24/7 Space News  





. NASA Mission Finds Link Between Big And Small Stellar Blasts

This composite image shows Z Camelopardalis, or Z Cam, a double-star system featuring a collapsed, dead star, called a white dwarf, and a companion star, as well as a ghostly shell around the system. The massive shell provides evidence of lingering material ejected during and swept up by a powerful classical nova explosion that occurred probably a few thousand years ago. The image combines data gathered from the far-ultraviolet and near-ultraviolet detectors on NASA's Galaxy Evolution Explorer on Jan. 25, 2004. The orbiting observatory first began imaging Z Cam in 2003. Z Cam is the largest white object in the image, located near the center. Parts of the shell are seen as a lobe-like, wispy, yellowish feature below and to the right of Z Cam, and as two large, whitish, perpendicular lines on the left.

Z Cam was one of the first known recurrent dwarf nova, meaning it erupts in a series of small, "hiccup-like" blasts, unlike classical novae, which undergo a massive explosion. That's why the huge shell around Z Cam caught the eye of astronomer Dr. Mark Seibert of Carnegie Institution of Washington in Pasadena, Calif. -- it could only be explained as the remnant of a full-blown classical nova explosion. This finding provides the first evidence that some binary systems undergo both types of explosions. Previously, a link between the two types of novae had been predicted, but there was no evidence to support the theory. The faint bluish streak in the bottom right corner of the image is ultraviolet light reflected by dust that may or may not be related to Z Cam. Numerous foreground and background stars and galaxies are visible as yellow and white spots. The yellow objects are strong near-ultraviolet emitters; blue features have strong far-ultraviolet emission; and white objects have nearly equal amounts of near-ultraviolet and far-ultraviolet emission. Image credit: NASA/JPL-Caltech

by Staff Writers
Los Angeles CA (SPX) Mar 08, 2007
Proof that certain double star systems can erupt in full-blown explosions and then continue to flare up with smaller bursts has been spotted by the ultraviolet eyes of NASA's Galaxy Evolution Explorer. The finding bolsters a 20-year-old theory that suggests such double-star, or binary systems, should eventually undergo both types of explosion, rather than just one or the other.

It implies the systems probably cycle between two blast types, hiccupping every few weeks with small surges until the next giant outburst about 10,000 years later.

"The new images are the strongest evidence yet in favor of the cyclic evolution of these binary stars," said Dr. Mike Shara of the American Museum of Natural History, New York, lead author of a new paper that details the finding in the March 8 issue of the journal Nature. "It's gratifying to see such strong evidence for this theory finally emerge after all this time."

The new discovery centers around Z Camelopardalis (Z Cam), a stellar system that astronomers have long known to be a cataclysmic binary - a system featuring a collapsed, dead star, or white dwarf, which behaves like a vampire sucking hydrogen-rich matter from a companion star. The stolen material forms a rotating disk of gas and dust around the white dwarf.

Astronomers divide cataclysmic binaries into two classes - dwarf novae, which erupt in smaller, "hiccup-like" blasts, and classical novae, which undergo huge explosions. Classical novae explosions are 10,000 to a million times brighter than those of dwarf novae, and they leave behind large shells of shocked gas.

About 530 light years from Earth, Z Cam was one of the first dwarf novae ever detected. For decades, observers have watched the system hiccup with regular outbursts. It brightens about 40-fold every 3 weeks or so, when an instability causes some of the material drawn by the stellar vampire to crash onto the white dwarf's surface.

Theory holds that Z Cam and other recurring dwarf novae should eventually accumulate enough matter and pressure from their swirling disks of hydrogen to trigger gigantic hydrogen bombs - classical novae explosions. But no one had found definitive evidence that a binary had experienced both types of blasts until the Galaxy Evolution Explorer's observations of Z Cam, which began in 2003.

