Iota Mensae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Mensa |
| Right ascension | 05h 35m 36.1787s |
| Declination | −78° 49′ 15.129″ |
| Apparent magnitude (V) | 6.00 - 6.05 |
| Characteristics | |
| Spectral type | B8 III |
| B−V color index | −0.022 |
| Variable type | Ellipsoidal? |
| Astrometry | |
| Radial velocity (Rv) | 12.6±4.3 km/s |
| Proper motion (μ) | RA: +5.547 mas/yr Dec.: +25.710 mas/yr |
| Parallax (π) | 3.7076±0.1819 mas |
| Distance | 880 ± 40 ly (270 ± 10 pc) |
| Absolute magnitude (MV) | −1.03 |
| Details | |
| Mass | 3.6 M☉ |
| Radius | 9.5 R☉ |
| Luminosity | 301 L☉ |
| Surface gravity (log g) | 3.4 cgs |
| Temperature | 11,272±264 K |
| Metallicity [Fe/H] | +0.13 dex |
| Age | 203 Myr |
| Other designations | |
| ι Men, CD−78°216, HD 38602, HIP 26264, HR 1991, SAO 256214 | |
| Database references | |
| SIMBAD | data |
Iota Mensae is a single star about 880 light years away in the faint constellation Mensa. It has a very slightly variable apparent magnitude of 6.0, making it visible with the naked eye under good skies.
Iota Mensae has a spectral type of B8III, indicating that it has exhausted hydrogen at its core and expanded away from the main sequence. It is about 3.6 times the mass (M☉), 301 times as luminous, and has swollen to 9.5 times the radius of the Sun (R☉). It is calculated to be 314 million years old.
It has been catalogued as a chemically peculiar star with abnormally strong lines of silicon in its spectrum but this classification is now considered doubtful. Its brightness varies by a few hundredths of a magnitude. Its period was initially measured at 2.6 days, but this is now considered to be a period of 5.3 days with primary and secondary minima of a similar depth. The variability is thought to be due to the rotation of the star.