Gliese 42
Star in the constellation of Sculptor
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Gliese 42 is a star in the southern constellation of Sculptor. It is too faint to be seen with the naked eye, having an apparent visual magnitude of +7.2. The annual parallax shift of 71.7 mas provides a distance estimate of 45 light years. It has a relatively high proper motion, advancing 0.62 arcseconds across the sky per annum,[11] and is moving closer to the Sun with a radial velocity of −13 km/s.[6]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sculptor[1] |
| Right ascension | 00h 53m 01.1349s[2] |
| Declination | −30° 21′ 24.891″[2] |
| Apparent magnitude (V) | +7.17[3] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | K2.5 V (k)[4] |
| B−V color index | 0.936[5] |
| Astrometry | |
| Radial velocity (Rv) | −13.021±0.0064[6] km/s |
| Proper motion (μ) | RA: +620.243[2] mas/yr Dec.: +31.770[2] mas/yr |
| Parallax (π) | 71.7259±0.0267 mas[2] |
| Distance | 45.47 ± 0.02 ly (13.942 ± 0.005 pc) |
| Absolute magnitude (MV) | +6.39[1] |
| Details | |
| Mass | 0.81[7] M☉ |
| Radius | 0.74[7] R☉ |
| Luminosity | 0.29[7] L☉ |
| Surface gravity (log g) | 4.60[7] cgs |
| Temperature | 4,921[7] K |
| Metallicity [Fe/H] | −0.21[4] dex |
| Rotational velocity (v sin i) | 1.8[8] km/s |
| Age | 6.67±4.74[9] Gyr |
| Other designations | |
| BD−31°325, GJ 42, HD 5133, HIP 4148, SAO 192793, LTT 498, 2MASS J00530108-3021249[10] | |
| Database references | |
| SIMBAD | data |
The spectrum of the star matches a stellar classification of K2.5 V (k),[4] indicating it is an ordinary K-type main-sequence star that is generating energy through hydrogen fusion at its core. It is radiating 29% of the Sun's luminosity from its photosphere at an effective temperature of 4,921 K.[7] The star has 74% of the Sun's radius.[7]
Debris disk
An infrared excess has been detected around this star,[12] most likely indicating the presence of a circumstellar disk at a radius of 45.7 astronomical units (6.84×109 km; 4.25×109 mi). The temperature of this dust was initially estimated as 30 K (−243.2 °C; −405.7 °F)[13] according to measurement by Herschel Space Observatory. Later that measurement was deemed questionable,[14] and fixed temperature of 62 K (−211.2 °C; −348.1 °F) was obtained in 2020.[15]