Archive for July 7, 2013

Intergalactic Magnifying Glasses Could Help Astronomers Map Galaxy Centres

An international team of astronomers may have found a new way to map quasars, the energetic and luminous central regions typically found in distant galaxies. Team leader Prof. Andy Lawrence of the Royal Observatory Edinburgh presents the new results on Monday 1 July at the RAS National Astronomy Meeting in St Andrews, Scotland.

If a star passes too close to a giant black hole found in the centre of a galaxy, it will be shredded by the strong gravitational field. This should produce a flare-up in the brightness of an otherwise normal looking galaxy that then fades over a few months. In a large scale survey Prof. Lawrence and his team studied galaxies to search for this effect, finding flare-ups but with very different behaviour to predictions.

In the new survey, the quasars are typically around 8 billion light years away, whereas the galaxies that host them are 3.4 billion light years distant. It could be that the estimated galaxy distances are wrong and that the black holes in the centre of the galaxies have flared up dramatically. But past studies of thousands of well known quasars have never shown events on this scale.

If however the estimated galaxy distances are right, then Prof. Lawrence and his team believe they are looking at a distant quasar through a foreground galaxy. Normally this has little effect on the light of the quasar, but if a single star in the foreground galaxy passes exactly in front of the quasar, it can produce a gravitational focusing of the light which makes the background quasar seem temporarily much brighter.

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UCSB Astronomer Uncovers The Hidden Identity Of An Exoplanet

Hovering about 70 light-years from Earth –– that’s “next door” by astronomical standards –– is a star astronomers call HD 97658, which is almost bright enough to see with the naked eye. But the real “star” is the planet HD 97658b, not much more than twice the Earth’s diameter and a little less than eight times its mass. HD 97658b is a super-Earth, a class of planet for which there is no example in our home solar system.

While the discovery of this particular exoplanet is not new, determining its true size and mass is, thanks to Diana Dragomir, with the UC Santa Barbara-affiliated Las Cumbres Observatory Global Telescope (LCOGT) network. Dragomir is also a UCSB astronomer from the Department of Physics. As part of her research, Dragomir looked for transits of this exoplanet with Canada’s Microvariability & Oscillations of Stars (MOST) space telescope. The telescope was launched in 2003 to a pole-over-pole orbit about 510 miles high. Dragomir analyzed the data using code written by LCOGT postdoctoral fellow Jason Eastman. The results were published online today in the Astrophysical Journal Letters.

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Revolutionary Instrument Delivers A Sharper Universe To Astronomers

Credit: Gemini Observatory/AURA

Credit: Gemini Observatory/AURA

Astronomers recently got their hands on Gemini Observatory’s revolutionary new adaptive optics system, called GeMS, “and the data are truly spectacular!” says Robert Blum, Deputy Director of the National Optical Astronomy Observatory with funding by the U.S. National Science Foundation. “What we have seen so far signals an incredible capability that leaps ahead of anything in space or on the ground – and it will for some time.” Blum is currently using GeMS to study the environments in and around star clusters, and his preliminary data, targeting the spectacular cluster identified as RMC 136, are among a set of seven images released today. The remaining six images –– spanning views of violent star-forming regions, to the graceful interaction of distant colliding galaxies –– only hint at the diversity of cutting-edge research that GeMS enables.

After more than a decade in development, the system, now in regular use at the Gemini South telescope in Chile, is streaming ultrasharp data to scientists around the world – providing a new level of detail in their studies of the universe. The images made public today show the scientific discovery power of GeMS (derived from the Gemini Multi-conjugate adaptive optics System), which uses a potent combination of multiple lasers and deformable mirrors to remove atmospheric distortions (blurriness) from ground-based images.

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New Insights Concerning The Early Bombardment History On Mercury

The surface of Mercury is rather different from those of well-known rocky bodies like the Moon and Mars. Early images from the Mariner 10 spacecraft unveiled a planet covered by smooth plains and cratered plains of unclear origin. A team led by Dr. Simone Marchi, a Fellow of the NASA Lunar Science Institute located at the Southwest Research Institute (SwRI) Boulder, Colo., office, collaborating with the MESSENGER team, including Dr. Clark Chapman of the SwRI Planetary Science Directorate, studied the surface to better understand if the plains were formed by volcanic flows or composed of material ejected from the planet’s giant impact basins.

Recent images from NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft provided new insights showing that at least the younger plains resulted from vigorous volcanic activity. Yet scientists were unable to establish limits on how far into the past this volcanic activity may have occurred, or how much of the planet’s surface may have been resurfaced by very old volcanic plains.

“By comparing the measured craters to the number and spatial distribution of large impact basins on Mercury, we found that they started to accumulate at about the same time, suggesting that the resetting of Mercury’s surface was global and likely due to volcanism,” said lead author Dr. Simone Marchi, who has a joint appointment between two of NASA’s Lunar Science Institutes, one at the SwRI in Boulder and another at the Lunar and Planetary Institute in Houston.

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