HD 137010
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Libra |
| Right ascension | 15h 24m 21.25106s |
| Declination | −19° 44′ 21.6785″ |
| Apparent magnitude (V) | 10.14 |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | K3.5 V |
| Astrometry | |
| Radial velocity (Rv) | +27.866 km/s |
| Proper motion (μ) | RA: +228.536 mas/yr Dec.: −248.158 mas/yr |
| Parallax (π) | 22.2922±0.0174 mas |
| Distance | 146.3 ± 0.1 ly (44.86 ± 0.04 pc) |
| Absolute magnitude (MV) | +7.2 |
| Details | |
| Mass | 0.726±0.017 M☉ |
| Radius | 0.707±0.023 R☉ |
| Luminosity | 0.232+0.023 −0.021 L☉ |
| Surface gravity (log g) | 4.60±0.03 cgs |
| Temperature | 4,770±90 K |
| Metallicity [Fe/H] | -0.22 dex |
| Age | 4.8-10 Gyr |
| Other designations | |
| BD−19 4097, HD 137010, HIP 75398, PPM 230195, EPIC 249661074, TIC 428919267 | |
| Database references | |
| SIMBAD | data |
HD 137010 is a K-type main-sequence star located approximately 146 light-years (44.86 parsecs) away in the zodiac constellation of Libra. It is a solar analog, though cooler, dimmer, and smaller than the Sun, with an apparent visual magnitude of 10.14, making it invisible to the naked eye but readily observable with a telescope. The star is notable for hosting the exoplanet candidate HD 137010 b, a potential Earth-sized exoplanet detected via a single transit in archival data from NASA's Kepler K2 mission.
Characteristics
HD 137010 has a spectral type of K3.5 V, indicating that it is a main-sequence star generating energy through the thermonuclear fusion of hydrogen in its core. Its effective temperature is 4,770 ± 90 K, giving the star an orange hue. The star's mass is 0.726 ± 0.017 M☉, its radius is 0.707 ± 0.023 R☉, and its luminosity is 0.232+0.023
−0.021 L☉. Its metallicity is slightly subsolar at [Fe/H] = −0.22 ± 0.07 dex.
The star's age is estimated between 4.8 and 10 billion years (one analysis gives 7.4 ± 2.6 Gyr), consistent with its low magnetic activity. Its surface gravity is log g = 4.60 ± 0.03 (cgs), and its density is 2.90+0.29
−0.26 g/cm³.
Planetary system
HD 137010 was observed by the Kepler space telescope for 88 days during K2 Campaign 15 (23 August to 19 November 2017). Photometry revealed a single, shallow 10-hour transit event with a depth of 225 ± 10 parts per million (ppm) and a duration of 9.76+0.21
−0.18 hours. The transit was identified through visual inspection of the light curve. Analysis of the K2 photometry, high-resolution imaging (including new speckle observations), archival radial velocities, and Gaia/Hipparcos astrometry ruled out all conventional false-positive scenarios, such as background eclipsing binaries, hierarchical triples, or instrumental artifacts. The event is best explained by a transiting planet candidate, designated HD 137010 b.
The candidate has a radius of 1.06+0.06
−0.05 R🜨, consistent with a rocky Super-Earth or Earth analog. Assuming negligible orbital eccentricity, the orbital period is estimated at 355+200
−59 days, with a semi-major axis of 0.88+0.32
−0.10 AU. The planet receives an incident stellar flux of 0.29+0.11
−0.13 times that of Earth, placing it near the outer edge of the habitable zone.
Its equilibrium temperature is approximately 205+17
−28 K (for a albedo of 0), potentially as low as 173 K for a higher albedo, this is colder than the average surface temperature of Mars. Models suggest a 40% probability of lying in the conservative habitable zone and 51% in the optimistic habitable zone, a thick CO₂-rich atmosphere could potentially allow liquid water despite the low insolation.
As of early 2026, HD 137010 b remains a planet candidate because only one transit has been observed, confirmation requires a second transit or supporting radial-velocity data. The host star's brightness (V = 10.14) makes it an excellent target for future follow-up observations.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b (unconfirmed) | — | 0.88+0.3 −0.1 |
355.0+200.0 −59.0 |
0 | >89.82+0.05 −0.03° |
1.06+0.06 −0.05 R🜨 |
References
- 1 2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
- 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- 1 2 3 4 5 "HD 137010". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-01-27.
- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Venner, Alexander; Vanderburg, Andrew; X. Huang, Chelsea; Dholakia, Shishir; Schwengeler, Hans Martin; Howell, Steve B.; Wittenmyer, Robert A.; Kristiansen, Martti H.; Omohundro, Mark; Terentev, Ivan A. (2026). "A Cool Earth-sized Planet Candidate Transiting a Tenth Magnitude K-dwarf From K2". The Astrophysical Journal. 997 (2): L38. arXiv:2601.19870. Bibcode:2026ApJ...997L..38V. doi:10.3847/2041-8213/adf06f.
- 1 2 3 4 5 6 "HD 137010 | NASA Exoplanet Archive". exoplanetarchive.ipac.caltech.edu. Retrieved 2026-03-29.
- 1 2 Martin, Pierre-Yves (2026). "Planet HD 137010 b". exoplanet.eu. Retrieved 2026-01-28.
- 1 2 "Discovery Alert: An Ice-Cold Earth? - NASA Science". 2026-01-27. Retrieved 2026-01-27.
- ↑ Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (July 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. doi:10.1086/504637. ISSN 0004-6256.
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