Astronomy Now Home
Home Magazine Sky Chart Resources Store

On Sale Now!

The April 2014 issue of Astronomy Now is on sale! Order direct from our store (free 1st class post & to UK addresses). The Astronomy Now iPad/iPhone editions are now available worldwide in the iTunes store.

Top Stories

Earthshine used to test life detection method
...By imagining the Earth as an exoplanet, scientists observing our planet's reflected light on the Moon with ESO's Very Large Telescope have demonstrated a way to detect life on other worlds...

Solid buckyballs discovered in space
...Astronomers using NASA’s Spitzer Space Telescope have detected a particular type of molecule, given the nickname “buckyball”, in a solid form for the first time...

Steamy water-world gets the Hubble treatment
...Hubble Space Telescope observations of a 7 Earth-mass planet find an unusual water-rich world swathed in a thick, steamy atmosphere...

Merging white dwarfs become supernovae
Posted: 07 January 2010

Bookmark and Share

New computer simulations confirm that some Type Ia supernova explosions are caused by the merging of two binary white dwarf stars.

Supernovae are caused by a variety of mechanisms – most stars die when their fuel runs out and their cores collapse in on themselves, while the most massive stars are thought to explode when their centres become so hot that matter and anti-matter particle pairs create a runaway thermonuclear reaction. White dwarfs, the compact cores of dead stars, can also undergo runaway nuclear fusion by accreting material from a companion star. Now, computer simulations show that supernova events can also result from the merging of two white dwarf stars.

Snapshots of the merger of two equal size white dwarf stars from 36 seconds prior to the explosion until 10 seconds afterwards. The colour-coding indicates the density of material, which is increasing from blue to red. Please note the different scaling on the plots. Image: Max Planck Institute for Astrophysics.

Once they have exhausted their hydrogen and helium fuel, intermediate mass stars like our own Sun end their lives as white dwarfs consisting of carbon and oxygen. In a binary system, two white dwarfs will form, and as they lose energy their orbits shrink inwards, ultimately resulting in a cataclysmic union.

Astronomers have long speculated that such an event would produce a Type Ia supernovae, and the detailed simulations show just that. In the example of the collision of two equal mass white dwarfs, part of the material of one dead star crashes into the other, heating up the carbon-oxygen mix such that a thermonuclear explosion disrupts the star in a spectacular supernova event.

“Supernovae are among the brightest observed cosmic explosions,” says Wolfgang Hillebrandt, director at the Max Planck Institute for Astrophysics. “How they form, however, remains largely unknown. With our simulations we have now shed light on at least part of the old riddle of the progenitors of Type Ia supernovae.”

The team matched the results of the simulations to the properties of real Type Ia supernovae, although the merging of two white dwarfs cannot account for all Type Ia explosions.

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!


© 2014 Pole Star Publications Ltd.