Archive for July, 2013

Capturing Black Hole Spin Could Further Understanding Of Galaxy Growth

Artist’s impression. Image credit: NASA/JPL-Caltech

Artist’s impression. Image credit: NASA/JPL-Caltech

Astronomers have found a new way of measuring the spin in supermassive black holes, which could lead to better understanding about how they drive the growth of galaxies.

The scientists at Durham University, observed a black hole – with mass 10 million times that of our Sun – at the centre of a spiral galaxy 500 million light years from Earth while it was feeding on the surrounding disc of material that fuels its growth and powers its activity.

By viewing optical, ultra-violet and soft x-rays generated by heat as the black hole fed, they were able to measure how far the disc was from the black hole.

This distance depends on black hole spin as a fast spinning black hole pulls the disc in closer to itself, the researchers said. Using the distance between the black hole and the disc, the scientists were able to estimate the spin of the black hole.

The scientists said that understanding spin could lead to greater understanding of galaxy growth over billions of years.

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This Is Your Galaxy: New Data Help Astronomers Explore The Hidden Milky Way

Today, astronomers with the Sloan Digital Sky Survey III (SDSS-III) released a new online public data set featuring 60,000 stars that are helping to tell the story of how our Milky Way galaxy formed.

The highlight of today’s “Data Release 10” is a new set of high-resolution stellar spectra — measurements of the amount of light given off by a star at each wavelength — using infrared light, invisible to human eyes but able to penetrate the veil of dust that obscures the center of the Galaxy.

“This is the most comprehensive collection of infrared stellar spectra ever made,” said Steven Majewski of the University of Virginia, the lead scientist for the APOGEE project. “Sixty thousand stars is almost ten times more high-resolution infrared stellar spectra than have ever been measured before, by all the world’s telescopes. Selected from all the different parts of our galaxy, from the nearly-empty outskirts to the dust-enshrouded center, these spectra are allowing us to peel back the curtain on the hidden Milky Way.”

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NASA’s Chandra Sees Eclipsing Planet In X-rays For First Time

For the first time since exoplanets, or planets around stars other than the sun, were discovered almost 20 years ago, X-ray observations have detected an exoplanet passing in front of its parent star.

An advantageous alignment of a planet and its parent star in the system HD 189733, which is 63 light-years from Earth, enabled NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM Newton Observatory to observe a dip in X-ray intensity as the planet transited the star.

“Thousands of planet candidates have been seen to transit in only optical light,” said Katja Poppenhaeger of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led a new study to be published in the Aug. 10 edition of The Astrophysical Journal. “Finally being able to study one in X-rays is important because it reveals new information about the properties of an exoplanet.”

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Comet Of The Century? Not Yet!

On September 2nd, 2012, two Russian astronomers discovered a comet designated as C/2012 S1 ISON. When the orbit was calculated, astronomers realized that the object would pass at only 1.3 solar radii from the Sun on November 28th, 2013. Numerous press articles contended that the object would be as bright as the full Moon and that in fact it could become “the comet of the century”.

Dr. Ignacio Ferrin, Astronomer from the Institute of Physics of the University of Antioquia, in Medellín, Colombia, has concluded a study of the comet, using the latest observations available. Dr. Ferrin is a researcher and Faculty Member in the Astronomy Program of that Institute. He is a recognized cometary specialist.

“Comet ISON has presented a peculiar behavior”, said Dr. Ferrín. “The light curve has exhibited a “slowdown event” characterized by a constant brightness with no indication of a brightness increase tendency. This slowdown took place around January 13th, 2013. For 132 days after that date and up to the last available observation, the brightness has remained constant”. Thus the astronomer concludes that it is highly unlikely that the comet will be as bright as the full Moon.

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The Largest Magnetic Fields In The Universe

An ultra-dense (“hypermassive”) neutron star is formed when two neutron stars in a binary system finally merge. Its short life ends with the catastrophic collapse to a black hole, possibly powering a short gamma-ray burst, one of the brightest explosions observed in the universe. Short gamma-ray bursts as observed with satellites like XMM Newton, Fermi or Swift release within a second the same amount of energy as our Galaxy in one year. It has been speculated for a long time that enormous magnetic field strengths, possibly higher than what has been observed in any known astrophysical system, are a key ingredient in explaining such emission. Scientists at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) have now succeeded in simulating a mechanism which could produce such strong magnetic fields (stronger than ten or hundred million billion times the Earth’s magnetic field)* prior to the collapse to a black hole.

* Strength inserted from elsewhere in the story.

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A New Baby Picture Of The Universe

THIS SPRING, HUMANITY WAS SHOWN ITS MOST DETAILED MAP of the early universe ever created. Generated by observations from the Planck spacecraft, the map shows fluctuations in temperature in the relic radiation left over from the Big Bang – the moment when space and time came into existence nearly 14 billion years ago. That relic radiation, a kind of afterglow from the Big Bang, is called the cosmic microwave background, or CMB. It streams toward Earth from everywhere in the sky, and it provides a snapshot of what the universe looked like when the CMB was generated 380,000 years after the Big Bang.

Recently, scientists on the Planck team found certain large-scale features on the CMB sky, which they called “anomalies,” that they cannot explain. One of them, for example, is a large cold spot, which corresponds to an anomalously large area of high density. What this means: the theory for how the universe began may need to be modified, amended or even fundamentally changed. In any of these cases, the result will be consequential to how we understand the evolution of existence.

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Galaxies, Comets, And Stars! Oh My!

Comet ISON. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Comet ISON. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

The sun-approaching Comet ISON floats against a seemingly infinite backdrop of numerous galaxies and a handful of foreground stars. The icy visitor, with its long gossamer tail, appears to be swimming like a tadpole through a deep pond of celestial wonders.

In reality, the comet is much, much closer. The nearest star to the Sun is over 60,000 times farther away, and the nearest large galaxy to the Milky Way is over thirty billion times more distant. These vast dimensions are lost in this deep space Hubble exposure that visually combines our view of the universe from the very nearby to the extraordinarily far away.

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