Kepler-11e

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Kepler-11e
Exoplanet Comparison Kepler-11 e.png
Size comparison of Kepler-11e (gray) with Neptune.
Discovery
Discovery date2 February 2011 [1]
Transit (Kepler Mission) [1]
Orbital characteristics
0.194 AU (29,000,000 km)
31.99590 [2] d
Inclination 88.8 [2]
Star Kepler-11 (KOI-157)
Physical characteristics
Mean radius
4.52 (± 0.43) [3] R🜨
Mass 8.4 +2.5
1.9
[3] ME
Mean density
0.5 (± 0.2) [3] g cm−3
Temperature 617 K (344 °C; 651 °F) [4]

    Kepler-11e is an exoplanet (extrasolar planet) discovered in the orbit of the sunlike star Kepler-11. It is the fourth of six planets around Kepler-11 discovered by NASA's Kepler spacecraft. Kepler-11e was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. Kepler-11e is most likely a gas giant like Neptune, having a density that is less than that of Saturn, the least dense planet in the Solar System. [5] Its low density can probably be attributed to a large hydrogen and helium atmosphere. [1] Kepler-11e has a mass eight times of Earth's mass and a radius 4.5 times that of Earth. The planet orbits its star every 31 days in an ellipse that would fit within the orbit of Mercury. Kepler-11e was announced on February 2, 2011 with its five sister planets after it was confirmed by several observatories.

    Contents

    Name and discovery

    At the time when Kepler-11 was first noted as a host to a potential transit event, the star was given the designation KOI-157. [2] It was later assigned the name "Kepler-11" after the Kepler spacecraft, a NASA satellite tasked with discovering planets in transit of, or crossing in front of, their stars. This transit causes a slight and regular change in the host star's brightness, which can then tested to prove the planet's existence and, later, to extrapolate the orbital parameters of the planet. [6] Kepler-11e is first given the designation by its host star, Kepler-11. Since Kepler-11e was announced with five other planets, the letters added to the star are sorted by the planet's distance from its star. Kepler-11e is the fourth planet from Kepler-11, it is given the designation "e".

    Follow-up confirmation observations were made by the Keck 1 telescope at the W. M. Keck Observatory in Hawaii, the Hale and Shane telescopes in California, the Harlan J. Smith and Hobby–Eberly telescopes in west Texas, the Nordic Optical Telescope in the Canary Islands, and by telescopes at the WIYN (including MMT) and Whipple observatories in Arizona. The Spitzer Space Telescope was also used. Kepler-11's planetary system became the first discovered extrasolar system with more than three transiting planets, as well as the most compact and flattest system yet discovered, according to NASA. [6] The planets of Kepler-11, including Kepler-11e, were announced jointly at a press conference on February 2, 2011. The findings were published in the journal Nature on February 3. [1]

    Host star

    Kepler-11 is a G-type star [4] located in the constellation of Cygnus. It has a mass of 0.95 Msun and a radius of 1.1 Rsun, and is thus almost the same mass and radius as the Sun. With an effective temperature of 5680 K, it is also almost as hot as the Sun, and with a metallicity of 0, Kepler-11 is almost as metal-rich as the Sun is. Metal-rich stars tend to have easily detectable planets [7] because higher metallicities tend to either facilitate the creation of gas giants or to promote planetary migration, in which the planet orbits more closely to its star. [8] However, Kepler-11 is almost 1.73 times older than the Sun, as it has an estimated age of eight billion years. [2] Kepler-11 is 613 parsecs away from the Earth; its distance contributes to its apparent magnitude of 14.2 (V). It, thus, cannot be seen with the naked eye. [2] Other than Kepler-11e, Kepler-11 is the host star of the planets Kepler-11b, Kepler-11c, Kepler-11d, Kepler-11f, and Kepler-11g. The inner five planets in the system orbit in a tightly knit configuration that would fit within the orbit of planet Mercury, while Kepler-11g, compared to its inner sister planets, orbits at a much further distance. [1]

    Characteristics

    A comparison of the Kepler planets as compared to Earth, Jupiter, and previous Kepler finds. Kepler-11e is in purple at the bottom. Kepler-11 planets comparison.jpg
    A comparison of the Kepler planets as compared to Earth, Jupiter, and previous Kepler finds. Kepler-11e is in purple at the bottom.

