List of exomoon candidates

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Artist's impression of the MOA-2011-BLG-262 system

As of 2023, there have been no positive confirmations of satellites of extra-solar planets (exomoons); however, some evidence in favour of their existence has been produced.

Timeline[edit]

  • 2012 — It has been surmised that the star V1400 Centauri's ringed companion, 1SWASP J1407b may have a few moons.[1]
  • 2012 — The confirmed extrasolar planet WASP-12b may also possess a moon.[2]
  • December 2013, April 2014 — — candidate exomoon of a free-floating planet MOA-2011-BLG-262, was announced, but due to degeneracies in the modelling of the microlensing event, the observations can also be explained as a Neptune-mass planet orbiting a low-mass red dwarf, a scenario the authors consider to be more likely.[3][4][5]
  • October 2018 — researchers using the Hubble Space Telescope published observations of the candidate exomoon Kepler-1625b I, which suggest that the host planet is likely several Jupiter masses, while the exomoon may have a mass and radius similar to Neptune. 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 existence and nature.[6][7]
    • April 2019 — reanalysis concluded that the data was fit better by a planet-only model. According to this study, the discrepancy was an artifact of the data reduction, and Kepler-1625b I likely does not exist.[8]
  • August 2020 — A paper by Chris Fox and Paul Wiegert examined the Kepler dataset for indications of exomoons solely from transit timing variations. Eight candidate signals were found that were consistent with an exomoon, however the signals could also be explained by the presence of another planet. Fox and Wiegert's conclusion was more and higher quality transit timing data would be required to establish whether these are truly moons or not.[9] David Kipping re-derived the timings of six of the eight targets (based on a pre-peer review version) and evaluated the TTV evidence as uncompelling. The same study finds that Kepler-1625b I remains an exomoon candidate.[10]
  • August 2021 — astronomers reported an habitable-zone 1.7 R🜨 exomoon candidate transiting one of the components in the planetary-mass binary 2MASS J1119-1137AB.[11]
  • January 2022 — an exomoon candidate was reported around the planet Kepler-1708b, and because it is orbiting a planet at approximately 1.6 AU from a star that is slightly more luminous than the Sun, it too could be within the habitable zone.[12] However, this candidate is based on limited observations (only two transits) and some consider the data to be non-convincing.[13]
  • November 2022 — another exomoon candidate was reported around the planet Kepler-1513b (KOI-3678.01). Unlike the previous giant exomoon candidates of Kepler-1625 and Kepler-1708, this exomoon would be terrestrial-mass, ranging from 0.76 Lunar masses to 0.34 Earth masses depending on the planet's mass and moon's orbital period.[14]
    • October 2023 — a follow-up study by the same team found that the observed TTVs are caused by a second planet in the system, and not by a moon.[15]
  • December 2023 — The exomoon candidate around Kepler-1625b was again challenged, along with the Kepler-1708b candidate. This study argues that the statistical significance of these exomoon candidates is lower than previously claimed (with false positive probabilities of 10.9% and 1.6%, respectively) and that true giant exomoons would have stronger evidence. Evidence for exomoon transits may be caused by stellar activity in the Kepler light curves.[16] Kipping's team published a response arguing that these exomoon candidates remain possible.[17]

Table[edit]

