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Post Info TOPIC: Novae


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NASA's Fermi Space Telescope Reveals New Source of Gamma Rays

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Observations by NASA's Fermi Gamma-ray Space Telescope of several stellar eruptions, called novae, firmly establish these relatively common outbursts almost always produce gamma rays, the most energetic form of light.
A nova is a sudden, short-lived brightening of an otherwise inconspicuous star caused by a thermonuclear explosion on the surface of a white dwarf, a compact star not much larger than Earth. Each nova explosion releases up to 100,000 times the annual energy output of our sun. Prior to Fermi, no one suspected these outbursts were capable of producing high-energy gamma rays, emission with energy levels millions of times greater than visible light and usually associated with far more powerful cosmic blasts.

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Title: A WISE view of novae
Authors: A. Evans (Astrophysics Group, Keele University), R. D. Gehrz, C. E. Woodward (Minnesota Institute for Astrophysics), L. A. Helton (SOFIA Science Center, USRA)

We present the result of trawling through the WISE archive for data on classical and recurrent novae. The data show a variety of spectral energy distributions, including stellar photospheres, dust and probable line emission. During the mission WISE also detected some novae which erupted subsequent to the survey, providing information about the progenitor systems.

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An international team of nuclear astrophysicists has shed new light on the explosive stellar events known as novae.

These dramatic explosions are driven by nuclear processes and make previously unseen stars visible for a short time. The team of scientists measured the nuclear structure of the radioactive neon produced through this process in unprecedented detail. Their findings, reported in the US journal Physical Review Letters, show there is much less uncertainty in how quickly one of the key nuclear reactions will occur as well as in the final abundance of radioactive isotopes than has previously been suggested.
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Title: Infrared emission from novae
Authors: A. Evans (Keele University, UK), R. D. Gehrz (University of Minnesota, USA)

We review infrared observations of classical and recurrent novae, at wavelengths >3microns, including both broad-band and spectroscopic observations. In recent years infrared spectroscopy in particular has revolutionised our understanding of the nova phenomenon, by revealing fine-structure and coronal lines, and the mineralogy of nova dust. Infrared spectroscopic facilities that are, or will be, becoming available in the next 10 - 20 years have the potential for a comprehensive study of nova line emission and dust mineralogy, and for an unbiased assessment of the extragalactic nova populations.

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Exploding stars reveal never-before seen patterns

Astronomers have for the first time, observed post star explosion pauses, flickers and flares- patterns that aren't yet accounted for in our current understanding of how these eruptions occur.
Using data from a sensitive instrument aboard a satellite that images the entire sky every 102 minutes, they studied four of these stars, or novae, that exploded so violently their light would have been visible without a telescope and measured their brightness over the course of the outburst.
The instrument they used - the Solar Mass Ejection Imager - was developed by a team led by astrophysicist Bernard Jackson at the Center for Astrophysics and Space Sciences at the University of California, San Diego, to study the sun. Rebekah Hounsell, a graduate student at Liverpool John Moores University in Britain made the measurements while visiting UC San Diego.

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New observations of exploding stars reveal pauses, flickers and flares not reliably seen before

Astronomers have traced the waxing and waning light of exploding stars more closely than ever before and seen patterns that aren't yet accounted for in our current understanding of how these eruptions occur.
Using data from a sensitive instrument aboard a satellite that images the entire sky every 102 minutes, they studied four of these stars, or novae, that exploded so violently their light would have been visible without a telescope and measured their brightness over the course of the outburst.
Three of the novae stalled before reaching a peak, and all flickered or flared as the explosions ran their course, they report in The Astrophysical Journal.

Source: University of California - San Diego

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