all Mark Reid stories

Milky Way bigger, faster than previously thought

404132862 — Mon, 05 Jan 2009 15:01:39 -0500

Our own Milky Way galaxy, long considered a “little sister” to the larger Andromeda Galaxy, is all grown-up, according to new research presented today that shows the Milky Way to be bigger and faster than previously thought.

The findings, presented at a meeting of the American Astronomical Society in Long Beach, Calif., by Harvard-Smithsonian Center for Astrophysics (CfA) researchers, show that the galaxy has about 50 percent more mass — about the same as Andromeda — and is rotating about 100,000 mph faster than previously thought.

Astronomers measure slowest motion across the sky

70652986 — Mon, 26 Mar 2007 06:17:40 -0400

"A snail crawling on Mars would appear to be moving across the surface more than 100 times faster than the motion we measured for this galaxy," said Mark Reid of the Harvard-Smithsonian Center for Astrophysics, a co-author on the paper. Reid and his colleagues used the National Science Foundation's Very Long Baseline Array (VLBA) to measure the motion across the sky of a galaxy located nearly 2.4 million light-years from Earth. While scientists have been measuring the motion of galaxies directly toward or away from Earth for decades, this is the first time that the transverse motion (called proper motion by astronomers) has been measured for a galaxy that is not a nearby satellite of the Milky Way.

Even stars use sunscreen!

70652986 — Mon, 26 Mar 2007 05:20:06 -0400

Mira variable stars are named after the red giant star Mira (omicron Ceti) in the constellation Cetus the Whale. Variable stars brighten, then dim, then brighten again. While astronomers have known of the existence of these dramatically changing stars for hundreds of years, the cause of their variability has been hard to identify. Now, two researchers at the Harvard-Smithsonian Center for Astrophysics have solved this long-standing mystery. The key, say Mark Reid and Joshua Goldston, is the formation of light-absorbing chemicals in the star's gaseous atmosphere -- the same chemicals found in sunscreen. "Long before there were professional astronomers, people looked at the heavens and noted that some stars seemed to vanish and then reappear," says Reid. "Only now are we beginning to understand more fully why that happens." Their findings were published in the April 1, 2002 issue of the Astrophysical Journal.