Astronomy:OGLE-2012-BLG-0950Lb

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Short description: Sub-Saturn exoplanet 8,500 light years away

OGLE-2012-BLG-0950Lb is a sub-Saturn (super-Neptune)-type planet 2,600 parsecs (8,500 ly) away with 39[1] or 35[2] Earth masses. This type of planet was once thought to be extremely rare because of runaway gas accretion, which would create a gap between 4 and 8 Earth radii or 20 and 80 Earth masses, peaking around 32-64 Earth masses.[3] The planet is 2.6 AU from its star.[1][4] It is likely near-impossible to know much else about the planet's properties (or its star's) because it was detected by gravitational microlensing.[4] The mass of the host star is approximately 0.56 solar masses (consistent with an M0-0.5V-type star).[5] This exoplanet was the first to have its mass found out using only microlens parallax and lens flux.[5]

According to microlensing and Kepler data, analogues to this world should be common, showing that our Solar System is not necessarily a perfect model for planetary formation and the runaway gas accretion model may be incorrect or incomplete. This has implications for habitability because gas/ice giants like Jupiter and Neptune greatly influenced the Earth's water content (see Grand Tack hypothesis).[6]

Composition

Sub-Saturns have a wide range of makeups, from puffy planets to large-core worlds.[7] With a radius of 6.5 Earth radii (predicted based on mass-radius relationships), the density would be 0.87 (39 Earth masses) or 0.7 g/cm3 (35 Earth masses), implying a Saturn-like composition closer to a standard gas giant than an ice giant. Tholins, a building block of life, are very common in these types of planets as well as the universe as a whole and thus may be present here.[8]

See also

References

  1. ↑ 1.0 1.1 Bartelspublished, Meghan (2019-01-12). "'Sub-Saturns' May Force Scientists to Revise Idea of How Planets Form" (in en). https://www.space.com/42958-sub-saturn-exoplanets-are-common-after-all.html. 
  2. ↑ "OGLE-2012-BLG-0950L | NASA Exoplanet Archive". https://kvmexoweb.ipac.caltech.edu/overview/OGLE-2012-BLG-0950L%20b#planet_OGLE-2012-BLG-0950L-b_collapsible. 
  3. ↑ Russell, David G. (2024-01-01). "A sub-Saturn mass-radius desert for planets with equilibrium temperature". Icarus 407: 115798. doi:10.1016/j.icarus.2023.115798. ISSN 0019-1035. https://www.sciencedirect.com/science/article/pii/S0019103523003767. 
  4. ↑ 4.0 4.1 "Exoplanet-catalog" (in en). https://exoplanets.nasa.gov/exoplanet-catalog/3406/ogle-2012-blg-0950l-b/. 
  5. ↑ 5.0 5.1 Koshimoto, N.; Udalski, A.; Beaulieu, J. P.; Sumi, T.; Bennett, D. P.; Bond, I. A.; Rattenbury, N.; Fukui, A. et al. (2016-12-14). "OGLE-2012-bLG-0950Lb: the First Planet Mass Measurement From Only Microlens Parallax and Lens Flux" (in en). The Astronomical Journal 153 (1): 1. doi:10.3847/1538-3881/153/1/1. ISSN 0004-6256. https://ntrs.nasa.gov/citations/20170003332. 
  6. ↑ Suzuki, Daisuke; Bennett, David P.; Ida, Shigeru; Mordasini, Christoph; Bhattacharya, Aparna; Bond, Ian A.; Donachie, Martin; Fukui, Akihiko et al. (2018-12-19). "Microlensing Results Challenge the Core Accretion Runaway Growth Scenario for Gas Giants". The Astrophysical Journal 869 (2): L34. doi:10.3847/2041-8213/aaf577. ISSN 2041-8213. Bibcode: 2018ApJ...869L..34S. 
  7. ↑ Petigura, Erik A.; Sinukoff, Evan; Lopez, Eric D.; Crossfield, Ian J. M.; Howard, Andrew W.; Brewer, John M.; Fulton, Benjamin J.; Isaacson, Howard T. et al. (2017). "Four Sub-Saturns with Dissimilar Densities: Windows into Planetary Cores and Envelopes". The Astronomical Journal 153 (4): 142. doi:10.3847/1538-3881/aa5ea5. Bibcode: 2017AJ....153..142P. 
  8. ↑ Haynes, Korey (2019-03-18). "What are tholins? The mysterious substance that turned Ultima Thule red | Astronomy.com" (in en-US). https://www.astronomy.com/science/what-are-tholins-the-mysterious-substance-that-turned-ultima-thule-red/. 



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