| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Leo |
| Right ascension | 09h 23m 47.08737s[1] |
| Declination | +20° 21′ 52.0349″[1] |
| Apparent magnitude (V) | +7.73[2] |
| Characteristics | |
| Spectral type | G0V[2] |
| B−Vcolor index | 0.680±0.012 |
| Astrometry | |
| Radial velocity (Rv) | +49.270±0.0017[3] km/s |
| Proper motion (μ) | RA: −151.265±0.045mas/yr[1] Dec.: 35.708±0.036mas/yr[1] |
| Parallax (π) | 29.0635±0.0414 mas[1] |
| Distance | 112.2 ± 0.2 ly (34.41 ± 0.05 pc) |
| Absolute magnitude (MV) | 5.12[4] |
| Details | |
| Mass | 0.962±0.040[5] M☉ |
| Radius | 0.91+0.01 −0.03[6] R☉ |
| Luminosity | 0.838±0.018[7] L☉ |
| Surface gravity (log g) | 4.48[2] cgs |
| Temperature | 5,753[2] K |
| Metallicity [Fe/H] | −0.06±0.03[4] dex |
| Rotation | 15.98 d[7] |
| Rotational velocity (v sin i) | 5.3[2] km/s |
| Age | 1.79+0.30 −0.26[7] Gyr |
| Other designations | |
| BD+20°2374,FK5 4836,GC 12951,HD 81040,HIP 46076,SAO 80800,PPM 99541[8] | |
| Database references | |
| SIMBAD | data |
HD 81040 is astar in theequatorialconstellation ofLeo. With anapparent visual magnitude of +7.73[2] it is too dim to be visible to the naked eye but can be viewed with a small telescope. The star is located at a distance of 112 light years from theSun based onparallax. It is drifting further away with aradial velocity of +49 km/s,[3] having come to within 48 light-years some 527,000 years ago.
This is an ordinaryG-type main-sequence star with astellar classification of G0V.[2] The Sun somewhat dwarfs HD 81040 in terms of physical characteristics: it has 87% of theSun's mass and 91% of theradius of the Sun. It is spinning with aprojected rotational velocity of 5.3 km/s,[2] and has near solarmetallicity.[4] The age of the star is not precisely known; theELODIE spectrograph suggested 0.8 Gyr and found it to have a youngdust disk.[9] Later measurements by modellingchromosperic activity suggested an age of 4.18 Gyr.[citation needed]
On November 24, 2005, asuperjovianplanet was announced by Sozzetti et al.[9] It was discovered using the radial velocity method.Astrometric measurements usingGaia, published in several papers, show that the inclination of its orbit is about 111 degrees, so its true mass is somewhat higher than that predicted from itsminimum mass.[7][5]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 7.53±0.032 MJ | 1.946±0.014 | 1,004.7±3.0 | 0.525+0.024 −0.026 | 111.4+4.4 −4.7° | — |
