Gliese 555
Gliese 555 is a small star with one or more orbiting exoplanets in the constellation Libra. It has the variable star designation HN Librae, abbreviated HN Lib. With an apparent visual magnitude of 11.32, it can only be viewed through a telescope. The system is located at a distance of 20.4 light years based on parallax measurements, but is drifting closer to the Sun with a radial velocity of −1.4 km/s. It does not appear to belong to any known stellar moving group or association.
A visual band light curve for HN Librae, adapted from Weis (1994) | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Libra |
| Right ascension | 14h 34m 16.81166s |
| Declination | −12° 31′ 10.4145″ |
| Apparent magnitude (V) | 11.32 |
| Characteristics | |
| Spectral type | M4.0V |
| B−V color index | 1.633±0.052 |
| Variable type | BY Dra |
| Astrometry | |
| Radial velocity (Rv) | −1.36±0.20 km/s |
| Proper motion (μ) | RA: −355.138 mas/yr Dec.: 593.040 mas/yr |
| Parallax (π) | 159.9225 ± 0.0546 mas |
| Distance | 20.395 ± 0.007 ly (6.253 ± 0.002 pc) |
| Absolute magnitude (MV) | 12.41 |
| Details | |
| Mass | 0.291±0.013 M☉ |
| Radius | 0.299±0.009 R☉ |
| Luminosity (bolometric) | 0.010106±0.000069 L☉ |
| Surface gravity (log g) | 4.76±0.13 cgs |
| Temperature | 3347±50 K |
| Metallicity [Fe/H] | −0.18±0.15 dex |
| Rotation | 96±2 d |
| Rotational velocity (v sin i) | <2.0 km/s |
| Age | 0.8–8.0 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Gliese 555 Location of Gliese 555 in the constellation Libra | |
This is an M-type main-sequence star, a red dwarf, with a stellar classification of M4.0V. The chromosphere of this star is weakly active, causing starspots that vary the stellar luminosity as it rotates. It has 29% of the mass of the Sun and 30% of the Sun's girth. On average, the star is radiating just 1% of the luminosity of the Sun from its photosphere at an effective temperature of 3,347 K. The star is spinning slowly with a rotation period of around 96 days.