| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 18h 45m 09.1490s[1] |
| Declination | +42° 27′ 03.891″[1] |
| Apparent magnitude (V) | 13.9 |
| Characteristics | |
| Spectral type | F5V |
| Astrometry | |
| Proper motion (μ) | RA: 2.176(12)mas/yr[1] Dec.: 3.851(14)mas/yr[1] |
| Parallax (π) | 0.9842±0.0105 mas[1] |
| Distance | 3,310 ± 40 ly (1,020 ± 10 pc) |
| Details | |
| Mass | 1.213 M☉ |
| Radius | 1.486 R☉ |
| Temperature | 6213 K |
| Age | 3.84 Gyr |
| Other designations | |
| KOI-10,KIC 6922244,2MASS J18450914+4227038[2] | |
| Database references | |
| SIMBAD | data |
| KIC | data |
Kepler-8 is astar located in theconstellationLyra in the field of view of theKepler Mission, aNASA-led operation tasked with discoveringterrestrial planets. The star, which is slightly hotter, larger, and more massive than theSun, has one gas giant in its orbit,Kepler-8b. This gas giant is larger thanJupiter, but is less massive, and thus more diffuse. The planet's discovery was announced to the public on January 4, 2010 along with four other planets. As the fifth confirmed planetary system verified by Kepler, it helped demonstrate the capabilities of the Kepler spacecraft.
Kepler-8 was named the way it was because it is home to the eighth planetary system confirmed during the course of theKepler Mission, aNASA-directed program tasked with searching a region of the sky for terrestrial planets thattransit, or cross in front of (and thereby, for a while, make dimmer) the stars that they orbit with respect toEarth.[3] The planet in orbit around Kepler-8, Kepler-8b, was the fifth of the first five planets discovered by the Kepler spacecraft; the first three planets confirmed by Kepler had been previously discovered, and were only used to verify the accuracy of Kepler's measurements.[4] Kepler-8b's discovery was announced to the public on January 4, 2010 at the215th meeting of theAmerican Astronomical Society inWashington, D.C., alongside planets in orbit aroundKepler-4,Kepler-5,Kepler-6, andKepler-7.[5]
The data that was used to identify Kepler-8b's existence was re-examined and verified by observatories in Hawaii, Arizona, Texas, California, and the Canary Islands.[6]
Kepler-8 is situated some 1020pc (or 3,300light years) from Earth.[1] With a mass of 1.213Msun and a radius of 1.486Rsun, Kepler-8 is more massive than the Sun by about a fifth of the Sun's mass, and is nearly three halves its size. The star is predicted to be 3.84 (± 1.5) billion years old, compared to the Sun's age at 4.6 billion years.[7] Kepler-8 has ametallicity of [Fe/H] = -0.055 (± 0.03), making it 12% less metal-rich than the metal-rich Sun; metallicity is important in stars because stars richer in metal are more likely to harbor planets.[8] The star also has aneffective temperature of 6213 (± 150)K, meaning that it is hotter than the Sun, which has an effective temperature of 5778 K.[9][10]
Kepler-8 has anapparent magnitude of 13.9; in other words, as seen from Earth, Kepler-8 is an extremely dim star. It cannot be seen with thenaked eye.[10]
Kepler-8b is the only planet that has been discovered orbiting of Kepler-8.[11] With a mass of .603MJ and a radius of 1.419RJ, the planet is 60% the mass of, but 42% larger than planet Jupiter. The planet is diffuse, with adensity of .261 grams/cc, especially in comparison to Jupiter and its density of 5.515 grams/cc. At a distance of .0483AU, Kepler-8b orbits its star every 3.5225 days. Theeccentricity of Kepler-8 is assumed to be 0, which would give the planet a circular orbit.[4] In comparison, planetMercury orbits the Sun at .3871 AU every 87.97 days. Mercury also has an elliptical orbit, with an eccentricity of .2056.[12]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.603 MJ | 0.0483 | 3.5225 | 0 | — | 1.419 RJ |
