| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | 19h 33m 02.6305s[2] |
| Declination | +44° 52′ 08.020″[2] |
| Apparent magnitude (V) | 13.7[3] |
| Characteristics | |
| Evolutionary stage | Main sequence[3] |
| Spectral type | G4V[3] |
| Astrometry | |
| Radial velocity (Rv) | −38.7±0.1[3] km/s |
| Proper motion (μ) | RA: −9.713(16)mas/yr[2] Dec.: −6.683(15)mas/yr[2] |
| Parallax (π) | 1.3650±0.0122 mas[2] |
| Distance | 2,390 ± 20 ly (733 ± 7 pc) |
| Details | |
| Mass | 0.88+0.04 −0.03[4] M☉ |
| Radius | 1.20±0.05[4] R☉ |
| Luminosity | 1.57[5] L☉ |
| Surface gravity (log g) | 4.37±0.11[6] cgs |
| Temperature | 5,784±36[6] K |
| Metallicity[Fe/H] | −0.29±0.15[3] dex |
| Age | 12.7+2.4 −1.3[4] Gyr |
| Other designations | |
| KIC 8692861[7],KOI-172 | |
| Database references | |
| SIMBAD | data |
Kepler-69 (KOI-172,2MASS J19330262+4452080,KIC 8692861) is aG-type main-sequence star similar to theSun in the constellationCygnus, located about 2,390 ly (730 pc) fromEarth. On April 18, 2013 it was announced that the star has two planets.[3][8] Although initial estimates indicated that the terrestrial planetKepler-69c might be within the star'shabitable zone, further analysis showed that the planet very likely is interior to the habitable zone and is far more analogous to Venus than to Earth and thus completely inhospitable.[9]
Prior to Kepler observation, Kepler-69 had the2MASS catalogue number 2MASS J19330262+4452080. In the Kepler Input Catalog it has the designation of KIC 8692861, and when it was found to have transiting planet candidates it was given theKepler object of interest number of KOI-172.
The star's planets were discovered byNASA'sKepler Mission, a mission tasked with discovering planets intransit around their stars. The transit method that Kepler uses involves detecting dips in brightness in stars. These dips in brightness can be interpreted as planets whose orbits move in front of their stars from the perspective ofEarth. The name Kepler-69 derives directly from the fact that the star is the catalogued 69th star discovered byKepler to have confirmed planets.
The designationsb,c derive from the order of discovery. The designation ofb is given to the first planet orbiting a given star, followed by the other lowercase letters of the alphabet.[10] In the case of Kepler-69, all of the known planets in the system were discovered at one time, sob is applied to the closest planet to the star andc to the farthest.
Kepler-69 is aG4 star that is approximately 81% the mass of and 93% the radius of theSun. It has a surface temperature of 5638 ± 168K and is 9.8 billion years old. In comparison, the Sun has a surface temperature of 5778 K and is 4.6 billion years old.[11]
The star'sapparent magnitude, or how bright it appears from Earth's perspective, is 13.7.[3] Therefore, Kepler-69 is too dim to be seen with the naked eye.
Kepler-69 has two known planets orbiting around it.[3] Kepler-69b is a hotsuper-Earth-sizedexoplanet.Kepler-69c is a super-Earth-sized exoplanet, about 2.2 times larger than Earth. It receives a similar amount of flux from its star as Venus does from the Sun, and is thus a likely candidate for a super-Venus.[9] Newer measurements suggest higher planetary radii than previous estimates: 2.80 and 2.17 R🜨 for Kepler 69 b and c respectively,[12] in contrast with the earlier estimate from Barclayet al. (2013): 2.24 and 1.71 R🜨.[3]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | — | 0.1105+0.0027 −0.0026 | 13.722341+0.000035 −0.000036 | 0.16+0.17 −0.0010 | 89.62+0.26 −0.45° | 2.80+0.09 −0.07 R🜨 |
| c | 2.14 M🜨 | 0.7494+0.0184 −0.0173 | 242.4613+0.0059 −0.0064 | 0.14+0.18 −0.10 | 85.85+0.03 −0.08° | 2.17+0.02 −0.08 R🜨 |
