HAT-P-27

HAT-P-27, also known as WASP-40, is the primary of a binary star system about 650 light-years away. It is a G-type main-sequence star. The star's age is similar to the Sun's at 4.4 billion years.[2] HAT-P-27 is enriched in heavy elements, having a 195% concentration of iron compared to the Sun.

HAT-P-27
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo
Right ascension 14h 51m 04.1870s[1]
Declination +05° 56′ 50.5482″[1]
Apparent magnitude (V) 12.214[2]
Characteristics
Evolutionary stage main-sequence star
Spectral type G8
Astrometry
Radial velocity (Rv)-15.901[1] km/s
Proper motion (μ) RA: -28.621[1] mas/yr
Dec.: -2.757[1] mas/yr
Parallax (π)4.9922 ± 0.0360 mas[3]
Distance653 ± 5 ly
(200 ± 1 pc)
Orbit[4]
PrimaryHAT-P-27
CompanionHAT-P-27 B
Semi-major axis (a)0.656±0.021"
(131 AU)
Details[2]
Mass0.945±0.035 M☉
Radius0.898+0.054
−0.039 R☉
Luminosity0.57+0.09
−0.07 L☉
Surface gravity (log g)4.51±0.04 cgs
Temperature5300±90 K
Metallicity [Fe/H]0.29±0.10 dex
Rotation0.4±0.4
Rotational velocity (v sin i)0.6+0.7
−0.4[5] km/s
Age4.4+3.8
−2.6 Gyr
Other designations
HAT-P-27, Gaia DR2 1159336403336463872, WASP-40, GSC 00333-00351, 2MASS J14510418+0556505[1]
Database references
SIMBADdata
Yellow Dwarf

The very dim stellar companion was detected in 2015 at a projected separation of 0.656″[4] and proven to be physically bound to the system in 2016.[6]

Planetary system

In 2011 a transiting hot Jupiter type planet b was detected in a mildly eccentric orbit. The planetary equilibrium temperature is 1207±41 K.[2] The survey in 2013 failed to find any Rossiter-McLaughlin effect and therefore was unable to constrain the inclination of planetary orbit to the equatorial plane of the parent star.[5] No orbital decay was detected as in 2018, despite the close proximity of the planet to the star.[7]

The presence of an additional planet in the system has been suspected since 2015.[8]

The HAT-P-27 planetary system[2]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 0.660±0.033 MJ 0.0403±0.0005 3.039586±0.000012 0.078±0.047 85.0±0.2[5]° 1.038+0.077
−0.058 RJ

References
  1. "HAT-P-27". SIMBAD. Centre de données astronomiques de Strasbourg.
  2. Béky, B.; Bakos, G. Á.; Hartman, J.; Torres, G.; Latham, D. W.; Jordán, A.; Arriagada, P.; Bayliss, D.; Kiss, L. L.; Kovács, Géza; Quinn, S. N.; Marcy, G. W.; Howard, A. W.; Fischer, D. A.; Johnson, J. A.; Esquerdo, G. A.; Noyes, R. W.; Buchhave, L. A.; Sasselov, D. D.; Stefanik, R. P.; Perumpilly, G.; Lázár, J.; Papp, I.; Sári, P. (2011), "HAT-P-27b: A HOT JUPITER TRANSITING A G STAR ON A 3 DAY ORBIT", The Astrophysical Journal, 734 (2): 109, arXiv:1101.3511, Bibcode:2011ApJ...734..109B, doi:10.1088/0004-637X/734/2/109, S2CID 31357299
  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. Wöllert, Maria; Brandner, Wolfgang (2015), "A Lucky Imaging search for stellar sources near 74 transit hosts", Astronomy & Astrophysics, 579: A129, arXiv:1506.05456, Bibcode:2015A&A...579A.129W, doi:10.1051/0004-6361/201526525, S2CID 118903879
  5. Brown, D. J. A.; Collier Cameron, A.; Díaz, R. F.; Doyle, A. P.; Gillon, M.; Lendl, M.; Smalley, B.; Triaud, A. H. M. J.; Anderson, D. R.; Enoch, B.; Hellier, C.; Maxted, P. F. L.; Miller, G. R. M.; Pollacco, D.; Queloz, D.; Boisse, I.; Hébrard, G. (2013), "Analysis of Spin-Orbit Alignment in the Wasp-32, Wasp-38, and Hat-P-27/Wasp-40 Systems", The Astrophysical Journal, 760 (2): 139, arXiv:1303.5649, doi:10.1088/0004-637X/760/2/139, S2CID 54033638
  6. Ngo, Henry; Knutson, Heather A.; Hinkley, Sasha; Bryan, Marta; Crepp, Justin R.; Batygin, Konstantin; Crossfield, Ian; Hansen, Brad; Howard, Andrew W.; Johnson, John A.; Mawet, Dimitri; Morton, Timothy D.; Muirhead, Philip S.; Wang, Ji (2016), "FRIENDS OF HOT JUPITERS. IV. STELLAR COMPANIONS BEYOND 50 au MIGHT FACILITATE GIANT PLANET FORMATION, BUT MOST ARE UNLIKELY TO CAUSE KOZAI–LIDOV MIGRATION", The Astrophysical Journal, 827 (1): 8, arXiv:1606.07102, Bibcode:2016ApJ...827....8N, doi:10.3847/0004-637X/827/1/8, S2CID 41083068
  7. Penev, Kaloyan; Bouma, L. G.; Winn, Joshua N.; Hartman, Joel D. (2018), "EMPIRICAL TIDAL DISSIPATION IN EXOPLANET HOSTS FROM TIDAL SPIN–UP", The Astronomical Journal, 155 (4): 165, arXiv:1802.05269, Bibcode:2018AJ....155..165P, doi:10.3847/1538-3881/aaaf71, PMC 6510550, PMID 31080254, S2CID 64370118
  8. Ground-based transit observations of the HAT-P-18,HAT-P-19, HAT-P-27/WASP40 and WASP-21 systems


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