UZ Pyxidis
Star in the constellation Pyxis
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UZ Pyxidis (HD 75021) is a semiregular variable star in the constellation Pyxis. It is located about 3,600 light-years (1,100 parsecs) away from the Earth.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pyxis |
| Right ascension | 08h 46m 36.3323s[2] |
| Declination | −29° 43′ 41.203″[2] |
| Apparent magnitude (V) | 6.99 - 7.63[3] |
| Characteristics | |
| Spectral type | C55J (R8)[3] |
| U−B color index | +2.99[4] |
| B−V color index | +2.01[4] |
| Variable type | SRb[5] |
| Astrometry | |
| Radial velocity (Rv) | 13.00[6] km/s |
| Proper motion (μ) | RA: −5.767[2] mas/yr Dec.: 1.674[2] mas/yr |
| Parallax (π) | 0.8949±0.0183 mas[2] |
| Distance | 3,640 ± 70 ly (1,120 ± 20 pc) |
| Absolute magnitude (MV) | −1.2[7] |
| Details | |
| Mass | 2.1[8] M☉ |
| Radius | 221[9] R☉ |
| Luminosity | 5,649[10] L☉ |
| Surface gravity (log g) | −0.236[8] cgs |
| Temperature | 3,325[10] K |
| Metallicity [Fe/H] | −0.32[8] dex |
| Other designations | |
| UZ Pyx, CD-29°6735, HD 75021, HIP 43093, SAO 176458, GC 12117 | |
| Database references | |
| SIMBAD | data |
UZ Pyxidis lies directly between α and γ Pyxidis. It has a common proper motion companion, HD 75022,[11] less than 2' away but the two are not listed in double star catalogues.
UZ Pyxidis is a carbon star. These types of stars are known for having large amounts of carbon in their atmospheres, forming carbon compounds that make the star appear strikingly red. It was first recognised as having an unusual spectrum in 1893.[12] Under the Morgan–Keenan classification of carbon stars, UZ Pyxidis' spectral type is C55; if it were a normal giant star, this would correspond to a spectral type of about K5.[13] It is also unusual in that it has very strong isotopic bands of C2 and CN.[14]
There were hints that the star is variable as early as the late 19th century,[15] and its variability was firmly established by Olin J. Eggen in 1972.[16][11] The variable star designation UZ Pyxidis was assigned in 1978.[17] UZ Pyxidis is classified as a semiregular variable with a dominant period of 159.6 days. It varies in brightness between magnitude 6.99 and 7.63.[3]