A mega-Earth is a proposed neologism for a massive terrestrial exoplanet that is at least ten times the mass of Earth. Mega-Earths would be substantially more massive than super-Earths (terrestrial and ocean planets with masses around 5–10 Earths). The term "mega-Earth" was coined in 2014, when Kepler-10c was revealed to be a Neptune-mass planet with a density considerably greater than that of Earth,[1] though it has since been determined to be a typical volatile-rich planet weighing just under half that mass.[2]
Size comparison of Kepler-10c, with Earth and Neptune
Kepler-10c was the first exoplanet to be classified as a mega-Earth. At the time of its discovery, it was believed to have a mass around 17 times that of Earth (ME) and a radius around 2.3 times Earth's (R🜨), giving it a high density that implied a mainly rocky composition. However, several follow-up radial velocity studies produced different results for Kepler-10c's mass, all much below the original 17 ME estimate. In 2017, a more careful analysis using data from multiple different telescopes and spectrographs found that Kepler-10c is more likely around 7.4 ME, making it a typical volatile-rich mini-Neptune and not a mega-Earth.[3][2]
K2-56b, also designated BD+20594b, is a much more likely mega-Earth,[4] with about 16 ME and 2.2 R🜨. At the time of its discovery in 2016, it had the highest chance of being rocky for a planet its size, with a posterior probability that it is dense enough to be terrestrial at about 0.43. For comparison, at the time the corresponding probability for Kepler-10c was calculated as 0.1, and as 0.002 for Kepler-131b.[5]
Kepler-145b is one of the most massive planets classified as mega-Earths, with a mass of 37.1 ME and a radius of 2.65 R🜨, so large that it could belong to a sub-category of mega-Earths known as supermassive terrestrial planets (SMTP). It likely has an Earth-like composition of rock and iron without any volatiles. A similar mega-Earth, K2-66b, has a mass of about 21.3 ME and a radius of about 2.49 R🜨, and orbits a subgiant star. Its composition appears to be mainly rock with a small iron core and a relatively thin steam atmosphere.[6]
Kepler-277b and Kepler-277c are a pair of planets orbiting the same star, both thought to be mega-Earths with masses of about 87.4 ME and 64.2 ME, and radii of about 2.92 R🜨 and 3.36 R🜨, respectively.[7]
PSR J1719−1438 b is the most massive mega-Earth ever known with a mass of about 330 ME and a radius less than 4 R🜨. PSR J1719−1438 b is a pulsar planet which is most likely composed largely of crystalline carbon but with a density far greater than diamond.[8][9]
^ abThe mass of Kepler-10c revisited: upping the radial velocities game, Leonardo dos Santos, 7 August 2017, Astrobites
^Pinning down the mass of Kepler-10c: the importance of sampling and model comparison, Vinesh Rajpaul, Lars A. Buchhave, Suzanne Aigrain, 19 July 2017
^Futó, P (2017). BD+20594B: A Mega-Earth Detected in the C4 field of the Kepler K2 mission(PDF). 48th Lunar and Planetary Science Conference. Retrieved 6 September 2020.
^Discovery and Validation of a High-Density sub-Neptune from the K2 Mission, Néstor Espinoza, Rafael Brahm, Andrés Jordán, James S. Jenkins, Felipe Rojas, Paula Jofré, Thomas Mädler, Markus Rabus, Julio Chanamé, Blake Pantoja, Maritza G. Soto, Katie M. Morzinski, Jared R. Males, Kimberly Ward-Duong, Laird M. Close, Submitted on 28 January 2016, last revised 14 July 2016
^Futó, P (2018). Kepler-145b and K2-66b: A Kepler- and a K2-Mega-Earth with Different Compositional Characteristics(PDF). 49th Lunar and Planetary Science Conference. Retrieved 6 September 2020.
^Futó, P (2020). Kepler-277 b: A Supermassive Terrestrial Exoplanet in the Kepler-277 Planetary System(PDF). 51st Lunar and Planetary Science Conference. Retrieved 6 September 2020.
^Hirschler, Ben (25 August 2011). "Astronomers discover planet made of diamond". Reuters. Retrieved 25 August 2011.
^Bailes, M.; Bates, S. D.; et al. (25 August 2011). "Transformation of a Star into a Planet in a Millisecond Pulsar Binary". Science. 333 (6050): 1717–1720. arXiv:1108.5201. Bibcode:2011Sci...333.1717B. doi:10.1126/science.1208890. PMID 21868629. S2CID 206535504.
Works citededit
Futó, P; Gucsik, A (2018). Basic Mineralogical Models for Silicate- and Carbon-Rich Mega-Earths Considering Compositional and Geophysical Constraints(PDF). 49th Lunar and Planetary Science Conference. Retrieved 6 September 2020.[unreliable source?]