Host star
of the
host planet(s)
Planet designation Planet mass Planet
semimajor
axis (AU)
Exomoon
semimajor
axis
Exomoon
mass (ME)
Notes
V1400 Centauri J1407b[18] 14–26 MJ 2.2–5.6 0.24 AU <0.3 Two possible exomoons residing in small ring gaps around J1407b.
0.25 AU
0.40 AU <0.8 Possible exomoon residing in a large ring gap around J1407b.
N/A 2MASS J1119-1137A or B 3.7 MJ 3.6 ± 0.9
separation from each other
0.004 - 0.009 AU 0.5 - 1 Found using the transit method. A habitable-zone exomoon candidate transiting a directly imaged free-floating planet or isolated planetary-mass object.[11]
DH Tauri DH Tauri b 10.6 MJ 330 10 AU 318 Candidate Jupiter-mass satellite from direct imaging. If confirmed, it could also be considered a planet orbiting a brown dwarf.[19]
HD 189733 HD 189733 b 1.13 MJ 0.031 0.0087 AU ? Found by studying periodic increases and decreases in light given off from HD 189733 b. Outside of planet's Hill sphere.[20]
<0.00112 AU ~ 0.015 Exo-Io candidate;[21] The sodium and potassium data[22][23] at HD189733b is consistent with evaporating exomoons and/or their corresponding gas torus.[24]
Kepler-409 Kepler-409b 1.00 ME 0.320 0.222 RHill 0.300 Possible exomoon from transit timing variations,[9] since deemed unlikely.[10]
Kepler-517 Kepler-517b 7.59 ME 0.298 0.278 RHill 0.499 Possible exomoon from transit timing variations,[9] since deemed unlikely.[10]
Kepler-809 Kepler-809b 38.02 ME 0.308 0.289 RHill 2.931 Possible exomoon from transit timing variations.[9]
Kepler-857 Kepler-857b 14.13 ME 0.376 0.208 RHill 1.636 Possible exomoon from transit timing variations.[9]
Kepler-1000 Kepler-1000b 19.95 ME 0.534 0.235 RHill 1.551 Possible exomoon from transit timing variations,[9] since deemed unlikely.[10]
Kepler-1326 Kepler-1326b 24.55 ME 0.2691 0.295 RHill 6.057 Possible exomoon from transit timing variations,[9] since deemed unlikely.[10]
Kepler-1442 Kepler-1442b 14.13 ME 0.405 0.208 RHill 1.586 Possible exomoon from transit timing variations,[9] since deemed unlikely.[10]
Kepler-1625 Kepler-1625b <11.6 MJ[25] 0.98 0.022 AU 19.0 Possible Neptune-sized exomoon or double planet, indicated by transit observations.[26][7]
Kepler-1708 Kepler-1708b <4.6 MJ 1.64 0.005 AU
(11.7 RP)
<37 Possible Neptune-sized exomoon or double planet, indicated by transit observations.[12]
KOI-268 KOI-268.01 9.33 ME 0.47 0.217 RHill 0.817 Possible exomoon from transit timing variations,[9] since deemed unlikely.[10]
N/A MOA-2011-BLG-262L[27] 3.6 MJ N/A 0.13 AU 0.54 Found by microlensing; however it is unknown if the system is a sub-Earth-mass exomoon orbiting a free-floating planet, or a Neptune-mass planet orbiting a low-mass red dwarf star.[28]
N/A MOA-2015-BLG-337L 9.85 MJ N/A 0.24 AU 33.7 Found by microlensing; however it is unknown if the system is a super-Neptune-mass planet orbiting a free-floating planet, or a binary brown dwarf system.[29]
WASP-12 WASP-12b[30] 1.465 MJ 0.0232 6 RP 0.57–6.4
[citation needed]
Found by studying periodic increases and decreases in light given off from WASP-12b. Outside of planet's Hill sphere.[20]
WASP-49 WASP-49b 0.37 MJ 0.0379 < 1.74 RP ~ 0.015 Exo-Io candidate; The sodium exosphere around WASP-49b could be due to a volcanically active Io-like exomoon.[21]
WASP-76 WASP-76b 0.92 MJ 0.033 1.125 RP ~ 0.015 Exo-Io candidate; Sodium detected via absorption spectroscopy around WASP-76b[31] is consistent with an extrasolar toroidal atmosphere[32] generated by an evaporating exomoon.[24]
WASP-121 WASP-121b 1.184 MJ 0.02544 ~ 1.9 RP ~ 0.015 Exo-Io candidate; The sodium detected via absorption spectroscopy around WASP-121b[33] is consistent with an extrasolar gas torus possibly fueled by a hidden exo-Io.[24]

References[edit]

