Qatar-2

Short description: Star in the constellation Virgo

Qatar-2  Observation data
Equinox J2000.0]] (ICRS)

Constellation | Virgo
Right ascension |  13h 50m 37.4100s[1]
Declination | −06° 48′ 14.4199″[1]
Apparent magnitude (V) | 13.3[2]
Characteristics
Spectral type | K5V[1]
Astrometry
Radial velocity (Rv)| -23.55 km/s
Proper motion (μ)|  RA: -88.184[1] mas/yr
Dec.: -15.290[1] mas/yr
Parallax (π)| 5.4849 ± 0.0365[3] mas
Distance| 595 ± 4 ly
(182 ± 1 pc)
Details[4][2]
Mass| 0.727±0.024 M☉
Radius| 0.7033±0.0080 R☉
Surface gravity (log g)| 4.601±0.018 cgs
Temperature| 4645±50 K
Metallicity [Fe/H]| 0.13±0.1[5] dex
Rotation| 18.0±0.2
Rotational velocity (v sin i)| 2.0±0.2 km/s
Age| 9 Gyr
Other designations

Gaia DR2 3620030644476623616, GSC 04974-00112, 2MASS J13503740-0648145[1]

Database references
SIMBAD| data

Qatar-2 is a K-type main-sequence star about 595 light-years away in the constellation of Virgo. The star is much older than Sun, and has a concentration of heavy elements similar to solar abundance.[2] The star features a numerous and long-lived starspots,[4] and belongs to a peculiar variety of inflated K-dwarfs with strong magnetic activity inhibiting internal convection.[6]

## Planetary system

In 2011 a transiting superjovian planet Qatar-2b was detected by the Qatar Exoplanet Survey.[2] The planet has a large measured temperature difference between dayside (1368±32 K) and nightside (724±135 K).[7] The planetary orbit is well aligned with the equatorial plane of the star,[5] misalignment angle equal to 4.3±4.5◦.[8] No orbital decay was detected.[9] The color of planetary atmosphere is blue due to Rayleigh scattering of light,[8] and albedo is very low, being below 0.06.[9]

An additional massive companion on wide orbit was suspected in 2011,[2] but search utilizing transit-timing variation method has yielded zero results in 2017.[4]

The Qatar-2 planetary system[2][4] Companion
(in order from star) | Mass | Semimajor axis
(AU) | Orbital period
(days) | Eccentricity | Inclination | Radius

|
|
|
|
|
|

b | 2.466±0.062 MJ | 0.02136±0.00024  | 1.33711677±0.00000010  | 0  | 88.99±0.20° | 1.115±0.013 RJ

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Qatar 2 -- Star
2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Bryan, Marta L.; Alsubai, Khalid A.; Latham, David W.; Parley, Neil R.; Collier Cameron, Andrew; Quinn, Samuel N.; Carter, Joshua A.; Fulton, Benjamin J. et al. (2011), "Qatar-2: A K dwarf orbited by a transiting hot Jupiter and a more massive companion in an outer orbit", The Astrophysical Journal 750: 84, doi:10.1088/0004-637X/750/1/84
3. ↑ Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
4. ↑ 4.0 4.1 4.2 4.3 Močnik, T.; Southworth, J.; Hellier, C. (2017), "Recurring sets of recurring starspot occultations on exoplanet-host Qatar-2", Monthly Notices of the Royal Astronomical Society 471 (1): 394–403, doi:10.1093/mnras/stx1557, Bibcode: 2017MNRAS.471..394M
5. ↑ 5.0 5.1 Esposito, M.; Covino, E.; Desidera, S.; Mancini, L.; Nascimbeni, V.; Zanmar Sanchez, R.; Biazzo, K.; Lanza, A. F. et al. (2017), "The GAPS Programme with HARPS-N at TNG. XIII. The orbital obliquity of three close-in massive planets hosted by dwarf K-type stars: WASP-43, HAT-P-20 and Qatar-2", Astronomy & Astrophysics 601: A53, doi:10.1051/0004-6361/201629720, Bibcode: 2017A&A...601A..53E
6. ↑ Maxted, P. F. L.; Serenelli, A. M.; Southworth, J. (2015), "A comparison of gyrochronological and isochronal age estimates for transiting exoplanet host stars", Astronomy & Astrophysics 577: A90, doi:10.1051/0004-6361/201525774, Bibcode: 2015A&A...577A..90M
7. ↑ May, E. M.; Stevenson, K. B.; Bean, Jacob L.; Bell, Taylor J.; Cowan, Nicolas B.; Dang, Lisa; Desert, Jean-Michel; Fortney, Jonathan J. et al. (2022), "A New Analysis of Eight Spitzer Phase Curves and Hot Jupiter Population Trends: Qatar-1b, Qatar-2b, WASP-52b, WASP-34b, and WASP-140b", The Astronomical Journal 163 (6): 256, doi:10.3847/1538-3881/ac6261, Bibcode: 2022AJ....163..256M
8. ↑ 8.0 8.1 Mancini, L.; Southworth, J.; Ciceri, S.; Tregloan-Reed, J.; Crossfield, I.; Nikolov, N.; Bruni, I.; Zambelli, R. et al. (2014), "Physical properties, starspot activity, orbital obliquity, and transmission spectrum of the Qatar-2 planetary system from multi-colour photometry", Monthly Notices of the Royal Astronomical Society 443 (3): 2391, doi:10.1093/mnras/stu1286, Bibcode: 2014MNRAS.443.2391M
9. ↑ 9.0 9.1 Dai, Fei; Winn, Joshua N.; Yu, Liang; Albrecht, Simon (2016), "The Stellar Obliquity, Planet Mass, and Very Low Albedo of Qatar-2 from K2 Photometry", The Astronomical Journal 153: 40, doi:10.3847/1538-3881/153/1/40

Coordinates:  13h 50m 37.4100s, −06° 48′ 14.4199″

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*[RA:]: Right Ascension
*[Dec.:]: Declination