Further readingedit
Astronomers Find "Mega-Earth," Most Massive Rocky Planet Yet, BY MARCUS WOO FOR NATIONAL GEOGRAPHIC, JUNE 5, 2014
Impossibly heavy planet is the first 'mega-Earth', New Scientist, 2 June 2014, By Jacob Aron
Kepler space telescope spies a ‘Mega-Earth’, Washington Post, June 2 2014
'Godzilla of Earths': Alien Planet 17 Times Heavier Than Our World Discovered, By Miriam Kramer June 02, 2014
April 10, 2024
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A mega Earth is a proposed neologism for a massive terrestrial exoplanet that is at least ten times the mass of Earth Mega Earths would be substantially more massive than super Earths terrestrial and ocean planets with masses around 5 10 Earths The term mega Earth was coined in 2014 when Kepler 10c was revealed to be a Neptune mass planet with a density considerably greater than that of Earth 1 though it has since been determined to be a typical volatile rich planet weighing just under half that mass 2 Size comparison of Kepler 10c with Earth and Neptune Contents 1 Examples 2 See also 3 References 3 1 Works cited 4 Further readingExamples editKepler 10c was the first exoplanet to be classified as a mega Earth At the time of its discovery it was believed to have a mass around 17 times that of Earth ME and a radius around 2 3 times Earth s R giving it a high density that implied a mainly rocky composition However several follow up radial velocity studies produced different results for Kepler 10c s mass all much below the original 17 ME estimate In 2017 a more careful analysis using data from multiple different telescopes and spectrographs found that Kepler 10c is more likely around 7 4 ME making it a typical volatile rich mini Neptune and not a mega Earth 3 2 K2 56b also designated BD 20594b is a much more likely mega Earth 4 with about 16 ME and 2 2 R At the time of its discovery in 2016 it had the highest chance of being rocky for a planet its size with a posterior probability that it is dense enough to be terrestrial at about 0 43 For comparison at the time the corresponding probability for Kepler 10c was calculated as 0 1 and as 0 002 for Kepler 131b 5 Kepler 145b is one of the most massive planets classified as mega Earths with a mass of 37 1 ME and a radius of 2 65 R so large that it could belong to a sub category of mega Earths known as supermassive terrestrial planets SMTP It likely has an Earth like composition of rock and iron without any volatiles A similar mega Earth K2 66b has a mass of about 21 3 ME and a radius of about 2 49 R and orbits a subgiant star Its composition appears to be mainly rock with a small iron core and a relatively thin steam atmosphere 6 Kepler 277b and Kepler 277c are a pair of planets orbiting the same star both thought to be mega Earths with masses of about 87 4 ME and 64 2 ME and radii of about 2 92 R and 3 36 R respectively 7 PSR J1719 1438 b is the most massive mega Earth ever known with a mass of about 330 ME and a radius less than 4 R PSR J1719 1438 b is a pulsar planet which is most likely composed largely of crystalline carbon but with a density far greater than diamond 8 9 See also editSub Neptune Super NeptuneReferences edit Astronomers Find a New Type of Planet The Mega Earth 2014 14 Archived from the original on 2 June 2014 a b The mass of Kepler 10c revisited upping the radial velocities game Leonardo dos Santos 7 August 2017 Astrobites Pinning down the mass of Kepler 10c the importance of sampling and model comparison Vinesh Rajpaul Lars A Buchhave Suzanne Aigrain 19 July 2017 Futo P 2017 BD 20594B A Mega Earth Detected in the C4 field of the Kepler K2 mission PDF 48th Lunar and Planetary Science Conference Retrieved 6 September 2020 Discovery and Validation of a High Density sub Neptune from the K2 Mission Nestor Espinoza Rafael Brahm Andres Jordan James S Jenkins Felipe Rojas Paula Jofre Thomas Madler Markus Rabus Julio Chaname Blake Pantoja Maritza G Soto Katie M Morzinski Jared R Males Kimberly Ward Duong Laird M Close Submitted on 28 January 2016 last revised 14 July 2016 Futo P 2018 Kepler 145b and K2 66b A Kepler and a K2 Mega Earth with Different Compositional Characteristics PDF 49th Lunar and Planetary Science Conference Retrieved 6 September 2020 Futo P 2020 Kepler 277 b A Supermassive Terrestrial Exoplanet in the Kepler 277 Planetary System PDF 51st Lunar and Planetary Science Conference Retrieved 6 September 2020 Hirschler Ben 25 August 2011 Astronomers discover planet made of diamond Reuters Retrieved 25 August 2011 Bailes M Bates S D et al 25 August 2011 Transformation of a Star into a Planet in a Millisecond Pulsar Binary Science 333 6050 1717 1720 arXiv 1108 5201 Bibcode 2011Sci 333 1717B doi 10 1126 science 1208890 PMID 21868629 S2CID 206535504 Works cited edit Futo P Gucsik A 2018 Basic Mineralogical Models for Silicate and Carbon Rich Mega Earths Considering Compositional and Geophysical Constraints PDF 49th Lunar and Planetary Science Conference Retrieved 6 September 2020 unreliable source Further reading editAstronomers Find Mega Earth Most Massive Rocky Planet Yet BY MARCUS WOO FOR NATIONAL GEOGRAPHIC JUNE 5 2014 Impossibly heavy planet is the first mega Earth New Scientist 2 June 2014 By Jacob Aron Kepler space telescope spies a Mega Earth Washington Post June 2 2014 Godzilla of Earths Alien Planet 17 Times Heavier Than Our World Discovered By Miriam Kramer June 02 2014 Retrieved from https en wikipedia org w index php title Mega Earth amp oldid 1199635171, wikipedia, wiki, book, books, library,
