7 Ceti
Star in the constellation Cetus
From Wikipedia, the free encyclopedia
7 Ceti is a single,[10] variable star in the equatorial constellation of Cetus. It has the variable star designation AE Ceti.[11] The star is visible to the naked eye with a baseline apparent visual magnitude of 4.44.[2] Based upon an annual parallax shift of only 7.3 mas,[1] it is located roughly 450 light years away. It is moving closer to the Sun with a heliocentric radial velocity of −23 km/s.[6] Eggen (1965) listed it as a probable member of the Wolf 630 group of co-moving stars.[12]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 00h 14m 38.41655s[1] |
| Declination | −18° 55′ 58.3145″[1] |
| Apparent magnitude (V) | 4.44[2] (4.26–4.46)[3] |
| Characteristics | |
| Evolutionary stage | AGB[4] |
| Spectral type | M1 III[5] |
| B−V color index | 1.640±0.044[2] |
| Variable type | LB:[3] |
| Astrometry | |
| Radial velocity (Rv) | −22.9±1.0[6] km/s |
| Proper motion (μ) | RA: −26.15[1] mas/yr Dec.: −73.58[1] mas/yr |
| Parallax (π) | 7.29±0.28 mas[1] |
| Distance | 450 ± 20 ly (137 ± 5 pc) |
| Absolute magnitude (MV) | –1.24[2] |
| Details | |
| Radius | 69[7] R☉ |
| Luminosity | 1,011[7] L☉ |
| Surface gravity (log g) | 0.77[8] cgs |
| Temperature | 3,909[7] K |
| Metallicity [Fe/H] | +0.50[8] dex |
| Other designations | |
| 3 Cet, AE Ceti, BD−19°21, HD 1038, HIP 1170, HR 48, SAO 147169[9] | |
| Database references | |
| SIMBAD | data |
This is an aging red giant star with a stellar classification of M1 III,[5] currently on the asymptotic giant branch.[4] In 1959, Alan William James Cousins announced the detection of variability in the brightness of 7 Ceti.[13] It was given its variable star designation in 1973.[14] Samus et al. (2017) has it classed as a slow irregular variable of type LB:, and ranges in magnitude from 4.26 down to 4.46.[3] Tabur et al. (2009) list it as a semiregular variable with four known periods ranging in frequency from 19.2 to 41.7 days.[11] The stellar atmosphere of 7 Ceti has expanded to an estimated 69 times the Sun's radius.[7] It is radiating around 1,011 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,909 K.[7]
| Period (Days) |
Amplitude (Mag.) |
|---|---|
| 19.2 | 0.018 |
| 19.6 | 0.020 |
| 27.1 | 0.018 |
| 41.7 | 0.017 |