Kepler-12b

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Kepler-12b
Discovery
Discovered by Fortney et al. [1]
Discovery site Kepler spacecraft
Discovery datePublished September 5, 2011 [1]
radial velocity/transit [1]
Orbital characteristics
0.0556 (± 0.0007) [2] AU
Eccentricity 0.01 [2]
4.4379637 (± 0.0007) [2] d
Inclination 88.76 (±0.08) [2]
Star Kepler-12
Physical characteristics
1.695 +0.028
0.032
[2] RJ
Mass 0.431 (± 0.041) [2] MJ
Mean density
0.111 +0.011
0.009
[1] g cm−3
Temperature 1711±223 K. [3]

    Kepler-12b is a hot Jupiter that orbits G-type star Kepler-12 some 900 parsecs (2,900 ly) away. The planet has an anomalously large radius that could not be explained by standard models at the time of its discovery, almost 1.7 times Jupiter's size while being 0.4 times Jupiter's mass. The planet was detected by the Kepler spacecraft, a NASA project searching for planets that transit (cross in front of) their host stars. The discovery paper was published on September 5, 2011.

    Contents

    Discovery

    NASA's Kepler spacecraft continuously observes a region of the night sky, searching for signs of transiting planets. While orbiting their host stars, such transiting planets cross in front of host stars as seen from Earth. The slight and periodic dimming in the star's brightness is used to determine whether or not the dimming was caused by a planet and not by a false positive. Analysis of Kepler's early data yielded evidence of a transit signal around a star designated as KIC 11804465, later known as Kepler-12. The transit signal was designated KOI-20. [1]

    The Keck Observatory collected observations to prove that Kepler-12b's signal was not actually caused by an eclipsing binary. Mauna Kea observatory.jpg
    The Keck Observatory collected observations to prove that Kepler-12b's signal was not actually caused by an eclipsing binary.

    The Kepler Follow-up Program (KFOP) worked to verify the existence of the planet. KFOP used the W.M. Keck Observatory's Keck I telescope to prove that Kepler-12 was not an eclipsing binary star (a possible false positive that mimics the transit signal). The WIYN Observatory, which was used for speckle imaging, supported Keck's findings and verified that the signal caused by KOI-20 was not caused by a nearby background star's interference. Adaptive optics imaging in the near-infrared was obtained on September 9, 2009 with the Palomar Observatory's PHARO camera on the Hale Telescope confirmed both the WIYN and Keck findings. [1]

    Keck's HIRES instrument measured Kepler-12's radial velocity, which was used to find more of Kepler-12's characteristics (and, by extension, deduce the characteristics of KOI-20 itself). The radial velocity measurements eventually led to the confirmation of Kepler-12b as a planet. [1] Kepler's data in its first 1.5 years of operation was processed and analyzed, yielding Kepler-12b's radius, mass and density. [1]

    The Spitzer Space Telescope's IRAC infrared adaptive optics camera was used to carry out program #60028, which observed the occultations by several giant planets detected by Kepler behind their host stars. The Kepler team, using the observations, tentatively concluded that Kepler-12b most likely did not experience a temperature inversion, in which the day-side temperature of the planet is lower than the night-side. Kepler-12b's discovery paper was published in the Astrophysical Journal on September 5, 2011. [1]

    Host star

    Kepler-12, known also as KIC 11804465 in the Kepler Input Catalog, is an early G-type to late F-type star. This corresponds strongly with a sunlike dwarf star nearing the end of the main sequence, and is about to become a red giant. [1] Kepler-12 is located approximately 900 parsecs (2,950 light years) away from Earth. The star also has an apparent magnitude of 13.438, which means that it cannot be seen from Earth with the unaided eye. [4]

    The star is slightly more massive, slightly more iron-rich and slightly hotter than the Sun. However, Kepler-12 is larger, with a radius of 1.483 times the Sun's radius. [4]

    Characteristics

    Kepler-12b is a Hot Jupiter, and (at the time of its discovery) was the least-irradiated of four Hot Jupiters experiencing a radius anomaly of approximately 1.7 times or more the mass of Jupiter. This radius anomaly entails Hot Jupiters experiencing massive radius increases for a reason not explained by scientific models. Although Kepler-12 is the least-irradiated of the four Hot Jupiters, its radius is just as large, suggesting that multiple mechanisms influencing the planet's inflation are at work. [1] Kepler-12b was compared to HD 209458 b in its discovery paper because both planets appear to release similar amounts of energy (flux); it was also compared to TrES-4b because of the similar radius of the planet. [1]

