Cannabaceae

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Distribution of mass versus orbital period for planets with a measured mass. Black lines represent the Neptunian desert. NGTS-4b is shown as a red cross.

The Neptunian desert or sub-Jovian desert is broadly defined as the region close to a star (period < 2–4 days) where no Neptune-sized (> 0.1 MJ) exoplanets are found.[1] This zone receives strong irradiation from the star, meaning the planets cannot retain their gaseous atmospheres: They evaporate, leaving just a rocky core.[2]

Neptune-sized planets should be easier to find in short-period orbits, and many sufficiently massive planets have been discovered with longer orbits from surveys such as CoRoT and Kepler.[1] The physical mechanisms that result in the observed Neptunian desert are currently unknown, but have been suggested to be due to a different formation mechanism for short-period super-Earth and Jovian exoplanets, similar to the reasons for the brown-dwarf desert.[1]

Candidates[edit]

NGTS-4b[edit]

The exoplanet NGTS-4b, with mass of 20 ME, and a radius 20% smaller than Neptune, was found to still have an atmosphere while orbiting every 1.3 days within the Neptunian desert of NGTS-4, a K-dwarf star located 922 light-years from Earth.[2] The atmosphere may have survived due to the planet's unusually high core mass, or it might have migrated to its current close-in orbit after this epoch of maximum stellar activity.[1]

LTT 9779 b[edit]

LTT 9779 b is an ultra-hot Neptune in the Neptunian desert. It has an unusually high albedo of 0.8, and likely has a metal-rich atmosphere.[3]

See also[edit]

Notes[edit]

  1. ^ a b c d Watson, Christopher A.; Walker, Simon R.; Udry, Stéphane; Thompson, Samantha J.; Sohy, Sandrine; Rauer, Heike; et al. (11 July 2019). "NGTS-4b: A sub-Neptune transiting in the desert". Monthly Notices of the Royal Astronomical Society. 486 (4): 5094–5103. arXiv:1809.00678. Bibcode:2019MNRAS.486.5094W. doi:10.1093/mnras/stz1084. ISSN 0035-8711.
  2. ^ a b "The 'Forbidden' planet has been found in the 'Neptunian Desert'". Phys.org. University of Warwick. 29 May 2019. Retrieved 29 May 2019.
  3. ^ Jenkins, James S.; Díaz, Matías R.; et al. (September 2020). "An Ultra-Hot Neptune in the Neptune desert". Nature Astronomy. 4 (12): 1148–1157. arXiv:2009.12832. Bibcode:2020NatAs...4.1148J. doi:10.1038/s41550-020-1142-z. S2CID 256707813.
source: https://en.wikipedia.org/wiki/Neptunian_desert

One thought on “Cannabaceae”

  1. Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
    View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction

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