Qatar-8 is a faint solar analog located in the northern circumpolar constellation Ursa Major. With an apparent magnitude of 11.71, it is impossible to detect with the naked eye, but can be located with a powerful telescope. Qatar-8 is currently 924 light-years (283 parsecs) away from the Solar System, but is drifting further away, with a radial velocity of 5.06 km/s.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 10h 29m 39.11s[1] |
| Declination | +70° 31′ 37.7″[1] |
| Apparent magnitude (V) | 11.71±0.12[2] |
| Characteristics | |
| Evolutionary stage | main-sequence star[3] |
| Spectral type | G0V[3] |
| Variable type | planetary transit |
| Astrometry | |
| Radial velocity (Rv) | 5.06±0.32[1] km/s |
| Proper motion (μ) | RA: −46.527±0.050 mas/yr[1] Dec.: −9.597±0.047 mas/yr[1] |
| Parallax (π) | 3.528 ± 0.0321 mas[1] |
| Distance | 924 ± 8 ly (283 ± 3 pc) |
| Details[3] | |
| Mass | 1.029 M☉ |
| Radius | 1.315 R☉ |
| Luminosity | 1.69 L☉ |
| Surface gravity (log g) | 4.214 cgs |
| Temperature | 5,738 K |
| Metallicity [Fe/H] | 0.025 dex |
| Rotational velocity (v sin i) | 2.7 km/s |
| Age | 8.3±2.1 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Properties
Qatar-8 is a relatively old star, with an age of 8.3 billion years. At this rate, it is on the final stages of the main sequence. It has a similar effective temperature to the Sun at 5,738 K. Despite that, it has a 69% greater luminosity than the Sun. Qatar-8 has a radius 31.5% greater than the Sun, and has a similar metallicity to the Sun despite its age.
Planetary system
In 2019, the Qatar Exoplanet Survey (QES) discovered planets around Qatar-9, itself, and Qatar-10. However, Qatar-8b is a puffy Hot Saturn unlike the other planets discovered. [3]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.371 MJ | 0.0474 | 3.719 | 0 | 89.29° | 1.285 RJ |
Since Qatar-8b is a puffy planet, it only has 37.1% the mass of Jupiter. Due to that, it puffs up to a radius that is 28.5% larger than the latter's. It also has an effective temperature of 1,457 K. Qatar-8b is ten times closer to its star than Mercury is to the Sun, which corresponds to a typical four-day orbit. [3]
| Discovery | |
|---|---|
| Discovery date | 2019 |
| Transit | |
| Orbital characteristics[3] | |
| 0.0474 AU | |
| Eccentricity | 0 |
| 3.714 days | |
| Semi-amplitude | 47.7 ± 8.0 ms -1 |
| Physical characteristics | |
Mean radius | 1.285 RJ[3] |
| Mass | 0.371 MJ[3] |
Mean density | 0.216 g cm−3[3] |
Companion
Qatar-8 was suspected to have a stellar companion, which makes it a binary star. However, a study in 2020 after analysis of many other stars show no stellar companion at all.[4]