Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



Dust Clouds In Cosmic Cycle

The planetary haze is created by a star like the sun, which has ejected most of its mass into space. The ejection happens when the light from the star is blocked by opaque carbon. In the middle of the planetary haze the star's core looks like it has become a so-called white dwarf.
by Staff Writers
Copenhagen, Denmark (SPX) Apr 09, 2007
It has been a mystery for astronomers how certain dying stars have their colossal quantities of material blown out into the universe and shrink into objects called "white dwarves". This is the basis of a ground-breaking new theory by astrophysicists Anja C. Andersen from the Dark Cosmology Centre at the University of Copenhagen and Susanne Hofner of the University of Uppsala.

Earth and the other planets in our solar system are built up of elements which have been produced in earlier generations of stars. Deep in the stars' very hot core, the elements are created out of hydrogen, and when the stars explode and die, the elements are shot out into the universe as huge clouds of gas and dust. Gradually, all that dust aggregates, eventually forming new stars and planets.

Pitch-black dust clouds
Stars smaller than our sun and up to eight times as large die by first swelling up to being a red giant, and then shrinking to a white dwarf. There are two types of red giants, one contains lots of carbon and the the other a lot of oxygen. When the carbon-rich stars die, large clouds of carbon particles such as soot and graphite are produced. Soot and graphite are pitch-black, so when the rays from the dying star hit the soot particles they stop the light and are pushed out into space, where they are seen as gigantic dust clouds. This is a 20 year old theory which fits both the observations and the model calculations.

Transparent dust clouds
But for the other type of red giant stars, which are oxygen-rich, it has been a mystery how their material is blown out into space. The oxygen-rich stars produce large quantities of water and silicates, like quartz or grains of sand. Water and silicates are transparent, which means that when rays from the star hit the particles, they go straight through-just like when the sun's rays go through glass. The star's radiation therefore, can't push on the particles and be the motor which drives the dust clouds out into space.

Theory discarded
So how does it happen? The astrophysicists, Anja C. Andersen and Susanne Hofner have pondered the problem for many years and weighed possible solutions. First they considered whether there could be iron in the silicates, so that it wasn't transparent. But then calculations showed that with iron, the dust grains would have melted and were therefore unstable.

Next they thought that perhaps many molecules had been produced, which could block out the light and thereby create a wind which blew the star's outermost layer into space. But the model calculations showed that the molecules could not block enough light to drive the process alone.

When the star becomes a red giant it pulses in it's death-throes, and perhaps this could "spark" the process into motion and force the star's material out. But this theory didn't tally with real observations of these stars.

A New Carbon Theory
It was back to the start, and suddenly it hit them. "What if the oxygen-rich stars also make some carbon that works with the transparent dust, and altogether can give a push to the process by forcing the star's outer layer into space"? They looked at each other and hardly dared to think that it could be so simple, that in reality it was the same process that was happening in both types of stars.

"It is so wonderful, that it can be so simple, and the theory fits with all our subsequent model calculations", says Anja C. Andersen. The theory also fits with the observations one has from dying red giants. The carbon may be the explanation for how both types of star blow their material into space, where they are ultimately reused in the cosmic cycle in new stars and planets.

Email This Article

Related Links
University of Copenhagen
Stellar Chemistry, The Universe And All Within It



Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


X-ray Satellites Catch Magnetar In Gigantic Stellar Hiccup
London, UK (SPX) Apr 09, 2007
Astronomers using data from several X-ray satellites have caught a magnetar - the remnant of a massive star with an incredibly strong magnetic field - in a sort of giant cosmic blench.







  • Fifth Space Tourist Soars Toward Space Station Holiday In Space
  • Gordon, Miller, Nelson Move Toward Hearings On NASA IG Investigation
  • The Facts On US Commercial Human Space Flight
  • Martha Stewart Gives Space-Bound Beau A Wild Send-Off

  • Global Warming Hits Mars Too
  • MARSIS Radar Estimates The Volume Of Water In The South Pole Of Mars
  • ESA Prepares For A Human Mission To Mars
  • Spirit Studies Rocks in Vicinity Of Home Plate

  • Arianespace To Launch Australian Satellite Optus D3
  • Arianespace To Launch Two Intelsat Payloads
  • Progress On The Sea Launch Investigation And Recovery
  • Two New Payloads For Ariane 5

  • ISRO To Focus On Societal Projects
  • USGS Defines Roles For New Satellite Mission
  • ESA Signs Arrangement With New Zealand On Tracking Station
  • DMCii To Launch New Higher-Resolution Satellite Imaging Service

  • Rosetta And New Horizons Watch Jupiter In Joint Campaign
  • New Horizons Shows Off Its Color Camera In Io Image
  • Alice Views Jupiter And Io
  • A Look From LEISA

  • X-ray Satellites Catch Magnetar In Gigantic Stellar Hiccup
  • NASA Finds Evidence For New Molecular Structure In Space
  • Dust Clouds In Cosmic Cycle
  • Hubble's View Of Barred Spiral Galaxy NGC 1672

  • Shanghai Vies To Win Battle Of Moon Rovers
  • A Piggyback Solution For Science Versus Exploration
  • Assembling Of Moon Mission Spacecraft Begins
  • Dust-Busting Lunar Style

  • Lockheed Martin Team Completes GPS 3 System Design Review On Schedule
  • Glonass System To Be Launched By Year-End
  • Haicom Is Proudly Announce The New HI-601VT GPS GSM Real-Time Tracker
  • Comtech To Supply Movement Tracking Systems To US Army

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights 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 SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement