all Robert Kirshner stories

White dwarf "sibling rivalry" explodes

404132862 — Thu, 01 Nov 2007 15:57:02 -0400

Astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) have found that a supernova discovered last year was caused by two colliding white dwarf stars. The white dwarfs were siblings orbiting each other. They slowly spiraled inward until they merged, touching off a titanic explosion. CfA observations show the strongest evidence yet of what was, until now, a purely theoretical mechanism for creating a supernova.

Harvard astronomers share dark prize

50443248 — Tue, 02 Oct 2007 10:02:27 -0400

Two teams who upset everyone's ideas about how the universe works and its future will share the $500,000 Gruber Cosmology Prize for discovering that 70 percent of the universe is nothing but a strange form of energy.

In 1998, a group called the High-z Supernova Search Team published irresistible evidence that the universe is expanding at a rate that may never slow down. Eleven of the 19 members of the High-z team are or were affiliated with Harvard University. Months later, a second team, the Supernova Cosmology Project, independently confirmed the startling finding. That team was lead by Saul Perlmutter of the University of California, Berkeley.

Do we live in a "stop and go" universe?

70652986 — Mon, 26 Mar 2007 05:30:59 -0400

At the 202nd meeting of the American Astronomical Society, Robert Kirshner (Harvard-Smithsonian Center for Astrophysics), on behalf of the international High-z Supernova Search Team led by Brian Schmidt (Mount Stromlo Observatory), presented evidence that the expanding universe slowed for billions of years before galaxies began accelerating, like cars that get past a bottleneck. "Right now, the universe is speeding up, with galaxies zooming away from each other like Indy 500 racers hitting the gas when the green flag drops and the pace car gets out of their way. But we suspect that it wasn't always this way," said Kirshner. John Tonry (University of Hawaii), principal investigator of the team for the new and collected previous observations reported on in May 2003, agreed. "We've been hoping to see this effect of slowing in the distant past. We saw evidence 5 years ago that the expansion of the universe currently is accelerating, but we didn't know for sure what it was doing 7 billion years ago. We are now seeing hints that, way back then, the universe was slowing down."

Telescope will look toward the edge of the universe

70652986 — Mon, 26 Mar 2007 05:07:29 -0400

A mountaintop in Chile provides one of the best places on Earth to see light that has been traveling toward our world for billions of years. "It's an inspiring place to be on a clear night with the center of the Milky Way directly overhead," says Robert Kirshner, a professor of astronomy. "You can see light that has been traveling from the center of our galaxy for 10,000 years, or from the far parts of the universe for billions of years." The center of the Milky Way cannot be seen well from the Northern Hemisphere; the nearest galaxies to the Earth and a large part of the sky around the South Pole cannot be seen at all. That's why Harvard astronomers erected a huge telescope on that Chilean mountaintop in December 2000 to see to the edges of the universe.