    Kepler-11e, which formed within the first few million years of the star system's formation, [9] has a mass 8.4 times that of Earth's, and radius 4.52 times that of Earth's. With a density of 0.5 grams/cm3, Kepler-11e has a density that is half of that of pure water at standard temperature and pressure and slightly less than the density of Saturn. [5] Kepler-11e has a surface equilibrium temperature of 617 K, and is thus has an equilibrium temperature approximately 2.4 times hotter than Earth's. Kepler-11e orbits its star at a mean distance of .194 AU, making it the fourth planet from its star. It completes an orbit every 31.995990 days. In comparison, Mercury orbits the Sun every 87.97 days at a distance of 0.387 AU. [10] Kepler-11e's orbital inclination is 88.8°, making it almost entirely edge-on to its star as seen from Earth. [2]

    Because it isn't as close to its star as its sister planets Kepler-11b and Kepler-11c, the Kepler team suggests that its light density may come from a large hydrogen and helium atmosphere that has not been blown away by the stellar wind. [1] In fact, formation models indicate that the planet has a gaseous envelope, somewhat less massive than 20% of it total mass, which account for ≈60% of its radius (or ≈90% of its volume). [11]

    Related Research Articles

    This page describes exoplanet orbital and physical parameters.

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    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 expected to soon reach the end of the main sequence. Kepler-7b is a hot Jupiter that is about half the mass of Jupiter, but is nearly 1.5 times its size; at the time of its discovery, Kepler-7b was the second most diffuse planet known, surpassed only by WASP-17b. It orbits its host star every five days at a distance of approximately 0,06 AU. Kepler-7b was announced at a meeting of the American Astronomical Society on January 4, 2010. It is the first extrasolar planet to have a crude map of cloud coverage.

    <span class="mw-page-title-main">Kepler-5b</span> Extrasolar planet

    Kepler-5b is one of the first five planets discovered by NASA's Kepler spacecraft. It is a hot Jupiter that orbits a subgiant star that is more massive, larger, and more diffuse than the Sun is. Kepler-5 was first flagged as the location of a possibly transiting planet, and was reclassified as a Kepler Object of Interest until follow-up observations confirmed the planet's existence and many of its characteristics. The planet's discovery was announced at a meeting of the American Astronomical Society on January 4, 2010. The planet has approximately twice the mass of Jupiter, and is about 1.5 times larger. It is also fifteen times hotter than Jupiter. Kepler-5b orbits Kepler-5 every 3.5 days at a distance of approximately 0.051 AU.

    Kepler-8 is a star located in the constellation Lyra in the field of view of the Kepler Mission, a NASA-led operation tasked with discovering terrestrial planets. The star, which is slightly hotter, larger, and more massive than the Sun, has one gas giant in its orbit, Kepler-8b. This gas giant is larger than Jupiter, but is less massive, and thus more diffuse. The planet's discovery was announced to the public on January 4, 2010 along with four other planets. As the fifth confirmed planetary system verified by Kepler, it helped demonstrate the capabilities of the Kepler spacecraft.

    <span class="mw-page-title-main">Kepler-9b</span> Extrasolar planet

    Kepler-9b is one of the first planets discovered outside the solar system (exoplanets) by NASA's Kepler Mission. It revolves around the star Kepler-9 within the constellation Lyra. Kepler-9b is the largest of three planets detected in the Kepler system by transit method; its mass is roughly half that of the planet Saturn, and it is the largest planet in its system. Kepler-9b and Kepler-9c display a phenomenon called orbital resonance, in which gravitational pull from each planet alters and stabilizes the orbit of the other. The planet's discovery was announced on August 26, 2010.

    <span class="mw-page-title-main">Kepler-9c</span> Extrasolar planet

    Kepler-9c is one of the first seven extrasolar planets, exoplanets, discovered by NASA's Kepler Mission, and one of at least two planets orbiting the star Kepler-9. Kepler-9c and Kepler-9b were the first exoplanets confirmed to be transiting their star. The planet's discovery was announced by the Kepler Mission team on August 26, 2010 after its initial discovery by Kepler. At the time, it was one of 700 planetary candidates noted by Kepler.

