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Post Info TOPIC: Supernova 2008ha


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Supernova 2008ha
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Title: Early and Late-Time Observations of SN 2008ha: Additional Constraints for the Progenitor and Explosion
Authors: Ryan J. Foley, Peter J. Brown, Armin Rest, Peter J. Challis, Robert P. Kirshner, W. Michael Wood-Vasey

We present a new maximum-light optical spectrum of the the extremely low luminosity and exceptionally low energy Type Ia supernova (SN Ia) 2008ha, obtained one week before the earliest published spectrum. Previous observations of SN 2008ha were unable to distinguish between a massive star and white dwarf origin for the SN. The new maximum-light spectrum, obtained one week before the earliest previously published spectrum, unambiguously shows features corresponding to intermediate mass elements, including silicon, sulphur, and carbon. Although strong silicon features are seen in some core-collapse SNe, sulphur features, which are a signature of carbon/oxygen burning, have always been observed to be weak in such events. It is therefore likely that SN 2008ha was the result of a thermonuclear explosion of a carbon-oxygen white dwarf. Carbon features at maximum light show that unburned material is present to significant depths in the SN ejecta, strengthening the case that SN 2008ha was a failed deflagration. We also present late-time imaging and spectroscopy that are consistent with this scenario.

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New Supernova Is Discovered by Young Citizen Scientist
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A 14-year-old student from New York state has become the youngest person in history to discover a supernova. And her find is also one of the most peculiar supernovae spotted to date.

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In November 2008, Caroline Moore, a 14-year-old student from upstate New York, discovered a supernova in a nearby galaxy, making her the youngest person ever to do so. Additional observations determined that the object, called SN 2008ha, is a new type of stellar explosion, 1000 times more powerful than a nova but 1000 times less powerful than a supernova. Astronomers say that it may be the weakest supernova ever seen.
Even though this explosion was a weakling compared to most supernovae, for a short time SN 2008ha was 25 million times brighter than the sun. However, since it is 70 million light years away, it appeared very faint viewed from Earth.

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A new class of dim supernovae
The colossal stellar explosions called supernovae come in many kinds and flavours. Some of them are produced when a massive star reaches the end of its life in a sudden gravitational collapse. Astronomers have just found one of these explosions that defies the current classification scheme. The results of this research have been published in Nature, and Calar Alto has contributed to this discovery.
Core-collapse (or gravitational) supernovae are among the most energetic and violent events in the universe. They constitute the final tremendous explosions that end the life cycles of stars more massive than approximately 8 times the Sun. After running out of fuel, the core of such a star collapses and forms a neutron star or a black hole. At the same time, the outer layers are ejected at high velocity (up to 10% of the speed of light) and shine as brightly as billions of stars together. The total energy suddenly released by such a typical supernova exceeds the total energy release of the Sun during its whole past and future life time of 10 billion years.
However, some core-collapse supernovae are up to 100 times less energetic and luminous than usual. These low-power explosions normally show the presence of hydrogen gas, but a new event, supernova SN 2008ha, is the first dim supernova in which no hydrogen could be detected. This research has been performed by an international team lead by the Italian astronomer Stefano Valenti (Queen's University in Belfast, United Kingdom), including scientists from Max Planck Institute for Astrophysics (Germany), the National Institute for Astrophysics (Italy), and various other institutions.

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A magnitude 18.2 Type Ia supernova, 2008ha, was discovered on the 7th November, 2008, by Caroline K. Moore and Jack Newton in the irregular galaxy UGC 12682 in the constellation Pegasus.
The supernova is located 12" west and 0".5 south from the centre of the galaxy.

Position(2000): R.A. = 23h34m52s.69, Dec = +1813'35".4
z = 0.004647

CBET 1567 (Subscription)


Caroline Moore, a ninth-grader at Warwick Valley High, is believed to be the youngest person to identify a supernova, which is a little more impressive than your ability to find the Big and Little dippers on a clear summer night.

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