Qatar-2
Observation data
Epoch J2000      Equinox J2000
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 mas[3]
Distance595 ± 4 ly
(182 ± 1 pc)
Details[4][2]
Mass0.727±0.024 M☉
Radius0.7033±0.0080 R☉
Surface gravity (log g)4.601±0.018 cgs
Temperature4645±50 K
Metallicity [Fe/H]0.13±0.1[5] dex
Rotation18.0±0.2
Rotational velocity (v sin i)2.0±0.2 km/s
Age9 Gyr
Other designations
Gaia DR2 3620030644476623616, GSC 04974-00112, 2MASS J13503740-0648145[1]
Database references
SIMBADdata

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. ^ a b c d e f Qatar 2 -- Star
  2. ^ a b c d e f Bryan, Marta L.; Alsubai, Khalid A.; Latham, David W.; Parley, Neil R.; Collier Cameron, Andrew; Quinn, Samuel N.; Carter, Joshua A.; Fulton, Benjamin J.; Berlind, Perry; Brown, Warren R.; Buchhave, Lars A.; Calkins, Michael L.; Esquerdo, Gilbert A.; Fűrész, Gábor; Jørgensen, Uffe Gråe; Horne, Keith D.; Stefanik, Robert P.; Street, Rachel A.; Torres, Guillermo; West, Richard G.; Dominik, Martin; Harpsøe, Kennet B. W.; Liebig, Christine; Calchi Novati, Sebastiano; Ricci, Davide; Skottfelt, Jesper F. (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, arXiv:1110.5912, doi:10.1088/0004-637X/750/1/84, S2CID 118627543
  3. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  4. ^ a b c d 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, arXiv:1608.07524, Bibcode:2017MNRAS.471..394M, doi:10.1093/mnras/stx1557, S2CID 119240651
  5. ^ a b Esposito, M.; Covino, E.; Desidera, S.; Mancini, L.; Nascimbeni, V.; Zanmar Sanchez, R.; Biazzo, K.; Lanza, A. F.; Leto, G.; Southworth, J.; Bonomo, A. S.; Suárez Mascareño, A.; Boccato, C.; Cosentino, R.; Claudi, R. U.; Gratton, R.; Maggio, A.; Micela, G.; Molinari, E.; Pagano, I.; Piotto, G.; Poretti, E.; Smareglia, R.; Sozzetti, A.; Affer, L.; Anderson, D. R.; Andreuzzi, G.; Benatti, S.; Bignamini, A.; 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, arXiv:1702.03136, Bibcode:2017A&A...601A..53E, doi:10.1051/0004-6361/201629720, S2CID 119341241
  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, arXiv:1503.09111, Bibcode:2015A&A...577A..90M, doi:10.1051/0004-6361/201525774, S2CID 53324330
  7. ^ May, E. M.; Stevenson, K. B.; Bean, Jacob L.; Bell, Taylor J.; Cowan, Nicolas B.; Dang, Lisa; Desert, Jean-Michel; Fortney, Jonathan J.; Keating, Dylan; Kempton, Eliza M.-R.; Komacek, Thaddeus D.; Lewis, Nikole K.; Mansfield, Megan; Morley, Caroline; Parmentier, Vivien; Rauscher, Emily; Swain, Mark R.; Zellem, Robert T.; Showman, Adam (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, arXiv:2203.15059, Bibcode:2022AJ....163..256M, doi:10.3847/1538-3881/ac6261, S2CID 247778438
  8. ^ a b Mancini, L.; Southworth, J.; Ciceri, S.; Tregloan-Reed, J.; Crossfield, I.; Nikolov, N.; Bruni, I.; Zambelli, R.; Henning, Th. (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, arXiv:1406.6714, Bibcode:2014MNRAS.443.2391M, doi:10.1093/mnras/stu1286, S2CID 119203713
  9. ^ a b 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, arXiv:1609.01314, doi:10.3847/1538-3881/153/1/40, S2CID 56019135



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