V509 Cassiopeiae

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V509 Cassiopeiae
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cassiopeia
Right ascension 23h00m05.1s
Declination +56°56′43″
Apparent magnitude (V) +4.6 - +5.2[1]
Spectral type G0Ia0[1]
U−B color index +1.16
B−V color index +1.0 - +1.7[1]
Variable type semiregular
Radial velocity (Rv) −58 km/s
Proper motion (μ) RA: −2.94 mas/yr
Dec.: −3.09 mas/yr
Parallax (π) 0.73 ± 0.25 mas
Distance 4,500[1] ly
(1,370[1] pc)
Absolute magnitude (MV) −8.6 (variable)[1]
Mass 11 (decreasing)[1] M
Radius 400 -900[1] R
Luminosity 200.000 - 400,000[1] L
Temperature 4,000-8,000 (increasing)[1] K
Metallicity ?
Rotation ?
Age ? years
Other designations
HR 8752, HD 217476, FK5 3839, HIP 113561, SAO 35039
Database references

V509 Cassiopeiae (V509 Cas) is a star in the constellation Cassiopeia.

V509 Cassiopeiae is yellow hypergiant with a G-type and an apparent magnitude that has varied from below +6 in historical times to a peak of +4.3 and now around +5.2. It is around 4,500 light years from Earth. It is classified as a semiregular variable star of type SRd. Characteristic periods around a year are reported[2] imposed on the slower secular variations. It is undergoing strong mass loss as part of its rapid evolution. It has recently passed through the yellow evolutionary void by ejecting around a solar mass of material in less than 50 years.[1]

A hot main sequence companion (B1V) was described in 1978 on the basis of a colour excess in the ultraviolet[3] but has not been reported since.

This type of star has evolved from an initial mass of 25-40 times the sun to a red hypergiant and is now shedding its remaining outer layers in a series of dramatic explosions, progressively increasing in temperature. It may become a blue supergiant or luminous blue variable before declining in luminosity as a late type Wolf–Rayet star, but is expected to explode as a supernova before that point.


  1. ^ a b c d e f g h i j k h. Nieuwenhuijzen, H.; c. De Jager, C.; i. Kolka, I.; g. Israelian, G.; a. Lobel, A.; e. Zsoldos, E.; a. Maeder, A.; g. Meynet, G. (2012). "The hypergiant HR 8752 evolving through the yellow evolutionary void". Astronomy & Astrophysics 546: A105. Bibcode:2012A&A...546A.105N. doi:10.1051/0004-6361/201117166.  edit
  2. ^ Bibcode1992A&A...263..123P
  3. ^ Bibcode1978A&A....70L..53S

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