milky-way-galaxy

Have you ever seen the Southern Cross? This famous constellation is best seen from Earth’s Southern Hemisphere. Captured from Rio de Janeiro, Brazil, the four bright stars that mark the Southern Cross are visible just above the horizon in the featured image. On the left of this constellation, also known as The Crux, is the orange star Gamma Crucis. The band of stars, dust, and gas rising through the middle of the image mosaic is part our Milky Way Galaxy. Just to the right of the Southern Cross is the dark Coal Sack Nebula, and the bright nebula at the top of the image is the Carina Nebula. The Southern Cross is such a famous constellation that it is depicted on the national flag of Australia.

Object Names: Southern Cross

Image Type: Astronomical

Credit: Carlos Fairbairn

Time And Space

Triple-star System Passes near Milky Way’s Central Black Hole

This illustration shows one possible mechanism for how the star HE 0437-5439 acquired enough energy to be ejected from our Milky Way galaxy.In this scenario, a triple-star system, consisting of a close binary system and another outer member bound to the group, is orbiting near the galaxy’s monster black hole. One star is captured by the black hole and the tightly bound pair gets ejected from the galaxy. As the duo speeds through the galaxy, one member evolves more quickly and consumes the other. The resulting rejuvenated star, massive and very blue, is called a blue straggler.

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Galactic Center of Our Milky Way

The Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory – collaborated to produce an unprecedented image of the central region of our Milky Way galaxy.

Observations using infrared light and X-ray light see through the obscuring dust and reveal the intense activity near the galactic core. The center of the galaxy is located within the bright white region in the upper portion of the image. The entire image covers about one-half a degree, about the same angular width as the full moon.

Each telescope’s contribution is presented in a different color:

  • Yellow represents the near-infrared observations of Hubble. They outline the energetic regions where stars are being born as well as reveal hundreds of thousands of stars.
  • Red represents the infrared observations of Spitzer. The radiation and winds from stars create glowing dust clouds that exhibit complex structures from compact, spherical globules to long, stringy filaments.
  • Blue and violet represents the X-ray observations of Chandra. X-rays are emitted by gas heated to millions of degrees by stellar explosions and by outflows from the supermassive black hole in the galaxy’s center. The bright blue blob toward the bottom of the full field image is emission from a double star system containing either a neutron star or a black hole.
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Astronomers at the European Southern Observatory’s Paranal Observatory in Chile have released a breathtaking new photograph showing the central area of our Milky Way galaxy. The photograph shows a whopping 84 million stars in an image measuring 108500×81500, which contains nearly 9 billion pixels.

Crops of the zoomable version.

You’re looking at The Milky Way Galaxy, As Seen From a 747

Astrophotographer Alex Merga captured the image June 7th, while aboard a red-eye flight from New York to London. The incredible shot was taken while traveling at 600 mph from around 37,000 feet above the Atlantic Ocean.

Over 90 exposures of 30 seconds or less were attempted with a fast lens and sensitive camera setting, using a small, flexible tripod and a blanket to block reflections of interior lighting.

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Mystery Signals from Space

Four powerful radio bursts have left astronomers puzzled.

If you’ve been waiting for mysterious radio signals from space, tune in. An international team of astronomers has detected four powerful bursts that appear to come from billions of light-years away. At that distance, the radio pulses would each have put out in a few thousandths of a second the same amount of energy that the Sun would need 10,000 years to emit.

(So no, it’s not E.T.)

The bizarre signals came to light as part of the High Time Resolution Universe survey, a project using the 64-meter Parkes radio telescope in Australia to search the sky for radio blips and pulsars, the spinning-lighthouse-like stellar corpses left behind by some supernovae. Because the pulsars we detect lie in our own galaxy, astronomers mostly look near the Milky Way’s plane when hunting for these zombie stars. But when grad student Dan Thornton (University of Manchester, U.K., and CSIRO, Australia) started digging through normally “boring” data far from the galaxy’s dusty gleam, he stumbled across the four enigmatic bursts.

The fast radio bursts (or FRBs) have a distinct look to them. They’re incredibly energetic and über-short, but their lower frequencies arrive noticeably later than their higher ones, spreading out the signal into a unique shape. This spreading happens because the lower radio frequencies interact more with intervening electrons, either in the Milky Way itself or the so-called intergalactic medium, the stuff between the universe’s massive stellar metropolises.

The pulse shape encodes how much stuff lies between us and a source, and the spread in these narrow signals’ arrival times implies that they came from far beyond the Milky Way. Throwing some assumptions into the mix, Thornton and his colleagues estimate the four bursts originated at redshifts from 0.45 to 0.96, or 5.5 to 10 billion light-years away.

That distance would give the bursts energies between 1037 and 1039 joules, or between 100 billion and 10 trillion times the energy the Sun puts out in a single second — and the FRBs did it in a few milliseconds.

These four bursts aren’t the first to baffle astronomers. In 2007 Duncan Lorimer (now at West Virginia University) and his colleagues reported a bizarre radio blast so strong that the software used to process the signals assumed it couldn’t be astrophysical and deleted part of it from the data. That “Lorimer burst” looks like the new four.

There was also a weird signal reported in 2012, but it’s unclear whether it came from the Milky Way or not. Plus, notes Bryan Gaensler (University of Sydney), a team reported a bunch of unidentified radio bursts back in 1989 that might or might not be similar. “No one knew what to make of that paper at the time, but now it’s somewhat more interesting,” he says.

So what are FRBs? “I don’t think we have any idea what these are,” Gaensler says. “It’s a mystery!” […]

Full Article

Reference: D. Thornton et al. “A Population of Fast Radio Bursts at Cosmological Distances.” Science, 5 July 2013.

Credit: Camille Carlisle/skyandtelescope.com