HAT-P-7

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Star system in Cygnus

title: "HAT-P-7" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["cygnus-(constellation)", "f-type-main-sequence-stars", "m-type-main-sequence-stars", "triple-star-systems", "planetary-systems-with-one-confirmed-planet", "planetary-transit-variables", "durchmusterung-objects", "kepler-objects-of-interest", "tess-objects-of-interest"] description: "Star system in Cygnus" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/HAT-P-7" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Star system in Cygnus ::

| name = HAT-P-7 | epoch = J2000 | constell = Cygnus | ra = | dec = | appmag_v = 10.46 | component1 = A | type = Main sequence | class = F6V | appmag_1_passband = B | appmag_1 = ~10.90 | appmag_2_passband = V | appmag_2 = ~10.46 | appmag_3_passband = J | appmag_3 = 9.555 ± 0.030 | appmag_4_passband = H | appmag_4 = 9.344 ± 0.029 | appmag_5_passband = K | appmag_5 = 9.334 ± 0.018 | variable = planetary transit | component2 = B | type2 = Main sequence | class2 = M5.5V | radial_v = | prop_mo_ra = | prop_mo_dec = | pm_footnote = | parallax = 2.9991 | p_error = 0.0114 | parallax_footnote = | absmag_v = | reference = | primary = A | name = B | axis_unitless = 730 AU | reference = | primary = A | name = C | axis_unitless = AU | eccentricity = | source = | component1 = A | mass = | radius = | luminosity = | gravity = | temperature = | metal_fe = | rotational_velocity = | age_gyr = | component1 = B | mass = 0.21 | component2 = C | mass2 = 0.19 | names = HAT-P-7, | Simbad = GSC03547-01402 | NSTED = HAT-P-7

HAT-P-7 is a triple star system located about 1,088 light-years away in the constellation Cygnus. The apparent magnitude of this star is 10.5, which means it is not visible to the naked eye but can be seen with a small telescope on a clear dark night.

Stellar system

The primary component of the HAT-P-7 system is an F-type main-sequence star with around 1.35 times the Sun's mass and twice the Sun's radius, hosting one known planet. The secondary is a red dwarf located 730 astronomical units away from the primary, with a spectral type of M5.5V and a mass of . The tertiary is also a red dwarf with a mass of at least ; it is in a highly-eccentric orbit with a semi-major axis of 32 AU.

The secondary star, component B, was discovered in 2012. Another companion (in addition to the second star and the planet) was suspected based on long-period radial velocity variations, but its nature was unknown until 2025, when it was found to be a third star.

Component B has also been referred to as HAT-P-7 East. HAT-P-7 West is another candidate companion, of spectral type M9V or L0V, but it is not confirmed to be associated with the system and is likely an unrelated background star.

Planetary system

The primary star has one known planet, HAT-P-7b, a hot Jupiter discovered in 2008. This star system was within the initial field of view of the Kepler planet-hunting spacecraft and was given the designation KOI-2 and later Kepler-2.

| table_ref = | exoplanet = b | mass = | period = | semimajor = | eccentricity = {{val|0.0040|p= | inclination = | radius =

References

References

  1. {{cite constellation. HAT-P-7
  2. (10 March 2021). "Revisiting the Kepler field with TESS: Improved ephemerides using TESS 2 min data". Monthly Notices of the Royal Astronomical Society.
  3. (2017). "The GAPS Programme with HARPS-N at TNG . XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". Astronomy and Astrophysics.
  4. {{Cite Gaia DR3. 2129256395211984000
  5. (2010). "Search for Outer Massive Bodies around Transiting Planetary Systems: Candidates of Faint Stellar Companions around HAT-P-7". Publications of the Astronomical Society of Japan.
  6. (December 2012). "A Common Proper Motion Stellar Companion to HAT-P-7". [[Publications of the Astronomical Society of Japan]].
  7. (2025-05-12). "A third star in the HAT-P-7 system, and a new dynamical pathway to misaligned hot Jupiters". The Astrophysical Journal.
  8. (2008). "HAT-P-7b: An Extremely Hot Massive Planet Transiting a Bright Star in the Kepler Field".
  9. "HAT-P-7".
  10. (2012). "Improved Spectroscopic Parameters for Transiting Planet Hosts". The Astrophysical Journal.
  11. (2019-10-01). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal.
  12. (2013). "Lucky imaging of transiting planet host stars with LuckyCam". Monthly Notices of the Royal Astronomical Society.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::

cygnus-(constellation)f-type-main-sequence-starsm-type-main-sequence-starstriple-star-systemsplanetary-systems-with-one-confirmed-planetplanetary-transit-variablesdurchmusterung-objectskepler-objects-of-interesttess-objects-of-interest