Wikipedia

Kepler-1625b

Kepler-1625b is a super-Jupiter exoplanet orbiting the Sun-like star Kepler-1625 about 2,500 parsecs (8,200 light-years) away in the constellation of Cygnus.[4] The large gas giant is approximately the same radius as Jupiter,[1] and orbits its star every 287.4 days.[5] In 2017, hints of a Neptune-sized exomoon in orbit of the planet were found using photometric observations collected by the Kepler Mission.[6][7] Further evidence for a Neptunian moon was found the following year using the Hubble Space Telescope, where two independent lines of evidence constrained the mass and radius to be Neptune-like.[1] The mass-signature has been independently recovered by two other teams.[8][9] However, the radius-signature was independently recovered by one of the teams[9] but not the other.[8] The original discovery team later showed that this latter study appears affected by systematic error sources that may have influenced its findings.[10]

Kepler-1625b
Artist's impression of the exoplanet Kepler-1625b and its candidate exomoon Kepler-1625b I.
Discovery
Discovery siteKepler Space Observatory
Discovery date10 May 2016
Transit (Kepler Mission)
Orbital characteristics[1]
0.98 ± 0.14 AU
287.378949 d
Inclination89.97 ± 0.02
Known satellitesKepler-1625b I?
StarKepler-1625
Physical characteristics
1.18+0.18
−0.32 RJ[2]
Mass≤11.60 MJ[3]

Characteristics

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Mass and radius

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Kepler-1625b is a Jovian-sized gas giant, a type of planet several times greater in radius than Earth and mostly composed of hydrogen and helium. It has been estimated to be 11.4±1.5 times Earth's radius, approximately equal to that of the planet Jupiter.[1] Its mass is unknown, but is constrained at 3-sigma confidence to be less than 11.6 times the mass of Jupiter (about 3,700 Earth masses), based on non-detection in radial velocity observations.[3] This indicates that it is below the deuterium-fusing limit, which is around 13 Jupiter masses, and so it is not a brown dwarf.[3]

Orbit and temperature

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Unlike the gas giants in our Solar System, Kepler-1625b orbits much closer, slightly closer than the orbital radius as the Earth around the Sun.[1] The planet takes 287 days (0.786 years; 9.43 months) to orbit Kepler-1625, as a result of the star's slightly greater mass than the Sun. Kepler-1625b receives 2.6 times more insolation than the Earth,[1] meaning it lies at the inner edge of the habitable zone.[11] However, as the planet has likely no solid surface, bodies of liquid water are impossible.

Candidate exomoon

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Kepler-1625b I
Exomoon Kepler-1625b I orbiting exoplanet Kepler-1625b (artist concept).[12]
Discovery[1]
Discovered byAlex Teachey, David M. Kipping and Allan R. Schmitt
Discovery date2017
Primary transit
Orbital characteristics
Satellite ofKepler-1625b
Physical characteristics
0.437 RJ
Mass19.069 M🜨
0.06 MJ[13]
Mean density
0.95 g/cm3

In July 2017, researchers found signs of a Neptune-sized exomoon (a moon in another solar system) orbiting Kepler-1625b using archival Kepler Mission data.[6][7]

In October 2018, researchers using the Hubble Space Telescope published new observations of the star Kepler-1625, conducted in October 2017, which revealed two independent lines of evidence indicative of a large exomoon Kepler-1625b I.[1][14] These were a 20-minute Transit Timing Variation signature that indicated an approximately Neptune-mass moon, and an additional photometric dip that indicated a Neptune-radius moon.[1] The relative phasing of the two signatures was also consistent with that which a real moon would cause, with the effects in anti-phase.[1] The study concluded that the exomoon hypothesis is the simplest and best explanation for the available observations, though warned that it is difficult to assign a precise probability to its reality and urged follow-up analyses.[15][1] Like several moons in the Solar System,[16] the large exomoon would theoretically be able to host its own moon, called a subsatellite, in a stable orbit, although no evidence for such a subsatellite has been found.[17]

Kepler-1625b i (on the right) would be located more than 3,000,000 km from Kepler-1625b (on the left), estimated using time deviations from the transit method[18] (approximately 8 times the distance between the Earth and the Moon). The objects are to scale (based on transit data) while the colors of the planets are based on speculative averages of data on the composition of nearby stars/clouds and photolysis, although these keep being speculative.

In February 2019, an independent reanalysis of the combined Kepler and Hubble observations recovered both a moon-like dip and similar transit timing variation signal.[9] However, the authors suggested that the data could also be explained by an inclined hot-Jupiter in the same system that has gone previously undetected, which could be tested using future Doppler spectroscopy radial velocity measurements. A second independent reanalysis was published in April 2019, which recovered one of the two lines of evidence, the transit timing variation, but the not the second, the moon-like dip.[8] The original discovery team responded to this soon after, finding that this re-analysis exhibits stronger systematics in their reduction which may be responsible for their differing conclusion.[10]

