R Cassiopeiae
Star in the constellation Cassiopeia
From Wikipedia, the free encyclopedia
R Cassiopeiae is a variable star in the northern constellation of Cassiopeia. It is located approximately 570 light years distant from the Sun, but is drifting closer with a radial velocity of −23 km/s.[5] This is a pulsating Mira-type variable star with a brightness that varies from magnitude +4.4 down to +13.5 over a period of 433.6 days.[3] At its maximum brightness, R Cassiopeiae is visible to the naked eye as a faint, red-hued star.
 | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Cassiopeia[1] |
| Right ascension | 23h 58m 24.868s[2] |
| Declination | +51° 23′ 19.71″[2] |
| Apparent magnitude (V) | 4.4 to 13.5[3] |
| Characteristics | |
| Spectral type | M6e–M10e[3] |
| U−B color index | +0.08[4] |
| B−V color index | +1.83[4] |
| Variable type | Mira[3] |
| Astrometry | |
| Radial velocity (Rv) | −22.94±0.72[5] km/s |
| Proper motion (μ) | RA: 82.847[2] mas/yr Dec.: 17.485[2] mas/yr |
| Parallax (π) | 5.7423±0.2011 mas[2] |
| Distance | 570 ± 20 ly (174 ± 6 pc) |
| Details | |
| Mass | 0.59[6] M☉ |
| Radius | 263[6] R☉ |
| Luminosity | 8,960[7] L☉ |
| Surface gravity (log g) | −0.50[8] cgs |
| Temperature | 2,812[6] K |
| Metallicity [Fe/H] | 0.50[8] dex |
| Other designations | |
| R Cas, BD+50°4202, HD 224490, HIP 118188, HR 9066, SAO 35938, ADS 17135, CCDM J23584+5123[9] | |
| Database references | |
| SIMBAD | data |
Norman Robert Pogson discovered the star, in 1853.[11][12] This aging red giant star has a stellar classification that varies from M6e to M10e,[3] where the 'e' suffix indicates emission features in the spectrum. Currently on the asymptotic giant branch,[13] it has 59%[6] of the mass of the Sun with an oxygen rich chemical abundance.[14] Having exhausted the supply of hydrogen at its core, the star has expanded to 263[6] times the Sun's radius. On average, the star is radiating 3,837[6] times the luminosity of the Sun from its swollen photosphere with an effective temperature ranging around 2,812 K.[6] It is losing mass at the rate of 1.3×10−6 M☉/yr−1[7] and is surrounded by a dusty circumstellar shell that extends out to 2.8′.[14]