That's when Dr. Mark Seibert of the Carnegie Institution of Washington in Pasadena, Calif., serendipitously noticed a never-before-seen arc and linear features surrounding Z Cam in imaging data the Galaxy Evolution Explorer collected during its Survey of Nearby Galaxies. The features indicated the presence of a massive shell around Z Cam - evidence that the dwarf nova had in fact undergone a classical nova explosion a few thousand years ago.

Previous observations had failed to reveal the massive shell because it cannot be easily detected at optical wavelengths. It is, however, easily seen at the ultraviolet wavelengths detected by the Galaxy Evolution Explorer.

"You could actually see it immediately," Seibert said. "But we had to convince ourselves that we were really seeing a nova remnant."

Narrowband images from Kitt Peak National Observatory near Tucson, Ariz., Palomar Observatory near San Diego, Calif., and the Wise Observatory near Mizpe Ramon, Israel, along with optical spectroscopic measurements made at the Lick Observatory near San Jose, Calif., by other team members confirmed that the structures detected in the Galaxy Evolution Explorer imaging data were indeed a massive shell of gas surrounding Z Cam.

The authors of the new paper write that Z Cam's classical nova explosion must have been quite spectacular. "During that eruption," they write, "it must have become, for a few days or weeks, one of the brightest stars in the sky."

Email This Article

Related Links
Galaxy Evolution Explorer at Caltech
Stellar Chemistry, The Universe And All Within It




Tempur-Pedic Mattress Comparison

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


hello world
AEGIS Survey Reveals New Principle Governing Galaxy Formation And Evolution
Santa Cruz CA (SPX) Mar 07, 2007
Faced with the bewildering array of galaxies in the universe, from orderly spirals to chaotic mergers, it is hard to imagine a unifying principle that describes them all with mathematical precision. But that is just what astronomers have now discovered.

.
Get Our Free Newsletters Via Email
  



  • Astronaut Fired A Month After Kidnap Attempt
  • Astrophysicist Hawking To Try Out Weightlessness
  • Impossible For Great Wall To Be Visible With Naked Eye From From Space
  • Japanese Instant Noodle Pioneer In Final Blastoff

  • Early Mars Had Underground Water System
  • Rosetta Delivers Phobos Transit Animation And Sees Mars In Stereo
  • SpaceDev's Starsys Division Awarded Contract For NASA Mars Science Explorer Mission
  • First Test Of New Autonomous Capability On Mars Is Promising

  • Russia May Open New Space Launch Site
  • Hyundai To Build First South Korea Launch Pad
  • Construction Of Soyuz Launch Base In French Guiana Begins
  • Iran Claims Of Satellite Launch Brought Down To Earth

  • Satellite Scientists Set To Descend On Hobart
  • CSIRO Imagery Shows Outer Great Barrier Reef At Risk From River Plumes
  • Scientists Gear Up For Envisat 2007 Symposium
  • ITT Passes Critical Design Review for GOES-R Advanced Baseline Imager

  • The Tip of the Iceberg
  • New Horizons Completes First Stage Of Long Journey To Pluto And Beyond
  • Pluto-Bound New Horizons Spacecraft Gets A Boost From Jupiter
  • Defining Planets

  • NASA Mission Finds Link Between Big And Small Stellar Blasts
  • Full-Spectrum Study Of Small Patch Of Sky Yields Portrait Of Maturing Universe
  • Hubble Pans Across Heavens To Harvest 50,000 Evolving Galaxies
  • AEGIS Survey Reveals New Principle Governing Galaxy Formation And Evolution

  • First Chinese Lunar Probe Assembled And Ready For Launch
  • Chinese Spacemen To Reach Moon In 15 Years
  • China To Launch Lunar Satellite Probe This Year
  • The Edge Of Luna Incognita By SMART-1

  • Raytheon To Pursue Air Force Upgrade For NextGen GPS Control Segment
  • Spirent Communications Announces Combined GPS Galileo Simulation System
  • ESA Award SSTL Contract To Build A Second GIOVE-A
  • Europe Moves To Safeguard Galileo Frequencies

  • 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