See also

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References

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  1. 1 2 3 4 5 6 7 8 9 10 11 Teachey, Alex; et al. (3 October 2018). "Evidence for a large exomoon orbiting Kepler-1625b". Science Advances. 4 (10) eaav1784. arXiv:1810.02362. Bibcode:2018SciA....4.1784T. doi:10.1126/sciadv.aav1784. PMC 6170104. PMID 30306135.
  2. ↑ Heller, René (1 February 2018). "The nature of the giant exomoon candidate Kepler-1625 b-i". Astronomy & Astrophysics. 610: A39. arXiv:1710.06209. doi:10.1051/0004-6361/201731760. ISSN 0004-6361.
  3. 1 2 3 Timmermann, Anina; Heller, Rene; Reiner, Ansgar; Zechmeister, Mathias (2020). "Radial velocity constraints on the long-period transiting planet Kepler-1625 b with CARMENES". Astronomy and Astrophysics. 635: 59. arXiv:2001.10867. Bibcode:2020A&A...635A..59T. doi:10.1051/0004-6361/201937325. S2CID 210942758.
  4. ↑ Luri, X.; Brown, A.; Sarro, L. (10 August 2018). "Gaia Data Release 2". Astronomy & Astrophysics. 616: 19. arXiv:1804.09376. Bibcode:2018A&A...616A...9L. doi:10.1051/0004-6361/201832964. S2CID 244895570. Retrieved 1 April 2022.
  5. ↑ "Exoplanet Exploration: Planets Beyond our Solar System". Exoplanet Exploration: Planets Beyond our Solar System.{{cite web}}: CS1 maint: deprecated archival service (link)
  6. 1 2 Crane, Leah (27 July 2017). "First exomoon might have been spotted 4000 light years away". NewScientist. Retrieved 1 April 2022.
  7. 1 2 Teachey, Alex; et al. (22 December 2017). "HEK. VI. On the Dearth of Galilean Analogs in Kepler, and the Exomoon Candidate Kepler-1625b I". The Astronomical Journal. 155 (1). 36. arXiv:1707.08563. Bibcode:2018AJ....155...36T. doi:10.3847/1538-3881/aa93f2. S2CID 118911978.
  8. 1 2 3 Kreidberg, Laura; Luger, Rodrigo; Bedell, Megan (24 April 2019). "No Evidence for Lunar Transit in New Analysis of Hubble Space Telescope Observations of the Kepler-1625 System". The Astrophysical Journal. 877 (2): L15. arXiv:1904.10618. Bibcode:2019ApJ...877L..15K. doi:10.3847/2041-8213/ab20c8. S2CID 129945202.
  9. 1 2 3 Heller, Rene; Rodenbeck, Kai; Giovanni, Bruno (17 April 2019). "An alternative interpretation of the exomoon candidate signal in the combined Kepler and Hubble data of Kepler-1625". Astronomy & Astrophysics. 624. 8. arXiv:1902.06018. Bibcode:2019A&A...624A..95H. doi:10.1051/0004-6361/201834913. S2CID 119311103. Retrieved 1 April 2022.
  10. 1 2 Teachey, Alex; Kipping, David M.; Burke, Christopher (5 March 2020). "Loose Ends for the Exomoon Candidate Host Kepler-1625b". The Astronomical Journal. 159 (4): 142. arXiv:1904.11896. Bibcode:2020AJ....159..142T. doi:10.3847/1538-3881/ab7001. S2CID 135465103.
  11. ↑ Zsom, Andras; Seager, Sara; et al. (2013). "Towards the Minimum Inner Edge Distance of the Habitable Zone". The Astrophysical Journal. 778 (2): 109. arXiv:1304.3714. Bibcode:2013ApJ...778..109Z. doi:10.1088/0004-637X/778/2/109. S2CID 27805994.
  12. ↑ Chou, Felicia; Villard, Ray; Hawkes, Alison; Brown, Katherine (3 October 2018). "Astronomers Find First Evidence of Possible Moon Outside Our Solar System". NASA. Retrieved 5 October 2018.
  13. ↑ "The Extrasolar Planet Encyclopaedia — Kepler-1625 b I". Extrasolar Planets Encyclopaedia. Archived from the original on 5 October 2018. Retrieved 7 October 2018.
  14. ↑ "Kelpler-1625b-I". Extrasolar Planets Encyclopaedia. 15 July 2019. Archived from the original on 5 October 2018. Retrieved 14 December 2020.
  15. ↑ Drake, Nadia (3 October 2018). "Weird giant may be the first known alien moon - Evidence is mounting that a world the size of Neptune could be orbiting a giant planet far, far away". National Geographic Society. Archived from the original on 3 October 2018. Retrieved 4 October 2018.
  16. ↑ Kollmeier, Juna A.; Raymond, Sean N. (21 November 2018). "Can moons have moons?". Monthly Notices of the Royal Astronomical Society: Letters. 483: L80–L84. arXiv:1810.03304. doi:10.1093/mnrasl/sly219.
  17. ↑ Forgan, Duncan H. (11 February 2019). "The habitable zone for Earth-like exomoons orbiting Kepler-1625b". International Journal of Astrobiology. 18 (6): 510–517. arXiv:1810.02712. Bibcode:2019IJAsB..18..510F. doi:10.1017/s1473550418000514. ISSN 1473-5504. S2CID 118857039.
  18. ↑ Teachey, Alex; Kipping, David M. (October 2018). "Evidence for a large exomoon orbiting Kepler-1625b". Science Advances. 4 (10) eaav1784. doi:10.1126/sciadv.aav1784. ISSN 2375-2548. PMC 6170104. PMID 30306135.
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