XO-5
Binary star in the constellation Lynx
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XO-5, formally named Absolutno, is a likely binary star system, made up of a G-type dwarf and a red dwarf companion, located approximately 893 light-years away from Earth in the Lynx constellation. It has a magnitude of about 12 and cannot be seen with the naked eye but is visible through a small telescope.[3][7]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lynx[1] |
| Right ascension | 07h 46m 51.9615s[2] |
| Declination | +39° 05′ 40.461″[2] |
| Apparent magnitude (V) | 12.13±0.03[3] |
| Characteristics | |
| Spectral type | G8V[3] + M[4] |
| Apparent magnitude (V) | 12.13±0.03[3] |
| Apparent magnitude (R) | 11.844[5] |
| Apparent magnitude (J) | 10.774±0.019[6] |
| Apparent magnitude (H) | 10.443±0.021[6] |
| Apparent magnitude (K) | 10.345±0.018[6] |
| Astrometry | |
| Radial velocity (Rv) | −9.47±0.65[2] km/s |
| Proper motion (μ) | RA: −21.509(18) mas/yr[2] Dec.: −23.910(13) mas/yr[2] |
| Parallax (π) | 3.6517±0.0173 mas[2] |
| Distance | 893 ± 4 ly (274 ± 1 pc) |
| Absolute magnitude (MV) | 5.06±0.12[7] |
| Details | |
| Mass | 1.04±0.03[8] M☉ |
| Radius | 1.13±0.03[8] R☉ |
| Luminosity | 0.88±0.09[7] L☉ |
| Surface gravity (log g) | 4.35±0.02[8] cgs |
| Temperature | 5430±70[8] K |
| Metallicity [Fe/H] | +0.05±0.06[7] dex |
| Rotational velocity (v sin i) | 0.7±0.5[7] km/s |
| Age | 7.0±7.0[9] Gyr |
| Other designations | |
| Absolutno, TOI-5373, TIC 9155187, GSC 02959-00729, 2MASS J07465196+3905404, UCAC2 45499774[10] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
XO-5 has a suspected red dwarf companion with a temperature of 3500+250
−150 K, on a wide orbit.[4] A 2024 study also identified it as a very likely binary star, with 94% probability.[11]
The name Absolutno was selected in the NameExoWorlds campaign by the Czech Republic, during the 100th anniversary of the IAU. Absolutno is a fictional miraculous substance in the Czech sci-fi novel Továrna na absolutno (The Factory for the Absolute).[12][13]
Planetary system
The exoplanet XO-5b was discovered by the XO Telescope using the transit method in 2008. This planet is classified as a hot Jupiter.[3] A search for transit timing variations caused by additional planets was negative.[14]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Makropulos | 1.19±0.03 MJ | 0.0515±0.0005 | 4.1877558(6) | 0 | 86.8±0.2° | 1.14±0.03 RJ |