Kepler-69c

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Kepler-69c
Kepler-69 and the Solar System.jpg
Artist's impression of the Kepler-69 system (sizes to scale) compared to the planets of the inner Solar System with their respective habitable zones.
Discovery
Discovered by Kepler spacecraft
Discovery date18 April 2013
Transit (Kepler Mission Method)
Orbital characteristics
0.64+0.15
−0.11 [1] [2] AU
Eccentricity 0.14+0.18
−0.1 [1] [2]
242.4613 ± 0.006 [1] [3] [2] d
Inclination 89.85+0.03
−0.08 [1] [2]
Star Kepler-69
Physical characteristics
Mean radius
1.71+0.34
−0.23 [3] R🜨
Mass 2.14 ME [4]
Mean density
2.36 g cm–3 [4]
0.73 g [4]
Temperature Teq: 325 K (52 °C; 125 °F)
Surface: 548 K (275 °C; 527 °F) [nb 1]

    Kepler-69c [3] [5] [6] (also known by its Kepler Object of Interest designation KOI-172.02) [2] [7] 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 (746 parsecs) from Earth.

    Contents

    Kepler-69c orbits its star at a distance of 0.64 AU (96,000,000 km; 59,000,000 mi) from its host star with an orbital period of roughly 242.46 days, has a mass at least 2.14 times that of Earth, and has a radius of around 1.7 times that of Earth. Initial findings found that it could possibly be habitable, however updated analysis shows that Kepler-69c resides outside of the inner edge of the habitable zone, and thus is highly likely to resemble the planet Venus with temperatures and conditions far too hot to sustain any life, making it uninhabitable. [4]

    The discovery of the exoplanet was announced in April 2013 by NASA as part of the Kepler spacecraft data release. [3] 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.

    Physical characteristics

    Mass, radius and temperature

    Kepler-69c is a super-Earth, an exoplanet that has a radius and mass larger than Earth, but smaller than that of the ice giants Uranus and Neptune. It has an estimated equilibrium temperature of 325 K (52 °C; 125 °F), but likely has a far hotter surface temperature of 548 K (275 °C; 527 °F). It has an estimated mass of around 2.14 ME and a radius of 1.71 R🜨. [4] [3] These characteristics make it an analog to Venus, but more massive, so it is called a "super-Venus". [4]

    Host star

    The planet orbits a (G-type) star named Kepler-69, orbited by a total of two planets. The star has a mass of 0.81 M☉ and a radius of 0.93 R☉. [3] It has a surface temperature of 5638 K and has an estimated age of around 9.8 billion years, [3] meaning it is probably nearing the end of its lifetime. In comparison, the Sun is about 4.6 billion years old [8] and has a surface temperature of 5778 K. [9]

    The star's apparent magnitude, or how bright it appears from Earth's perspective, is 13.7. [3] Therefore, Kepler-69 is too dim to be seen with the naked eye.

    Orbit

    Kepler-69c orbits its host star every 242 days at a distance of 0.64 times that of Earth. [3] This is very similar to that of Venus's orbital period and distance in the Solar System.

    Proposed habitability

    Artist's conception of a comparison between a Venus-like and Earth-like planet. Based on recent research, Kepler-69c is more likely a super-Venus, analogous to Venus but more massive, and completely uninhabitable. Toxic Wasteland or Lush Paradise%3F.jpg
    Artist's conception of a comparison between a Venus-like and Earth-like planet. Based on recent research, Kepler-69c is more likely a super-Venus, analogous to Venus but more massive, and completely uninhabitable.

    The exoplanet, along with the exoplanets Kepler-62e and Kepler-62f, were announced in the media as being located within the star's "habitable zone", a region where liquid water could exist on the surface of the planet. It was described as being one of the most Earth-like planets, in terms of size and temperature yet found and, according to the scientists, a "prime candidate to host alien life". [10]

    Due to uncertainties in the stellar parameters, the error bars on the value of the incident flux on this planet are quite large, at 1.91+0.43
    −0.56     times the level of Earth. Using the nominal parameters, the planet is too close to the star to be habitable, though the uncertainties allow for the possibility that it may actually lie in the innermost region of the habitable zone and be a desert planet, [11] however even with the lowest error bar measurement, a stellar flux of 1.35 S🜨 would still be high enough to boil away any oceans. A more recent analysis has shown that the planet is likely more analogous to Venus, which is known to be one of the most inhospitable places to life in the Solar System, and thus highly unlikely to be habitable to such organisms. [4]

    Artist's impression of Kepler-69c as a "super-Venus" exoplanet. Kepler-69c- Super-Venus.jpg
    Artist's impression of Kepler-69c as a "super-Venus" exoplanet.

