all Dimitar Sasselov stories

A new era in search for ‘sister Earths’?

404132862 — Fri, 25 Jul 2008 19:27:28 -0400

Research presented at a recent astronomical conference is being hailed as ushering in a new era in the search for Earth-like planets by showing that they are more numerous than previously thought and that scientists can now analyze their atmospheres for elements that might be conducive to life.

Laser precision added to search for new Earths

404132862 — Wed, 02 Apr 2008 14:46:48 -0400

Harvard scientists have unveiled a new laser-measuring device that they say will provide a critical advance in the resolution of current planet-finding techniques, making the discovery of Earth-sized planets possible.

The discovery of planets outside of our solar system, called “exoplanets,” is one of the hottest fields in astronomy and holds great promise to increase our understanding of Earth’s solar system and of how life first took hold on this planet.

J. Craig Venter named visiting scholar

404132862 — Fri, 29 Feb 2008 10:22:11 -0500

J. Craig Venter, the visionary biologist and intellectual entrepreneur who was a leading figure in the decoding of the human genome, will join Harvard University as a visiting scholar at the University’s Origins of Life Initiative.

Venter, who left his last academic post in 1982, is founder and president of the J. Craig Venter Institute. He accepted the one-year appointment last week (Feb. 22). It starts March 1.

Strange new planet baffles astronomers

70652986 — Mon, 26 Mar 2007 06:28:15 -0400

Using a network of small automated telescopes known as HAT, Smithsonian astronomers have discovered a planet unlike any other known world. This new planet, designated HAT-P-1, orbits one member of a pair of distant stars 450 light-years away in the constellation Lacerta.

"We could be looking at an entirely new class of planets," said Gaspar Bakos, a Hubble fellow at the Harvard-Smithsonian Center for Astrophysics (CfA). Bakos designed and built the HAT network and is lead author of a paper submitted to the Astrophysical Journal describing the discovery. That paper is available online at http://arxiv.org/abs/astro-ph/0609369.

With a radius about 1.38 times Jupiter's, HAT-P-1 is the largest known planet. In spite of its huge size, its mass is only half that of Jupiter.

"This planet is about one-quarter the density of water," Bakos said. "In other words, it's lighter than a giant ball of cork! Just like Saturn, it would float in a bathtub if you could find a tub big enough to hold it, but it would float almost three times higher."

HAT-P-1 revolves around its host star every 4.5 days in an orbit one-twentieth of the distance from Earth to the Sun. Once each orbit, it passes in front of its parent star, causing the star to appear fainter by about 1.5 percent for more than two hours, after which the star returns to its previous brightness.

HAT-P-1's parent star is one member of a double-star system called ADS 16402 and is visible in binoculars. The two stars are separated by about 1500 times the Earth-Sun distance. The stars are similar to the Sun but slightly younger - about 3.6 billion years old compared to the Sun's age of 4.5 billion years.

Major funding for HATnet was provided by NASA.

Most Milky Way stars are single

70652986 — Mon, 26 Mar 2007 06:24:33 -0400

Common wisdom among astronomers holds that most star systems in the Milky Way are multiple, consisting of two or more stars in orbit around each other. Common wisdom is wrong.

A new study by Charles Lada of the Harvard-Smithsonian Center for Astrophysics (CfA) demonstrates that most star systems are made up of single stars. Since planets probably are easier to form around single stars, planets also may be more common than previously suspected.

Astronomers have long known that massive, bright stars, including stars like the sun, are most often found to be in multiple star systems. This fact led to the notion that most stars in the universe are multiples. However, more recent studies targeted at low-mass stars have found that these fainter objects rarely occur in multiple systems. Astronomers have known for some time that such low-mass stars, also known as red dwarfs or M stars, are considerably more abundant in space than high- mass stars.

By combining these two facts, Lada came to the realization that most star systems in the Galaxy are composed of solitary red dwarfs.

"By assembling these pieces of the puzzle, the picture that emerged was the complete opposite of what most astronomers have believed," said Lada.

This research has been submitted to The Astrophysical Journal Letters for publication and is available online at http://arxiv.org/ abs/astro-ph/0601375

Planetary survivor strategy: Outeat, outweigh, outlast!

70652986 — Mon, 26 Mar 2007 05:34:56 -0400

Astronomers Myron Lecar and Dimitar Sasselov have found that planet formation is a contest, where a growing planet must fight for survival lest it be swallowed by the star that initially nurtured it. Of the first 100 stars found to harbor planets, more than 30 stars host a Jupiter-sized world in an orbit smaller than Mercury's, whizzing around its star in a matter of days (as opposed to our solar system where Jupiter takes 12 years to orbit the Sun). Such close orbits result from a race between a nascent gas giant and a newborn star. This research is described in the Oct. 10, 2003 issue of The Astrophysical Journal Letters. "The endgame is a race between the star and its giant planet," says Sasselov. "In some systems, the planet wins and survives, but in other systems, the planet loses the race and is eaten by the star."

New, far-out planet is discovered

70652986 — Mon, 26 Mar 2007 05:26:46 -0400

A planet discovered in the constellation Sagittarius is so distant that light takes 5,000 years to travel from there to here at a speed of 186,000 miles per second. Called OGLE-TR-56b, the planet orbits too close to its sun to be hospitable to living things. The way it was found could lead to the discovery of more planets like our lively Earth. "We have found a better way to detect new worlds in our own Milky Way galaxy, which makes future planetary discoveries easier," says Dimitar Sasselov, Thomas D. Cabot Associate Professor of Astronomy at the Harvard-Smithsonian Center for Astrophysics. Astronomers can't see such planets directly, even with the most powerful telescopes. They are too small compared with the stars they orbit, and they generate no light of their own.