Z Ursae Minoris
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ursa Minor |
| Right ascension | 15h 02m 01.36335s |
| Declination | +83° 03′ 48.6299″ |
| Apparent magnitude (V) | 10.8 - 19.0 |
| Characteristics | |
| Spectral type | C (R) |
| Variable type | R CrB |
| Astrometry | |
| Radial velocity (Rv) | −36.07±0.98 km/s |
| Proper motion (μ) | RA: −7.346 mas/yr Dec.: +4.322 mas/yr |
| Parallax (π) | 0.2159±0.0231 mas |
| Distance | approx. 15,000 ly (approx. 4,600 pc) |
| Details | |
| Mass | 0.7±0.2 M☉ |
| Luminosity | 7,900+12,000 −4,800 L☉ |
| Surface gravity (log g) | 0.5±0.3 cgs |
| Temperature | 5,250±250 K |
| Metallicity [Fe/H] | −1.85 dex |
| Other designations | |
| Z UMi, TYC 4634-1727-1, 2MASS J15020132+8303485 | |
| Database references | |
| SIMBAD | data |
Z Ursae Minoris (Z UMi) is a carbon star and R Coronae Borealis variable in the constellation Ursa Minor.
Z Ursae Minoris was discovered to be a variable star in 1934. It was catalogued as a probable Mira variable, due to its red colour and variations over several hundred days. It was discovered to be a carbon star in a survey published in 1985, and subsequently found also to be hydrogen-deficient. After fading by almost six magnitudes in 1992, it was classified as an R Coronae Borealis variable. It was confirmed as an R Coronae Borealis variable, one of the coolest in the class, after its spectrum was analysed in 2006.