Kepler-9

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Kepler-9
Kepler-9 Worlds on the Edge.jpg
An artist's impression of Kepler-9, including planets Kepler-9b and c
Observation data
Epoch J2000       Equinox J2000
Constellation Lyra [1]
Right ascension 19h 2m 17.7544s [2]
Declination +38° 24′ 03.177″ [2]
Apparent magnitude  (V)13.9 [3]
Astrometry
Proper motion (μ)RA: 2.472(13)  mas/yr [2]
Dec.: −14.691(15)  mas/yr [2]
Parallax (π)1.5823 ± 0.0120  mas [2]
Distance 2,060 ± 20  ly
(632 ± 5  pc)
Characteristics
Spectral type G2V
Details [4]
Mass 1.022+0.029
−0.039  M☉
Radius 0.958±0.020  R☉
Surface gravity (log g)4.49+0.02
−0.03  cgs
Temperature 5774±60  K
Metallicity [Fe/H]+0.05±0.07  dex
Rotation 16.746±0.077 days [5]
Rotational velocity (v sin i)2.74±0.40 [6]  km/s
Age 2.0+2.0
−1.3  Gyr
Other designations
KOI-377, KIC  3323887, 2MASS J19021775+3824032 [7]
Database references
SIMBAD data
KIC data

Kepler-9 is a sunlike star in the constellation Lyra. Its planetary system, discovered by the Kepler Mission in 2010 was the first detected with the transit method found to contain multiple planets.

Contents

Nomenclature and history

Kepler-9 was named for the Kepler Mission, a project headed by NASA that was designed to search for Earth-like planets. [8]

In June 2010, some 43 days after Kepler came online, its operating scientists submitted a list of over 700 exoplanet candidates for review. Of those, five were originally suspected to have more than one planet. Kepler-9 was one of the multiplanetary systems; it was identified as such when scientists noticed significant variations in the time intervals at which Kepler-9 was transited. [9] Kepler-9 holds the first multiplanetary system discovered using the transit method. It is also the first planetary system where transiting planets were confirmed through transit timing variations method, allowing to calculate the masses of planets. [10] The discovery of the planets was announced on August 26, 2010. [9]

Characteristics

Kepler-9 is located in the constellation Lyra that lies some 632 parsecs away from Earth. With a mass of 1.07  M☉ and a radius of 1.02  R☉, Kepler-9 is almost exactly the same size and width of the Sun, being only 7% more massive and 2% wider. Kepler-9 has an effective temperature of 5777 (± 61) K, as compared to the Sun's at 5778 K, [11] and is approximately 32% more metal-rich (in terms of iron) than the Sun. Kepler-9 is younger than the Sun, and is estimated to be one billion years old. [12]

Planetary system

Light curves of the transiting planets of Kepler-9. Kepler9bcdlightcurves-full.jpg
Light curves of the transiting planets of Kepler-9.

There are three confirmed planets, all in direct orbit. The outer two planets, Kepler-9b (the inner one) and Kepler-9c (the outer one), are low-density gas giants that are respectively 25% and 17% the mass of Jupiter and around 80% the radius of Jupiter. Both planets have a density less than that of water, similar to Saturn. The innermost planet, Kepler-9d, is a super-Earth with a radius that is 1.64 times that of Earth, [13] [12] orbiting the star every 1.6 days. It is estimated that there is a 0.59% chance that the discoveries are false. [12]

From Kepler-9d (closest to star) to Kepler-9b (second from star), the ratio of their orbits is 1:12. However, the ratio of the orbits of the two outer planets is 1:2, a relationship known as a mean motion resonance. Kepler-9b and Kepler-9c are the first transiting planets detected in such an orbital configuration. [14] The resonance causes the orbital speeds of each planet to change, and thus causes the transit times of the two planets to oscillate. The period of Kepler-9b is increasing by 4 minutes per orbit, while that of Kepler-9c is decreasing by 39 minutes per orbit. These orbital changes allowed the masses of the planets (a parameter not normally obtainable via the transit method) to be estimated using a dynamical model. The mass estimates were further refined using radial velocity measurements obtained with the HIRES instrument of the Keck 1 telescope. [14] [15]

Kepler-9b and 9c are thought to have formed beyond the "frost line". They are then thought to have migrated inward due to interactions with the remains of the protoplanetary disk. They would have been captured into orbital resonance during this migration. [14]

