Molecular Astrophysics
Molecules existed in the Universe before galaxies. Currently, they allow observations of the dynamics of star forming regions, and a variety of chemical species affect the evolution of the oldest stars in the Galaxy.
Chemical Control
The formation of all stars requires that gas remains cool as it collapses due to gravity. In the Universe H2 acted as the coolant regulating the birth of the first stars. CO is one of the most important coolants in star formation at the present epoch.
Magnetic fields regulate the birth of stars like the Sun throughout the Milky Way. Ractions between molecules, atomic and molecular ions, and dust grains establish the degree of ionization where stars form. The ionization properties affect the evolution of the magnetic fields.
Many stars thathave burned most of their primary fuel, hydrogen, lose mass over only about ten thousand years, roughly one one-millionth of the lifetime of the Sun. The presence of molecules in the outflows, the dust they create, and the interaction of the radiation fields with the molecules and dust cause the high mass loss rates.
Chemical Diagnostics
The dynamics of stellar birth are observed in the radiation at millimetre and sub-millimetre wavelengths emitted by molecules. The concentrations of the observed molecular species evolve during the collapse phase. Their time-dependent behaviour must be modelled with reaction networks to interpret the observations.
Molecular maser emissions are used in the measurements of the magnetic properties and velocities of the outflows of dying stars. A maser is a microwave relative of a laser, which is a device operating at visual and near visual wavelengths. The first theoretical studies of the roles of magnetic fields in the mass loss of such stars resulted as a consequence of the investigations of molecular masers.
Suggested Reading
Leeds' scientists are world leaders in the study of molecular astrophysical environments from star forming regions in the Milky Way to evolved stars within light years of the central, hundred million solar mass, black holes of quasars. They have coauthored, edited and coedited a number of volumes. A student considering a degree in physics, astronomy, or another science at university, can refer to:
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The Chemically Controlled Cosmos
Astronomical Molecules from the Big Bang to Exploding Stars
Published December 1995, 169 pages Cambridge University Press |
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Expositions appropriate for postgraduate students and specialists include:
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Molecular Astrophysics
A Volume Honouring Alexander Dalgarno
Published May 1990, 484 pages Cambridge University Press |
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The Molecular Astrophysics of Stars and Galaxies
Published May 1998, 558 pages Oxford University Press |
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Molecules in the Cosmos
A Volume Honouring David A. Williams
Astrophysics and Space Science, 2003 Volume 285, Numbers 3 and 4 Kluwer Academic Publishers |
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