  1. ^ "Saturn-like ring system eclipses Sun-like star". Archived from the original on 19 September 2016. Retrieved 9 March 2018. Mamajek thinks his team could be either observing the late stages of planet formation if the transiting object is a star or brown dwarf, or possibly moon formation if the transiting object is a giant planet
  2. ^ Российские астрономы впервые открыли луну возле экзопланеты Archived 10 March 2012 at the Wayback Machine (in Russian) – "Studying of a curve of change of shine of WASP-12b has brought to the Russian astronomers unusual result: regular splashes were found out.<...> Though stains on a star surface also can cause similar changes of shine, observable splashes are very similar on duration, a profile and amplitude that testifies for benefit of exomoon existence."
  3. ^ Bennett, D.P.; et al. (2014). "A Sub-Earth-Mass Moon Orbiting a Gas Giant Primary or a High Velocity Planetary System in the Galactic Bulge". The Astrophysical Journal. 785 (2): 155. arXiv:1312.3951. Bibcode:2014ApJ...785..155B. doi:10.1088/0004-637X/785/2/155. S2CID 118327512.
  4. ^ Clavin, Whitney (10 April 2014). "Faraway Moon or Faint Star? Possible Exomoon Found". NASA. Archived from the original on 12 April 2014. Retrieved 10 April 2014.
  5. ^ "First exomoon glimpsed – 1800 light years from Earth". New Scientist. Archived from the original on 20 December 2013. Retrieved 20 December 2013.
  6. ^ Teachey, Alex; et al. (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.
  7. ^ a b Teachey, Alex; Kipping, David M. (4 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.
  8. ^ Laura Kreidberg; Rodrigo Luger; Megan Bedell (24 April 2019), "No Evidence for Lunar Transit in New Analysis of HST Observations of the Kepler-1625 System", The Astrophysical Journal, 877 (2), arXiv:1904.10618, Bibcode:2019ApJ...877L..15K, doi:10.3847/2041-8213/ab20c8, S2CID 129945202
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  11. ^ a b Limbach, Mary Anne; Vos, Johanna M.; Winn, Joshua N.; Heller, Rene; Mason, Jeffrey C.; Schneider, Adam C.; Dai, Fei (2021-08-18). "On the Detection of Exomoons Transiting Isolated Planetary-mass Objects". The Astrophysical Journal Letters. 918 (2): L25. arXiv:2108.08323. Bibcode:2021ApJ...918L..25L. doi:10.3847/2041-8213/ac1e2d. S2CID 237213523.
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  15. ^ Yahalomi, Daniel A.; Kipping, David; et al. (January 2024). "Not So Fast Kepler-1513: A Perturbing Planetary Interloper in the Exomoon Corridor". Monthly Notices of the Royal Astronomical Society. 527 (1): 620–639. arXiv:2310.03802. Bibcode:2024MNRAS.527..620Y. doi:10.1093/mnras/stad3070.
  16. ^ Heller, René; Hippke, Michael (December 2023). "Large exomoons unlikely around Kepler-1625 b and Kepler-1708 b". Nature Astronomy. 8 (2): 193–206. arXiv:2312.03786. Bibcode:2024NatAs...8..193H. doi:10.1038/s41550-023-02148-w.
  17. ^ Kipping, David; Teachey, Alex (January 2024). "A Reply to: Large Exomoons unlikely around Kepler-1625 b and Kepler-1708 b". Nature Astronomy. arXiv:2401.10333.
  18. ^ "1SWASP J1407 b". Extrasolar Planets Encyclopaedia. Archived from the original on 1 February 2015. Retrieved 1 February 2015.
  19. ^ Lazzoni, C.; et al. (20 July 2020). "The search for disks or planetary objects around directly imaged companions: A candidate around DH Tau B". Astronomy & Astrophysics. 641: A131. arXiv:2007.10097. Bibcode:2020A&A...641A.131L. doi:10.1051/0004-6361/201937290. S2CID 220647289.
  20. ^ a b Ben-Jaffel, Lotfi; Ballester, Gilda (3 April 2014). "Transit of Exomoon Plasma Tori: New Diagnosis". The Astrophysical Journal. 785 (2): L30. arXiv:1404.1084. Bibcode:2014ApJ...785L..30B. doi:10.1088/2041-8205/785/2/L30. S2CID 119282630.
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  22. ^ Wyttenbach, A.; Ehrenreich, D.; Lovis, C.; Udry, S.; Pepe, F. (5 May 2015). "Spectrally resolved detection of sodium in the atmosphere of HD 189733b with the HARPS spectrograph". Astronomy & Astrophysics. 577: A62. arXiv:1503.05581. Bibcode:2015A&A...577A..62W. doi:10.1051/0004-6361/201525729. S2CID 54935174.
  23. ^ Keles, Engin; Mallonn, Matthias; von Essen, Carolina; Carroll, Thorsten; Alexoudi, Xanthippi; Pino, Lorenzo; Ilyin, Ilya; Poppenhager, Katja; Kitzmann, Daniel; Nascimbeni, Valerio; Turner, Jake D; Strassmeier, Klaus G (October 2019). "The potassium absorption on HD189733b and HD209458b". Monthly Notices of the Royal Astronomical Society: Letters. 489 (1): L37-L41. arXiv:1909.04884. Bibcode:2019MNRAS.489L..37K. doi:10.1093/mnrasl/slz123. S2CID 202134796.
  24. ^ a b c Gebek, Andrea; Oza, Apurva (29 July 2020). "Alkaline exospheres of exoplanet systems: evaporative transmission spectra". Monthly Notices of the Royal Astronomical Society. 497 (4): 5271–5291. arXiv:2005.02536. Bibcode:2020MNRAS.497.5271G. doi:10.1093/mnras/staa2193. S2CID 218516741. Retrieved 8 December 2020.
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  28. ^ Bennett, D.P.; et al. (13 December 2013). "A Sub-Earth-Mass Moon Orbiting a Gas Giant Primary or a High Velocity Planetary System in the Galactic Bulge". The Astrophysical Journal. 785 (2): 155. arXiv:1312.3951. Bibcode:2014ApJ...785..155B. doi:10.1088/0004-637X/785/2/155. S2CID 118327512.
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  32. ^ Johnson, Robert E.; Huggins, Patrick (August 2006). "Toroidal Atmospheres around Extrasolar Planets". Publications of the Astronomical Society of the Pacific. 118 (846): 1136–1143. arXiv:astro-ph/0605655. Bibcode:2006PASP..118.1136J. doi:10.1086/506183. S2CID 16201558.
  33. ^ Hoeijmakers, H.J.; Seidel, J.V.; Pino, L.; Kitzmann, D.; Sindel, J.P.; Ehrenreich, D.; Oza, A.V.; Bourrier, V.; Allart, R.; Gebek, A.; Lovis, C.; Yurchenko, S.N.; Astudillo-Defru, N.; Bayliss, D.; Cegla, H.; Lavie, B.; Lendl, M.; Melo, C.; Murgas, F.; Nascimbeni, V.; Pepe, F.; Segransan, D.; Udry, S.; Wyttenbach, A.; Heng, K. (18 September 2020). "Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) - IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b". Astronomy & Astrophysics. 641: A123. arXiv:2006.11308. Bibcode:2020A&A...641A.123H. doi:10.1051/0004-6361/202038365. S2CID 219966241.