Kepler-7 is a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

located in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Lyra Lyra (; Latin for lyre, from Greek ''λύρα'') is a small constellation. It is one of the 48 listed by the 2nd century astronomer Ptolemy, and is one of the modern 88 constellations recognized by the International Astronomical Union. Lyra was ...

in the field of view of the

Kepler Mission The Kepler space telescope is a disused space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orb ...

, a

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

operation in search of Earth-like planets. It is home to the fourth of the first five planets that Kepler discovered; this planet, a

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...

-size gas giant named

Kepler-7b Kepler-7b is one of the first five exoplanets to be confirmed by NASA's Kepler spacecraft, and was confirmed in the first 33.5 days of Kepler's science operations. It orbits a star slightly hotter and significantly larger than the Sun that is exp ...

, is as light as

styrofoam Styrofoam is a trademarked brand of closed-cell extruded polystyrene foam (XPS), commonly called "Blue Board", manufactured as foam continuous building insulation board used in walls, roofs, and foundations as thermal insulation and water barrie ...

. The star itself is more massive than the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

, and is nearly twice the Sun's radius. It is also slightly metal-rich, a major factor in the formation of planetary systems. Kepler-7's planet was presented on January 4, 2010 at a meeting of the

American Astronomical Society The American Astronomical Society (AAS, sometimes spoken as "double-A-S") is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC. The primary objective of the AAS is to promote the adv ...

Nomenclature and discovery

Kepler-7 received its name because it was the home to the seventh planetary system discovered by the NASA-led Kepler Mission, a project aimed at detecting

terrestrial planets A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Sun: Mercury, Ven ...

that

transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 ...

, or pass in front of, their host stars as seen from Earth. The planet orbiting Kepler-7 was the fourth planet to be discovered by the Kepler spacecraft; the first three planets combed from Kepler's data had been previously discovered, and were used to verify the accuracy of Kepler's measurements. Kepler-7b was announced to the public on January 4, 2010 at the 215th meeting of the

Washington, D.C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, ...

along with

Kepler-4b Kepler-4b, initially known as KOI 7.01, is an extrasolar planet first detected as a transit by the Kepler spacecraft The Kepler space telescope is a disused space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting ot ...

, Kepler-5b,

Kepler-6b __NOTOC__ Kepler-6b is an extrasolar planet in the orbit of the unusually metal-rich Kepler-6, a star in the field of view of the NASA-operated Kepler spacecraft, which searches for planets that cross directly in front of, or transit, their host ...

, and

Kepler-8b Kepler-8b is the fifth of the first five exoplanets discovered by NASA's Kepler (satellite), Kepler spacecraft, which aims to discover planets in a region of the sky between the constellations Lyra (constellation), Lyra and Cygnus (constellation) ...

. Kepler-7b was noted for its unusually and extremely low density. The planet's initial discovery by Kepler was verified by additional observations made at observatories in Hawaii, Texas, Arizona, California, and the Canary Islands.

Characteristics

Kepler-7 is a sunlike star that is 1.347 M_sun and 1.843 R_sun. This means that the star is about 35% more massive and 84% wider than the Sun. The star is estimated to be 3.5 (± 1) billion years old. It is also estimated to have a

metallicity In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...

of e/H= 0.11 (± 0.03), meaning that Kepler-7 is approximately 30% more metal-rich than the Sun; metallicity plays a significant role in the formation of planetary systems, as metal-rich stars tend to be more likely to have planets in orbit. The star's

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

is 5933 (± 44) K. In comparison, the 4.6 billion-year-old Sun releases less heat, with an effective temperature of 5778 K. Kepler first five exoplanet size

The star has an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

of 13, meaning that it is extremely dim as seen from Earth. It cannot be seen with the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection. Vision corrected to normal ...

. It is estimated to lie at approximately 3090 light years from the Solar System. There is a star that is 4

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

s dimmer located 1.90

arcseconds A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

away, whether this a gravitationally bound companion star or a chance optical alignment is unknown.

Planetary system

is the only planet that has been discovered in Kepler-7's orbit. It is .433 M_J and 1.478 R_J, meaning it is 43% the mass of planet

, but is nearly three halves its size. With a density of .166 grams/cc, the planet is approximately 17% the density of

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

. This is comparable to styrofoam. At a distance of .06224 AU from its host star, Kepler-7b completes an orbit around Kepler-7 every 4.8855 days. Planet

Mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...

, however, orbits the Sun at .3871 AU, and takes approximately 87.97 days to complete one orbit. Kepler-7b's

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-center, in geometry * Eccentricity (graph theory) of a v ...

is assumed to be 0, which would give Kepler-7b a circular orbit by definition.

References

External links

{{Stars of Lyra Planetary systems with one confirmed planet Lyra (constellation) 97 Planetary transit variables G-type stars

Nomenclature and discovery

Characteristics

Planetary system

See also

References

External links