Archive for the ‘Space’ Category

Just a couple of days after the orbiting observatory was brought back online, Hubble aimed its prime working camera, the Wide Field Planetary Camera, at a particularly intriguing target, a pair of gravitationally interacting called Arp 147.
Hubble Space Telescope is back in business. Just a couple of days after the orbiting observatory was brought back online, Hubble aimed its prime working camera, the Wide Field Planetary Camera 2 (WFPC2), at a particularly intriguing target, a pair of gravitationally interacting galaxies called Arp 147. The image demonstrated that the camera is working exactly as it was before going offline, thereby scoring a “perfect 10″ both for performance and beauty. The two galaxies happen to be oriented so that they appear to mark the number 10. The left-most galaxy, or the “one” in this image, is relatively undisturbed apart from a smooth ring of starlight. It appears nearly on edge to our line of sight. The right-most galaxy, resembling a zero, exhibits a clumpy, blue ring of intense star formation. The galaxy pair was photographed on October 27-28, 2008. Arp 147 lies in the constellation, and it is more than 400 million light-years away.

The image demonstrated that the camera is working exactly as it was before going offline, thereby scoring a “perfect 10″ both for performance and beauty.

The two galaxies happen to be oriented so that they appear to mark the number 10. The left-most galaxy, or the “one” in this image, is relatively undisturbed apart
from a smooth ring of starlight. It appears nearly on edge to our line of sight. The right-most galaxy, resembling a zero, exhibits a clumpy, blue ring of intense star formation.

The blue ring was most probably formed after the galaxy on the left passed through the galaxy on the right. Just as a pebble thrown into a pond creates an outwardly moving circular wave, a propagating density wave was generated at the point of impact and spread outward. As this density wave collided with material in the target galaxy that was moving inward due to the gravitational pull of the two galaxies, shocks and dense gas were produced, stimulating star formation.

The dusty reddish knot at the lower left of the blue ring probably marks the location of the original nucleus of the galaxy that was hit.

Arp 147 appears in the Arp Atlas of Peculiar Galaxies, compiled by Halton Arp in the 1960s and published in 1966. This picture was assembled from WFPC2 images taken with three separate filters. The blue, visible-light, and infrared filters are represented by the colors blue, green, and red, respectively.

The galaxy pair was photographed on October 27-28, 2008. Arp 147 lies in the constellation Cetus, and it is more than 400 million light-years away from Earth.

NASA’s Swift and Fermi spacecraft are monitoring a neutron star 30,000 light years from Earth that is drawing attention to itself with a series of powerful gamma-ray flares.

“At times, this remarkable object has erupted with more than a hundred flares in as little as 20 minutes,” said Loredana Vetere, who is coordinating the Swift observations at Pennsylvania State University. “The most intense flares emitted more total energy than the sun does in 20 years.”

The star, known as SGR J1550-5418, lies in the southern constellation Norma. It began a series of modest eruptions on Oct. 3, 2008, settled down for a while, then roared back to life on Jan. 22, 2009, with an intense episode.

Because of its rapid-fire outbursts and gamma-ray spectrum, astronomers classify the object as a “soft-gamma-ray repeater” — only the sixth known. In 2004, a giant flare from another soft-gamma-ray repeater was so intense it ionized Earth’s upper atmosphere from 50,000 light-years away.

Using data from an X-ray telescope onboard Swift, Jules Halpern at Columbia University captured the first “light echoes” ever seen from a soft-gamma-ray repeater. Images acquired when the latest flaring episode began show what appear to be expanding halos around the source. Multiple rings form as X-rays interact with dust clouds at different distances.

Scientists think the source of the flares is a spinning neutron star–the superdense, city-sized remains of a supernova. Although only about 12 miles across, a neutron star contains more mass than the sun. This particular neutron star is believed to be a “magnetar,” a neutron star with an incredibly intense magnetic field.

A popular theory of soft-gamma-ray repeaters holds that flares are caused by “starquakes” in the outer rigid crust of the magnetar. As a magnetar’s colossal magnetic field shifts, it strains the crust with monstrous magnetic forces, often breaking it. When the crust snaps, it vibrates with seismic waves like in an earthquake and emits a flash of gas

No one is really certain of the details, however, and much work remains to be done to understand these powerfully hyperactive stars.

NASA’s Fermi Gamma-ray Space Telescope, launched in June 2008, is ideal for this work. “The ability of Fermi’s gamma-ray burst monitor to resolve the fine structure within these events will help us better understand how magnetars unleash their energy,” said Chryssa Kouveliotou, an astrophysicist at NASA’s Marshall Space Flight Center in Huntsville, Ala. The object has triggered Fermi’s gamma-ray burst monitor more than 95 times since Jan. 22nd.

NASA’s Wind satellite, the joint NASA-Japan Suzaku mission, and the European Space Agency’s INTEGRAL satellite also have detected flares from SGR J1550-5418.