LHS 1140
 Artist's impression of LHS 1140 and LHS 1140b. | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 00h 44m 59.31s[1] |
| Declination | −15° 16′ 16.7″[1] |
| Apparent magnitude (V) | 14.18[2] |
| Characteristics | |
| Evolutionary stage | Red dwarf |
| Spectral type | M4.5V[2] |
| Astrometry | |
| Radial velocity (Rv) | −13.23 ± 0.60[2] km/s |
| Proper motion (μ) | RA: 317.585[3] mas/yr Dec.: −596.617[3] mas/yr |
| Parallax (π) | 66.6996 ± 0.0674[4] mas |
| Distance | 14.986 ± 0.015[5] pc |
| Details[6] | |
| Mass | 0.179 ± 0.014 M☉ |
| Radius | 0.2139 ± 0.0041 R☉ |
| Luminosity | 0.00441 ± 0.00013 L☉ |
| Temperature | 3216 ± 39 K |
| Metallicity [Fe/H] | −0.24 ± 0.10 dex |
| Rotation | 131 ± 5 d |
| Age | >5 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
LHS 1140 is a red dwarf in the constellation of Cetus. Based on its stellar properties, it is thought to be about 41 light-years away from the Sun.[2] 'LHS' refers to the Luyten Half-Second Catalogue of stars with proper motions exceeding half a second of arc annually.[7] The star is over 5 billion years old and has 15% of the mass of the Sun. LHS 1140's rotational period is 130 days. No flares have been observed.[8]
Planetary system[]
As of January 2019, LHS 1140 is known to have two confirmed rocky planets orbiting it, and a third candidate planet not yet confirmed.[9]
The first to be discovered was LHS 1140 b, discovered by the MEarth Project in 2017 using the transit method.[2] Follow-up radial velocities were measured by the High Accuracy Radial Velocity Planet Searcher instrument to confirm the planet and measure the mass.[8] The planet LHS 1140 b is a super-Earth in the habitable zone and transits the star every 24.7 days. This should allow its atmosphere to be studied in future: the combination of the transiting super-Earth and the relatively small and nearby host star make this system one of the most promising known for atmosphere studies, along with the TRAPPIST-1 system.[2][10] The mass of LHS 1140 b is about 7 times Earth's, and its radius about 1.7 times as large, giving it a density of about 7.5 g/cm3,[11] compared to Earth's 5.5 g/cm3.
In July 2018, Feng et al.. published a reanalysis of the radial velocity data for LHS 1140, and proposed the likely existence of two additional planets: an inner Earth-mass planet orbiting every 3.8 days and an outer Neptune-mass planet orbiting every 90 days.[12] The orbital period of the outer planet LHS 1140 d was refined to 78 days in 2020.[9]
In August 2018, Ment et al., using the transit method of detection, confirmed the existence of the inner planet LHS 1140 c with a mass about 1.8 times Earth's and a radius 1.3 times as large, giving it a density of about 5 g/cm3.[11]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| c | 1.77 ± 0.17 M
|