Astronomy:K2-315
 The location of K2-315 (circled in red) | |
| Observation data Epoch J2000.0 Equinox (celestial coordinates) | |
|---|---|
| Constellation | Libra[1] |
| Right ascension | 15h 12m 05.1944s[2] |
| Declination | −20° 06′ 30.5428″[2] |
| Apparent magnitude (V) | 17.67[3] |
| Characteristics | |
| Evolutionary stage | Red dwarf |
| Spectral type | M3.5±0.5 V[4] |
| Astrometry | |
| Radial velocity (Rv) | 6.25±0.17[4] km/s |
| Proper motion (μ) | RA: −120.013[2] mas/yr Dec.: +74.471[2] mas/yr |
| Parallax (π) | 17.6353 ± 0.0492[2] mas |
| Distance | 184.9 ± 0.5 ly (56.7 ± 0.2 pc) |
| Details[4] | |
| Mass | 0.174±0.004 M☉ |
| Radius | 0.2±0.01 R☉ |
| Luminosity | 0.398% L☉ |
| Surface gravity (log g) | 5.094±0.006 cgs |
| Temperature | 3,300±30 K |
| Metallicity [Fe/H] | −0.24±0.09 dex |
| Rotational velocity (v sin i) | <5 km/s |
| Age | >1 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
K2-315 is a star in the southern zodiac constellation Libra.[5] It has an apparent magnitude of 17.67,[3] requiring a powerful telescope to be seen. The star is relatively close at a distance of 185 light years[2] but is receding with a radial velocity of 6.25 km/s.[4]
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).[4] It has 17.4% the mass of the Sun and 20% its radius.[4] Typical for red dwarves, it has a luminosity less than 1% of the Sun, which yields an effective temperature of 3,300 K.[4] Unlike most planetary hosts, K2-315 is metal-deficient, with an iron abundance only 57% that of the Sun.[4] It is estimated to be over a billion years old, and has a projected rotational velocity less than 5 km/s.[4]
Planetary system
In 2020, an exoplanet was discovered orbiting the star via transit. Astronomers have nicknamed it the "Pi Planet" due to its orbit of 3.14 d.[6][7][4]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 1? M⊕ | 0.023±0.006 | 3.1443189±0.0000049 | — | 88.74+0.21−0.16° | 0.95±0.06 R⊕ |
See also
- K2-315b, an exoplanet rotating around K2-315.
References
- ↑ "Find the constellation which contains given sky coordinates". http://djm.cc/constellation.html.
- ↑ 2.0 2.1 2.2 2.3 2.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
- ↑ 3.0 3.1 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 <i>Transiting Exoplanet Survey Satellite</i>". The Astronomical Journal 155 (4): 180. doi:10.3847/1538-3881/aab710. Bibcode: 2018AJ....155..180M.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 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. doi:10.3847/1538-3881/aba95f. ISSN 0004-6256. Bibcode: 2020AJ....160..172N.
- ↑ "Odkryto "Ziemię Pi". Okrąża swoją gwiazdę raz na 3,14 dnia". https://www.national-geographic.pl/artykul/odkryto-ziemie-pi-jest-niemal-tej-wielkosci-co-nasza.
- ↑ "Astronomers discover an Earth-sized "pi planet" with a 3.14-day orbit" (in en). 21 September 2020. https://news.mit.edu/2020/earth-sized-pi-planet-0921.
- ↑ Starr, Michelle (22 September 2020). "Astronomers Discover 'Pi Earth' Exoplanet Orbits Its Star Once Every 3.14 Days". https://www.sciencealert.com/pi-earth-exoplanet-orbits-its-star-once-every-3-14-days.
 |  |