In 2021, it was found the orbital plane of Kepler-9b and Kepler-9c are slowly changing, likely under the gravitational influence of the additional giant planet. [16]

The Kepler-9 planetary system [13] [12]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
d —0.02730+0.00042
−0.00043		1.592851±0.0000450—1.64+0.19
−0.14  R🜨
b 44.71±0.24  M🜨 0.14276088±0.0000001419.2470.06378±0.0004088.936±0.030 ° 8.252±0.094  R🜨
c 30.79±0.17  M🜨 0.22889876±0.0000005338.9440.067990±0.00006889.180±0.015 ° 8.077±0.092  R🜨

See also

Related Research Articles

<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-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">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 2,150 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-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 spacecraft, 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.

Kepler-18 is a star with almost the same mass as the Sun in the Cygnus constellation.

Kepler-20 is a star about 934 light-years from Earth in the constellation Lyra with a system of at least five, and possibly six, known planets. The apparent magnitude of this star is 12.51, so it cannot be seen with the unaided eye. Viewing it requires a telescope with an aperture of 15 cm (6 in) or more. It is slightly smaller than the Sun, with 94% of the Sun's radius and about 91% of the Sun's mass. The effective temperature of the photosphere is slightly cooler than that of the Sun at 5466 K, giving it the characteristic yellow hue of a stellar class G8 star. The abundance of elements other than hydrogen or helium, what astronomers term the metallicity, is approximately the same as in the Sun. It may be older than the Sun, although the margin of error here is relatively large.

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-80, also known as KOI-500, is a red dwarf star of the spectral type M0V. This stellar classification places Kepler-80 among the very common, cool, class M stars that are still within their main evolutionary stage, known as the main sequence. Kepler-80, like other red dwarf stars, is smaller than the Sun, and it has both radius, mass, temperatures, and luminosity lower than that of our own star. Kepler-80 is found approximately 1,223 light years from the Solar System, in the stellar constellation Cygnus, also known as the Swan.

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 G-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.

<span class="mw-page-title-main">Kepler-25</span> Yellow-white hued star in the constellation Lyra

Kepler-25 is a star in the northern constellation of Lyra. It is slightly larger and more massive than the Sun, with a luminosity 21⁄2 times that of the Sun. With an apparent visual magnitude of 10.6, this star is too faint to be seen with the naked eye.

Kepler-102 is a star 353 light-years away in the constellation of Lyra. Kepler-102 is less luminous than the Sun. The star system does not contain any observable amount of dust. Kepler-102 is suspected to be orbited by a binary consisting of two red dwarf stars, at projected separations of 591 and 627 AU.

<span class="mw-page-title-main">Kepler-138</span> Red dwarf in the constellation Lyra

Kepler-138, also known as KOI-314, is a red dwarf located in the constellation Lyra, 219 light years from Earth. It is located within the field of vision of the Kepler spacecraft, the satellite that NASA's Kepler Mission used to detect planets transiting their stars.

Kepler-30 is a star in the northern constellation of Lyra. It is located at the celestial coordinates: Right Ascension 19h 01m 08.0747s Declination +38° 56′ 50.219″. With an apparent visual magnitude of 15.5, this star is too faint to be seen with the naked eye. Kepler-30 is exhibiting a strong starspot activity.

<span class="mw-page-title-main">Kepler-186</span> Star in the constellation Cygnus

Kepler-186 is a main-sequence M1-type dwarf star, located 178.5 parsecs away in the constellation of Cygnus. The star is slightly cooler than the sun, with roughly half its metallicity. It is known to have five planets, including the first Earth-sized world discovered in the habitable zone: Kepler-186f. The star hosts four other planets discovered so far, though they all orbit interior to the habitable zone.

<span class="mw-page-title-main">Kepler-444</span> Triple star system in the constellation of Lyra

Kepler-444 is a triple star system, estimated to be 11.2 billion years old, approximately 119 light-years (36 pc) away from Earth in the constellation Lyra. On 27 January 2015, the Kepler spacecraft is reported to have confirmed the detection of five sub-Earth-sized rocky exoplanets orbiting the main star. The star is a K-type main sequence star. All of the planets are far too close to their star to harbour life forms.