    Discovery

    In 2009, NASA's Kepler spacecraft was observing stars with its photometer, an instrument it uses to detect transit events, in which a planet crosses in front of and dims its host star for a brief and roughly regular period of time. In this last test, Kepler observed 50000 stars in the Kepler Input Catalog, including Kepler-69; the preliminary light curves were sent to the Kepler science team for analysis, who chose obvious planetary companions from the bunch for follow-up at observatories. Observations for the potential exoplanet candidates took place between 13 May 2009 and 17 March 2012. After observing the respective transits, which for Kepler-69c occurred roughly every 242 days (its orbital period), it was eventually concluded that a planetary body was responsible for the periodic 242-day transits. The discovery, along with the planetary system of the star Kepler-62 were announced on April 18, 2013. [3]

    On 9 May 2013, a congressional hearing by two U.S. House of Representatives subcommittees discussed "Exoplanet Discoveries: Have We Found Other Earths?," prompted by the discovery of exoplanet Kepler-69c, along with Kepler-62e and Kepler-62f. A related special issue of the journal Science, published earlier, described the discovery of the exoplanets. [12]

    Notable Exoplanets – Kepler Space Telescope
    Relative sizes of all of the habitable-zone planets discovered to date alongside Earth.jpg Comparison of the sizes of planets Kepler-69c, Kepler-62e, Kepler-62f, and the Earth.
    Exoplanets are artists' impressions.    		 LombergA1024.jpg The Kepler Space Telescope search volume, in the context of the Milky Way Galaxy.

    See also

    Related Research Articles

    <span class="mw-page-title-main">Super-Earth</span> Type of exoplanet

    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.

    <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 June 2024, there are 5,742 confirmed exoplanets in 4,237 planetary systems, with 904 systems having more than one planet. This is a list of the most notable discoveries.

    <span class="mw-page-title-main">Kepler-22b</span> Super-Earth exoplanet orbiting Kepler-22

    Kepler-22b is an exoplanet orbiting within the habitable zone of the Sun-like star Kepler-22. It is located about 640 light-years from Earth in the constellation of Cygnus. It was discovered by NASA's Kepler Space Telescope in December 2011 and was the first known transiting planet to orbit within the habitable zone of a Sun-like star, where liquid water could exist on the planet's surface. Kepler-22 is too dim to be seen with the naked eye.

    <span class="mw-page-title-main">Kepler-42</span> Red dwarf star in the constellation Cygnus

    Kepler-42, formerly known as KOI-961, is a red dwarf located in the constellation Cygnus and approximately 131 light years from the Sun. It has three known extrasolar planets, all of which are smaller than Earth in radius, and likely also in mass.

    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-62</span> K-type star in the constellation Lyra

    Kepler-62 is a K-type main sequence star cooler and smaller than the Sun, located roughly 980 light-years from Earth in the constellation Lyra. It resides 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 18, 2013, it was announced that the star has five planets, two of which, Kepler-62e and Kepler-62f are within the star's habitable zone. The outermost, Kepler-62f, is likely a rocky planet.

    <span class="mw-page-title-main">Kepler-62e</span> Habitable-zone super-Earth planet orbiting Kepler-62

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    <span class="mw-page-title-main">Kepler-62f</span> Super-Earth orbiting Kepler-62

    Kepler-62f is a super-Earth exoplanet orbiting within the habitable zone of the star Kepler-62, the outermost of five such planets discovered around the star by NASA's Kepler spacecraft. It is located about 980 light-years from Earth in the constellation of Lyra.

    <span class="mw-page-title-main">Kepler-69</span> Star in the constellation Cygnus

    Kepler-69 is a G-type main-sequence star similar to the Sun in the constellation Cygnus, located about 2,390 ly (730 pc) from Earth. On April 18, 2013 it was announced that the star has two planets. Although initial estimates indicated that the terrestrial planet Kepler-69c might be within the star's habitable zone, further analysis showed that the planet very likely is interior to the habitable zone and is far more analogous to Venus than to Earth and thus completely inhospitable.

    Kepler-62c is an approximately Mars-sized exoplanet discovered in orbit around the star Kepler-62, the second innermost of five discovered by NASA's Kepler spacecraft around Kepler-62. At the time of discovery it was the second-smallest exoplanet discovered and confirmed by the Kepler spacecraft, after Kepler-37b. It was found using the transit method, in which the dimming that a planet causes as it crosses in front of its star is measured. Its stellar flux is 25 ± 3 times Earth's. It is similar to Mercury.

    Kepler-62d is the third innermost and the largest exoplanet discovered orbiting the star Kepler-62, with a size roughly twice the diameter of Earth. It was found using the transit method, in which the dimming that a planet causes as it crosses in front of its star is measured. Its stellar flux is 15 ± 2 times Earth's. Due to its closer orbit to its star, it is a super-Venus or, if it has a volatile composition, a hot Neptune, with an estimated equilibrium temperature of 510 K, too hot to sustain life on its surface.

