11
Jan 12

Hubble solves mystery on source of supernova in nearby galaxy

Source: NASA Hubble Release 12-012


Emergence of an exploding star, called a supernova in Hubble Deep Field.
Image credits: NASA, ESA, A. Riess (Space Telescope Science Institute and The
Johns Hopkins University), and S. Rodney (The Johns Hopkins University)

Using NASA's Hubble Space Telescope, astronomers have solved a longstanding mystery on the type of star, or so-called
progenitor, which caused a supernova seen in a nearby galaxy. The finding yields new observational data for pinpointing one of several scenarios that trigger such outbursts.

Based on previous observations from ground-based telescopes, astronomers knew the supernova class, called a Type Ia, created a remnant named SNR 0509-67.5, which lies 170,000 light-years away in the Large Magellanic Cloud galaxy.

Theoretically, this kind of supernova explosion is caused by a star spilling material onto a white dwarf companion, the compact remnant of a normal star, until it sets off one of the most powerful explosions in the universe.

Astronomers failed to find any remnant of the companion star, however, and concluded that the common scenario did not apply in this case, although it is still a viable theory for other Type Ia supernovae. (read more)

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11
Jan 12

Fermi Space Telescope explores new energy extremes

Source: NASA Fermi


New sources emerge and old sources fade as the LAT's view extends into higher energies.
Credit: NASA/DOE/Fermi LAT Collaboration and A. Neronov et al.

After more than three years in space, NASA's Fermi Gamma-ray Space Telescope is extending its view of the high-energy sky into a largely unexplored electromagnetic range. Today, the Fermi team announced its first census of energy sources in this new realm.

Fermi's Large Area Telescope (LAT) scans the entire sky every three hours, continually deepening its portrait of the sky in gamma rays, the most energetic form of light. While the energy of visible light falls between about 2 and 3 electron volts, the LAT detects gamma rays with energies ranging from 20 million to more than 300 billion electron volts (GeV).

At higher energies, gamma rays are rare. Above 10 GeV, even Fermi's LAT detects only one gamma ray every four months. (read more)

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