Starburst definitions

Starburst definitions - ratio is referred to as the...

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Starburst definitions Several definitions of the term starburst galaxy exist and there is no strict definition on which all astronomers agree. However, many generally agree that the definition must in some way be related to these three factors: 1. the rate at which the galaxy is currently converting gas into stars (the star-formation rate , or SFR ) 2. the available quantity of gas from which stars can be formed 3. comparison of the timescale of star formation with the age or rotation period of the galaxy. Commonly used definitions include: Continued star-formation with the current SFR would exhaust the available gas reservoir in much less than the age of the Universe (the Hubble Time). This is sometimes referred to as a "true" starburst. Continued star-formation with the current SFR would exhaust the available gas reservoir in much less than the dynamical timescale of the galaxy (perhaps one rotation period in a disk type galaxy). The current SFR, normalised by the past-averaged SFR is much greater than unity. This
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Unformatted text preview: ratio is referred to as the birthrate parameter . Starburst triggering mechanisms As viewed from our position 12.2 billion light years away, the Baby Boom Galaxy is seen to be creating 4,000 stars per year. Credit: NASA Essentially to ignite a starburst, it is necessary to concentrate a large amount of cool molecular gas in a small volume. Such concentrations and perturbations are strongly suspected to cause global starburst phenomena in major galaxy mergers, although the exact mechanisms are not fully understood. Observational surveys have long since shown that there is often a burst of disk star-formation in merging and interacting pairs of galaxies. It is also currently believed that nearby interactions between galaxies that don't actually merge can trigger unstable rotation modes, such as the bar instability, that cause gas to be funneled towards the nucleus, igniting bursts of star formation near the galactic nucleus....
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Starburst definitions - ratio is referred to as the...

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