    <span class="mw-page-title-main">Discoveries of exoplanets</span> Detecting planets located outside the Solar System

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    <span class="mw-page-title-main">Kepler-10b</span> Terrestrial exoplanet orbiting Kepler-10

    Kepler-10b is the first confirmed terrestrial planet to have been discovered outside the Solar System by the Kepler Space Telescope. Discovered after several months of data collection during the course of the NASA-directed Kepler Mission, which aims to discover Earth-like planets crossing in front of their host stars, the planet's discovery was announced on January 10, 2011. Kepler-10b has a mass of 3.72±0.42 Earth masses and a radius of 1.47 Earth radii. However, it lies extremely close to its star, Kepler-10, and as a result is too hot to support life as we know it. Its existence was confirmed using measurements from the W.M. Keck Observatory in Hawaii.

    <span class="mw-page-title-main">Kepler-10</span> Sunlike star in the constellation Draco

    Kepler-10, formerly known as KOI-72, is a Sun-like star in the constellation of Draco that lies 607 light-years from Earth. Kepler-10 was targeted by NASA's Kepler spacecraft, as it was seen as the first star identified by the Kepler mission that could be a possible host to a small, transiting exoplanet. The star is slightly less massive, slightly larger, and slightly cooler than the Sun; at an estimated 11.9 billion years in age, Kepler-10 is 2.3 times the age of the Sun.

    <span class="mw-page-title-main">Kepler-11</span> Sun-like star in the constellation Cygnus

    Kepler-11, also designated as 2MASS J19482762+4154328, is a Sun-like star slightly larger than the Sun in the constellation Cygnus, located some 2,110 light years from Earth. It is located within the field of vision of the Kepler spacecraft, the satellite that NASA's Kepler Mission uses to detect planets that may be transiting their stars. Announced on February 2, 2011, the star system is among the most compact and flattest systems yet discovered. It is the first discovered case of a star system with six transiting planets. All discovered planets are larger than Earth, with the larger ones being about Neptune's size.

    <span class="mw-page-title-main">Kepler-11b</span> Exoplanet orbiting Kepler-11

    Kepler-11b is an exoplanet discovered around the star Kepler-11 by the Kepler spacecraft, a NASA-led mission to discover Earth-like planets. Kepler-11b is less than about three times as massive and twice as large as Earth, but it has a lower density, and is thus most likely not of Earth-like composition. Kepler-11b is the hottest of the six planets in the Kepler-11 system, and orbits more closely to Kepler-11 than the other planets in the system. Kepler-11b, along with its five counterparts, form the first discovered planetary system with more than three transiting planets—the most densely packed known planetary system. The system is also the flattest known planetary system. The discovery of this planet and its five sister planets was announced on February 2, 2011, after follow-up investigations.

    <span class="mw-page-title-main">Kepler-11c</span> Extrasolar planet orbiting Kepler-11

    Kepler-11c is an exoplanet discovered in the orbit of the Sun-like star Kepler-11 by the Kepler spacecraft, a NASA telescope aiming to discover Earth-like planets. It is the second planet from its star, and is most likely a water planet with a thin hydrogen–helium atmosphere. Kepler-11c orbits Kepler-11 every 10 days, and has an estimated density twice that of pure water. It is estimated to have a mass thirteen times that of Earth and a radius three times that of Earth. Kepler-11c and its five sister planets form the first discovered system with more than three transiting planets. The Kepler-11 system also holds the record of being the most compact and the flattest system discovered. Kepler-11c and the other Kepler-11 planets were announced to the public on February 2, 2011, and was published in Nature a day later.

    <span class="mw-page-title-main">Kepler-11d</span> Extrasolar planet

    Kepler-11d is an exoplanet discovered in the orbit of the sun-like star Kepler-11. It is named for the telescope that discovered it, a NASA spacecraft named Kepler that is designed to detect Earth-like planets by measuring small dips in the brightness of their host stars as the planets cross in front. This process, known as the transit method, was used to note the presence of six planets in orbit around Kepler-11, of which Kepler-11d is the third from its star. Kepler-11d orbits Kepler-11 well within the orbit of Mercury approximately every 23 days. The planet is approximately six times more massive than the Earth, and has a radius that is three and a half times larger than that of Earth's. It is, however, far hotter than Earth is. Its low density, comparable to that of Saturn, suggests that Kepler-11d has a large hydrogen–helium atmosphere. Kepler-11d was announced with its five sister planets on February 2, 2011 after extensive follow-up studies.

