Kepler-11

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Kepler-11
Kepler11.png
Artist's conception of a simultaneous transit of three planets before Kepler-11 observed by NASA's Kepler spacecraft on Aug. 26, 2010.
Observation data
Epoch J2000       Equinox J2000
Constellation Cygnus
Right ascension 19h 48m 27.6226s [1]
Declination +41° 54′ 32.903″ [1]
Apparent magnitude  (V)14.2 [2]
Characteristics
Spectral type G6V [2]
Astrometry
Proper motion (μ)RA: 0.106(13)  mas/yr [1]
Dec.: −7.103(15)  mas/yr [1]
Parallax (π)1.5476 ± 0.0117  mas [1]
Distance 2,110 ± 20  ly
(646 ± 5  pc)
Absolute magnitude  (MV)4.7 [3]
Details [3]
Mass 1.042±0.005  M☉
Radius 1.021±0.025  R☉
Surface gravity (log g)4.44±0.02  cgs
Temperature 5836±7  K
Metallicity [Fe/H]0.062±0.007  dex
Rotational velocity (v sin i)2.2±0.2 km/s
Age 3.2±0.9  Gyr
Other designations
KOI-157, KIC  6541920, 2MASS J19482762+4154328 [4]
Database references
SIMBAD data
KIC data

Kepler-11, also designated as 2MASS J19482762+4154328, [5] 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.

Contents

Nomenclature and history

Kepler-11 and its planets were discovered by NASA's Kepler Mission, a mission tasked with discovering planets in transit around their stars. The transit method that Kepler uses involves detecting dips in brightness in stars. These dips in brightness can be interpreted as planets whose orbits move in front of their stars from the perspective of Earth. Kepler-11 is the first discovered exoplanetary system with more than three transiting planets. [6]

Kepler-11 is named for the Kepler Mission: it is the 11th star with confirmed planets discovered in the Kepler field of view. The planets are named alphabetically, starting with the innermost: b, c, d, e, f, and g, distinguishers that are tagged onto the name of their home star.

The orbit of the Kepler-11 planets in comparison to orbits of planets Mercury and Venus. Kepler-11 System.jpg
The orbit of the Kepler-11 planets in comparison to orbits of planets Mercury and Venus.

Characteristics

Kepler-11 is a G-type star that is approximately 104% the mass of and 102% the radius of the Sun. It has a surface temperature of about 5836 K and is estimated to have an age of around 3.2 billion years. [3] In comparison, the Sun is about 4.6 billion years old [7] and has a surface temperature of 5778 K. [8]

With an apparent magnitude of 14.2, it is too faint to be seen with the naked eye. [2]

Planetary system

All known planets transit the star; this means that all six planets' orbits appear to cross in front of their star as viewed from the Earth's perspective. Their inclinations relative to Earth's line of sight, or how far above or below the plane of sight they are, vary by a little more than a degree. This allows direct measurements of the planets' periods and relative diameters (compared to the host star) by monitoring each planet's transit of the star. Simulations suggest that the mean mutual inclinations of the planetary orbits are about 1°, meaning the system is probably more coplanar (flatter) than the Solar System, where the corresponding figure is 2.3°. [2]

The estimated masses of planets b - f fall in the range between those of Earth and Neptune. Their estimated densities, all lower than that of Earth, imply that none of them have an Earth-like composition; [9] a significant hydrogen/helium atmosphere is predicted for planets c, d, e, f, and g, while planet b may be surrounded by a steam atmosphere or perhaps by a hydrogen atmosphere. [10] [11] The low densities likely result from high-volume extended atmospheres that surround cores of iron, rock, and possibly H2O. [11] [12] The inner constituents of the Kepler-11 system were, at the time of their discoveries, the most comprehensively understood extrasolar planets smaller than Neptune. [13] Currently, observations do not place a firm constraint on the mass of planet g (<25 ME). [10] However, formation and evolution studies indicate that the mass of planet g is not much greater than about 7 ME. [11]

Kepler-11 planets may have formed in situ (i.e., at their observed orbital locations) or ex situ, that is, they may have started their formation farther away from the star while migrating inward through gravitational interactions with a gaseous protoplanetary disk. This second scenario predicts that a substantial fraction of the planets' mass is in H2O. [11] Regardless of the formation scenario, the gaseous component of the planets accounts for less than about 20% of their masses but for ≈40 to ≈60% of their radii. In 2014, the dynamical simulation shown what the Kepler-11 planetary system have likely to undergone a substantial inward migration in the past, producing an observed pattern of lower-mass planets on tightest orbits. [14] Additional yet unobserved gas giant planets on wider orbit are likely necessary for migration of smaller planets to proceed that far inward. [15]

