KOI-5
Triple star system in Cygnus
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KOI-5 is a triple star system composed of three stars: KOI-5 A, KOI-5 B and KOI-5 C, orbiting 1,870±70 light-years away.
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | 19h 18m 57.5306s[2] |
| Declination | +44° 38′ 50.619″[2] |
| Apparent magnitude (V) | 11.78[3] |
| Characteristics | |
| Spectral type | G2V[4] |
| Astrometry | |
| Radial velocity (Rv) | −35.16[2] km/s |
| Proper motion (μ) | RA: +3.216[2] mas/yr Dec.: −10.925[2] mas/yr |
| Parallax (π) | 1.7436±0.0666 mas[2] |
| Distance | 1,870 ± 70 ly (570 ± 20 pc) |
| Position (relative to KOI-5A)[3] | |
| Component | KOI-5B |
| Epoch of observation | 2016 |
| Angular distance | 0.029±0.050″ |
| Position angle | 142.1±1.0° |
| Projected separation | 16[citation needed] AU |
| Position (relative to KOI-5A)[3] | |
| Component | KOI-5C |
| Epoch of observation | 2016 |
| Angular distance | 0.141±0.050″ |
| Position angle | 304.3±2.2° |
| Projected separation | 78[citation needed] AU |
| Details[5] | |
| KOI-5A | |
| Mass | 1.13[6] M☉ |
| Radius | 1.840±0.017 R☉ |
| Luminosity | 3.86±0.17 L☉ |
| Surface gravity (log g) | 4.19[7] cgs |
| Temperature | 5861[7] K |
| Age | 3.49±0.41 Gyr |
| KOI-5B | |
| Mass | 1.09[6] M☉ |
| Other designations | |
| TOI-1241, 2MASS J19185753+4438507, KIC 8554498, Gaia EDR3 2126945668448657664 | |
| KOI-5A: | |
| KOI-5B: | |
| Database references | |
| SIMBAD | data |
The two dim stellar companions to KOI-5A were discovered in 2016.[3] KOI-5 A and B orbit each other every 29 years, and KOI-5 C orbits stars A and B every 400 years.[6] KOI-5C is physically associated with the core stellar pair with probability 99.98%.[8]
Planetary system
Two planets orbiting one of KOI-5's stars were suspected since 2009 based on Kepler data, but KOI-5Ab was confirmed only in January 2021 after TESS determined the planet is orbiting KOI-5A. The exoplanet has caused interest in the scientific community because its orbital plane is misaligned with the closer star, suggesting it gave KOI-5Ab a gravitational kick during its development, resulting in the misalignment and inward migration to the current orbit.[6][9] However, the confirmation of this planet has yet to be published in any peer-reviewed journal.
A second candidate planet was initially suspected, but was later found to be a false positive.[10]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | 0.179 MJ | 0.0596060 | 5 | — | — | 7.07 R🜨 |