TZ Cassiopeiae
 Location of TZ Cas |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 23h 52m 56.23733s |
| Declination | 61° 00′ 08.3786″ |
| Apparent magnitude (V) | 9.18(+8.86 - +10.5) |
| Characteristics | |
| Spectral type | M3 Iab |
| U−B color index | +2.43 |
| B−V color index | +2.57 |
| Variable type | Lc |
| Astrometry | |
| Radial velocity (Rv) | −54.28 km/s |
| Proper motion (μ) |
RA: −2.77 mas/yr Dec.: −3.10 mas/yr |
| Parallax (π) | 0.39 ± 0.76mas |
| Distance | 2,400pc |
| Absolute magnitude (MV) | −5.98 |
| Details | |
| Mass | 15 M☉ |
| Radius | 645-800 R☉ |
| Luminosity | 69,000 L☉ |
| Surface gravity (log g) | −0.01 cgs |
| Temperature | 3,670 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
TZ Cassiopeaie (TZ Cas, HIP 117763, SAO 20912) is a variable star in the constellation Cassiopeia with an apparent magnitude of around +9 to +10. It is approximately 8,000 light-years away from Earth. The star is a red supergiant star with a spectral type of M3 and a temperature of 3,670 Kelvin. It is currently around 15 M☉
TZ Cassiopeiae was reported as being variable by Williamina Fleming and published posthumously in 1911. It is a slow irregular variable star with a possible period of 3,100 days. It is approximately 69,000 times the luminosity of the Sun, and it is 645 to 800 times bigger than the Sun. It is a member of the Cas OB5 stellar association, together with the nearby red supergiant PZ Cassiopeiae.
TZ Cas is losing mass through a powerful stellar wind at two millionths of a solar mass each year. It is unclear whether this is sufficient to cause the star to lose its atmosphere and become a blue supergiant before the core exhausts its fuel and collapses as a supernova. Either as a red or blue supergiant, or a Wolf-Rayet star, it will inevitably end its life violently in a supernova explosion when the core collapse occurs.
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