star on the asymptotic giant branch located around 2,200 light years away. It is an S-type star ranging between spectral types S2.5,9e to S6,9e(Tc).

BC Cygni star

BC Cygni is a red supergiant and pulsating variable star of spectral type M3.5Ia in the constellation Cygnus.

RW Cygni

RW Cygni is a semiregular variable star in the constellation Cygnus, about a degree east of 2nd magnitude γ Cygni. Its apparent magnitude varies between 8.05 and 9.70 and its spectral type between M3 and M4.

BI Cygni

BI Cygni(BI Cyg, IRC +40408, BD+36 4025) is a red supergiant in the constellation Cygnus. It is an irregular variable star with a maximum brightness of magnitude 8.4 and a minimum of magnitude 9.9. It is considered a member of the stellar Cygnus OB1 association, its distance is around 1,400 parsecs of the Solar System. It is less than a degree south of another variable red supergiant, BC Cygni.

WR 140 is a visually moderately bright Wolf-Rayet star placed within the spectroscopic binary star, SBC9 1232, whose primary star is an evolved spectral class O4-5 star. It is located in the constellation of Cygnus, lying in the sky at the centre of the triangle formed by Deneb, γ Cygni and δ Cygni.

CH Cygni variable star in the Cygnus constellation

CH Cygni is a red giant, variable, symbiotic binary in the constellation Cygnus. It is the nearest symbiotic star to Earth, and one of the brightest, making it an ideal candidate for study.

References

  1. 1 2 3 4 5 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv: 0708.1752 . Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID   18759600.
  2. 1 2 3 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. 1 2 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. Bibcode:2009yCat....102025S.
  4. Prinja, R. K.; Massa, D. L. (2010). "Signature of wide-spread clumping in B supergiant winds". Astronomy and Astrophysics. 521: L55. arXiv: 1007.2744 . Bibcode:2010A&A...521L..55P. doi:10.1051/0004-6361/201015252. S2CID   59151633.
  5. Zorec, J.; Cidale, L.; Arias, M. L.; Frémat, Y.; Muratore, M. F.; Torres, A. F.; Martayan, C. (2009). "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff". Astronomy and Astrophysics. 501 (1): 297–320. arXiv: 0903.5134 . Bibcode:2009A&A...501..297Z. doi:10.1051/0004-6361/200811147. S2CID   14969137.
  6. 1 2 3 4 Kraus, M.; Haucke, M.; Cidale, L. S.; Venero, R. O. J.; Nickeler, D. H.; Németh, P.; Niemczura, E.; Tomić, S.; Aret, A.; Kubát, J.; Kubátová, B.; Oksala, M. E.; Curé, M.; Kamiński, K.; Dimitrov, W.; Fagas, M.; Polińska, M. (2015). "Interplay between pulsations and mass loss in the blue supergiant 55 Cygnus = HD 198 478". Astronomy & Astrophysics. 581: A75. arXiv: 1507.01846 . Bibcode:2015A&A...581A..75K. doi:10.1051/0004-6361/201425383. S2CID   55392478.
  7. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
  8. 1 2 Markova, N.; Puls, J. (2008). "Bright OB stars in the Galaxy. IV. Stellar and wind parameters of early to late B supergiants". Astronomy and Astrophysics. 478 (3): 823. arXiv: 0711.1110 . Bibcode:2008A&A...478..823M. doi:10.1051/0004-6361:20077919. S2CID   14510634.
  9. 1 2 3 Searle, S. C.; Prinja, R. K.; Massa, D.; Ryans, R. (2008). "Quantitative studies of the optical and UV spectra of Galactic early B supergiants. I. Fundamental parameters". Astronomy and Astrophysics. 481 (3): 777. arXiv: 0801.4289 . Bibcode:2008A&A...481..777S. doi:10.1051/0004-6361:20077125. S2CID   1552752.
  10. Lefèvre, L.; Marchenko, S. V.; Moffat, A. F. J.; Acker, A. (2009). "A systematic study of variability among OB-stars based on HIPPARCOS photometry". Astronomy and Astrophysics. 507 (2): 1141. Bibcode:2009A&A...507.1141L. doi: 10.1051/0004-6361/200912304 .
  11. Yadav, Abhay Pratap; Glatzel, Wolfgang (2016). "Stability analysis, non-linear pulsations and mass loss of models for 55 Cygni (HD 198478)". Monthly Notices of the Royal Astronomical Society. 457 (4): 4330–4339. Bibcode:2016MNRAS.457.4330Y. doi: 10.1093/mnras/stw236 . ISSN   0035-8711.
  12. Maharramov, Y. M. (2013). "Spectral variability of the STAR 55 Cyg B3 Ia". Astronomy Reports. 57 (4): 303–309. Bibcode:2013ARep...57..303M. doi:10.1134/S1063772913030037. S2CID   121606849.
  13. Morgan, W. W.; Roman, Nancy G. (1950). "Revised Standards for Supergiants on the System of the Yerkes Spectral Atlas". Astrophysical Journal. 112: 362. Bibcode:1950ApJ...112..362M. doi:10.1086/145351.