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The Older We Get, The Less We Know (Cosmologically)

May 23, 2012
The universe is a marvelously complex place, filled with galaxies and larger-scale structures that have evolved over its 13.7-billion-year history. Those began as small perturbations of matter that grew over time, like ripples in a pond, as the universe expanded. By observing the large-scale cosmic wrinkles now, we can learn about the initial conditions of the universe. But is now really the best time to look, or would we get better information billions of years into the future - or the past?

New calculations by Harvard theorist Avi Loeb show that the ideal time to study the cosmos was more than 13 billion years ago, just about 500 million years after the Big Bang. The farther into the future you go from that time, the more information you lose about the early universe.

CFA Press Release

Black hole caught in a feeding frenzy

May 17, 2012

Scientists were able to observe the demise of a star and its digestion by a previously dormant supermassive black hole in real time. f a star passes too close to a black hole, tidal forces can rip it apart, and its constituent gases then swirl in toward the black hole. Friction heats the gases and causes them to glow. By searching for newly glowing supermassive black holes, astronomers can spot them in the midst of a feast. Harvard Professor Edo Berger is a co-author on this study. 

Read more at Astronomy Magazine or read the CFA press release

Credit: NASA/S. Gezari (JHU)/A. Rest (STScI)/R. Chornock (Harvard-Smithsonian CfA)

One supernova type, two different sources

May 17, 2012

The Tycho supernova remnant is the result of a Type Ia supernova explosion. The explosion was observed by Danish astronomer Tycho Brahe in 1572. More than 400 years later, the ejecta from that explosion has expanded to fill a bubble 55 light-years across. In this image, low-energy X-rays (red) show expanding debris from the supernova explosion and high energy X-rays (blue) show the blast wave - a shell of extremely energetic electrons. Credit: X-ray: NASA/CXC/Rutgers/K.Eriksen et al.; Optical: DSS

CFA Clay Fellow R. Foley and Harvard Astronomy Professor R. Kirshner publish new findings. The exploding stars known as Type Ia supernovae serve an important role in measuring the universe, and were used to discover the existence of dark energy. They're bright enough to see across large distances, and similar enough to act as a "standard candle" - an object of known luminosity. The 2011 Nobel Prize in Physics was awarded for the discovery of the accelerating universe using Type Ia supernovae. However, an embarrassing fact is that astronomers still don't know what star systems make Type Ia supernovae.

See this article in

CFA Press Release

Rating research risk - Nature Jobs by Abraham Loeb

April 12, 2012

In physics, the value of a theory is measured by how well it agrees with experimental data. But how should the physics community gauge the value of an emerging theory that cannot yet be tested experimentally? With no reality check, a less than rigorous hypothesis such as string theory may linger on, even though physicists have been unable to work out its actual value in describing nature.

Nature Article by Abraham Loeb

Shooting for the Stars

March 29, 2012

A vibrant online astronomy community created by PhD students highlights new research and advice for professional growth. 

Among the founders and contributors of Astrobites are, from left, Aaron Bray (G2), Elisabeth Newton (G2), Nathan Sanders (G2), Joshua Suresh (G2), Christopher Faesi (G1), and Courtney Dressing (G2), here pictured on their home turf, the observatory at 60 Garden Street.

GSAS Article

Astrobites Website

Planet Starship: Runaway Planets Zoom at a Fraction of Light-Speed

March 24, 2012

Cambridge, MA - Seven years ago, astronomers boggled when they found the first runaway star flying out of our Galaxy at a speed of 1.5 million miles per hour. The discovery intrigued theorists, who wondered: If a star can get tossed outward at such an extreme velocity, could the same thing happen to planets?

New research shows that the answer is yes. Not only do runaway planets exist, but some of them zoom through space at a few percent of the speed of light - up to 30 million miles per hour.

CFA Press Release

Time Magazine


Using galaxies as yardsticks Astronomy Professor Daniel Eisenstein builds a 3-D map of universe

March 6, 2012

Stephanie Mitchell/Harvard Staff Photographer

Daniel Eisenstein is investigating the universe, using galaxies as his ruler, seeking to understand the cosmos’ large-scale structure and confirm theories about the dark energy that drives its expansion. Read more in this Harvard Gazette Article: Using galaxies as yardsticks Astronomy Professor Daniel Eisenstein builds a 3-D map of universe.

... Read more about Using galaxies as yardsticks Astronomy Professor Daniel Eisenstein builds a 3-D map of universe

Synopsis: Tidal Disruption of a Star (N. Stone and A. Loeb)

February 9, 2012

NASA/Goddard Space Flight Center/Swift

The cores of most galaxies are thought to harbor black holes with masses of a million or more suns. But many remain unseen until an unlucky star passes too close and is pulled apart by tidal forces. The stellar debris gathers into a disk and spirals towards the black hole in the center. As it does, it may form a jet of material that beams high-energy light like a flashlight. Last spring, the Swift satellite measured a flare of x rays and gamma rays from a distant galaxy that has the hallmarks of such a jet that happens to point right at us.... Read more about Synopsis: Tidal Disruption of a Star (N. Stone and A. Loeb)

Tough Science: Five Experiments as Hard as Finding the Higgs - feature Astronomy Alumni

January 10, 2012

This article appeared in Nature magazine entitled "Tough Science: Five Experiments as Hard as Finding the Higgs," by science writer Nicola Jones,The five projects with highlighted researchers that he selected are:

NASA’s Kepler Spacecraft Announces Two Earth-Size Planets Are Discovered

December 21, 2011

Astronomers from NASA’s Kepler spacecraft announced Tuesday that they had discovered a pair of planets the size of Earth orbiting a distant star. The new planets, one about as big as Earth and the other slightly smaller than Venus, are the smallest yet found beyond the solar system. Harvard Astronomy Professor David Charbonneau was a member of the team that made the observations, led by his colleague Francois Fressin.... Read more about NASA’s Kepler Spacecraft Announces Two Earth-Size Planets Are Discovered

Is There a City on Pluto? Before You Answer, Consider: We've Never Looked.

November 10, 2011

Link to Time Magazine article

Before Ed Turner and Avi Loeb tell you about their research, they want to make one thing perfectly clear: they do not claim there's a city on Pluto. But if there were, they say, we could see it. And, as they suggest in a paper they've submitted to the journal Astrobiology, it's worth taking a look, just in case.

... Read more about Is There a City on Pluto? Before You Answer, Consider: We've Never Looked.

Searching for the origins of life... and our future (BBC News)

November 8, 2011

By Karen Weintraub Cambridge, Massachusetts
November 8, 2011

Hollywood is wrong about aliens. They don't have oddly shaped
heads, bulging eyes or even an eery green hue. Dimitar Sasselov is
pretty convinced of that.

He's not even sure we'll know them when we see them. Prof
Sasselov, an astrophysicist, thinks that if life exists elsewhere - and
he believes it does - it will likely be based on different building
blocks than ours, and so may not even be recognizable as life.

A project he's heading at Harvard University, called the Origins of...

Read more about Searching for the origins of life... and our future (BBC News)