K2-3d

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K2-3d
Exoplanet Size Comparison K2-3d.png
Size comparison between the
Earth and K2-3d.
Discovery [1]
Discovery site Kepler Space Observatory
Discovery date2015
Transit
Orbital characteristics [2]
0.2014+0.0034
−0.0033  AU
Eccentricity 0.091+0.120
−0.064
44.55603+0.00013
−0.00012  d
Inclination 89.788°+0.033°
−0.029° [3]
Semi-amplitude <0.39  m/s [3]
Star K2-3
Physical characteristics [2]
1.458+0.056
−0.051  R🜨
Mass <1.6  M🜨 [3]
Mean density
<2.1  g/cm3 [3]
Temperature 305.2+3.1
−3.2  K (32.1 °C; 89.7 °F, equilibrium)

    K2-3d, also known as EPIC 201367065 d, is a confirmed exoplanet of probable mini-Neptune type orbiting the red dwarf star K2-3, and the outermost of three such planets discovered in the system. It is located 143 light-years (44 parsecs ) away from Earth in the constellation of Leo. [4] [5] 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. It was the first planet in the Kepler "Second Light" mission to receive the letter "d" designation for a planet. Its discovery was announced in January 2015. [1]

    Contents

    Characteristics

    Mass, radius, density and temperature

    K2-3d is a super-Earth or a mini-Neptune, meaning it has a mass and radius bigger than Earth's, but smaller than that of the ice giants Uranus and Neptune. It has an equilibrium temperature of 305 K (32 °C; 89 °F) and a radius of 1.5 [2] to 1.6 R🜨. [3] The planet is likely to be a mini-Neptune, with no solid surface. [6] While originally estimated to have a very high density, [4] later analysis of HARPS data in 2018 constrained the mass to less than 4 ME to a 1σ confidence, [7] and by 2023 this upper limit has been reduced to 2 ME. [3] This corresponds to a relatively low density, similar to that of Neptune, suggesting a very large volatile layer and significantly reducing the potential habitability of the world.

    Host Star

    The planet orbits a (M-type) red dwarf star named K2-3, orbited by a total of three known planets, of which K2-3d has the longest orbital period. [1] The star has a mass of 0.60 M☉ and a radius of 0.56 R☉. [5] [1] It has a temperature of 3896 K and is about 1 billion years old. [5] In comparison, the Sun is 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 12.168. [10] Therefore, it is too dim to be seen with the naked eye.

    Orbital statistics

    K2-3d orbits its host star, which has about 6% of the Sun's luminosity, with an orbital period of 44 days and an orbital radius of about 0.2 times that of Earth (compared to the distance of Mercury from the Sun, which is about 0.38 AU). [5]

    Habitability

    The planet orbits on the edge of the inner (empirical) habitable zone, a region where, with the proper atmospheric properties and pressure, liquid water may exist on the surface of the planet. However, it is very likely tidally locked to its star, with one side facing towards its star in scorching heat, and the opposite side in bitter darkness. [11] Despite this, there is an area – the terminator line – where the surface temperatures may be comfortable enough to support liquid water. However, given that most models of the habitable zone parameters put K2-3d slightly beyond the inner edge of the habitable zone, it is likely to be too hot even at the terminator line and thus not habitable at all. Also, the stellar flux for the planet is an abnormally high 1.4 times that of Earth, [1] which could result in surface temperatures of up to 400–500 K (127–227 °C; 260–440 °F) because of a runaway greenhouse effect.

    Discovery

    The planet, along with the other two known planets in the K2-3 system, was announced in early January 2015 as part of the first results from the second mission of the Kepler spacecraft. With this, it was the first multiplanetary system of the mission as well. [1]

    See also

    Related Research Articles

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

    A Super-Earth or super-terran 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 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-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.

