Variable Stars and the Stories They Tell: Exoplanets and the Search for Extraterrestrial Life
©February 2018 by Dale Alan Bryant
(In memory of M.I.T. astrophysicist Dr. Philip Morrison - who started all this...)
Though the figures are tough to keep up with - they are changing, almost daily - the Kepler Space Telescope (KST) has discovered, to date, over 4,500 exoplanet candidates, ~3,400+ of which have been confirmed.
RR Lyrae, 1 degree field, DSS I survey plate
(copyright 1993-1995 CalTech/STScI)
Distances in the universe are so vast that we do not have a simple way of measuring them. For distances within the solar system we can measure them directly, using radar for example, and some very straightforward trigonometry. But radar is hard to use when it takes light minutes or hours to cross the solar system; and the nearest star is four light years awa
Variable stars highlight an important fact about the heavens above us: the universe is always changing. The universe is very large, stars and galaxies are very far away, and many changes occur on timescales far longer than we can see. Most things in the sky -- stars, nebulae, and galaxies -- don't appear to change at all during the course of a human lifetime.
A gamma-ray burst (GRB) is a brief flash of gamma rays coming from an astrophysical source at great distances from us, often from hundreds of millions of light years away. Gamma rays are a kind of light (like visible light, microwaves, or X-rays) that is very energetic, and whatever produces gamma rays must therefore contain (and unleash) a large amount of energy in a very short amount of time. Thus the study of gamma ray bursts is a study of some of the most violent events in the universe.