Kepler-419 is an F-type main-sequence star located about 3,400 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. In 2012, a potential planetary companion in a very eccentric orbit was detected around this star, but its planetary nature was not confirmed until 12 June 2014, when it was named Kepler-419b. A second planet was announced orbiting further out from the star in the same paper, named Kepler-419c.

K2-19 is an early K-type or late G-type main sequence star that is magnetically active, and has a light curve that exhibits variations in brightness of ~1%. It is located approximately 976 light-years away in the constellation Virgo. Three confirmed transiting exoplanets are known to orbit this star.

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi: 10.1086/132034 . Vizier query form
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  3. ↑ "Planet Kepler-9 b". Extrasolar Planets Encyclopaedia . Retrieved 19 December 2017.
  4. ↑ Borsato, L.; et al. (2019). "HARPS-N radial velocities confirm the low densities of the Kepler-9 planets". Monthly Notices of the Royal Astronomical Society. 484 (3): 3233–3243. arXiv: 1901.05471 . Bibcode:2019MNRAS.484.3233B. doi:10.1093/mnras/stz181. S2CID   85454312.
  5. ↑ McQuillan, A.; Mazeh, T.; Aigrain, S. (2013). "Stellar Rotation Periods of The Kepler objects of Interest: A Dearth of Close-In Planets Around Fast Rotators". The Astrophysical Journal Letters. 775 (1). L11. arXiv: 1308.1845 . Bibcode: 2013ApJ...775L..11M . doi: 10.1088/2041-8205/775/1/L11 .
  6. ↑ Wang, Songhu; et al. (2018). "Stellar Spin–Orbit Alignment for Kepler-9, a Multi-transiting Planetary System with Two Outer Planets Near 2:1 Resonance". The Astronomical Journal. 155 (2). 70. arXiv: 1712.06409 . Bibcode: 2018AJ....155...70W . doi: 10.3847/1538-3881/aaa2fb .
  7. ↑ "Kepler-9". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2019-11-29.
  8. ↑ "Mission overview". Kepler and K2. NASA. 13 April 2015. Retrieved 2 December 2017.
  9. 1 2 "NASA's Kepler Mission Discovers Two Planets Transiting Same Star" (Press release). Pasadena, California: Jet Propulsion Laboratory. 2010-08-26. Retrieved 2019-11-28.
  10. ↑ Nancy Atkinson (26 August 2010). "Kepler Discovers Multi-Planet System". Universe Today. Retrieved 13 January 2011.
  11. ↑ David Williams (1 September 2004). "Sun Fact Sheet". Goddard Space Flight Center . NASA . Retrieved 20 March 2011.
  12. 1 2 3 4 Torres, Guillermo; et al. (2011). "Modeling Kepler Transit Light Curves as False Positives: Rejection of Blend Scenarios for Kepler-9, and Validation of Kepler-9 d, A Super-earth-size Planet in a Multiple System". The Astrophysical Journal. 727 (1). 24. arXiv: 1008.4393 . Bibcode: 2011ApJ...727...24T . doi: 10.1088/0004-637X/727/1/24 .
  13. 1 2 Freudenthal, J.; et al. (2018). "Kepler Object of Interest Network. II. Photodynamical modelling of Kepler-9 over 8 years of transit observations". Astronomy and Astrophysics. 618. A41. arXiv: 1807.00007 . Bibcode: 2018A&A...618A..41F . doi: 10.1051/0004-6361/201833436 .
  14. 1 2 3 Holman, M. J.; et al. (2010). "Kepler-9: A System of Multiple Planets Transiting a Sun-Like Star, Confirmed by Timing Variations" (PDF). Science. 330 (6000): 51–54. Bibcode:2010Sci...330...51H. doi:10.1126/science.1195778. PMID   20798283. S2CID   8141085.
  15. ↑ Alexander, Amir (2010-08-27). "From the Ground and from Space, New Planetary Systems Unveiled". Planetary Society web site. The Planetary Society. Archived from the original on 2010-09-01. Retrieved 2010-08-27.
  16. ↑ Shahaf, Sahar; Mazeh, Tsevi; Zucker, Shay; Fabrycky, Daniel (2021), "Systematic search for long-term transit duration changes in Kepler transiting planets", Monthly Notices of the Royal Astronomical Society, 505: 1293–1310, arXiv: 2105.04318 , doi:10.1093/mnras/stab1359
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