Gamma Cassiopeiae

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Multiple star
γ Cassiopeiae
Amateur shot of Gamma Cassiopeiae
Amateur shot of Gamma Cassiopeiae
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Cassiopeia
Right ascension 00 h 56 m 42.53 s
declination + 60 ° 43 ′ 0.3 ″
Apparent brightness 2.15 (1.6 to 3) mag
Typing
B − V color index −0.15 
U − B color index −1.08 
R − I index −0.08 
Spectral class B0 IVe
Variable star type GCAS 
Astrometry
Radial velocity (−4.8 ± 1.9) km / s
parallax (5.94 ± 0.12)  mas
distance (549 ± 11)  ly
(168 ± 3)  pc  
Visual absolute brightness M vis −4 likes
Proper movement 
Rec. Share: (+25.17 ± 0.08)  mas / a
Dec. portion: (−3.92 ± 0.08)  mas / a
Physical Properties
Dimensions 15  M ☉
radius 14  R ☉
Luminosity

70000  L ☉

Effective temperature 25,000  K
Other names
and catalog entries
Bayer name γ Cassiopeiae
Flamsteed name 27 Cassiopeiae
Bonn survey BD + 59 ° 144
Bright Star Catalog HR 264 [1]
Henry Draper Catalog HD 5394 [2]
Hipparcos catalog HIP 4427 [3]
SAO catalog SAO 11482 [4]
2MASS catalog 2MASS J00564251 + 6043002 [5]
Other names FK5  32
annotation
  1. ↑ roughly estimated from apparent brightness and distance

γ Cassiopeiae ( Gamma Cassiopeiae , γ Cas for short ) is a multiple star system , the brightest component of which is an eruptive variable star . Its apparent visual brightness fluctuates irregularly between +1.6 mag and +3.4 mag over the course of a few decades. The system is the prototype of the so-called Gamma Cassiopeiae analogs , a subgroup of the Be stars . In 2009 the star had a magnitude of +2.15 mag. It belongs to the spectral class B0 and is approx. 550  light years away.

The star has the proper name Tsih (also Cih , from Chinese ).

system

Gamma Cassiopeiae A, the bright primary component, is a spectroscopic binary star with an orbital period of about 200 days. The companion appears to have a mass similar to the Sun , although it does not appear to be a main sequence star . It may have already degenerated and transferred mass to the primary star.

Gamma Cassiopeiae has two other weak optical companions that are listed as components B and C. Component B is about 2 arc seconds away with magnitude 11 and has practically the same speed in space as the primary star. Component C has magnitude 13 and is about 1 arc second away.

The two reflection and emission nebulae IC 59 and IC 63 are located around three to four light years away .

Trivia

The occasional name Navi for this star is of modern origin and goes back to a joke by the Apollo astronaut Virgil "Gus" Grissom , who used the names of the Apollo 1 team as "Navi" (for Virgil Ivan Grissom), " Dnoces " (for Edward H. White II (= the second )) and " Regor " (for Roger Chaffee) on a list of navigation stars.

See also

Web links

Commons : Gamma Cassiopeiae  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c Hipparcos catalog (ESA 1997)
  2. ↑ a b gam Cas. In: VSX. AAVSO, accessed September 29, 2018 .
  3. ↑ a b c Bright Star Catalog
  4. ↑ Pulkovo radial velocities for 35493 HIP stars
  5. ↑ a b c Hipparcos, the New Reduction (van Leeuwen, 2007)
  6. ↑ Nemravová: Properties and nature of Be stars. 29. Orbital and long-term spectral variations of γ Cassiopeiae . In: Astronomy & Astrophysics . 537, 2012, p. A59. arxiv : 1111.3761 . bibcode : 2012A & A ... 537A..59N . doi : 10.1051 / 0004-6361 / 201117922 .
  7. ↑ Miroschnichenko: Binary nature and long term nature of Gamma Cassiopeiae . In: Publications of the Astronomical Society of the Pacific . 114, No. 801, 2002. bibcode : 2002PASP..114.1226M . doi : 10.1086 / 342766 .
  8. ↑ Mason: The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog . In: The Astronomical Journal . 122, No. 6, 2001, p. 3466. bibcode : 2001AJ .... 122.3466M . doi : 10.1086 / 323920 .
  9. ^ Aitken: New general catalog of double stars within 120 ° of the North pole . Carnegie Institution of Washington , 1932.
  10. ^ VizieR
  11. ^ Dommanget: Catalog des composantes d'etoiles doubles et multiples (CCDM) premiere edition - Catalog of the components of double and multiple stars (CCDM) first edition . In: Com. de l'Observ. Royal de Belgique . 115, 1994, p. 1. bibcode : 1994CoORB.115 .... 1D .
  12. ↑ Apollo 15 Lunar Surface Journal: Post-Landing Activities, Commentary on 105: 11: 33