    Kepler-12b has a mass of 0.431 Jupiters. Its radius of 1.695 Jupiter radii, however, indicates that the planet is almost 70% more than the size of Jupiter. With an orbit of 0.0556 AU, Kepler-12b's average orbit is approximately 5% the average distance between the Earth and Sun. The orbit lasts 4.4379637 days. Kepler-12b has an orbital inclination of 88.86º, indicating that the planet is seen as nearly edge-on with respect to the Earth and to its host star. [2] According to Kepler's official website, the mass and radius of the planet can be compared to 137 Earths (in mass) and 19 Earths (for its radius). The planet's density is 0.111 grams/cm3, about a tenth of the density of water, and its equilibrium temperature is 1481 K (some 5.8 times greater than Jupiter's equilibrium temperature). Additionally, Kepler-12b has an almost totally circular orbit, with an orbital eccentricity of less than 0.01. [4]

    The planet is likely to be tidally locked to the parent star. In 2015, the planetary nightside temperature was estimated to be equal to 1711±223 K. [3] The brightest spot in the planetary atmosphere is shifted westward from the substellar point, indicating a strong winds. [5]

    Related Research Articles

    <span class="mw-page-title-main">Kepler-7b</span> Planet orbiting Kepler-7

    Kepler-7b is one of the first five exoplanets to be confirmed by NASA's Kepler spacecraft, and was confirmed during the first 34 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-4b</span> Extrasolar planet in the constellation Draco

    Kepler-4b, initially known as KOI 7.01, is an extrasolar planet first detected as a transit by the Kepler spacecraft. Its radius and mass are similar to that of Neptune; however, due to its proximity to its host star, it is substantially hotter than any planet in the Solar System. The planet's discovery was announced on January 4, 2010, in Washington, D.C., along with four other planets that were initially detected by the Kepler spacecraft and subsequently confirmed by telescopes at the W.M. Keck Observatory.

    <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.

    <span class="mw-page-title-main">Kepler-6b</span> Extrasolar planet orbiting Kepler-6

    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 stars. It was the third planet to be discovered by Kepler. Kepler-6 orbits its host star every three days from a distance of .046 AU. Its proximity to Kepler-6 inflated the planet, about two-thirds the mass of Jupiter, to slightly larger than Jupiter's size and greatly heated its atmosphere.

    <span class="mw-page-title-main">Kepler-8b</span> Extrasolar planet

    Kepler-8b is the fifth of the first five exoplanets discovered by NASA's Kepler spacecraft, which aims to discover planets in a region of the sky between the constellations Lyra and Cygnus that transit their host stars. The planet is the hottest of the five. Kepler-8b was the only planet discovered in Kepler-8's orbit, and is larger than Jupiter. It orbits its host star every 3.5 days. The planet also demonstrates the Rossiter–McLaughlin effect, where the planet's orbit affects the redshifting of the spectrum of the host star. Kepler-8b was announced to the public on January 4, 2010 at a conference in Washington, D.C. after radial velocity measurements conducted at the W.M. Keck Observatory confirmed its detection by Kepler.

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

    An exoplanet is a planet located outside the Solar System. The first evidence of an exoplanet was noted as early as 1917, but was not recognized as such until 2016; no planet discovery has yet come from that evidence. What turned out to be the first detection of an exoplanet was published among a list of possible candidates in 1988, though not confirmed until 2003. The first confirmed detection came in 1992, with the discovery of terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method and the radial-velocity method. As of 24 July 2024, there are 7,026 confirmed exoplanets in 4,949 planetary systems, with 1007 systems having more than one planet. This is a list of the most notable discoveries.

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

    Kepler-10c is an exoplanet orbiting the G-type star Kepler-10, located around 608 light-years away in Draco. Its discovery was announced by the Kepler space telescope team in May 2011, although it had been seen as a planetary candidate since January 2011, when Kepler-10b was discovered. The team confirmed the observation using data from NASA's Spitzer Space Telescope and a technique called BLENDER that ruled out most false positives. Kepler-10c was the third transiting planet to be confirmed statistically, after Kepler-9d and Kepler-11g. The Kepler team considers the statistical method that led to the discovery of Kepler-10c as what will be necessary to confirm many planets in Kepler's field of view.

    <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 space telescope, 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-11e</span> Extrasolar planet orbiting Kepler-11

    Kepler-11e is an exoplanet 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 space telescope. 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. Its low density can probably be attributed to a large hydrogen and helium atmosphere. 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.

    <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 space telescope, 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 space telescope, 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.

