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Atomic physics plays a key role in astrophysics as astronomers' only information about a particular object comes through the light that it emits, and this light arises through atomic transitions. Molecular astrophysics , developed into a rigorous field of investigation by theoretical astrochemist Alexander Dalgarno beginning in 1967, concerns ...
Some molecules have simple spectra which are easy to identify, whilst others (even some small molecules) have extremely complex spectra with flux spread among many different lines, making them far harder to detect. [3] Interactions between the atomic nuclei and the electrons sometimes cause further hyperfine structure of the spectral lines.
For this reason, molecules and molecular ions which are unstable on Earth can be highly abundant in space, for example the H 3 + ion. Astrochemistry overlaps with astrophysics and nuclear physics in characterizing the nuclear reactions which occur in stars, as well as the structure of stellar interiors.
Astronomers have detected water molecules on the surface of asteroids for the first time, a surprising find given that the space rocks were thought to be “completely dry.”
This definition goes beyond atoms and molecules, however, to include substances made from these building blocks that are not simply atoms or molecules, for example electron beams in an old cathode ray tube television, or white dwarf matter—typically, carbon and oxygen nuclei in a sea of degenerate electrons. At a microscopic level, the ...
The term outward space existed in a poem from 1842 by the English poet Lady Emmeline Stuart-Wortley called "The Maiden of Moscow", [13] but in astronomy the term outer space found its application for the first time in 1845 by Alexander von Humboldt. [14] The term was eventually popularized through the writings of H. G. Wells after 1901. [15]
Compare this with a number density of roughly 10 25 molecules per m 3 for air at sea level, and 10 16 molecules per m 3 (10 quadrillion molecules per m 3) for a laboratory high-vacuum chamber. Within our galaxy, by mass , 99% of the ISM is gas in any form, and 1% is dust. [ 2 ]
Evidence suggests the main growth of asteroids can result from gas-assisted accretion of chondrules, which are millimeter-sized spherules that form as molten (or partially molten) droplets in space before being accreted to their parent asteroids. [34] In the inner Solar System, chondrules appear to have been crucial for initiating accretion. [35]