    Kepler-22 is a Sun-like star in the northern constellation of Cygnus, the swan, that is orbited by 1 planet found to be unequivocally within the star's habitable zone. It is located at the celestial coordinates: Right Ascension 19h 16m 52.2s, Declination +47° 53′ 3.9″. With an apparent visual magnitude of 11.7, this star is too faint to be seen with the naked eye. It can be viewed with a telescope having an aperture of at least 4 in (10 cm). The estimated distance to Kepler-22 is 644 light-years.

    K2-3, also known as EPIC 201367065, is a red dwarf star with three known planets. It is on the borderline of being a late orange dwarf/K-type star, but because of its temperature, it is classified as a red dwarf.

    K2-3b, also known as EPIC 201367065 b, is an exoplanet orbiting the red dwarf K2-3 every 10 days. It is the largest and most massive planet of the K2-3 system, with about 2.1 times the radius of Earth and about 5 times the mass. Its density of about 3.1 g/cm3 may indicate a composition of almost entirely water, or a hydrogen envelope comprising about 0.7% of the planet's mass.

    <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 space telescope on its "Second Light" mission. It is located about 453 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">K2-72e</span> Goldilocks terrestrial exoplanet orbiting K2-72

    K2-72e (also known by its EPIC designation EPIC 206209135.04), is a confirmed exoplanet, likely rocky, orbiting within the habitable zone of the red dwarf star K2-72, the outermost of four such planets discovered in the system by NASA's Kepler spacecraft on its "Second Light" mission. It is located about 217.1 light-years (66.56 parsecs, or nearly 2.0538×1015 km) away from Earth in the constellation of Aquarius. 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.

    Kepler-419 is an F-type main-sequence star located about 3,280 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.

    <span class="mw-page-title-main">LHS 1140 b</span> Super-Earth orbiting LHS 1140

    LHS 1140 b is an exoplanet orbiting within the conservative habitable zone of the red dwarf LHS 1140. Discovered in 2017 by the MEarth Project, LHS 1140 b is about 5.6 times the mass of Earth and about 70% larger in radius, putting it within the super-Earth category of planets. It was initially thought to be a dense rocky planet, but refined measurements of its mass and radius have found a lower density, indicating that it is likely an ocean world with 9-19% of its mass composed of water. LHS 1140 b orbits entirely within the star's habitable zone and gets 43% the incident flux of Earth. The planet is 49 light-years away and transits its star, making it an excellent candidate for atmospheric studies with ground-based and/or space telescopes.

    Kepler-1652b is a super-Earth exoplanet, orbiting within the habitable zone of the red dwarf Kepler-1652 about 822 light-years away in the Cygnus constellation. Discovered by NASA's Kepler spacecraft, Kepler-1652b was first announced as a candidate in 2013, but wasn't validated until four years later in 2017. It is a potential super-Earth with 160% Earth's radius. The planet orbits well within the habitable zone of its system, the region where liquid water can exist on a planet's surface. The planet is an eyeball planet candidate.

    <span class="mw-page-title-main">K2-138</span> Star in the constellation Aquarius

    K2-138, also designated EPIC 245950175 or EE-1, is a large early K-type main sequence star with a system of at least 6 planets discovered by citizen scientists. Four were found in the first two days of the Exoplanet Explorers project on Zooniverse in early April 2017, while two more were revealed in further analysis. The system is about 660 light-years away in the constellation Aquarius, within K2 Campaign 12.

    K2-141b is a massive rocky exoplanet orbiting extremely close to a K Type orange main-sequence star K2-141. The planet was first discovered by the Kepler space telescope during its K2 “Second Light” mission and later observed by the HARPS-N spectrograph. It is classified as an ultra-short period planet (USP) and is confirmed to be terrestrial in nature. Its high density implies a massive iron core taking up between 30% and 50% of the planet's total mass.

    K2-155d is a potentially habitable Super-Earth exoplanet in the K2-155 system. It is the outermost of three known planets orbiting around the K-type star K2-155 in the constellation Taurus. It is one of 15 new exoplanets around red dwarf stars discovered by Japanese astronomer Teruyuki Hirano of the Tokyo Institute of Technology and his team. The team used data from NASA's Kepler Space Telescope during its extended K2 "Second Light" mission. K2-155d orbits near the so-called habitable zone of its system, and has the potential to host liquid water.