    <span class="mw-page-title-main">Kepler-9d</span> Super-Earth orbiting Kepler-9

    Kepler-9d is a planet in orbit around the Sun-like star Kepler-9. Initially discovered by Kepler space telescope, a terrestrial planet-searching satellite built and operated by NASA, Kepler-9d is most likely a Super-Earth, with an estimated radius approximately 60% larger than that of Earth's, although its exact mass cannot be determined. Kepler-9d orbits Kepler-9 every 1.56 days at a distance of .0273 AU from its star, an extremely close distance. Although Kepler-9d is the closest planet to its star in its system, it is named Kepler-9d instead of Kepler-9b because two gas giants, Kepler-9b and Kepler-9c, were confirmed first. The original studies into the system first suggested that Kepler-9d might be a planet, but a follow-up investigation made by the Kepler team later confirmed that it was; the confirmation of Kepler-9d as a planet was made public with the team's paper, which was published in the Astrophysical Journal on January 1, 2011. The team used telescopes at the W.M. Keck Observatory in Hawaii to follow up on the Kepler space telescope's initial discovery.

    A Kepler object of interest (KOI) is a star observed by the Kepler space telescope that is suspected of hosting one or more transiting planets. KOIs come from a master list of 150,000 stars, which itself is generated from the Kepler Input Catalog (KIC). A KOI shows a periodic dimming, indicative of an unseen planet passing between the star and Earth, eclipsing part of the star. However, such an observed dimming is not a guarantee of a transiting planet, because other astronomical objects—such as an eclipsing binary in the background—can mimic a transit signal. For this reason, the majority of KOIs are as yet not confirmed transiting planet systems.

    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-14b is an extrasolar planet in orbit around the primary star of the binary Kepler-14 system. It is currently the only planet known to exist in this star system. Kepler-14b is 8.4 times the mass of Jupiter and has a radius 1.14 times that of Jupiter, and it orbits its host star every 6.79 days. It was discovered by NASA-led Kepler mission, which noted the planet as a planetary candidate as early as March 2009, around the same time as the discovery of the first five planets discovered by Kepler. However, the team was unable to confirm the planet until extensive follow-up observations, as high-resolution imaging resolved the star Kepler-14 as a closely orbiting binary system. The Kepler team would have not noticed that Kepler-14 was a binary star based solely on initial radial velocity measurements, and found that if they had not realized this, their data on Kepler-14b would have been very inaccurate.

    Kepler-14 is a binary star system targeted by the Kepler spacecraft. It is host to one known planet: the Jupiter-like Kepler-14b. The star system was identified by Kepler as a possible planetary host, but when imaging revealed that Kepler-14 was a binary star system and not a single star, the confirmation process became protracted. The stars are separated by at least 280 AU, and the stars complete an orbit around a common center of mass every 2800 years. Both stars are larger than the Sun. They are of similar absolute magnitudes; however, the primary star is brighter as seen from Earth.

    Kepler-12 is a star with a transiting planet Kepler-12b in a 4-day orbit.

    Kepler-70, also known as KIC 5807616 and KOI-55, is a star about 3,600 light-years away in the constellation Cygnus, with an apparent visual magnitude of 14.87. This is too faint to be seen with the naked eye; viewing it requires a telescope with an aperture of 40 cm (20 in) or more. A subdwarf B star, Kepler-70 passed through the red giant stage some 18.4 million years ago. In its present-day state, it is fusing helium in its core. Once it runs out of helium it will contract to form a white dwarf. It has a relatively small radius of about 0.2 times the Sun's radius; white dwarfs are generally much smaller. The star may be host to a planetary system with two planets, although later research indicates that this is not in fact the case.

    <span class="mw-page-title-main">Kepler-1520b</span> Exoplanet orbiting the star Kepler 1520

    Kepler-1520b, is a confirmed exoplanet orbiting the K-type main sequence star Kepler-1520. It is located about 2,020 light-years away from Earth in the constellation of Cygnus. The exoplanet 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. The planet was previously proposed in 2012 when reports of its host star recorded drops in its luminosity varying from 0.2% to 1.3%, which indicated a possible planetary companion rapidly disintegrating. In 2015, the planetary nature of the cause of the dips was finally verified. It is expected to disintegrate in about 40–400 million years.

    References

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    2. 1 2 3 4 5 6 7 Jean Schneider (2011). "Notes for star Kepler-12". Extrasolar Planets Encyclopaedia . Archived from the original on 5 October 2011. Retrieved 12 September 2011.
    3. 1 2 A Comprehensive Study of Kepler Phase Curves and Secondary Eclipses:Temperatures and Albedos of Confirmed Kepler Giant Planets
    4. 1 2 3 "Datatable of Kepler Discoveries". Ames Research Center . NASA. 2011. Archived from the original on 2010-05-27. Retrieved 12 September 2011.
    5. Shporer, Avi; Hu, Renyu (2015), "Studying Atmosphere-Dominated Hot Jupiter Kepler Phase Curves: Evidence That Inhomogeneous Atmospheric Reflection is Common", The Astronomical Journal, 150 (4): 112, arXiv: 1504.00498 , Bibcode:2015AJ....150..112S, doi:10.1088/0004-6256/150/4/112, S2CID   33182939