The system is among the most compact known; the orbits of planets b - f would easily fit inside the orbit of Mercury, with g only slightly outside it. Despite this close packing of the orbits, dynamical integrations indicate the Kepler-11 system has the potential to be stable on a time scale of billions of years. [2] However, it may be approaching instability due to a secular resonance involving b and c. If this happens, b will most likely become eccentric enough that it collides with c. [16]

None of the planets are in low-ratio orbital resonances, in which multiple planets gravitationally tug on and stabilize each other's orbits, resulting in simple ratios of their orbital periods. [12] However, b and c are close to a 5:4 ratio. [2]

There could conceivably be other planets in the system that do not transit the star, but they would only be detectable by the effects of their gravity on the motion of the visible planets (much as how Neptune was discovered). The presence of additional gas giant planets is currently excluded up to orbital radius of 30 AU. [17]

The Kepler-11 planetary system [10] [18]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 2.78+0.64
−0.66  M🜨 		0.091±0.00110.3039+0.0006
−0.0010		0.045+0.068
−0.042		89.64+0.36
−0.18 ° 		1.83+0.07
−0.04  R🜨
c 5.0+1.3
−1.35  M🜨 		0.107±0.00113.0241+0.0013
−0.0008		0.026+0.063
−0.013		89.59+0.41
−0.16 ° 		2.87+0.05
−0.06  R🜨
d 8.13+0.67
−0.66  M🜨 		0.155±0.00122.6845±0.00090.004+0.007
−0.002		89.67+0.13
−0.16 ° 		3.12+0.06
−0.07  R🜨
e 9.48+0.86
−0.88  M🜨 		0.195±0.00231.9996+0.0008
−0.0012		0.012+0.006
−0.006		89.89+0.02
−0.02 ° 		4.19+0.07
−0.09  R🜨
f 2.43+0.49
−0.45  M🜨 		0.250±0.00246.6888+0.0027
−0.0032		0.013+0.011
−0.009		89.47±0.04° 2.49+0.04
−0.07  R🜨
g <25  M🜨 0.466±0.004118.3807+0.0010
−0.0006		0.013+0.011
−0.009		89.87+0.05
−0.06 ° 		3.33+0.06
−0.08  R🜨
Kepler-11 side view with solar system.svg
Relative size and positions of the 6 planets of Kepler-11, and of the innermost Solar System for comparison.
The diameters of the planets (but not of the stars) are scaled up by a factor of 50.

See also

Related Research Articles

<span class="mw-page-title-main">Kepler space telescope</span> NASA satellite for exoplanetology (2009–2018)

The Kepler space telescope is a defunct 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 orbit. The principal investigator was William J. Borucki. After nine and a half years of operation, the telescope's reaction control system fuel was depleted, and NASA announced its retirement on October 30, 2018.

<span class="mw-page-title-main">Super-Earth</span> Planet with a mass between Earth and Uranus

A Super-Earth is a type of exoplanet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability. The alternative term "gas dwarfs" may be more accurate for those at the higher end of the mass scale, although "mini-Neptunes" is a more common term.

This page describes exoplanet orbital and physical parameters.

<span class="mw-page-title-main">Hot Neptune</span> Planet with a mass similar to Uranus or Neptune orbiting close to its star

A hot Neptune or Hoptune is a type of giant planet with a mass similar to that of Uranus or Neptune orbiting close to its star, normally within less than 1 AU. The first hot Neptune to be discovered with certainty was Gliese 436 b in 2007, an exoplanet about 33 light years away. Recent observations have revealed a larger potential population of hot Neptunes in the Milky Way than was previously thought. Hot Neptunes may have formed either in situ or ex situ.

<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">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 1 March 2024, there are 5,640 confirmed exoplanets in 4,155 planetary systems, with 895 systems having more than one planet. This is a list of the most notable discoveries.

<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-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-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 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. 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 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-19b is a planet orbiting around the star Kepler-19. The planet has an orbital period of 9.3 days, with an estimated radius of roughly 2.2 times that of the Earth, with a mass around 8.4 times that of the Earth. It is one of three planets orbiting Kepler-19.

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.

