LHS 1140

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.[5] 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.[6]

LHS 1140

Artist's impression of LHS 1140 and LHS 1140b.
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Cetus
Right ascension	00^h 44^m 59.31^s[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[3] mas/yr Dec.: -589[3] mas/yr
Distance	40.67 ± 1.37 ly (12.47 ± 0.42[2] pc)
Details[4]
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±5d
Age	>5 Gyr
Other designations
GJ 3053, G 270-58, G 268-38, 2MASS J00445930-1516166
Database references
SIMBAD	data
ARICNS	data

As of Jan. 2019, LHS 1140 is known to have two confirmed rocky planets orbiting it, and a third candidate planet not yet confirmed.

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.[6] The planet LHS 1140b 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][7] The mass of LHS 1140b 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,[8] 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.[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.[8]

The LHS 1140 planetary system[2][8][9]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
c	1.81 ± 0.39 M⊕	0.02675 ± 0.00070	3.777931 ± 0.000003	< 0.31	89.92°	1.282 ± 0.024 R⊕
b	6.98 ± 0.89 M⊕	0.0936 ± 0.0024	24.73712 ± 0.00025	< 0.06	89.912 ± 0.071°	1.727 ± 0.032 R⊕
d (candidate)	9.64-11.11 M⊕	0.210	92-93	0-0.03	~90°	—

See also

• MEarth Project
• Planetary habitability
• High Accuracy Radial Velocity Planet Searcher (HARPS)
• Super-Earth
• Habitability of red dwarf systems
• Gliese 1132 b
• GJ 1214 b

References

1. Cutri, R. M.; et al. (2003). "2MASS All-Sky Catalog of Point Sources". VizieR On-line Data Catalog. 2246. Bibcode:2003yCat.2246....0C.
2. Dittmann, Jason A.; Irwin, Jonathan M.; Charbonneau, David; Bonfils, Xavier; Astudillo-Defru, Nicola; Haywood, Raphaëlle D.; Berta-Thompson, Zachory K.; Newton, Elisabeth R.; Rodriguez, Joseph E.; Winters, Jennifer G.; Tan, Thiam-Guan; Almenara, Jose-Manuel; Bouchy, François; Delfosse, Xavier; Forveille, Thierry; Lovis, Christophe; Murgas, Felipe; Pepe, Francesco; Santos, Nuno C.; Udry, Stephane; Wünsche, Anaël; Esquerdo, Gilbert A.; Latham, David W.; Dressing, Courtney D. (2017). "A temperate rocky super-Earth transiting a nearby cool star". Nature. 544 (7650): 333–336. arXiv:1704.05556. Bibcode:2017Natur.544..333D. doi:10.1038/nature22055. PMID 28426003.
3. Salim, Samir; Gould, Andrew (2003). "Improved Astrometry and Photometry for the Luyten Catalog. II. Faint Stars and the Revised Catalog". The Astrophysical Journal. 582 (2): 1011–1031. arXiv:astro-ph/0206318. Bibcode:2003ApJ...582.1011S. doi:10.1086/344822.
4. Ferraz-Mello, S.; Gomes, G. O. (2020). "Tidal evolution of exoplanetary systems hosting potentially habitable exoplanets. The cases of LHS-1140 b-c and K2-18 b-c". Monthly Notices of the Royal Astronomical Society. 494 (4): 5082–5090. arXiv:2005.10318. Bibcode:2020MNRAS.494.5082G. doi:10.1093/mnras/staa1110.
5. Luyten, Willem Jacob, Catalogue of stars with proper motions exceeding 0"5 annually, University of Minnesota, 1979
6. Dickinson, David (19 April 2017). "Welcome to LHS 1140b: A Super-Earth in the Habitable Zone". Sky & Telescope. Retrieved 19 April 2017.
7. Overbye, Dennis (19 April 2017). "A New Exoplanet May Be Most Promising Yet in Search for Life". New York Times. Retrieved 20 April 2017.
8. "A second planet with an Earth-like composition orbiting the nearby M dwarf LHS 1140". Kristo Ment, Jason A. Dittmann, Nicola Astudillo-Defru, David Charbonneau, Jonathan Irwin, Xavier Bonfils, Felipe Murgas, Jose-Manuel Almenara, Thierry Forveille, Eric Agol, Sarah Ballard, Zachory K. Berta-Thompson, Franc¸ois Bouchy, Ryan Cloutier, Xavier Delfosse, Rene Doyon, Courtney D. Dressing, Gilbert A. Esquerdo, Raphaelle D. Haywood, David M. Kipping, David W. Latham, Christophe Lovis, Elisabeth R. Newton, Francesco Pepe, Joseph E. Rodriguez, Nuno C. Santos, Thiam-Guan Tan, Stephane Udry, Jennifer G. Winters, and Anael W unsche (August 3, 2018).
9. Feng, Fabo; Tuomi, Mikko; Jones, Hugh R. A. (2018). "Minimizing the bias in exoplanet detection - application to radial velocities of LHS 1140". arXiv:1807.02483 [astro-ph.EP].