28
Dec 10

Galileo pathfinder GIOVE-A achieves five years in orbit

Source: ESA

ESA’s GIOVE-A satellite – the first prototype of Europe’s Galileo satellite navigation system – is still working well after five years in space.

The first ‘Galileo In-Orbit Validation Element’, GIOVE-A, was launched on 28 December 2005 by a Soyuz rocket from Baikonur in Kazakhstan, carrying a prototype rubidium atomic clock designed for the Galileo constellation.(read more)

It was joined on 27 April 2008 by GIOVE-B, equipped with an ultra-precise passive hydrogen maser design as well as a second rubidium clock. Operational Galileo satellites will carry both clock designs for maximum reliability.

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28
Dec 10

Sun layers by SOHO

Source: ESA/ESTEC/SOHO

The SOHO team has released a composite image of the Sun that reveales several layers of the star that heats our planet.

One can virtually peer through layers of the Sun to see different kinds of features using images taken at almost the same time (Dec. 19, 2010). Each STEREO spacecraft images the Sun in four wavelengths of extreme UV light.

People cannot see UV light, but carefully designed instruments can. Frames from each wavelength are colorized so that scientists know instantly which wavelength they are observing. And each wavelength is imaging different material at different layers and temperatures.

By superimposing images on top of one another, and moving from the just above the Sun to further out in the Sun's outer atmosphere, we can illustrate how different features are revealed.

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28
Dec 10

Beautiful Supernova Bubble

Source: NASA/Chandra (Image Release)


SNR 0509-67.5
Credits: X-ray: NASA/CXC/SAO/J.Hughes et al.
Optical: NASA/ESA/Hubble Heritage Team (STScI/AURA)

This colorful creation was made by combining data from two of NASA's Great Observatories. Optical data of SNR 0509-67.5 and its accompanying star field, taken with the Hubble Space Telescope, are composited with X-ray energies from the Chandra X-ray Observatory. The result shows soft green and blue hues of heated material from the X-ray data surrounded by the glowing pink optical shell which shows the ambient gas being shocked by the expanding blast wave from the supernova. Ripples in the shell's appearance coincide with brighter areas of the X-ray data.

The Type 1a supernova that resulted in the creation of SNR 0509-67.5 occurred nearly 400 years ago for Earth viewers. The supernova remnant, and its progenitor star reside in the Large Magellanic Cloud (LMC), a small galaxy about 160,000 light-years from Earth. The bubble-shaped shroud of gas is 23 light-years across and is expanding at more than 11 million miles per hour (5,000 kilometers per second).

Data from Hubble's Advanced Camera for Surveys, taken in 2006 with a filter that isolates light from glowing hydrogen were combined with visible-light images of the surrounding star field that were imaged with Hubble's Wide Field Camera 3 in 2010. These data were then merged with X-ray data from the Chandra X-ray Observatory taken with the Advanced CCD Imaging Spectrometer (ACIS) in 2000 and 2007.

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28
Dec 10

How Often do Giant Black Holes Become Hyperactive?

Source: NASA/Chandra


Composite images of galaxies Abell 644, left, and galaxy SDSS J1021+131.
Image credit: X-ray: NASA/CXC/Northwestern Univ/D.Haggard et al. Optical: SDSS

A new study from NASA's Chandra X-ray Observatory tells scientists how often the biggest black holes have been active over the last few billion years. This discovery clarifies how supermassive black holes grow and could have implications for how the giant black hole at the center of the Milky Way will behave in the future.

Most galaxies, including our own, are thought to contain supermassive black holes at their centers, with masses ranging from millions to billions of times the mass of the Sun. For reasons not entirely understood, astronomers have found that these black holes exhibit a wide variety of activity levels: from dormant to just lethargic to practically hyper.

The most lively supermassive black holes produce what are called "active galactic nuclei," or AGN, by pulling in large quantities of gas. This gas is heated as it falls in and glows brightly in X-ray light. (read more)

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