K2-155d

Last updated
K2-155d
Discovery
Discovered by Teruyuki Hirano et al. [1]
Discovery site Tokyo Institute of Technology
Discovery dateMarch 2018
Transit method
Designations
LP 415-17 c, EPIC 210897587 c [2]
Orbital characteristics
0.1886 (± 0.0066) [3] AU
Eccentricity unknown
40.6835 (± 0.0031) [3] d
Inclination unknown
Star K2-155
Physical characteristics
Mean radius
1.64 +0.18
−0.17 [3] R🜨
Mean density
5.41±1.11  g/cm3
Temperature 289 K (16 °C; 61 °F) [4]

    K2-155d is a potentially habitable Super-Earth exoplanet in the K2-155 system. [5] It is the outermost of three known planets orbiting around the K-type star K2-155 in the constellation Taurus. [6] 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. [1] 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. [7] [5]

    Contents

    Discovery and observations

    K2-155d is one of 15 exoplanets discovered by a team of Japanese astronomers led by Teruyuki Hirano at the Tokyo Institute of Technology. [5] Its discovery is based on data from the K2 mission of NASA's Kepler spacecraft. [5] The exoplanet has also been observed from ground-based telescopes including the Nordic Optical Telescope (NOT) in La Palma and the Subaru Telescope in Hawaii. [5] Its characteristics were confirmed using speckle imaging and high-dispersion optical spectroscopy. [3] The mass of K2-155d and the brightness of its host star may be measured by future observations from the W. M. Keck Observatory and the James Webb Space Telescope. [3] The brightness of its host star makes K2-155d a good target for future studies using instruments such as the James Webb Space Telescope. [3]

    Characteristics

    K2-155d is a super-Earth exoplanet with a radius 1.64 times that of Earth, near the transition zone between small rock-based and larger gaseous planets. [8] [3] [7] Climate models predict that it is located near its star's habitable zone and has an insolation 1.67 ± 0.38 (between 1.29 and 2.05) times that of Earth. [3] Its physical temperature is estimated to be 289 K (16 degrees Celsius or 61 degrees Fahrenheit). [4] Studies have shown that the planet would maintain a moderate surface temperature if its insolation is smaller than ~1.5 times that of Earth. [3]

    K2-155d is one of three known planets in the system orbiting K2-155, a red dwarf star located 62.3 parsecs (203 ly) from Earth. [3] Its parent star has 88% less volume than the Sun. [9] K2-155d orbits its star with a 40.7 day period, but as the planet is tidally locked the same side always faces its sun. [5] K2-155d has an orbital radius of 0.1886 AU [8] and studies suggest that the planet has a low orbital eccentricity. [10]

    Potential habitability

    K2-155d has been labeled a potentially habitable planet that may be able to harbor liquid water. [7] [5] A three-dimensional climate simulation was used to confirm the possibility of the existence of water. [5] However, its discoverer Teruyuki Hirano was cautious about the findings, stating that they do not guarantee K2-155d is habitable, as the ranges in its orbit and temperature allow the possibility of it being outside the habitable zone. [7] Factors such as the absence of solar flares could also decide if K2-155d is habitable. [5]

    Related Research Articles

    <span class="mw-page-title-main">Exoplanet</span> Planet outside the Solar System

    An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not then recognized as such. The first confirmation of the detection occurred in 1992. A different planet, first detected in 1988, was confirmed in 2003. As of 1 May 2024, there are 5,662 confirmed exoplanets in 4,169 planetary systems, with 896 systems having more than one planet. The James Webb Space Telescope (JWST) is expected to discover more exoplanets, and to give more insight into their traits, such as their composition, environmental conditions, and potential for life.

    <span class="mw-page-title-main">Kepler space telescope</span> NASA spacecraft 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">Habitable zone</span> Orbits where planets may have liquid surface water

    In astronomy and astrobiology, the habitable zone (HZ), or more precisely the circumstellar habitable zone (CHZ), is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure. The bounds of the HZ are based on Earth's position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to Earth's biosphere, the nature of the HZ and the objects within it may be instrumental in determining the scope and distribution of planets capable of supporting Earth-like extraterrestrial life and intelligence.