Kepler-32 is an M-type main sequence star located about 1070 light years from Earth, in the constellation of Cygnus. Discovered in January 2012 by the Kepler spacecraft, it shows a 0.58 ± 0.05 solar mass (M☉), a 0.53 ± 0.04 solar radius (R☉), and temperature of 3900.0 K, making it half the mass and radius of the Sun, two-thirds its temperature and 5% its luminosity.

<span class="mw-page-title-main">Kepler-90</span> Star in the constellation Draco, orbited by eight planets

Kepler-90, also designated 2MASS J18574403+4918185, is a F-type star located about 2,790 light-years (855 pc) from Earth in the constellation of Draco. It is notable for possessing a planetary system that has the same number of observed planets as the Solar System.

Kepler-61 is a K-type main-sequence star approximately 1,100 light years from Earth in the constellation Cygnus. It is located within the field of vision of the Kepler spacecraft, the satellite that NASA's Kepler Mission used to detect planets that may be transiting their stars. On April 24, 2013 it was announced that the star has an extrasolar planet orbiting in the inner edge of the habitable zone, named Kepler-61b.

<span class="mw-page-title-main">K2-33b</span> Young Super-Neptune orbiting K2-33

K2-33b is a very young super-Neptune exoplanet, orbiting the pre-main-sequence star K2-33. It was discovered by NASA's Kepler spacecraft on its "Second Light" mission. It is located about 456 light-years away from Earth in the constellation of Scorpius. 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.

<span class="mw-page-title-main">K2-33</span> Star in the constellation Scorpius

K2-33 is an extremely young pre-main-sequence star located about 456 light-years (140 pc) away from the Earth in the constellation of Scorpius. It is known to host one planet, a super-Neptune, named K2-33b. It is also notable for its young age.

References

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  2. 1 2 3 4 5 6 Lissauer, Jack J.; et al. (2011). "A closely packed system of low-mass, low-density planets transiting Kepler-11". Nature. 470 (7332): 53–58. arXiv: 1102.0291 . Bibcode:2011Natur.470...53L. doi:10.1038/nature09760. PMID   21293371. S2CID   4388001.
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  5. ↑ "2MASS J19482762+4154328". SIMBAD . Centre de données astronomiques de Strasbourg.
  6. ↑ Michael Mewhinney; Rachel Hoover; Trent J. Perrotto (2 February 2011). "NASA's Kepler Spacecraft Discovers Extraordinary New Planetary System". NASA. Retrieved 4 February 2011.
  7. ↑ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
  8. ↑ Fraser Cain (September 15, 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
  9. ↑ Boyle, Alan (2 February 2011). "Planetary six-pack poses a puzzle". MSNBC Cosmic Log. Archived from the original on 4 February 2011. Retrieved 4 February 2011.
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  11. 1 2 3 4 D'Angelo, G.; Bodenheimer, P. (2016). "In Situ and Ex Situ Formation Models of Kepler 11 Planets". The Astrophysical Journal. 828 (1): id. 33 (32 pp.). arXiv: 1606.08088 . Bibcode:2016ApJ...828...33D. doi: 10.3847/0004-637X/828/1/33 . S2CID   119203398.
  12. 1 2 Naeye, Robert (2 February 2011). "Kepler's Outrageous System of Six Planets". Sky & Telescope. Retrieved 4 February 2011.
  13. ↑ John Matson (2 February 2011). "A Wealth of Worlds: Kepler Spacecraft Finds 6 New Exoplanets and Hints at 1,200 More". Scientific American . Retrieved 20 February 2011.
  14. ↑ T. O. Hands, R. D. Alexander, W. Dehnen, "Understanding the assembly of Kepler's compact planetary systems", 2014
  15. ↑ Hands, T. O.; Alexander, R. D. (2015), "There might be giants: unseen Jupiter-mass planets as sculptors of tightly-packed planetary systems", Monthly Notices of the Royal Astronomical Society, 456 (4): 4121–4127, arXiv: 1512.02649 , doi:10.1093/mnras/stv2897, S2CID   55175754
  16. ↑ Contreras, A. P. Granados; Boley, A. C. (5 March 2018). "The Dynamics of Tightly-packed Planetary Systems in the Presence of an Outer Planet: Case Studies Using Kepler-11 and Kepler-90". The Astronomical Journal. 155 (3): 139. arXiv: 1802.01702 . Bibcode:2018AJ....155..139G. doi: 10.3847/1538-3881/aaac82 . S2CID   56471148.
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