Archive

Archive for April, 2014

Astro Pro-Am: Professional And Amateur Astronomers Join Forces


Credit: X-ray: NASA/CXC/SAO; Optical: Detlef Hartmann; Infrared: NASA/JPL-Caltech

Credit: X-ray: NASA/CXC/SAO; Optical: Detlef Hartmann; Infrared: NASA/JPL-Caltech

Long before the term “citizen science” was coined, the field of astronomy has benefited from countless men and women who study the sky in their spare time. These amateur astronomers devote hours exploring the cosmos through a variety of telescopes that they acquire, maintain, and improve on their own. Some of these amateur astronomers specialize in capturing what is seen through their telescopes in images and are astrophotographers.

What happens when the work of amateur astronomers and astrophotographers is combined with the data from some of the world’s most sophisticated space telescopes? Collaborations between professional and amateur astronomers reveal the possibilities and are intended to raise interest and awareness among the community of the wealth of data publicly available in NASA’s various mission archives. This effort is particularly appropriate for this month because April marks Global Astronomy Month, the world’s largest global celebration of astronomy.

The images in this quartet of galaxies represent a sample of composites created with X-ray data from NASA’s Chandra X-ray Observatory, infrared data from the Spitzer Space Telescope, and optical data collected by an amateur astronomer.

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Astronomical Forensics Uncover Planetary Disks In NASA’s Hubble Archive


Image Credit: NASA/ESA, R. Soummer, Ann Feild (STScI)

Image Credit: NASA/ESA, R. Soummer, Ann Feild (STScI)

Astronomers using NASA’s Hubble Space Telescope have applied a new image processing technique to obtain near-infrared scattered light photos of five disks observed around young stars in the Mikulski Archive for Space Telescopes database. These disks are telltale evidence for newly formed planets.

If astronomers initially miss something in their review of data, they can make new discoveries by revisiting earlier data with new image processing techniques, thanks to the wealth of information stored in the Hubble data archive. This is what Rémi Soummer, of the Space Telescope Science Institute (STScI) in Baltimore, Md., and his team recently did while on a hunt for hidden Hubble treasures.

The stars in question initially were targeted with Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) based on unusual heat signatures obtained from NASA’s Spitzer Space Telescope and the Infrared Astronomical Satellite that flew in 1983. The previous data provided interesting clues that dusty disks could exist around these stars. Small dust particles in the disks might scatter light and therefore make the disks visible. But when Hubble first viewed the stars between 1999 and 2006, no disks were detected in the NICMOS pictures.

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‘Upside-Down Planet’ Reveals New Method For Studying Binary Star Systems


Simulation. Credit: NASA

Simulation. Credit: NASA

What looked at first like a sort of upside-down planet has instead revealed a new method for studying binary star systems, discovered by a University of Washington student astronomer.

Working with UW astronomer Eric Agol, doctoral student Ethan Kruse has confirmed the first “self-lensing” binary star system — one in which the mass of the closer star can be measured by how powerfully it magnifies light from its more distant companion star. Though our sun stands alone, about 40 percent of similar stars are in binary (two-star) or multi-star systems, orbiting their companions in a gravitational dance.

Kruse’s discovery confirms an astronomer’s prediction in 1973, based on stellar evolution models of the time, that such a system should be possible. A paper by Kruse and Agol was published in the April 18 edition of Science.

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A Dance Of Black Holes


Artist’s impression of a pair of black holes.  © ESA/C. Carreau

Artist’s impression of a pair of black holes. © ESA/C. Carreau

A pair of supermassive black holes in orbit around one another have been discovered by an international research team including Stefanie Komossa from the Max Planck Institute for Radio Astronomy in Bonn, Germany. This is the first time such a pair could be found in an ordinary galaxy. They were discovered because they ripped apart a star when ESA’s space observatory XMM-Newton happened to be looking in their direction.

The findings are published in the May 10 issue of the “Astrophysical Journal”, and appeared online today at the astrophysics preprint server.

Most massive galaxies in the Universe are thought to harbour at least one supermassive black hole at their centre. Two supermassive black holes are the smoking gun that the galaxy has merged with another. Thus, finding binary supermassive black holes can tell astronomers about how galaxies evolved into their present-day shapes and sizes.

To date, only a few candidates for close binary supermassive black holes have been found. All are in active galaxies where they are constantly ripping gas clouds apart, in the prelude to crushing them out of existence.

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NOAO: A Sharp Eye On Southern Binary Stars


Unlike our sun, with its retinue of orbiting planets, many stars in the sky orbit around a second star. These binary stars, with orbital periods ranging from days to centuries, have long been the primary tool for measuring basic quantities like the star’s mass. While masses of normal stars are now well determined, some binaries present special interest because their stars are unusual (e.g. very young) or because they may contain planets, gas clouds, or other stars.

Now, astronomers at the Cerro Tololo Inter-American Observatory (CTIO) and at the US Naval Observatory (USNO) are making use of the latest technology, speckle imaging, to measure the separation of close binary stars. By observing them over a period of years, their obits have been determined with exquisite precision.

