. Medical and Hospital News .




.
STELLAR CHEMISTRY
Homing in on supernova origins
by Staff Writers
Pasadena, CA (SPX) May 09, 2012

The research team studied 23 Type Ia supernovae to look for signatures of gas around the supernovae, which should be present only in single-degenerate systems.

Type Ia supernovae are important stellar phenomena, used to measure the expansion of the universe. But astronomers know embarrassingly little about the stars they come from and how the explosions happen. New research from a team led by Harvard University and including Carnegie's Josh Simon, Chris Burns, Nidia Morrell, and Mark Phillips examined 23 Type Ia supernovae and helped identify the formation process for at least some of them.

Type Ia supernovae are violent stellar explosions. Observations of their brightness are used to determine distances in the universe and have shown scientists that the universe is expanding at an accelerating rate.

The Nobel Prize in Physics was awarded December 10, 2011, to three astronomers for their "discovery of the accelerating expansion of the Universe through observations of distant supernovae."

Type Ia supernovae are believed to be thermonuclear explosions of a white dwarf star that's part of a binary system--two stars that are physically close together and orbit around a common center of mass. But there are two different possibilities for how Type Ia supernovae are created from this type of binary system.

In the so-called double-degenerate model, the orbit between two white dwarf stars gradually shrinks until the lighter star gets so close to its companion that it is ripped apart by tidal forces.

Some of the lighter star's matter is then absorbed into the primary white dwarf, causing an explosion. In the competing single-degenerate model, the white dwarf slowly accretes mass from an ordinary, non-white dwarf star, until it reaches an ignition point.

"Previous studies have produced conflicting results. The conflict disappears if both types of explosion are happening," explained lead author Ryan Foley of the Harvard-Smithsonian Center for Astrophysics.

The research team studied 23 Type Ia supernovae to look for signatures of gas around the supernovae, which should be present only in single-degenerate systems.

They found that the more powerful explosions tended to come from "gassy" systems, or systems with outflows of gas. However, only a fraction of supernovae show evidence for outflows--the remainder likely come from double-degenerate systems.

This finding has important implications for how astronomers use supernovae to measure the universe's expansion. "To maximize the accuracy of our measurements we may have to separate the two kinds of Type Ia supernovae," Simon said. "This study gives us one potential way to tell them apart."

Their work will be published in The Astrophysical Journal and is available online.

Related Links
Carnegie Institution
Stellar Chemistry, The Universe And All Within It




.
.
Get Our Free Newsletters Via Email
...
Buy Advertising Editorial Enquiries




.

. Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle



STELLAR CHEMISTRY
Rogue Stars Ejected from the Galaxy are Found in Intergalactic Space
Nashville TN (SPX) May 09, 2012
It's very difficult to knock a star out of the galaxy. In fact, the main mechanism that astronomers have come up with that can give a star the two-million-plus mile-per-hour kick it takes involves tangling with the supermassive black hole at the galaxy's core. So far astronomers have found 16 of these "hypervelocity" stars. Although they are traveling fast enough to eventually escape galax ... read more


STELLAR CHEMISTRY
2012 not end of world for Mayans after all

Japan to take control of Fukushima operator TEPCO

Munich Re reports return to profit after tsunami blow

Clinton to leave China for Bangladesh cauldron

STELLAR CHEMISTRY
S. Korea to urge N. Korea to stop GPS jamming

Next Galileo satellites to launch after the summer

Czech Republic approves EU Galileo agency move to Prague

China launches two navigation satellites

STELLAR CHEMISTRY
Tablet in Turkey contains unknown language

Scripps Research Institute scientists show how a gene duplication helped our brains become 'human'

Cautious Asians split as Obama backs gay marriage

Emotion Reversed In Left-Handers' Brains Holds New Implications For Treatment Of Anxiety And Depression

STELLAR CHEMISTRY
Endangered species, languages linked at high biodiversity regions

UGA study finds in extinction risk, there's not always safety in numbers

Camera trap video offers rare glimpse of world's rarest gorilla

UI professor identifies largest known crocodile

STELLAR CHEMISTRY
Advanced genetic screening method may speed vaccine development

African scientist, designer partner to fashion anti-malaria garment that wards off bugs

US experts urge approval of first AIDS prevention pill

Canada researchers find clues to a universal flu vaccine

STELLAR CHEMISTRY
China moves Mongol dissident to 'luxury resort'

Chen says China authorities targeting relatives

Blind activist challenges China over house arrest

Al-Jazeera shuts bureau after China expels reporter

STELLAR CHEMISTRY
War planes strike suspected Somali pirate base: coastguard

India proposes norms for Indian Ocean anti-piracy patrols

Iran navy rescues China crew from hijacked freighter

Drones will seek pirates at sea

STELLAR CHEMISTRY
Toshiba's profit drops by nearly half to $921 mn

Outside View: U.S. work force shrinks

Outside View: Modest U.S. jobs growth

China and India manufacturing boosts recovery hopes


Memory Foam Mattress Review

Newsletters :: SpaceDaily Express :: SpaceWar Express :: TerraDaily Express :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

.

The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement