VV Cephei ( lat.VV Cephei ) is an eclipsing binary star of the Algol type in the constellation Cephei , which is located at a distance of about 5000 light-years from Earth. Component A is the seventh largest star known to science in 2015 and one of the largest stars in the Milky Way Galaxy (along with UY Shield and VY Canis Major ).
| VV Cepheus | |||
|---|---|---|---|
| Double star | |||
 Sun compared to VV Cepheus A. | |||
| Observational data ( Age J2000.0 ) | |||
| Right ascension | |||
| Declination | |||
| Distance | 5000 St. years old | ||
| Visible magnitude ( V ) | 5.18 | ||
| Constellation | Cepheus | ||
| Astrometry | |||
| Radial velocity ( R v ) | -18.7 km / s | ||
| Own movement (μ) | RA: -0.33 mas per year Dec: -3.82 mas per year | ||
| Parallax (π) | 0.39 ± 0.53 mas | ||
| Absolute magnitude (V) | -9 | ||
| Specifications | |||
| Spectral class | M2Iab / B0Ve | ||
| Color Index ( B - V ) | 0.3 | ||
| Color Index ( U - B ) | 1,6 | ||
| Variability | Algol | ||
| physical characteristics | |||
| Weight | <25 / <20 M ☉ | ||
| Radius | 1050 [1] -1900 [2] / 8 [3] R ☉ | ||
| Age | 25 million years old | ||
| Temperature | ~ 3800 / ~ 25000 K | ||
| Luminosity | 200000-320000 / ~ 10000 L ☉ | ||
| |||
| Database Information | |||
| SIMBAD | |||
Content
VV Cepheus A
The red hypergiant VV Cephei A of spectral class M2 is the third largest in our galaxy (after the hypergiant UY Shield and VY Canis Major ).
The radius of the star is approximately equal to 1050-1900 radii of the Sun , if we take the average value of 1700, then this star can be larger in radius than UY Scuti, but the diameter of VV Cephei is more than ~ 270 million km . This star has the largest diameter. [to clarify ] , and luminosity - 275,000-575,000 times greater [ what? ] . A star fills the Roche lumen , and its substance flows to a nearby companion. The flow rate of gases reaches 200 km / s [4] . It was established that VV Cephei A is a physical variable pulsating with a period of 150 days. The speed of stellar wind flowing from a star reaches 25 km / s [5] . Judging by the orbital motion, the mass of the star is about 100 solar, however, its luminosity indicates a mass of 25-40 solar.
VV Cepheus B
In 1936 , the American astronomer Dean McLaughlin established that VV Cepheus is a double eclipse variable. After 1936, B-star eclipses were observed every 20 years. According to observations between the eclipses of 1956 and 1976 . and during the eclipse of 1976 - 1977 . managed to clarify the main parameters of this binary system. VV Cepheus B, the blue star of the main sequence of class B0, rotates around VV Cepheus A in an elliptical orbit with a period of 7430 days (about 20 years ). The eclipse of one star to another lasts 1300 days (3.6 years), the total phase of the eclipse is 16 months. A star is about 8 times larger than the Sun in diameter and 10,000 times in luminosity. From changes in radial velocities, the distance between the centers of stars was determined, which varies from 17 to 34 a. e.
A class M star has an extended atmosphere, so even before the eclipse of the white giant begins, the so-called chromospheric lines appear in its spectrum due to the absorption of B-star light in the atmosphere of the M-star.
See also
- List of the biggest stars
- List of the most massive stars.
- List of the brightest stars
- List of stars of the constellation Cepheus
- W Cepheus
Notes
- ↑ Bauer, WH; Gull, TR; Bennett, PD Spatial Extension in the Ultraviolet Spectrum of Vv Cephei (Eng.) // The Astronomical Journal : journal. - IOP Publishing 2008. - Vol. 136 , no. 3 . - P. 1312 . - DOI : 10.1088 / 0004-6256 / 136/3/1312 . - .
- ↑ C .; Moellenhoff; Schaifers, K. Spectroscopic observations of VV Cep. II - the egress phase of the 1976/78 eclipse (Eng.) // Astronomy and Astrophysics : journal. - EDP Sciences , 1981. - Vol. 94 . - P. 333 . - .
- ↑ WH; Bauer; Stencel, RE; Neff, DH Twelve years of IUE spectra of the interacting binary VV Cephei (Eng.) // Astronomy and Astrophysics Supplement Series : journal. - EDP Sciences 1991. - Vol. 90 . - P. 175 . - .
- ↑ Red supergiant VV Cepheus - Stars . cosmoportal.net (October 23, 2007). Date of treatment April 14, 2019. Archived July 7, 2012.
- ↑ Bauer, Wendy Hagen; Philip D. Bennett; Alexander Brown. An Ultraviolet Spectral Atlas of VV Cephei during Total Eclipse // The Astrophysical Journal : journal. - IOP Publishing 2007. - Vol. 171 . - P. 249—259 . - DOI : 10.1086 / 514334 .
Links
- VV Cepheus (inaccessible link) . Archived March 22, 2012.
- Jim Kaler: VV Cephei (link not available) Archived February 1, 2009.
- SIMBAD Astronomical Database
- Space.Com (English)
- Universe Today
- Google Video (Scale of VV Cephei compared to Earth Video)