Qatar-8
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]
Distance924 ± 8 ly
(283 ± 3 pc)
Details[3]
Mass1.029 M☉
Radius1.315 R☉
Luminosity1.69 L☉
Surface gravity (log g)4.214 cgs
Temperature5,738 K
Metallicity [Fe/H]0.025 dex
Rotational velocity (v sin i)2.7 km/s
Age8.3±2.1 Gyr
Other designations
2MASS J10293910+7031378, Gaia DR2 1076515002779544960
Database references
SIMBADdata
Exoplanet Archivedata

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.

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]

The Qatar-8 planetary system
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]

Qatar-8b
Discovery
Discovery date2019
Transit
Orbital characteristics[3]
0.0474 AU
Eccentricity0
3.714 days
Semi-amplitude47.7 ± 8.0 ms -1
Physical characteristics
Mean radius
1.285 RJ[3]
Mass0.371 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]

    References

    1. 1 2 3 4 5 6 Gaia Collaboration (2018-04-01). "VizieR Online Data Catalog: Gaia DR2 (Gaia Collaboration, 2018)". VizieR Online Data Catalog. 1345. Bibcode:2018yCat.1345....0G. doi:10.26093/cds/vizier.1345.
    2. ↑ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000-03-01). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361.
    3. 1 2 3 4 5 6 7 8 9 Alsubai, Khalid; Tsvetanov, Zlatan I.; Pyrzas, Stylianos; Latham, David W.; Bieryla, Allyson; Eastman, Jason; Mislis, Dimitris; Esquerdo, Gilbert A.; Southworth, John; Mancini, Luigi; Esamdin, Ali (2019-06-01). "Qatar Exoplanet Survey: Qatar-8b, 9b, and 10b---A Hot Saturn and Two Hot Jupiters". The Astronomical Journal. 157 (6): 224. arXiv:1903.09258. Bibcode:2019AJ....157..224A. doi:10.3847/1538-3881/ab19bc. ISSN 0004-6256. S2CID 85459500.
    4. ↑ Maciejewski, G. (2020-09-01). "Search for Planets in Hot Jupiter Systems with Multi-Sector TESS Photometry. I. No Companions in Planetary Systems KELT-18, KELT-23, KELT-24, Qatar-8, WASP-62, WASP-100, WASP-119, and WASP-126". Acta Astronomica. 70 (3): 181–202. arXiv:2010.11977. Bibcode:2020AcA....70..181M. doi:10.32023/0001-5237/70.3.2. ISSN 0001-5237. S2CID 225061977.
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