Discovery – Page 14 – A Darker View

Keck Observatory Astronomer Wins Top Award

A Keck Observatory astronomer who led the way to the discovery of a super-massive black hole at the center of our galaxy has been recognized this week with the 2012 Crafoord Prize in Astronomy, an award almost as prestigious for astronomers as a Nobel Prize.

“This is a big one. I’m thrilled,” said Andrea Ghez of the University of California at Los Angeles. For more than 16 years Ghez and her team have been pushing the frontiers of high-resolution imaging technologies with the twin 10-meter Keck telescopes in order to explore the center of the Milky Way. By tracking the rapid, small-scale orbits of stars at the Galactic Center, they discovered the presence of a source of tremendous gravity – the best evidence yet that a supermassive black hole exists there. The reality of such an object confronts and challenges our knowledge of fundamental physics.

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Most Distant Dwarf Galaxy Detected

W. M. Keck Observatory Press Release…

Scientists have long struggled to detect the dim dwarf galaxies that orbit our own galaxy. So it came as a surprise on Jan. 18 when a team of astronomers using Keck II telescope’s adaptive optics has announced the discovery of a dwarf galaxy halfway across the universe.

The new dwarf galaxy found by MIT’s Dr. Simona Vegetti and colleagues is a satellite of an elliptical galaxy almost 10 billion light-years away from Earth. The team detected it by studying how the massive elliptical galaxy, called JVAS B1938 + 666, serves as a gravitational lens for light from an even more distant galaxy directly behind it. Their discovery was published in the Jan. 18 online edition of the journal Nature.

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Small Solar System Found

For years the search for exoplanets has largely been like Gulliver’s visit to Brobdingnag: colossal systems of giant gas planets orbiting mammoth stars. But astronomers have finally landed on the shores of Lilliput. They have found a tiny star with three puny planets, each smaller than Earth, zooming around it.

The three small exoplanets orbit a star called KOI-961. Their radii are calculated to be 78, 73 and 57 percent that of Earth. The sizes of the planets were worked out by Kepler Telescope observations that measured the dimming of the star KOI-961 as each planet passes in front of it. This plus crucial information about the star from Keck and Palomar telescopes enabled researchers to determine the sizes of the planets.

Although the masses of the three planets are unknown, they are suspected of being rocky, like Earth, Venus, Mars and Mercury. But they orbit too close to their star to be in the habitable zone where liquid water could exist. The three planets take less than two days to orbit around KOI-961, which is a red dwarf with a diameter one-sixth that of our sun, making it just 70 percent bigger than Jupiter.

“This is the tiniest solar system found so far,” said John Johnson, the principal investigator of the research from NASA’s Exoplanet Science Institute at the California Institute of Technology in Pasadena. “It’s actually more similar to Jupiter and its moons in scale than any other planetary system. The discovery is further proof of the diversity of planetary systems in our galaxy.”

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Keck and a Nobel Prize

We are celebrating a bit at Keck today. It is somewhat unusual for an astronomer to be awarded the Nobel Prize in Physics. Today it was announced that three astronomers will share the award for their work in cosmology. Saul Perlmutter, Brian Schmidt, and Adam Riess led a pair of teams that were investigating the expansion of the universe through observing type Ia supernovae. Saul Perlmutter led the Supernova Cosmology Project, while Brian Schmidt and Adam Riess led a separate group, the High-Z Supernova Search, performing nearly identical work.

Both teams discovered something disturbing in the data. The expansion of our universe appeared not to be slowing as astronomers expected, but actually accelerating. The result, had both teams scrambling to understand the data, checking and triple checking everything in an attempt to see where they had gone wrong in their analysis. When each team finally published they were glad to see that they were not alone, that another group had independently confirmed this unexpected discovery.

A couple decades later we have come to accept this result as further data has accumulated. We now understand that there is another element of the universe that had not been appreciated before. What the astronomers had found was the effects of something that had been hinted at in a number of physicists theories (including Einstein), something we now call Dark Energy.

SN2011fe in M101 — Type Ia supernova, SN2011fe, in the galaxy M101

The teams used a number of different telescopes in a coordinated effort to both discover and then obtian the spectral data on the supernovae. Smaller telescopes would be used to discover the supernovae, searching wide swaths of sky looking for these rare events. Then the team would use large telescopes, like Keck, to gather the spectral data of the supernovae. The spectra would confirm the event as a type Ia supernova and give the redshift.

The most critical data, the spectra of the furthest and faintest supernovae, were made possible by the Keck telescopes, then the largest in the world. It is these most distant objects where the effect of our universe’s accelerated expansion is most noticeable. Looking through the tables of data in the original scientific papers, the Keck Observatory is often credited.

It is somewhat unfortunate that only a few individuals are named with a Nobel Prize. The discovery of dark energy and the acceleration of the expansion was an effort made by teams of individuals. Both supernovae search teams and all the members deserve real recognition for this. In turn their efforts depended on the staffs of the observatories that made the observations possible. Big discoveries are rarely made by individual scientists, but by the cooperative effort of many. There are only three names on the Nobel Prize, but a lot of folks are celebrating today.

Titan before Rings

A world shrouded in hydrocarbon smog, where there are rivers and lakes collecting methane rain. Despite numerous flybys of the Cassini spacecraft and landing of Huygens probe on the surface, Titan remains a very mysterious world. A thick atmosphere and exotic chemistries create conditions that might even harbor some form of life.

