Tholin

Mordor Macula, a dark region on Charon's north pole. The region is stained a dark brown by deposits of tholins

Tholins (after the Greek θολός (tholós) "hazy" or "muddy";[1] from the ancient Greek word meaning "sepia ink") are a wide variety of organic compounds formed by solar ultraviolet or cosmic ray irradiation of simple carbon-containing compounds such as carbon dioxide (CO
2), methane (CH
4) or ethane (C
2H
6), often in combination with nitrogen (N
2) or water (H
2O).[2][3] Tholins are disordered polymer-like materials made of repeating chains of linked subunits and complex combinations of functional groups, typically nitriles and hydrocarbons, and their degraded forms such as amines and phenyls. Tholins do not form naturally on modern-day Earth, but they are found in great abundance on the surfaces of icy bodies in the outer Solar System, and as reddish aerosols in the atmospheres of outer Solar System planets and moons.

In the presence of water, tholins could be raw materials for prebiotic chemistry (i.e., the non-living chemistry that forms the basic chemicals of which life is made). Their existence has implications for the origins of life on Earth and possibly on other planets. As particles in an atmosphere, tholins scatter light, and can affect habitability.

Tholins may be produced in a laboratory, and are usually studied as a heterogeneous mixture of many chemicals with many different structures and properties. Using techniques like thermogravimetric analysis, astrochemists analyze the composition of these tholin mixtures, and the exact character of the individual chemicals within them.[4]

  1. ^ Cite error: The named reference sagan1979 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference cometary tholins was invoked but never defined (see the help page).
  3. ^ Sarah Hörst "What in the world(s) are tholins?", Planetary Society, July 23, 2015. Retrieved 30 Nov 2016.
  4. ^ Nna-Mvondo, Delphine; de la Fuente, José L.; Ruiz-Bermejo, Marta; Khare, Bishun; McKay, Christopher P. (September 2013). "Thermal characterization of Titan's tholins by simultaneous TG–MS, DTA, DSC analysis". Planetary and Space Science. 85: 279–288. Bibcode:2013P&SS...85..279N. doi:10.1016/j.pss.2013.06.025.