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New Discovery challenges star theory

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20.11.2008

Researchers have made a discovery which poses a major challenge to current theories of how stars reach the ends of their lives.

In a paper entitled A Planetary Nebula around Nova V458 Vul Undergoing Flash Ionization, which will be published in Astrophysical Journal Letters on Thursday 20 November, researchers from the University of Hertfordshire are part of a team which has revealed the phenomenon of a planetary nebula around a nova, which was only ever known once before.

A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by many stars as they approach the end of their lives, while a nova is a cataclysmic nuclear explosion caused by the accretion of hydrogen onto the surface of a nearly-dead white dwarf star in a close binary.
The two are not expected to be seen together because the planetary nebula should fade from sight before enough hydrogen fuel accumulates for the nova explosion, posing a problem for how this system has come to be.

According to Professor Janet Drew, this is the first instance of a planetary nebula linked to a nova since 1901, which IPHAS - the survey of the Northern Galactic Plane using the 2.5-metre Isaac Newton Telescope, led by the University of Hertfordshire - has been able to identify in images obtained before the nova exploded in August 2007. Uniquely, this has made it possible to follow the impact of the nova brightening on matter closely enshrouding it in real time.

“It is the first time that we can use observations of the ionising effect of the hugely brightened nova on the gas in its immediate vicinity to determine the distance to the nova,” said Professor Drew. “Distances to novae are usually incredibly difficult to pin down. This nova system looks to be very distant and very massive, which makes it highly likely to go supernova one day.”

Other partners in this research are: R. Wesson, M. Barlow (UCL), R. Napiwotzki (UoH), R. Corradi (IAC, Spain), P. Groot (Nijmegen, Netherlands), C. Knigge (Southampton), D. Steeghs, B. Gaensicke (Warwick), and others

Emma Roberts | Source: alphagalileo
Further information: www.herts.ac.uk

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