Kepler-1625
Star with exoplanet
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Kepler-1625 is a 14th-magnitude solar-mass star located in the constellation of Cygnus approximately 7,200 light-years (2,200 parsecs) away. Its mass is within 5% of that of the Sun, but its radius is approximately 70% larger reflecting its more evolved state. A candidate gas giant exoplanet was detected by the Kepler Mission around the star in 2015,[8] which was later validated as a real planet to >99% confidence in 2016.[9] In 2018, the Hunt for Exomoons with Kepler project reported evidence for a Neptune-sized exomoon around this planet, based on observations from NASA's Kepler mission and the Hubble Space Telescope.[10][4] Subsequently, the evidence for and reality of this exomoon candidate has been subject to debate.[11][12][13][14]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | 19h 41m 43.04008s[2] |
| Declination | +39° 53′ 11.4990″[2] |
| Apparent magnitude (V) | 16.1[3] |
| Characteristics | |
| Evolutionary stage | subgiant[2][4] |
| Spectral type | G[5] |
| Apparent magnitude (K) | 13.916[6] |
| Astrometry | |
| Proper motion (μ) | RA: −2.088(32) mas/yr[2] Dec.: −4.804(32) mas/yr[2] |
| Parallax (π) | 0.4548±0.0289 mas[2] |
| Distance | 7,200 ± 500 ly (2,200 ± 100 pc) |
| Details | |
| Mass | 1.04±0.08[4] M☉ |
| Radius | 1.73±0.24[4] R☉ |
| Luminosity (bolometric) | 2.57±0.68[4] L☉ |
| Surface gravity (log g) | 3.99±0.10[4] cgs |
| Temperature | 5,563±86[4] K |
| Metallicity [Fe/H] | 0.06±0.13[4] dex |
| Age | 8.7±2.1[4] Gyr |
| Other designations | |
| Kepler-1625, KOI-5084, KIC 4760478, 2MASS J19414304+3953115[7] | |
| Database references | |
| SIMBAD | data |
Stellar characteristics
Kepler-1625 is an approximately solar-mass star and yet is 1.7 times larger in diameter.[4] Its effective temperature is around 5,550 K, slightly lower than that of the Sun.[15][4] These parameters suggest that Kepler-1625 may be a yellow subgiant nearing the end of its life, with an age of approximately 8.7 billion years.[4] The star has been observed to be photometrically quiet, with periodic variability below 0.02%.[13] Kepler-1625 is located approximately 7,200 light-years away[2] in the constellation Cygnus.[15]
Planetary system
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≤11.6[16] MJ | 0.98±0.14 | 287.3727±0.0022 | — | 89.97±0.02° | 11.4±1.6 R🜨 |
The star is known to have one validated planet. Designated Kepler-1625b, it is a Jovian-sized planet orbiting its star every 287.3 Earth days. No other candidate transiting planets have been found around the star.[13]
Potential exomoon
The Kepler Mission recorded three planetary transits of Kepler-1625b from 2009 to 2013.[8] From these, anomalous out-of-transit flux decrements indicated the possible existence of a Neptune-sized exomoon, as first reported by the Hunt for Exomoons with Kepler project in 2018.[10] The Kepler data were inconclusive and so the planetary transit was re-observed by the Hubble Space Telescope in October 2018. The light curve from Hubble exhibited evidence for both a moon-like transit and a transit timing variation, both of which were consistent as being caused by the same Neptune-sized moon in orbit of Kepler-1625b.[4] The transit timing variation has been independently recovered by two teams analyzing the same data.[11][12] One of these teams also independently recovered the moon-like transit, but suggest that radial velocity measurements are needed to exclude the possibility of a close-in masquerading planet.[11] The other team are unable to recover the moon-like transit and suggested it may be an artifact of the data reduction.[12] This conclusion was challenged by the original team soon after, who showed that the other analysis exhibits larger systematics that may explain their differing conclusion.[13]