Alpha Caeli
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Caelum |
| A | |
| Right ascension | 04h 40m 33.71251s |
| Declination | −41° 51′ 49.5045″ |
| Apparent magnitude (V) | 4.44 – 4.47 |
| B | |
| Right ascension | 04h 40m 33.92449s |
| Declination | −41° 51′ 56.3362″ |
| Apparent magnitude (V) | 12.5 |
| Characteristics | |
| A | |
| Evolutionary stage | main sequence |
| Spectral type | F2V |
| Apparent magnitude (U) | 4.79 |
| Apparent magnitude (B) | 4.79 |
| Apparent magnitude (R) | 4.11 |
| Apparent magnitude (G) | 4.35 |
| Apparent magnitude (I) | 3.90 |
| Apparent magnitude (J) | 3.944±0.354 |
| Apparent magnitude (H) | 3.654±0.292 |
| Apparent magnitude (K) | 3.724±0.324 |
| U−B color index | 0.01 |
| B−V color index | +0.34 |
| Variable type | suspected Delta Scuti |
| B | |
| Evolutionary stage | Red dwarf |
| Spectral type | M0.5V |
| Variable type | Flare star |
| Astrometry | |
| A | |
| Radial velocity (Rv) | 0.65±0.3 km/s |
| Proper motion (μ) | RA: −139.843 mas/yr Dec.: −75.677 mas/yr |
| Parallax (π) | 49.062±0.00937 mas |
| Distance | 66.48 ± 0.01 ly (20.382 ± 0.004 pc) |
| Absolute magnitude (MV) | 2.93±0.01 |
| B | |
| Absolute magnitude (MV) | 9.8 |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 460,000 days (1,260 years) |
| Semi-major axis (a) | 133.1 AU |
| Details | |
| A | |
| Mass | 1.54 M☉ |
| Radius | 1.546 R☉ |
| Luminosity | 5.156 L☉ |
| Surface gravity (log g) | 4.12 cgs |
| Temperature | 7,002 K |
| Metallicity [Fe/H] | −0.06±0.06 dex |
| Rotation | 1.4 days |
| Rotational velocity (v sin i) | 47.8±2.4 km/s |
| Age | 1.5 Gyr |
| B | |
| Radius | 0.45 R☉ |
| Temperature | 3,355 K |
| Position (relative to A) | |
| Component | B |
| Epoch of observation | 2008 |
| Angular distance | 6.6″ |
| Other designations | |
| α Caeli, GJ 174.1, GJ 9164, HD 29875, HIP 21770, HR 1502, PPM 308904, WDS J04406-4152, TIC 77263680, TYC 7589-1693-1, GSC 07589-01693, IRAS 04389-4157, 2MASS J04403374-4151495, WISE J044033.59-415150.2 | |
| Database references | |
| SIMBAD | A |
| B | |
Alpha Caeli is a binary star system in the southern constellation Caelum. Its name is a Bayer designation that is Latinized from α Caeli, and abbreviated Alpha Cae or α Cae. With a combined apparent visual magnitude of 4.45, it is only visible to the naked eye in places far from light pollution, but still is the brightest star in the constellation. Parallax measurements by the Gaia spacecraft indicate a distance of 66.48 light-years (20.38 pc) to Alpha Caeli. It has a relatively low radial velocity, estimated at 0.7 km/s relative to the Sun.
This system consists of an F-type star of magnitude 4.46 and a small red dwarf of magnitude 12.5. As of 2008, they are separated by 6.6" in the sky. A debris disk has been detected around the primary component of the system.