Interstellar ice

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Interstellar ice , or cosmic ice , consists of grains of volatile substances in the solid phase that form in the interstellar medium .

Emergence

Ice and grains of dust are the main material from which the solar system was formed. Ice grains can be found in the dense regions of the molecular clouds , in which new stars are also formed. Temperatures in these regions can be up to ten Kelvin , which means that molecules that collide with the grains of ice can form an icy coat. Then the elements involved are thermally moved over the surface and ultimately form connections with other elements. This leads to the formation of water and methanol . Other compounds such as ammonia , carbon monoxide and carbon dioxide are also found in this water and methanol ice . Frozen formaldehyde and molecular hydrogen can also be present. Nitriles , ketones , esters and carbonyl sulfide are found to a lesser extent . The coats of interstellar ice grains are generally amorphous and only become crystalline in the presence of a star .

Research shows that much of the water in the solar system, like water on Earth, in the discs around Saturn and the meteorites of other planets, was present before the sun was born and comes from interstellar ice.

composition

The composition of the interstellar ice can be determined by its infrared spectrum . As starlight passes through an ice-laden molecular cloud, the molecules in the cloud absorb energy. This absorption occurs at the characteristic oscillation frequencies of the gas and the dust. Ice features in the cloud are relatively prominent in these spectra and the composition of the ice can be determined by comparing it to samples of ice materials on Earth. The interstellar ice in the places that can be observed directly from the earth consists of about 60-70% water, which shows a strong emission when the OH bond is stretched at 3.05 μm.

In September 2012, NASA scientists reported that polycyclic aromatic hydrocarbons (PAHs), exposed to the conditions of the interstellar medium, are converted into more complex organics through hydrogenation , oxygenation and hydroxylation . This is a step on the way to amino acids and nucleotides , which are the raw materials of proteins and DNA . As a result of these transformations, the PAHs lose their spectroscopic signature. This could be one of the reasons why there is no PAH detection in interstellar ice grains, especially in the outer regions of cold, dense clouds or the upper molecular layers of protoplanetary disks .

Comet 67P / Churyumov-Gerasimenko

On November 18, 2014, the Philae spacecraft revealed the presence of large amounts of water ice on Comet 67P / Churyumov-Gerasimenko . The report states that "the strength of the ice under a layer of dust on the first landing pad is surprisingly high". The team responsible for the MUPUS (Multi-Purpose Sensors for Surface and Sub-Surface Science) instrument that struck a probe in the comet stated that the comet was as hard as ice. "Although the hammer's impact power increased gradually, we could not penetrate deep into the surface," explained Tilman Spohn from the DLR Institute of Planetary Research, who led the research team.

Individual evidence

  1. ↑ a b c E. L. Gibb, DCB Whittet, ACA Boogert, AGGM Tielens: Interstellar Ice: The Infrared Space Observatory Legacy . In: The Astrophysical Journal Supplement Series . tape 151 , no. 1 , 2004, ISSN  0067-0049 , p. 35–73 , doi : 10.1086 / 381182 ( iop.org [accessed February 16, 2019]).
  2. ↑ Louis J. Allamandola, Max P. Bernstein, Scott A. Sandford, Robert L. Walker: Evolution of Interstellar Ices . In: Space Science Reviews . tape 90 , no. 1 , October 1, 1999, ISSN  1572-9672 , p. 219-232 , doi : 10.1023 / A: 1005210417396 .
  3. ↑ Cosmic rays, supernovae and the interstellar medium: proceedings of the NATO Advanced Study Institute on Cosmic Rays, Supernovae and the Interstellar Medium, Erice, Italy, July 26 - August 5, 1990 . Kluwer Acad. Publ., Dordrecht a. a. 1991, ISBN 978-0-7923-1278-9 ( worldcat.org [accessed February 16, 2019]).
  4. ↑ Elizabeth Gibney: Earth has water older than the Sun . In: Nature News . doi : 10.1038 / nature.2014.16011 ( nature.com [accessed on February 16, 2019]).
  5. ↑ Solid state astro chemistry . Kluwer Academic Publishers, Dordrecht 2003, ISBN 978-1-4020-1558-8 ( worldcat.org [accessed February 16, 2019]).
  6. ↑ SPACE com Staff 2012-09-20T11: 29: 42Z search for life: NASA Cooks Up Icy Organics to Mimic Life's Origins. Retrieved February 16, 2019 .
  7. ↑ Murthy S. Gudipati, Rui Yang: IN-SITU PROBING OF RADIATION-INDUCED PROCESSING OF ORGANICS IN ASTROPHYSICAL ICE ANALOGS — NOVEL LASER DESORPTION LASER IONIZATION TIME-OF-FLIGHT MASS SPECTROSCOPIC STUDIES . In: The Astrophysical Journal . tape 756 , no. 1 , September 1, 2012, ISSN  2041-8205 , p. L24 , doi : 10.1088 / 2041-8205 / 756/1 / L24 ( iop.org [accessed February 16, 2019]).
  8. ^ Philae reveals the presence of large amount of water ice on the comet - Times of India. Retrieved February 16, 2019 .