Kepler-70
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cygnus[1][note 1] |
Right ascension | 19h 45m 25.4746s[2] |
Declination | +41° 5′ 33.8820″[2] |
Apparent magnitude (V) | 14.87[3] |
Characteristics | |
Spectral type | sdB[1] |
Apparent magnitude (U) | 13.80[3] |
Apparent magnitude (B) | 14.71[3] |
Apparent magnitude (R) | 15.43[3] |
Apparent magnitude (I) | 15.72[3] |
Apparent magnitude (J) | 15.36[3] |
Apparent magnitude (H) | 15.59[3] |
Astrometry | |
Proper motion (μ) | RA: ±0.061 7.185[2] mas/yr Dec.: ±0.060 −3.134[2] mas/yr |
Parallax (π) | 0.7850 ± 0.0314[2] mas |
Distance | 4,200 ± 200 ly (1,270 ± 50 pc) |
Details | |
Mass | 0.496 ± 0.002[1] M☉ |
Radius | 0.203 ± 0.007[1] R☉ |
Luminosity (bolometric) | 22.9 ± 3.1 L☉ |
Temperature | 27,730 ± 260[1] K |
Other designations | |
Database references | |
SIMBAD | data |
KIC | data |
Kepler-70, formerly known as KOI-55, is a star in the constellation Cygnus with an apparent visual magnitude of 14.87.[3] This is too faint to be seen with the naked eye; viewing it requires a telescope with an aperture of 40 cm (20 in) or more.[4]
A subdwarf B star, Kepler-70 passed through the red giant stage some 18.4 million years ago. In its present-day state, it is fusing helium in its core. Once it runs out of helium it will contract to form a white dwarf. It has a relatively small radius of about 0.2 times the Sun's radius; white dwarfs are generally much smaller.[5] The star is host to a planetary system with two planets, Kepler-70b and Kepler-70c.[6] The innermost planet has the highest temperature of any known planet known so far.
Planetary system
On December 26, 2011, evidence for two extremely short-period planets was announced. They were detected by the reflection of starlight caused by the planets themselves, rather than through a variation in apparent stellar magnitude caused by them transiting the star.
The measurements also suggested a smaller body between the two confirmed planets; this remains unconfirmed.
Orbits of Kepler-70b and Kepler-70c have 7:10 orbital resonance and have the closest approach between planets of any known planetary system.
Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 0.440 M⊕ | 0.0060 | 0.2401 | — | 20–80, likely 65 [note 2]° | 0.759 R⊕ |
KOI-55.03 (unconfirmed) | 0.222 M⊕ | 0.0065 | — | — | — | 0.605 R⊕ |
c | 0.655 M⊕ | 0.0076 | 0.34289 | — | 20–80, likely 65° | 0.867 R⊕ |
Notes
References
- 1 2 3 4 5 "Notes for Planet KOI-55 b". Extrasolar Planet Database. Archived from the original on 19 January 2012. Retrieved 1 January 2012.
- 1 2 3 4 5 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- 1 2 3 4 5 6 7 8 9 "KPD 1943+4058". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 1 January 2012.
- ↑ Sherrod, P. Clay; Koed, Thomas L. (2003), A Complete Manual of Amateur Astronomy: Tools and Techniques for Astronomical Observations, Astronomy Series, Courier Dover Publications, p. 9, ISBN 0-486-42820-6
- ↑ Cain, Fraser (4 February 2009). "White Dwarf Stars". Universe Today. Retrieved 8 January 2012.
- 1 2 Charpinet, S.; et al. (December 21, 2011), "A compact system of small planets around a former red-giant star", Nature, 480 (7378): 496–499, Bibcode:2011Natur.480..496C, doi:10.1038/nature10631, PMID 22193103