P Cygni
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Star P Cygni |
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| AladinLite | |||||||||||||||||||||
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | swan | ||||||||||||||||||||
| Right ascension | 20 h 17 m 47.2 s | ||||||||||||||||||||
| declination | + 38 ° 01 ′ 58.6 ″ | ||||||||||||||||||||
| Apparent brightness | 4.8 mag; variable with amplitude of approx. 0.2 mag |
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| Typing | |||||||||||||||||||||
| B − V color index | +0.42 | ||||||||||||||||||||
| U − B color index | −0.58 | ||||||||||||||||||||
| R − I index | +0.26 | ||||||||||||||||||||
| Spectral class | B1 Ia + | ||||||||||||||||||||
| Variable star type | Luminous blue changer | ||||||||||||||||||||
| Astrometry | |||||||||||||||||||||
| Radial velocity | (−8.9 ± 0.8) km / s | ||||||||||||||||||||
| distance | approx. 6000 to 7000 ly approx. 1800 to 2200 pc |
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| Visual absolute brightness M vis | −8.6 mag | ||||||||||||||||||||
| Proper movement | |||||||||||||||||||||
| Rec. Share: | (−3.18 ± 0.13) mas / a | ||||||||||||||||||||
| Dec. portion: | (−6.45 ± 0.15) mas / a | ||||||||||||||||||||
| Physical Properties | |||||||||||||||||||||
| Dimensions | 30 to 60 M ☉ | ||||||||||||||||||||
| radius | 76 R ☉ | ||||||||||||||||||||
| Luminosity |
560000 to 900000 L ☉ |
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| Effective temperature | 18,000 to 20,000 K | ||||||||||||||||||||
| Rotation time | 50 d | ||||||||||||||||||||
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Other names and catalog entries |
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P Cygni is a Luminous Blue Variable (LBV) in the constellation Swan (Cygnus).
It was unknown until the 17th century . P Cygni was first observed on August 18, 1600 by Willem Blaeu , a Dutch astronomer, mathematician and cartographer. The star then grew darker and darker for six years until it was no longer visible to the naked eye in 1626. It was visible again from 1655 to 1662. Until 1715 the brightness of P Cygni fluctuated again and again. Over time, he won his current brightness of 4.8 likes ± 0.5. P Cygni is a hypergiant hypergiant of the spectral type B2 Ia approx. 6000 to 7000 light years away from the earth . It is one of the brightest stars in our Milky Way . Determining the exact distance is difficult because its parallax is only 0.52 thousandths of an arc second (Hipparcos measurement).
Due to its sudden fluctuations in brightness, P Cygni was also often referred to as a "permanent nova", although its actual behavior does not correspond to the behavior of a real nova .
Bright blue variables like P Cygni are very rare and have a short lifespan. They are also only found in parts of galaxies in which intensive star formation processes take place. Due to its mass (approx. 50 solar masses ) and the intense energy output (ten thousand times brighter than the sun ), the LBV's nuclear fuel is very quickly exhausted. After a few million years, the life of these stars ends in a supernova . The supernova SN 2006gy was likely the end of an LBV star similar to P Cygni.
The P-Cygni profile of spectral lines is named after this star .
Web links
- WikiSky coordinates
- Spektrum .de: amateur recordings [7]
Individual evidence
- ^ Hipparcos catalog (ESA 1997)
- ↑ a b c Bright Star Catalog
- ↑ Pulkovo radial velocities for 35493 HIP stars
- ↑ a b c d e f g Chris Clowes: "P Cygni" in "Chris's No-Frills Home Page" ( Memento of the original from May 27, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ Hipparcos, the New Reduction (van Leeuwen, 2007)
