K2-315b

K2-315b
Size comparison of the planet K2-315b (artistic concept) with Earth
Discovery
Discovered byKepler (K2)
Discovery date2020
Transit
Orbital characteristics
0.02±0.00 AU
3.14±0.00 d
Inclination88.7°±0.2°
Physical characteristics
0.95±0.06 R🜨
Temperature460 ± 5 K (186.85 ± 5.00 °C; 368.33 ± 9.00 °F)

K2-315b is an exoplanet located 185.3 light-years away from Earth in the southern zodiac constellation Libra. It orbits the red dwarf K2-315.

Discovery

K2-315b was discovered in 2020 by astronomers in an observatory using the Kepler space telescope. It is also nicknamed the "Pi Planet" or "Pi Earth" because it takes approximately 3.14 days to orbit the host star.

Physical properties

The planet is thought to be small and rocky, although composition is unknown. Since it orbits very close to its star, it is too hot to host life, due to it having a temperature of 450 K. It has a radius 95% that of Earth, very similar to Venus.

Host star

K2-315
The location of K2-315 (circled in red)
The location of K2-315 (circled in red)
Observation data
Epoch J2000.0      Equinox ICRS
Constellation Libra
Right ascension 15h 12m 05.1944s
Declination −20° 06′ 30.5428″
Apparent magnitude (V) 17.67
Characteristics
Evolutionary stage Red dwarf
Spectral type M3.5±0.5 V
Astrometry
Radial velocity (Rv)6.25±0.17 km/s
Proper motion (μ) RA: −120.013 mas/yr
Dec.: +74.471 mas/yr
Parallax (π)17.6353±0.0492 mas
Distance184.9 ± 0.5 ly
(56.7 ± 0.2 pc)
Details
Mass0.174±0.004 M☉
Radius0.2±0.01 R☉
Luminosity0.398% L☉
Surface gravity (log g)5.094±0.006 cgs
Temperature3,300±30 K
Metallicity [Fe/H]−0.24±0.09 dex
Rotational velocity (v sin i)<5 km/s
Age>1 Gyr
Other designations
K2-315, EPIC 249631677
Database references
SIMBADdata

K2-315 is a star in the southern zodiac constellation Libra. It has an apparent magnitude of 17.67, requiring a powerful telescope to be seen. The star is relatively close at a distance of 185 light-years but is receding with a radial velocity of 6.25 km/s.

K2-315 has a stellar classification of M3.5±0.5 V, indicating that it is a M-type main-sequence star (with 14% uncertainty). It has 17.4% the mass of the Sun and 20% its radius. Typical for red dwarfs, it has a luminosity less than 1% of the Sun, which yields an effective temperature of 3,300 K. Unlike most planetary hosts, K2-315 is metal-deficient, with an iron abundance only 57% that of the Sun. It is estimated to be over a billion years old, and has a projected rotational velocity less than 5 km/s.

References

  1. 1 2 3 4 5 Niraula, Prajwal; de Wit, Julien; Rackham, Benjamin V.; Ducrot, Elsa; Burdanov, Artem; Crossfield, Ian J. M.; Van Grootel, Valérie; Murray, Catriona; Garcia, Lionel J.; Alonso, Roi; Beard, Corey; Chew, Yilen Gómez Maqueo; Delrez, Laetitia; Demory, Brice-Olivier; Fulton, Benjamin J.; Gillon, Michaël; Günther, Maximilian N.; Howard, Andrew W.; Issacson, Howard; Jehin, Emmanuël; Pedersen, Peter P.; Pozuelos, Francisco J.; Queloz, Didier; Rebolo-López, Rafael; Sairam, Lalitha; Sebastian, Daniel; Thompson, Samantha; Triaud, Amaury H. M. J. (2020). "Π Earth: A 3.14 day Earth-sized Planet from K2's Kitchen Served Warm by the SPECULOOS Team". The Astronomical Journal. 160 (4): 172. arXiv:2006.07308. Bibcode:2020AJ....160..172N. doi:10.3847/1538-3881/aba95f. S2CID 219635862.
  2. ↑ "Exoplanet-catalog". Exoplanet Exploration: Planets Beyond our Solar System. NASA. Retrieved 2020-10-22.
  3. ↑ Wall, Mike (22 September 2020). "'Pi planet' alien world takes 3.14 days to orbit its star". Space.com. Retrieved 2020-10-22.
  4. 1 2 Starr, Michelle (22 September 2020). "Astronomers Discover "Pi Earth" Exoplanet Orbits Its Star Once Every 3.14 Days". ScienceAlert. Retrieved 2020-10-21.
  5. ↑ Ciaccia, Chris (2020-09-29). "Mysterious 'pi planet' discovered in deep space". Retrieved 2025-05-06.
  6. ↑ Anderson, Paul Scott (2020-10-04). "Meet the Pi planet. It orbits its star every 3.14 days". earthsky.org. Retrieved 2025-05-06.
  7. ↑ "Exoplanet Archive". exoplanetarchive.ipac.caltech.edu. Retrieved 2020-10-21.
  8. ↑ "Find the constellation which contains given sky coordinates". djm.cc. Retrieved 2026-08-09.
  9. 1 2 3 4 5 6 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  10. 1 2 Muirhead, Philip S.; Dressing, Courtney D.; Mann, Andrew W.; Rojas-Ayala, Bárbara; Lépine, Sébastien; Paegert, Martin; De Lee, Nathan; Oelkers, Ryan (4 April 2018). "A Catalog of Cool Dwarf Targets for the Transiting Exoplanet Survey Satellite". The Astronomical Journal. 155 (4): 180. arXiv:1710.00193. Bibcode:2018AJ....155..180M. doi:10.3847/1538-3881/aab710. eISSN 1538-3881.
  11. 1 2 3 4 5 6 7 8 9 Niraula, Prajwal; et al. (21 September 2020). "π Earth: A 3.14 day Earth-sized Planet from K2's Kitchen Served Warm by the SPECULOOS Team". The Astronomical Journal. 160 (4): 172. arXiv:2006.07308. Bibcode:2020AJ....160..172N. doi:10.3847/1538-3881/aba95f. eISSN 1538-3881. ISSN 0004-6256.
  12. ↑ "Odkryto "Ziemię Pi". Okrąża swoją gwiazdę raz na 3,14 dnia". national-geographic.pl (in Polish).