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Astronomers discover white dwarf with an oxygen atmosphere

3 April 2016 Astronomy Now

Researchers have discovered a white dwarf star with an atmosphere dominated by oxygen — a type of white dwarf that has been theorised to exist but not identified to date. The finding could challenge the textbook wisdom of single stellar evolution, and provide a critical link to some types of supernovae discovered over the past decade.

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Trigger for Milky Way’s youngest supernova identified

31 March 2016 Astronomy Now

Astronomers have used data from NASA’s Chandra X-ray Observatory and the VLA to determine the likely trigger for the most recent supernova in the Milky Way. They applied a new technique that could have implications for understanding other Type Ia supernovae, a class of stellar explosions that scientists use to determine the expansion rate of the universe.

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First discovery of a binary companion for a Type Ia supernova

23 March 2016 Astronomy Now

A team of astronomers has detected a flash of light from the companion star to supernova 2012cg that lies in the edge-on spiral NGC 4424, 50 million light-years away in the constellation Virgo. This is the first time that the impact of an exploding star on its neighbour has been witnessed.

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The icy blue wings of a bipolar planetary nebula

8 February 2016 Astronomy Now

Planetary nebulae such as Hen 2-437 form when an ageing low-mass star — such as the Sun — reaches the final stages of life. The star swells to become a red giant, before casting off its gaseous outer layers into space. Hen 2-437 is a bipolar nebula — the material ejected by the dying star has streamed out into space to create the two icy blue lobes pictured here.

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Astronomer solves mystery of ‘born again’ stars with Hubble

7 December 2015 Astronomy Now

University of Texas astronomer Natalie Gosnell has used the Hubble Space Telescope to better understand why some stars aren’t evolving as predicted. These so-called “blue stragglers” look hotter and bluer than they should for their advanced age. It’s almost as it they were somehow reinvigorated to look much younger than they really are.

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Hottest white dwarf discovered in our Galaxy

29 November 2015 Astronomy Now

With a temperature of 250,000 °C — 45 times that at the surface of our Sun — astronomers believe that this dying star in the outskirts of the Milky Way may have peaked at 400,000 °C a thousand years ago. The researchers were also the first to observe an intergalactic gas cloud moving towards the Milky Way — indicating that galaxies collect fresh material from deep space, which they can use to make new stars.

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Asteroid ripped apart to form star’s glowing ring system

11 November 2015 Astronomy Now

The remains of a fatal interaction between a dead star and its asteroid supper have been observed in detail for the first time. An international team of astronomers used the Very Large Telescope at ESO’s Paranal Observatory in Chile and other observatories to study the shattered remains of an asteroid around a stellar remnant — a white dwarf.

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White dwarf “Death Star” seen destroying a planet

21 October 2015 Astronomy Now

The Death Star of the movie Star Wars may be fictional, but planetary destruction is real. Astronomers announced today that they have spotted a large, rocky object disintegrating in its death spiral around a distant white dwarf star. The discovery also confirms a long-standing theory behind the source of white dwarf “pollution” by metals.

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Hubble sees an ageing star wave goodbye

9 October 2015 Astronomy Now

When stars that are around the mass of the Sun reach their final stages of life, they shed their outer layers into space, which appear as glowing clouds of gas called planetary nebulae. In the case of Menzel 2, otherwise known as PK 329-02.2, the nebula forms a winding blue cloud that perfectly aligns with two stars at its centre.

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Discovery of white dwarf companions of millisecond pulsars

4 October 2015 Astronomy Now

When a massive star ends its life in a spectacular supernova explosion, it can leave behind a rapidly spinning neutron star with a period of 1-10 milliseconds. Such objects that emit electromagnetic radiation in a lighthouse-like beam sweeping past the Earth are known as millisecond pulsars. CfA astronomers have identified white dwarf companions of two more millisecond pulsars in the spectacular globular cluster 47 Tucanae.