HAT-P-27
Star in the constellation Virgo
title: "HAT-P-27" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["virgo-(constellation)", "g-type-main-sequence-stars", "binary-stars", "planetary-systems-with-one-confirmed-planet", "planetary-transit-variables", "tess-objects-of-interest", "wide-angle-search-for-planets"] description: "Star in the constellation Virgo" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/HAT-P-27" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Star in the constellation Virgo ::
| name = HAT-P-27 | epoch = J2000 | constell = Virgo | ra = | dec = | appmag_v = 12.214 | type = main-sequence star | class = G8 | radial_v = | prop_mo_ra = | prop_mo_dec = | pm_footnote = | parallax = 4.9528 | p_error = 0.0169 | parallax_footnote = | reference = | primary = HAT-P-27 | name = HAT-P-27 B | period = | period_unitless = | axis = 0.656 | axis_unitless = 131 AU | eccentricity = | inclination = | node = | periastron = | periarg = | periarg_primary = | k1 = | k2 = | source = | mass = 0.945 | radius = 0.898 | gravity = 4.51 | luminosity = 0.57 | temperature = 5300 | metal_fe = 0.29 | rotation = 0.4 | rotational_velocity =0.6 | age_gyr = 4.4 | names = | Simbad = HAT-P-27 | NSTED = HAT-P-27
HAT-P-27, also known as WASP-40, is the primary of a binary star system about 659 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. HAT-P-27 is enriched in heavy elements, having a 195% concentration of iron compared to the Sun.
A very dim stellar companion was detected in 2015 at a projected separation of 0.656″ and proven to be physically bound to the system in 2016.
Planetary system
In 2011 a transiting hot Jupiter type planet b was detected in a mildly eccentric orbit. The planetary equilibrium temperature is 1207 K. A 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. No orbital decay was detected as of 2018, despite the close proximity of the planet to the star.
The presence of an additional planet in the system has been suspected since 2015.
In 2024, a detection of a possible Neptune-like planet was reported. It is expected to be an analog of Neptune in terms of radius, although much hotter due to the low orbital separation; one year on this planet lasts one day and five hours, causing the planetary equilibrium temperature to be 1426 K. More observations are needed to validate its existence.
| table_ref =
| exoplanet = b
| mass = 0.660
| radius = 1.038
| semimajor = 0.0403
| period = 3.039586
| eccentricity = 0.078
| inclination = 85.0
| exoplanet = c
| mass_earth = 17.8
| radius_earth = 4.33
| semimajor =
| period =
| eccentricity =
| inclination =
References
References
- {{Cite Gaia DR3. 1159336403336463872
- "HAT-P-27".
- {{cite constellation. HAT-P-27
- (2015). "Ground-based transit observations of the HAT-P-18, HAT-P-19, HAT-P-27/WASP40 and WASP-21 systems". Monthly Notices of the Royal Astronomical Society.
- (2015). "A Lucky Imaging search for stellar sources near 74 transit hosts". Astronomy & Astrophysics.
- (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.
- (2013). "Analysis of Spin-Orbit Alignment in the Wasp-32, Wasp-38, and Hat-P-27/Wasp-40 Systems". The Astrophysical Journal.
- (2018). "Empirical Tidal Dissipation in Exoplanet Hosts from Tidal Spin-up". The Astronomical Journal.
- (2011). "HAT-P-27b: A Hot Jupiter Transiting a G Star on a 3 Day Orbit". The Astrophysical Journal.
- (2024). "The SHERLOCK pipeline: new exoplanet candidates in the WASP-16, HAT-P-27, HAT-P-26, and TOI-2411 systems". [[Monthly Notices of the Royal Astronomical Society]].
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