    Kepler-62b is the innermost and the second smallest discovered exoplanet orbiting the star Kepler-62, with a diameter roughly 30% larger than Earth. It was found using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. It is likely to have an equilibrium temperature slightly higher than the surface temperature of Venus, high enough to melt some types of metal. Its stellar flux is 70 ± 9 times Earth's.

    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">Kepler-186f</span> Terrestrial exoplanet orbiting Kepler-186

    Kepler-186f is an Earth-sized exoplanet orbiting within the habitable zone of the red dwarf star Kepler-186, the outermost of five such planets discovered around the star by NASA's Kepler spacecraft. It is located about 580 light-years from Earth in the constellation of Cygnus.

    <span class="mw-page-title-main">Kepler-438b</span> Super-Earth orbiting Kepler-438

    Kepler-438b is a confirmed near-Earth-sized exoplanet. It is likely rocky. It orbits on the inner edge of the habitable zone of a red dwarf, Kepler-438, about 472.9 light-years from Earth in the constellation Lyra. It receives 1.4 times our solar flux. The planet was discovered by NASA's Kepler spacecraft using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. NASA announced the confirmation of the exoplanet on 6 January 2015.

    <span class="mw-page-title-main">Kepler-442b</span> Super-Earth orbiting Kepler-442

    Kepler-442b is a confirmed near-Earth-sized exoplanet, likely rocky, orbiting within the habitable zone of the K-type main-sequence star Kepler-442, about 1,206 light-years (370 pc) from Earth in the constellation of Lyra.

    Kepler-296e is a confirmed super-Earth exoplanet orbiting within the habitable zone of Kepler-296. The planet was discovered by NASA's Kepler spacecraft using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. NASA announced the discovery of the exoplanet on 26 February 2014.

    Kepler-1229 is a red dwarf star located about 875 light-years (268 pc) away from the Earth in the constellation of Cygnus. It is known to host a super-Earth exoplanet within its habitable zone, Kepler-1229b, which was discovered in 2016.

    Kepler-737b is a super-Earth exoplanet 669 light years away. There is a chance it could be on the inner edge of the habitable zone.

    References

    1. 1 2 3 4 Staff (January 7, 2013). "Kepler KOI Search Results for KOI-172.02". Space Telescope Science Institute . Retrieved January 11, 2013.
    2. 1 2 3 4 5 Staff. "NASA Exoplanet Archive -KOI-172.02". Caltech . Retrieved January 11, 2013.
    3. 1 2 3 4 5 6 7 8 9 10 Barclay, Thomas; et al. (2013). "A super-Earth-sized planet orbiting in or near the habitable zone around Sun-like star". The Astrophysical Journal. 768 (2): 101. arXiv: 1304.4941 . Bibcode:2013ApJ...768..101B. doi:10.1088/0004-637X/768/2/101. S2CID   51490784.
    4. 1 2 3 4 5 6 7 Kane, Stephen; et al. (2013). "A Potential Super-Venus in the Kepler-69 System". The Astrophysical Journal Letters. 770 (2): L20. arXiv: 1305.2933 . Bibcode:2013ApJ...770L..20K. doi:10.1088/2041-8205/770/2/L20. S2CID   9808447.
    5. ↑ Johnson, Michele; Harrington, J.D. (18 April 2013). "NASA's Kepler Discovers Its Smallest 'Habitable Zone' Planets to Date". NASA . Retrieved 18 April 2013.
    6. ↑ Overbye, Dennis (18 April 2013). "2 Good Places to Live, 1,200 Light-Years Away". New York Times . Retrieved 18 April 2013.
    7. ↑ Johnston, Wm. Robert (October 2, 2011). "List of Extrasolar Planets". JohnstonArchive.com. Retrieved January 11, 2013.
    8. ↑ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today . Retrieved 19 February 2011.
    9. ↑ Fraser Cain (September 15, 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
    10. ↑ Moskowitz, Clara (January 9, 2013). "Most Earth-Like Alien Planet Possibly Found". Space.com . Retrieved January 9, 2013.
    11. ↑ L. Kaltenegger; D. Sasselov; S. Rugheimer (2013). "Water Planets in the Habitable Zone: Atmospheric Chemistry, Observable Features, and the case of Kepler-62e and -62f". arXiv: 1304.5058v1 [astro-ph.EP].
    12. ↑ "Special Issue: Exoplanets". Science . 340 (6132). 3 May 2013. Retrieved 18 May 2013.

    Notes

    1. ↑ Based on improved models of Kepler-69c after it was found to be uninhabitable.
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