Taken from this angle, the view looks toward the side of Titan that always faces away from Saturn. Keep in mind that Titan is 5,150 kilometers (3,200 miles across), much smaller than the Earth, but quite a bit larger than our Moon. The image was taken with the Cassini spacecraft narrow-angle camera on Aug. 9, 2011 using a spectral filter sensitive to wavelengths of near-infrared light centered at 938 nanometers. The view was acquired at a distance of approximately 1.4 million kilometers (870,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 35 degrees. Image scale is 8 kilometers (5 miles) per pixel.

Titan before Rings — Saturn’s large moon, Titan, with edge-on rings seen behind, image taken 9Aug2011, acquired by the Cassini narrow angle camera and a 938nm infrared filter, credit NASA/JPL-Caltech/Space Science Institute

Nobel Prize in Physics Awarded for Accelerating Expansion of the Universe

W.M. Keck Press Release…

The expansion of the universe is accelerating, and this is likely driven by dark energy, a mysterious repulsive force. Three astronomers won the Nobel prize on Tuesday for their research on exploding stars, or supernovae, that led to this profound cosmological conclusion. They are Saul Perlmutter of the Lawrence Berkeley National Laboratory in Berkeley, California, Brian P. Schmidt of the Australian National University in Weston Creek, Australia, and Adam G. Riess of the Space Telescope Science Institute and Johns Hopkins University in Baltimore, Maryland. Their discovery relied fundamentally on spectroscopy using the W. M. Keck Observatory and its LRIS spectrograph, in the period 1995 to 1997.

Perlmutter, Schmidt and Riess were members of two competing teams who were both studying the most distant supernovae. These Type Ia supernovae have been demonstrated to be “standard candles” and can thus yield relatively precise cosmological distances. The Keck spectra of the extremely distant supernova candidates were essential in order to indicate they are Type Ia, and to determine the redshift, or its velocity as seen from Earth, of the galaxy hosting the supernova. It was the redshifts and distances of a modest number of distant supernovae that revealed that the expansion of the universe was not slowing down, as was predicted, but in fact was inexplicably speeding up. The accelerating expansion of the Universe, first reported in 1998, was confirmed by the two separate groups. This accelerating cosmological expansion and the hypothesis that it is driven by dark energy has now become one of the most important areas of study in astronomy and physics today.

At the time, “We were a little scared,” Schmidt said. Subsequent cosmological measurements have confirmed that roughly 70 percent of the universe by mass or energy consists of this anti-gravitational force called dark energy.

In fact, Albert Einstein introduced this bizarre behavior with a fudge factor in his equations in 1917 to stabilize the universe against collapse. He later abandoned this idea, and then considered it his greatest blunder. “Every test we have made has come out perfectly in line with Einstein’s original cosmological constant in 1917,” Schmidt said.

In the years since then the three astronomers, along with their collaborators, have shared a number of awards, including the Shaw Prize in Astronomy, for this ground breaking research.

Perlmutter, who led the Supernova Cosmology Project out of Berkeley, will get half of the prize of 10 million Swedish kronor ($1.4 million). The other half will be shared between Dr. Schmidt, leader of the rival High-Z Supernova Search Team, and Riess, who was the lead author of the 1998 paper in The Astronomical Journal, in which the dark energy result was first published. They will receive their prizes in Stockholm on December 10.

“The recognition by the Nobel Committee of the importance of this work validates the enormous value to our society of ground-based optical / infrared astronomy,” said Taft Armandroff, Director of the W. M. Keck Observatory. “By making our two Keck telescopes and their instruments work at the highest performance, transformational science like that of Saul Perlmutter, Brian Schmidt and Adam Riess happens.”

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system. The Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Neptune and Triton

Mike Brown did more than give a lecture while in Hawai’i. He just finished a four day observing run using Keck 2 with AO and OSIRIS, as well as gathering data with NIRSPEC. The target? Among other things Mike and his team observed Neptune and the large moon Triton. Triton is thought to be a captured KBO (Kuiper Belt Object). These objects, including well known Pluto, and lesser known, but just as large objects like Eris, Haumea, Makemake and Quaoar, are Mike’s area of expertise.

It is always nice to see a system I help maintain operating well and producing images like this…

Triton and Neptune — A Keck AO / OSIRIS photo of Neptune and the large moon Triton, credit Mike Brown/CalTech

Keck and Kepler Team Up to Find Other Earths

W. M. Keck Observatory press release…

For nearly a decade, Cal-Berkeley astronomer Geoff Marcy and his colleagues have been using the W. M. Keck telescopes to discover giant planets orbiting distant stars. Now, with the successful launch of NASA’s Kepler mission, they will be using Keck I’s ten-meter astronomical eye to discover distant Earths. Kepler will pick out Earth-like candidates. Keck will then zero in on them and determine, with certainty, if they are at all similar to our home planet.

“Keck and NASA have a long-standing partnership to push astronomy research to its fullest potential. This Keck-Kepler collaboration gives that partnership a compelling new scientific focus,” said Taft Armandroff, the Director of Keck Observatory headquartered in Kamuela, HI.

Kepler was launched from NASA’s Kennedy Space Center last Friday. Aboard the spacecraft is an 84-megapixel camera that will focus on a single region of the sky and snap repeated images of 100,000 stars looking for those that dim periodically. By studying the stars’ episodic decreases in starlight, astronomers will be able to determine the diameter of the object that passes in front of the star, blocks its light and causes the dimming.

“Kepler does not tell astronomers with certainty if the object taking a bite out of the starlight is a planet or another star. That is where Keck plays a crucial role to the Kepler mission,” said Marcy, a frequent Keck user and Kepler mission co-investigator. He, along with a large international planet-hunting team, has discovered nearly half of the 300-plus known planets outside the Solar System.

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