    <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 May 2024, there are 5,662 confirmed exoplanets in 4,169 planetary systems, with 896 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-61b is a super-Earth exoplanet orbiting within parts of the habitable zone of the K-type main-sequence star Kepler-61. It is located about 1,100 light-years from Earth in the constellation of Cygnus. It was discovered in 2013 using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured, by NASA's Kepler spacecraft.

    <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.

    <span class="mw-page-title-main">K2-3d</span> Mini-Neptune orbiting K2-3

    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 away from Earth in the constellation of Leo. 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.

    Kepler-419c is a super-Jupiter exoplanet orbiting within the habitable zone of the star Kepler-419, the outermost of two such planets discovered by NASA's Kepler spacecraft. It is located about 3,400 light-years from Earth in the constellation Cygnus. The exoplanet was found by using the transit timing variation method, in which the variations of transit data from an exoplanet are studied to reveal a more distant companion.

    <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-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.

    K2-148b is a confirmed super-Earth, probably rocky, closely orbiting a small orange dwarf star. It is the innermost of three Super-Earths around the star K2-148, which is in a wide binary pair with the M0.5V red dwarf EPIC 220194953. K2-148b is the smallest planet of the system, at about a third larger than Earth, and could be terrestrial in nature. However, the three planets do not exhibit significant transit timing variations, implying that they could have relatively low masses. The planet was validated in early 2018 by Hirano et al. and is too hot for known life.

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

    K2-288Bb is a super-Earth or mini-Neptune exoplanet orbiting in the habitable zone of K2-288B, a low-mass M-dwarf star in a binary star system in the constellation of Taurus about 226 light-years from Earth. It was discovered by citizen scientists while analysing data from the Kepler spacecraft's K2 mission, and was announced on 7 January 2019. K2-288 is the third transiting planet system identified by the Exoplanet Explorers program, after the six planets of K2-138 and the three planets of K2-233.

    <span class="mw-page-title-main">Kepler-1649c</span> Earth-size exoplanet orbiting Kepler-1649

    Kepler-1649c is an Earth-sized exoplanet, likely rocky, orbiting within the habitable zone of the red dwarf star Kepler-1649, the outermost planet of the planetary system discovered by Kepler’s space telescope. It is located about 301 light-years (92 pc) away from Earth, in the constellation of Cygnus.

    K2-415b is an Earth-sized exoplanet located 72 light-years from Earth orbiting the red dwarf star K2-415.

    References

    1. 1 2 "15 new planets confirmed around cool dwarf stars". Tokyo Tech News. March 12, 2018.
    2. ↑ "The Extrasolar Planet Encyclopaedia — K2-155 d". Extrasolar Planets Encyclopaedia . Retrieved 2024-04-29.
    3. 1 2 3 4 5 6 7 8 9 10 Hirano, Teruyuki; et al. (March 2018). "K2-155: A Bright Metal-poor M Dwarf with Three Transiting Super-Earths". The Astronomical Journal . 155 (3): 11. arXiv: 1801.06957 . Bibcode:2018AJ....155..124H. doi: 10.3847/1538-3881/aaaa6e . S2CID   73590567. 124.
    4. 1 2 "HEC: Exoplanets Calculator (K2-155d)". Planetary Habibility Laboratory. Archived from the original on 2017-08-24. Retrieved 2018-03-30.
    5. 1 2 3 4 5 6 7 8 9 Mack, Eric (March 13, 2018). "A super-Earth around a red star could be wet and wild". CNET .
    6. ↑ "K2-155 PLANET HOST OVERVIEW PAGE". NASA Exoplanet Archive.
    7. 1 2 3 4 Dovey, Dana (March 14, 2018). "Super Earth 200 Light-Years Away May Hold Ideal Temperatures For Liquid Water And Life". Newsweek .
    8. 1 2 "Confirmed Planet Overview Page: K2-155d". NASA Exoplanet Archive. 2018.
    9. ↑ "K2-155d". Exoplanet Data Explorer. 2018. Archived from the original on 2018-03-22. Retrieved 2018-03-21.
    10. ↑ Eylen, Vincent; Albrecht, Simon (May 11, 2015). "Eccentricity from transit photometry: small planets in Kepler multi-planet systems have low eccentricities". The Astrophysical Journal. 808 (2): 126. arXiv: 1505.02814 . Bibcode:2015ApJ...808..126V. doi:10.1088/0004-637X/808/2/126. S2CID   14405731.
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