Using the new speckle camera at the 4.1-m Southern Astrophysical Research Telescope (SOAR) in Chile with its novel electron-multiplication CCD detector, the team is able to measure the angular separation of stars down to 25 milli arcseconds: this is equivalent to measuring the size of a quarter atop the Empire State building in New York – from Washington, DC. This is over 2000 times better than the human eye can resolve. As Dr. Andrei Tokovinin, the lead author on the paper, said: “This camera surpasses adaptive-optics instruments at the 8-m telescopes, which work in the infrared and can only resolve binaries wider than 50 milli arcseconds.“

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Meteorites Yield Clues To Red Planet’s Early Atmosphere


Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks. Their study, published April 17 in the journal Nature, shows that the atmospheres of Mars and Earth diverged in important ways very early in the 4.6 billion year evolution of our solar system.

Heather Franz, a former University of Maryland research associate who now works on the Curiosity rover science team at the NASA Goddard Space Flight Center, led the study with James Farquhar, co-author and UMD geology professor. The researchers measured the sulfur composition of 40 Mars meteorites—a much larger number than in previous analyses. Of more than 60,000 meteorites found on Earth, only 69 are believed to be pieces of rocks blasted off the Martian surface.

The meteorites are igneous rocks that formed on Mars, were ejected into space when an asteroid or comet slammed into the red planet, and landed on Earth. The oldest meteorite in the study is about 4.1 billion years old, formed when our solar system was in its infancy. The youngest are between 200 million and 500 million years old.

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Press Release: Computers Beat Brainpower In Counting Stars


A team of University of Sydney astronomers has developed a new way to automatically classify huge numbers of astronomical objects, and to discover new, exotic ones almost as soon as they happen.

Massive torrents of raw data are now collected by telescopes on a daily basis creating an urgent need to massively accelerate the reliable classification of millions of stars and galaxies, and to quickly highlight objects that might be new discoveries or that have unusual properties.

“Next generation telescopes like the Square Kilometre Array will produce enough raw data to fill up 15 million iPods every day,” said Kitty Lo, lead author of the research published in The Astrophysical Journal.

“It will be too much for humans to sift through, and this is where computer classification comes in,” said Ms Lo.

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The Laws That Determine How Dust Affects The Light That Reaches Us From The Stars Are Being Rewritten


Credit: NASA, N. Walborn, J. Maíz-Apellániz and R. Barbá

Credit: NASA, N. Walborn, J. Maíz-Apellániz and R. Barbá

If the space traversed by light to reach our eyes were empty, knowing the properties of a star could be as simple as taking a picture of it and measuring its glow (something known as photometry). But the interstellar environment is strewn with dust that absorbs and scatters light, making objects look less luminous and redder—or colder—than they actually are. A recently published paper makes it possible, at last, to correct this distorting effect adequately.

“In the range of wavelengths that our eyes perceive -the visible light- of every billion photons that a star in the centre of the Milky Way emits, only one reaches our eyes,” says Jesús Maíz Apellániz, researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) in charge of the publication. “This is an extreme example of how dust affects the light of stars, a phenomenon that takes place in every single environment, albeit with less intensity.”

The effect of dust, then, must be reckoned with in any astronomical observation before trying to extract the characteristics of an object. Maíz Apellániz, together with an international team of collaborators, showed that the laws used since 1989 to calculate the extinction of light produced by dust had serious limitations and yielded, among others, erroneous temperature estimates for stars. So they took it upon themselves to change those laws.

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Beauty From Chaos


Copyright ESA/DLR/FU Berlin

Copyright ESA/DLR/FU Berlin

Beautiful streamlined islands and narrow gorges were carved by fast-flowing water pounding through a small, plateau region near the southeastern margin of the vast Vallis Marineris canyon system.

Images captured on 7 December 2013 by ESA’s Mars Express show the central portion of Osuga Valles, which has a total length of 164 km. It is some 170 km south of Eos Chaos, which lies in the far eastern section of Valles Marineris.

Osuga Valles is an outflow channel that emanates from a region of chaotic terrain at the edge of Eos Chaos to the west (top in the main images). Such landscape is dominated by randomly oriented and heavily eroded blocks of terrain. Another example is seen at the bottom of this scene, filling the 2.5 km-deep depression into which Osuga Valles empties.

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Faraway Moon Or Faint Star? Possible Exomoon Found


Titan, Europa, Io and Phobos are just a few members of our solar system’s pantheon of moons. Are there are other moons out there, orbiting planets beyond our sun?

NASA-funded researchers have spotted the first signs of an “exomoon,” and though they say it’s impossible to confirm its presence, the finding is a tantalizing first step toward locating others. The discovery was made by watching a chance encounter of objects in our galaxy, which can be witnessed only once.

“We won’t have a chance to observe the exomoon candidate again,” said David Bennett of the University of Notre Dame, Ind., lead author of a new paper on the findings appearing in the Astrophysical Journal. “But we can expect more unexpected finds like this.”

The international study is led by the joint Japan-New Zealand-American Microlensing Observations in Astrophysics (MOA) and the Probing Lensing Anomalies NETwork (PLANET) programs, using telescopes in New Zealand and Tasmania. Their technique, called gravitational microlensing, takes advantage of chance alignments between stars. When a foreground star passes between us and a more distant star, the closer star can act like a magnifying glass to focus and brighten the light of the more distant one. These brightening events usually last about a month.

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