    <span class="mw-page-title-main">K2-288Bb</span> Mini-Neptune orbiting K2-288B

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    <span class="mw-page-title-main">K2-18</span> Red dwarf star in the constellation Leo

    K2-18, also known as EPIC 201912552, is a red dwarf star with two planetary companions located 124 light-years from Earth, in the constellation of Leo.

    K2-66b is a confirmed mega-Earth orbiting the subgiant K2-66, about 520 parsecs (1,700 ly) from Earth in the direction of Aquarius. It is an extremely hot and dense planet heavier than Neptune, but with only about half its radius.

    TOI-2257 b is an extremely eccentric (0.496) exoplanet in or near the circumstellar habitable zone of the star TOI-2257, 188 light-years away. It is likely a sub-Neptune exoplanet, with a mass of 5.71 Mearth and a radius of 2.19 Rearth. As a small planet in the habitable zone, it is included in the Planetary Habitability Laboratory's list of potentially habitable exoplanets.

    References

    1. 1 2 3 4 5 6 Crossfield, Ian J. M.; et al. (2015). "A Nearby M Star with Three Transiting Super-Earths Discovered by K2". The Astrophysical Journal. 804 (1). 10. arXiv: 1501.03798 . Bibcode:2015ApJ...804...10C. doi: 10.1088/0004-637X/804/1/10 .
    2. 1 2 3 Diamond-Lowe, Hannah; Kreidberg, Laura; Harman, C. E.; Kempton, Eliza M.-R.; Rogers, Leslie A.; Joyce, Simon R. G.; Eastman, Jason D.; King, George W.; Kopparapu, Ravi; Youngblood, Allison; Kosiarek, Molly R.; Livingston, John H.; Hardegree-Ullman, Kevin K.; Crossfield, Ian J. M. (2022), "The K2-3 System Revisited: Testing Photoevaporation and Core-powered Mass Loss with Three Small Planets Spanning the Radius Valley", The Astronomical Journal, 164 (5): 172, arXiv: 2207.12755 , Bibcode:2022AJ....164..172D, doi: 10.3847/1538-3881/ac7807 , S2CID   251067119
    3. 1 2 3 4 5 6 Bonomo, A. S.; Dumusque, X.; et al. (April 2023). "Cold Jupiters and improved masses in 38 Kepler and K2 small-planet systems from 3661 high-precision HARPS-N radial velocities. No excess of cold Jupiters in small-planet systems". Astronomy & Astrophysics . arXiv: 2304.05773 . doi:10.1051/0004-6361/202346211. S2CID   258078829.
    4. 1 2 "K2-3 d CONFIRMED PLANET OVERVIEW PAGE". NASA Exoplanet Archive. Retrieved 2015-10-17.
    5. 1 2 3 4 "The Extrasolar Planet Encyclopaedia — K2-3 d". Extrasolar Planets Encyclopaedia .
    6. ↑ Angus, Ruth (31 July 2014). "Most 1.6 Earth-radius planets are not rocky". Astrobites.
    7. ↑ Damasso, Mario; et al. (2018). "Eyes on K2-3: A system of three likely sub-Neptunes characterized with HARPS-N and HARPS". Astronomy and Astrophysics. 615. A69. arXiv: 1802.08320 . Bibcode:2018A&A...615A..69D. doi:10.1051/0004-6361/201732459. S2CID   58923147.
    8. ↑ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today . Retrieved 19 February 2011.
    9. ↑ Fraser Cain (15 September 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
    10. ↑ Henden, A. A.; et al. (2016). "VizieR Online Data Catalog: AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)". VizieR On-line Data Catalog: II/336. Originally Published in: 2015AAS...22533616H. 2336. Bibcode:2016yCat.2336....0H. Vizier catalog entry
    11. ↑ "K2-3 d (M-Warm Terran)". phl.upr.edu. July 2018. Archived from the original on 9 August 2019. Retrieved 30 June 2024.
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