Kepler-70
 The Kepler-70 system if confirmed | |
| 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: 7.185±0.061[2] mas/yr Dec.: −3.134±0.060[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, also known as KIC 5807616 and formerly as KOI-55, is a star in the constellation Cygnus with an apparent visual magnitude of 14.87,[3] and is 4200 light-years away. 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 may be host to a planetary system with two planets,[6] although later research[7][8] indicates that this is not in fact the case. If they are confirmed to exist, then the innermost planet has the highest temperature of any known planet.
Properties[]
Kepler-70 is an sdB (B-type subdwarf star with a temperature of 27,730 K,[9] equivalent to that of a B0-type star. It has a luminosity of 18.9 L☉,[10][9] a radius of 0.203 R☉, and a mass about half of that of the sun. The star was an evolutionary giant less than 20 million years ago.[10]
Kepler-70 is still fusing.[9][10] When it runs out of helium, it will contract into a white dwarf.[10]
Planetary system[]
On December 26, 2011, evidence for two extremely short-period planets, Kepler-70b and Kepler-70c, was announced by Charpinet et al.[6] 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 candidate planets; this remains unconfirmed.
If these planets exist, then the orbits of Kepler-70b and Kepler-70c have 7:10 orbital resonance and have the closest approach between planets of any known planetary system. However, later research[7] suggested that what had been detected was not in fact the reflection of light from exoplanets, but star pulsation "visible beyond the cut-off frequency of the star." Further research[8] indicated that star pulsation modes were indeed the more likely explanation for the signals found in 2011, and that the two exoplanets probably did not exist.
If Kepler-70b exists, then it has a temp of 7288 K,[10] the same as that of an F0 star.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (unconfirmed) | 0.440 M
|