Binary white dwarf stars

May 4, 2011
An artist's conception of two orbiting white dwarf stars, showing schematically that they radiate gravitational waves as they orbit each other. Scientists have found a newly discovered white dwarf pair that will merge in about 37 million years to be reborn again as a normal star. Credit: Tod Strohmayer (GSFC), CXC, NASA, Illustration: Dana Berry (CXC)

(PhysOrg.com) -- When a star like our sun gets to be very old, after another seven billion years or so, it will no longer be able to sustain burning its nuclear fuel.

With only about half of the its mass remaining, it will shrink to a fraction of its radius and become a white dwarf star. are common, the most famous one being the companion to the brightest star in the sky, Sirius.

But although they are common, and although they represent the final stage of our own sun, astronomers still do not understand their full range of character, or the parameters that determine what they ultimately become.

One reason is that many white dwarfs are, like the companion of Sirius, located in binary systems in which the companion stars influence the details of how they age.

CfA astronomers Mukremin Kilic, Warren Brown, and Scott Kenyon, with six colleagues, used the MMT to discover that the companion of a previously known white dwarf is actually another white dwarf star.

The two orbit each other in only 39.1 minutes, separated by a distance that is only 32% of the radius of the sun. Perhaps the most remarkable feature of this particular binary is its fate.

White dwarf binary stars in general are extreme systems that radiate as they orbit each other.

To balance the loss of this energy, the gradually come closer together until eventually they merge. Many white dwarf binaries will explode as when they merge, but this newly discovered one is too small to trigger such an explosion.

Instead, it will probably start fusing its helium atoms, and when it does - in about 37 million years - it will shine like a normal star again.

Explore further: Two dying stars reborn as one (w/ video)

Related Stories

Two dying stars reborn as one (w/ video)

April 6, 2011

White dwarfs are dead stars that pack a Sun's-worth of matter into an Earth-sized ball. Astronomers have just discovered an amazing pair of white dwarfs whirling around each other once every 39 minutes. This is the shortest-period ...

A sub-stellar Jonah: Brown dwarf survives being swallowed

August 2, 2006

Using ESO's Very Large Telescope, astronomers have discovered a rather unusual system, in which two planet-size stars, of different colours, orbit each other. One is a rather hot white dwarf, weighing a little bit less than ...

White dwarf and ultra-cool dwarf keep their distance

April 18, 2007

Scientists from the University of Hertfordshire have discovered a rare binary system consisting of a white dwarf, a Sun-like star that has reached the end of its life, and an ultra-cool dwarf, which is the smallest kind of ...

XMM-Newton uncovers a celestial Rosetta stone

September 3, 2009

(PhysOrg.com) -- ESA's XMM-Newton orbiting X-ray telescope has uncovered a celestial Rosetta stone: the first close-up of a white dwarf star, circling a companion star, that could explode into a particular kind of supernova ...

Hubble 'weighs' Dog Star's companion

December 13, 2005

For astronomers, it's always been a source of frustration that the nearest white-dwarf star is buried in the glow of the brightest star in the nighttime sky. This burned-out stellar remnant is a faint companion of the brilliant ...

Recommended for you

Hubble catches a transformation in the Virgo constellation

December 9, 2016

The constellation of Virgo (The Virgin) is especially rich in galaxies, due in part to the presence of a massive and gravitationally-bound collection of over 1300 galaxies called the Virgo Cluster. One particular member of ...

Scientists sweep stodgy stature from Saturn's C ring

December 9, 2016

As a cosmic dust magnet, Saturn's C ring gives away its youth. Once thought formed in an older, primordial era, the ring may be but a mere babe – less than 100 million years old, according to Cornell-led astronomers in ...

Khatyrka meteorite found to have third quasicrystal

December 9, 2016

(Phys.org)—A small team of researchers from the U.S. and Italy has found evidence of a naturally formed quasicrystal in a sample obtained from the Khatyrka meteorite. In their paper published in the journal Scientific Reports, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.