V762 Cassiopeiae
Red supergiant star in the constellation Cassiopeia
From Wikipedia, the free encyclopedia
V762 Cassiopeiae is a star in the constellation of Cassiopeia. Its apparent magnitude vary between 5.82 and 5.95, which makes it faintly visible to the naked eye under dark skies. Parallax measurements give it a distance of 2,500 light-years.
The location of V762 Cassiopeiae | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cassiopeia[1] |
| Right ascension | 01h 16m 11.902s[2] |
| Declination | +71° 44′ 37.83″[2] |
| Apparent magnitude (V) | 5.82 – 5.95[3] |
| Characteristics | |
| Evolutionary stage | RSG[4] or AGB[5] |
| Spectral type | K5I[4][3] or M3II[6] |
| Variable type | Semi-regular variable[7] |
| Astrometry | |
| Radial velocity (Rv) | −21.37±0.91[2] km/s |
| Proper motion (μ) | RA: −1.658 mas/yr[2] Dec.: +1.791 mas/yr[2] |
| Parallax (π) | 1.3148±0.0693 mas[2] |
| Distance | 2,500 ± 100 ly (760 ± 40 pc) |
| Details | |
| Mass | 16.9±2.2[8] M☉ |
| Radius | 265.7[5] R☉ |
| Luminosity | 14,970[5] L☉ |
| Surface gravity (log g) | 0.90[9] cgs |
| Temperature | 3,869±145[4][5] K |
| Metallicity [Fe/H] | −0.18[9] dex |
| Age | 10.0±1.6[8] Myr |
| Other designations | |
| V762 Cas, BD+70 90, HD 7389, HIP 5926, HR 365, SAO 4358, TYC 4305-2038-1[10] | |
| Database references | |
| SIMBAD | data |
Characteristics
V762 Cassiopeiae has a spectral classification of K5 I,[4] suggesting that it is an evolved K-type red supergiant star. Other catalogues have published spectral types of K4,[12] M,[13] and M3II.[6] The Bright Star Catalogue assigned a class of K1V,[14] which originated from one of the earliest observations of this star[15] and was adopted by the General Catalogue of Variable Stars.[14] Recent estimates of the star's physical properties, considering its distance in excess of a thousand light-years,[2] found that it is a red supergiant[4] or asymptotic giant branch star.[5]
At an estimated to be ten million years old, has around 16.9 times the Sun's mass[8] and has expanded to 266 times the Sun's radius. It radiates 15,000 times the solar luminosity from its photosphere at an effective temperature of 3,869 K,[5] which gives it an orange-red hue.[16] Parallax measurements from the Gaia spacecraft show that V762 Cassiopeiae is located about 2,500 light-years away.[2] At the estimated distance, V762 Cassiopeiae's apparent brightness is diminished by 1.04 magnitudes due to interstellar extinction.[5]
Hipparcos satellite data showed that the star is variable, and because of that it was given the variable-star designation V762 Cassiopeiae, in 1999.[17] The variability amplitude in visible light is only about 0.1 magnitudes.[3] The star was catalogued as a semi-regular variable.[7]
Distance and titleholding
Some websites claim V762 Cassiopeiae is the "farthest star visible to the naked eye", at a distance of 16,300 light-years.[18][19] This distance is apparently based on the first Hipparcos published parallax of 0.22±0.59 mas, approximately 5,000 pc or 16,300 light years. However, given the statistical margin of error, the distance is meaningless. The Hipparcos new reduction gives a parallax of 1.18±0.45 mas, corresponding to a distance of about 2,800 light-years,[20] and Gaia DR3 lists a parallax of 1.3148±0.0693 mas, corresponding to a distance of about 2,500 light-years.[2]