Runaway anti-matter production makes for a spectacular stellar explosion

Jan 04, 2010 BY WILLIAM G. GILROY

(PhysOrg.com) -- University of Notre Dame astronomer Peter Garnavich and a team of collaborators have discovered a distant star that exploded when its center became so hot that matter and anti-matter particle pairs were created. The star, dubbed Y-155, began its life around 200 times the mass of our Sun but probably became "pair-unstable" and triggered a runaway thermonuclear reaction that made it visible nearly halfway across the universe.

Garnavich and his collaborators discovered the during the "ESSENCE" supernova search that identified over 200 weaker stellar explosions.

"ESSENCE found many explosions in our 6 years of searching, but Y-155 stood out as the most powerful and unusual of all our discoveries" says Garnavich.

Y-155 exploded about 7 billion years ago, when the universe was half its current age. It was discovered in the constellation Cetus (just south of Pisces) with the National Optical Astronomy Observatory's (NOAO) 4-m Blanco telescope in Chile in November of 2007 during the last weeks of the six-year ESSENCE project. The Keck 10-m telescope in Hawaii, the 6.5-m Magellan telescope in Chile, and the MMT telescope in Arizona rapidly focused on the new star, revealing that the wavelengths of light emitted from the supernova were stretched or "redshifted" by 80% due to the expansion of the universe.

Once the distance to the explosion was established, Garnavich and his collaborators calculated that, at its peak, Y-155 was generating energy at a rate 100 billion times greater than the sun's output. To do this, Y-155 must have synthesized between 6 and 8 solar masses of radioactive nickel. It is the decay of radioactive elements that drives the light curves of supernovae. A normal "Type Ia" thermonuclear supernova makes about one tenth as much radioactive nickel.

"In our images, Y-155 appeared a million times fainter than the unaided human eye can detect, but that is because of its enormous distance," Garnavich said. "If Y-155 had exploded in the Milky Way it would have knocked our socks off."

Over 40 years ago scientists proposed that massive stars could become unstable through the production of matter/ particle pairs, but only recently have large-scale searches of the sky, like the ESSENCE project, permitted the discovery of these bright, but rare, events.

Most stars bigger than 8 times the Sun's mass lose their battle with gravity and produce a "core-collapse" supernova or directly form a black hole. But there is a range of masses, 150 to 300 times the mass of the sun, where the pair-instability is thought to operate. Such massive stars are expected to form in pristine gas that has not been polluted with elements heavier than hydrogen and helium by early generations of stars. Deep imaging with the Large Binocular Telescope in Arizona shows that Y-155 originated in a very low mass host galaxy. On average, small galaxies have a low abundance of heavy atoms, so are excellent locations for pair-instability explosions.

The ESSENCE project was a six-year NOAO Survey Program led by Christopher Stubbs of Harvard University and included an international team of astronomers from the United States, Germany, Australia, and Chile. The ESSENCE project was designed to precisely map the expansion history of the universe by discovering type Ia supernovae and using them as distance markers. The ultimate goal is to understand the mysterious dark energy that is driving the accelerating expansion.

The discovery was announced today at the 215th meeting of the American Astronomical Society in Washington, D.C., with coauthors Peter Garnavich (University of Notre Dame) and the ESSENCE collaboration (www.ctio.noao.edu/essence/team.html).

Explore further: New window on the early Universe

Related Stories

First science from the Large Binocular Telescope

Mar 15, 2007

An international team headed by University of Notre Dame astrophysicist Peter M. Garnavich has reported the first scientific result from the Large Binocular Telescope (LBT). The team imaged a distant “afterglow” ...

Hubble Snaps Images of a Pinwheel-Shaped Galaxy

Feb 07, 2006

Looking like a child's pinwheel ready to be set a spinning by a gentle breeze, this dramatic spiral galaxy is one of the latest viewed by NASA's Hubble Space Telescope. Stunning details of the face-on spiral ...

The Hooked Galaxy

Jun 28, 2006

Life is not easy, even for galaxies. Some indeed get so close to their neighbours that they get rather distorted. But such encounters between galaxies have another effect: they spawn new generations of stars, ...

The purple rose of Virgo

Mar 27, 2007

Until now NGC 5584 was just one galaxy among many others, located to the West of the Virgo Cluster. Known only as a number in galaxy surveys, its sheer beauty is now revealed in all its glory in a new VLT image. ...

Exploding star in NGC 2397

Mar 31, 2008

NGC 2397, pictured in this image from Hubble, is a classic spiral galaxy with long prominent dust lanes along the edges of its arms, seen as dark patches and streaks silhouetted against the starlight. Hubble’s ...

Recommended for you

New window on the early Universe

15 minutes ago

Scientists at the Universities of Bonn and Cardiff see good times approaching for astrophysicists after hatching a new observational strategy to distill detailed information from galaxies at the edge of ...

Chandra's archives come to life

2 hours ago

Every year, NASA's Chandra X-ray Observatory looks at hundreds of objects throughout space to help expand our understanding of the Universe. Ultimately, these data are stored in the Chandra Data Archive, ...

New robotic telescope revolutionizes the study of stars

2 hours ago

In the last 8 months a fully robotic telescope in Tenerife has been carrying out high-precision observations of the motion of stellar surfaces. The telescope is the first in the SONG telescope network and ...

User comments : 5

Adjust slider to filter visible comments by rank

Display comments: newest first

Oliver_k_Manuel
3 / 5 (4) Jan 04, 2010
the neutron star formed in this explosion is the seed for a new star much like the sun formed from the remnants of a previous star we all know there are no such things as black holes

with kind regards
blah blah blah
brant
1 / 5 (3) Jan 04, 2010
It also possible that neutron stars dont exist, and that energy concentrations are the result of aether densities at that point in space?
Phelankell
4.3 / 5 (3) Jan 05, 2010
Neither is reasonable nor accurate.

Both black holes and neutron stars exist. The math and observations support it. If we could travel to one we could prove it conclusively, however, that is not an available action at this point in time.
Arkaleus
not rated yet Jan 05, 2010
Oliver,

I wonder if the key to understanding dark matter is understanding galactic evolution. The emergence of a galactic core may form a quasar, whose evolution may generate the dark matter we see surrounding galaxies.

If this is so, then there may be much more to stellar dynamics than baryonic transformations.
Question
not rated yet Jan 10, 2010
Quote:
(PhysOrg.com) -- "University of Notre Dame astronomer Peter Garnavich and a team of collaborators have discovered a distant star that exploded when its center became so hot that matter and anti-matter particle pairs were created."

I find the quote above a little confusing. Wouldn't it take exactly the same amount of energy to produce the matter and anti-matter pairs as would be released when they annihilate each other later? It would seem like a zero sum game to me.