Alpha Sextantis
Alpha Sextantis (α Sex, α Sextantis) is the brightest star in the equatorial constellation of Sextans. It is visible to the naked eye on a dark night with an apparent visual magnitude of 4.49. The distance to this star, as determined from parallax measurements, is around 280 light years. This is considered an informal "equator star", as it lies less than a quarter of a degree south of the celestial equator. In 1900, it was 7 minutes of arc north of the equator. As a result of a shift in the Earth's axial tilt, it crossed over to the southern hemisphere in December 1923.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sextans |
| Right ascension | 10h 07m 56.29556s |
| Declination | −0° 22′ 17.8621″ |
| Apparent magnitude (V) | 4.49 |
| Characteristics | |
| Spectral type | A0 III |
| U−B color index | −0.07 |
| B−V color index | −0.04 |
| Astrometry | |
| Radial velocity (Rv) | 10.00 km/s |
| Proper motion (μ) | RA: −25.83 mas/yr Dec.: −4.25 mas/yr |
| Parallax (π) | 11.51 ± 0.98 mas |
| Distance | 280 ± 20 ly (87 ± 7 pc) |
| Absolute magnitude (MV) | −0.29±0.21 |
| Details | |
| Mass | 2.57±0.32 M☉ |
| Radius | 3.07 R☉ |
| Luminosity | 90 L☉ |
| Surface gravity (log g) | 3.55 cgs |
| Temperature | 9,984 K |
| Metallicity [Fe/H] | −0.03±0.18 dex |
| Rotational velocity (v sin i) | 21 km/s |
| Age | 385 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The variability of Alpha Sextantis was discovered by Aven Magded Hamadamen and included in the International Variable Star Index. The star undergoes pulsations with a period of 9.1 hours.
This is an evolved A-type giant star with a stellar classification of A0 III. It has around 2.5 times the mass of the Sun and three times the Sun's radius. The abundance of elements is similar to that in the Sun. It radiates 90 times the solar luminosity from its outer atmosphere at an effective temperature of 9,984 K. Alpha Sextantis is nearing the end of its life as a main-sequence star; it is around 385 million years old with a projected rotational velocity of 21 km/s.