    <span class="mw-page-title-main">Kepler-11f</span> Extrasolar planet

    Kepler-11f is an exoplanet discovered in the orbit of the sun-like star Kepler-11 by NASA's Kepler spacecraft, which searches for planets that transit their host stars. Kepler-11f is the fifth planet from its star, orbiting one quarter of the distance of the Earth from the Sun every 47 days. It is the furthest of the first five planets in the system. Kepler-11f is the least massive of Kepler-11's six planets, at nearly twice the mass of Earth; it is about 2.6 times the radius of Earth. Along with planets d and e and unlike the two inner planets in the system, Kepler-11f has a density lower than that of water and comparable to that of Saturn. This suggests that Kepler-11f has a significant hydrogen–helium atmosphere. The Kepler-11 planets constitute the first system discovered with more than three transiting planets. Kepler-11f was announced to the public on February 2, 2011, after follow-up investigations at several observatories. Analysis of the planets and study results were published the next day in the journal Nature.

    <span class="mw-page-title-main">Kepler-11g</span> Extrasolar planet

    Kepler-11g is an exoplanet discovered in the orbit of the sunlike star Kepler-11 by the Kepler spacecraft, a NASA satellite tasked with searching for terrestrial planets. Kepler-11g is the outermost of the star's six planets. The planet orbits at a distance of nearly half the mean distance between Earth and the Sun. It completes an orbit every 118 days, placing it much further from its star than the system's inner five planets. Its estimated radius is a little over three times that of Earth, i.e. comparable to Neptune's size. Kepler-11g's distance from the inner planets made its confirmation more difficult than that of the inner planets, as scientists had to work to exhaustively disprove all reasonable alternatives before Kepler-11g could be confirmed. The planet's discovery, along with that of the other Kepler-11 planets, was announced on February 2, 2011. According to NASA, the Kepler-11 planets form the flattest and most compact system yet discovered.

    Kepler-40b, formerly known as KOI-428b, is a hot Jupiter discovered in orbit around the star Kepler-40, which is about to become a red giant. The planet was first noted as a transit event by NASA's Kepler spacecraft. The Kepler team made data collected by its satellite publicly available, including data on Kepler-40; French and Swiss astronomers used the equivalent to one night of measurements on the SOPHIE échelle spectrograph to collect all the data needed to show that a planet was producing the periodic dimming of Kepler-40. The planet, Kepler-40b, is twice the mass of Jupiter and slightly larger than it in size, making it as dense as Neptune. The planet is also nearly thirteen times hotter than Jupiter and orbits five times closer to its star than Mercury is from the Sun.

    Kepler-47 is a binary star system in the constellation Cygnus located about 3,420 light-years away from Earth. The stars have three exoplanets, all of which orbit both stars at the same time, making this a circumbinary system. The first two planets announced are designated Kepler-47b, and Kepler-47c, and the third, later discovery is Kepler-47d. Kepler-47 is the first circumbinary multi-planet system discovered by the Kepler mission. The outermost of the planets is a gas giant orbiting within the habitable zone of the stars. Because most stars are binary, the discovery that multi-planet systems can form in such a system has impacted previous theories of planetary formation.

    <span class="mw-page-title-main">Kepler-69c</span> Super-Earth orbiting Kepler-69

    Kepler-69c is a confirmed super-Earth extrasolar planet, likely rocky, orbiting the Sun-like star Kepler-69, the outermore of two such planets discovered by NASA's Kepler spacecraft. It is located about 2,430 light-years from Earth.

    Kepler-277c is the third most massive and second-largest rocky planet ever discovered, with a mass about 64 times that of Earth. Discovered in 2014 by the Kepler Space Telescope, Kepler-277c is a Neptune-sized exoplanet with a very high mass and density for an object of its radius, suggesting a composition made mainly of rock with some amounts of water. Along with its sister planet, Kepler-277b, the planet's mass was determined using transit-timing variations (TTVs).

    <span class="mw-page-title-main">K2-288Bb</span> Mini-Neptune orbiting K2-288B

    K2-288Bb is a super-Earth or mini-Neptune exoplanet orbiting in the habitable zone of K2-288B, a low-mass M-dwarf star in a binary star system in the constellation of Taurus about 226 light-years from Earth. It was discovered by citizen scientists while analysing data from the Kepler spacecraft's K2 mission, and was announced on 7 January 2019. K2-288 is the third transiting planet system identified by the Exoplanet Explorers program, after the six planets of K2-138 and the three planets of K2-233.

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