Kepler-4b



































































































































Kepler-4b

Exoplanet
List of exoplanets

Exoplanet Comparison Kepler-4 b.png
Size comparison of Neptune (left) with Kepler-4b (right).
Parent star
Star
Kepler-4[1]
Constellation Draco
Right ascension (α) 19h 2m 27.6981s[2]
Declination (δ) +50° 8′ 08.704″[2]
Apparent magnitude (mV) 12.6[1]
Distance
7003161000000000000♠1610±20[2] ly
(7002495000000000000♠495±6[2] pc)
Mass (m)
7000111700000000000♠1.117+0.021
−0.029[3] M☉
Radius (r)
7000155500000000000♠1.555±0.012[3] R☉
Temperature (T)
7003578100000000000♠5781±76[4] K
Metallicity [Fe/H]
6998900000000000000♠0.09±0.10[4]
Age
7000671000000000000♠6.71+0.77
−0.67[3] Gyr
Physical characteristics
Mass (m) .077[1]MJ
Radius (r) 0.357[1]RJ
(3.878 R⊕)
Stellar flux (F⊙) ~168 ⊕
Temperature (T) 1650[1]

Orbital elements
Semi-major axis (a) .04558[1]AU
Eccentricity (e) 0.25 ± 0.12[5]
Orbital period (P) 3.2135[1]d
Inclination (i) 89.76[1]°
Discovery information
Discovery date 2010-01-04[6]
Discoverer(s)
Discovery method
Transit (Kepler Mission)[7]
Other detection methods Radial velocity
Discovery status Conference announcement[6]

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.[1][8] 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.




Contents






  • 1 Nomenclature and history


  • 2 Host star


  • 3 Characteristics


  • 4 See also


  • 5 References


  • 6 External links





Nomenclature and history


Kepler-4b was named because it was the first planet discovered in the orbit of its star, Kepler-4. The star was, in turn, named for the Kepler Mission, a NASA satellite whose purpose is to discover Earth-like planets in a section of the sky between constellations Cygnus and Lyra using the transit method. Using this method, Kepler notes small and steady decreases in a star's brightness that are measured as a planet crosses in front of it.[7] Initially, Kepler-4b was detected as a transit event by the Kepler telescope and considered a Kepler Object of Interest with the designation KOI 7.01.[9]


Subsequent radial velocity measurements by the High Resolution Echelle Spectrometer on the telescopes of W.M. Keck Observatory confirmed the planetary nature of the transit event and established a mass estimate for the planet.[10] The planet's existence was announced on January 4, 2010 along with four other planets detected by Kepler: Kepler-5b, 6b, 7b and 8b[8] at the 215th meeting of the American Astronomical Society in Washington, D.C.[6]



Host star


Main article: Kepler-4

Kepler-4 is located within the Draco constellation on the sky, and is approximately 495 parsecs[2] from the Solar System. It has an effective temperature almost identical to the Sun at 5857 kelvins, but a mass and radius that are somewhat larger than the sun: respectively, 1.092 M⊙{displaystyle {begin{smallmatrix}M_{odot }end{smallmatrix}}}{begin{smallmatrix}M_{odot }end{smallmatrix}} and 1.533 R⊙{displaystyle {begin{smallmatrix}R_{odot }end{smallmatrix}}}{begin{smallmatrix}R_{odot }end{smallmatrix}}.[4] The star is thought to be around 4.5 billion years old, and at or very near the end of its main-sequence hydrogen burning phase. In several tens of millions of years it will likely become a subgiant star.[10]



Characteristics


Kepler-4b orbits its host star in 3.213 days at a distance of 0.046 AU.[10] This places it almost 10 times closer to its star than Mercury is to the Sun. Consequently, Kepler-4b is thought to be extremely hot, with an equilibrium temperature greater than 1700 kelvins (2600 °F).[5] The planet is estimated to be 25 times more massive than the Earth with a radius that is 4 times greater than the Earth.[10] This makes it similar to Neptune in terms of size and mass, but with a temperature that is not comparable to any planet in the Solar System (Venus, the hottest planet, is only 735 kelvins). Kepler-4b's eccentricity was assumed to be 0, however an independent reanalysis of the discovery data found a value of 0.25 ± 0.12[5], and a later reanalysis of the light curve discovered a secondary eclipse with depth 7.47 ± 1.82ppm at a phase of about 0.7.[11]




A picture showing the relative sizes of the first five planets discovered by Kepler. Kepler-4b is the smallest of the five, highlighted in purple.



See also



  • Kepler-5b

  • Kepler-6b

  • Kepler-7b

  • Kepler-8b

  • Kepler-9b

  • Kepler-10b



References





  1. ^ abcdefghi "Summary Table of Kepler Discoveries". NASA. 2010-03-15. Retrieved 2010-03-18..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}


  2. ^ abcde Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
    Gaia Data Release 2 Vizier catalog entry


  3. ^ abc Silva Aguirre, V.; et al. (2015). "Ages and fundamental properties of Kepler exoplanet host stars from asteroseismology". Monthly Notices of the Royal Astronomical Society. 452 (2): 2127–2148. arXiv:1504.07992. Bibcode:2015MNRAS.452.2127S. doi:10.1093/mnras/stv1388.


  4. ^ abc Huber, Daniel; et al. (2013). "Fundamental Properties of Kepler Planet-candidate Host Stars using Asteroseismology". The Astrophysical Journal. 767 (2). 127. arXiv:1302.2624. Bibcode:2013ApJ...767..127H. doi:10.1088/0004-637X/767/2/127.


  5. ^ abc Kipping, David; Bakos, Gáspár (2011). "An Independent Analysis of Kepler-4b through Kepler-8b". The Astrophysical Journal. 730 (1). 50. arXiv:1004.3538. Bibcode:2011ApJ...730...50K. doi:10.1088/0004-637X/730/1/50.


  6. ^ abc Rich Talcott (5 January 2010). "215th AAS meeting update: Kepler discoveries the talk of the town". Astronomy.com. Astronomy magazine. Retrieved 11 March 2011.


  7. ^ ab "Mission overview". Kepler and K2. NASA. Retrieved 3 December 2017.


  8. ^ ab Ron Cowen (2010-01-04). "Kepler space telescope finds its first extrasolar planets". Science News. Retrieved 2010-01-04.


  9. ^ Borucki, William J; et al. (2011-02-01). "Characteristics of planetary candidates observed by Kepler, II: Analysis of the first four months of data" (PDF). NASA. Retrieved 2011-03-07.


  10. ^ abcd Borucki, William J.; et al. (2010). "Kepler-4b: A Hot Neptune-like Planet of a G0 Star Near Main-sequence Turnoff". The Astrophysical Journal Letters. 713 (2): L126–L130. arXiv:1001.0604. Bibcode:2010ApJ...713L.126B. doi:10.1088/2041-8205/713/2/L126.


  11. ^ Sheets, Holly A.; Deming, Drake (2017). "Average Albedos of Close-in Super-Earths and Super-Neptunes from Statistical Analysis of Long-cadence Kepler Secondary Eclipse Data". The Astronomical Journal. 154 (4). 160. arXiv:1708.08459. Bibcode:2017AJ....154..160S. doi:10.3847/1538-3881/aa88b9.




External links


Media related to Kepler-4 b at Wikimedia Commons


  • http://kepler.nasa.gov/Mission/discoveries/kepler4b/


Coordinates: Sky map19h 2m 27.7s, +50° 8′ 8.7″







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