Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

FUSE pierces the Veil

04.06.2004


Satellite pins down distance to important exploded star


An image of the entire Cygnus Loop in the light of hydrogen-alpha, 656.3 nm. (Data courtesy of Nancy Levenson.)



The Veil Nebula, a delicate network of glowing gaseous filaments in the northern constellation of Cygnus the Swan, has long been a favorite of both amateur and professional astronomers. Part of a much larger nebula known as the Cygnus Loop, the Veil is comprised of the leftovers of a star that exploded between 5,000 and 8,000 years ago.

For at least half a century, scientists have probed the Cygnus Loop with various techniques, trying to understand its physical characteristics as a model for comprehending a whole class of similar objects that cannot be observed in such detail. Even with intensive study, however, many of the Loop’s basic parameters, such as its distance and the density of its gaseous filaments, have been poorly understood.


But a creative new observation of a star situated behind the Veil Nebula may alter the way scientists think about this supernova remnant. At an American Astronomical Society meeting in Denver this week, astronomers from The Johns Hopkins University will provide confirmation that the Cygnus Loop is closer to Earth than many have thought. These new findings, obtained largely using the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite, have a major impact on the derived properties of this important, prototypical object.

"The key to this result was in finding a background star with sufficient far-ultraviolet output to be observed with FUSE," says William P. Blair, a research professor at The Johns Hopkins University and the principal author of the study.

To identify the candidate star, Blair and his colleagues used an image of the Veil Nebula taken with the Ultraviolet Imaging Telescope on a 1995 space shuttle flight. In the far-ultraviolet, most stars visible at optical wavelengths simply fade away.

"It was a real stroke of luck to find an ultraviolet-bright star located behind the Veil," Blair said.

Late last year, Blair and his colleagues trained FUSE -- a NASA satellite designed at and operated by a team at Johns Hopkins -- on the star, known only as KPD2055+311. The resulting spectrum of the star in ultraviolet light shows many absorption lines, or dips, in light intensity. Some of these dips arise in the star’s atmosphere or from cold molecular gas in the interstellar space along the way to the star. But some absorptions, attributable to very hot gas, must arise from the absorption within the Veil Nebula itself.

"Indeed, this confirmed for us that the star is behind the Cygnus Loop," Blair said.

Part two of the story involves the star itself. Blair’s group used the observed properties of the star and a model of the star’s emission to calculate a distance of 1,860 light years to KPD2055+311. (A light year is the distance light travels in one year, about 6 trillion miles.) Until a few years ago, astronomers placed the Cygnus Loop more than 2,500 light years distant.

In 1999, astronomers using the Hubble Space Telescope revised that estimate to 40 percent closer, or 1,470 light years. Nevertheless, uncertainties and assumptions used in making that estimate left some researchers unpersuaded. Because the star’s distance is well determined and it is located behind the Cygnus Loop, it places an upper boundary on the distance and provides an independent confirmation of the shorter distance scale.

According to Blair, the shorter distance makes "a tremendous difference" in the calculated size, age, energy and average expansion velocity of the supernova remnant compared with previous estimates.

"Since we want to use the Cygnus Loop to scale to similar objects, it is important to have an accurate starting point," Blair said. "This observation goes a long way toward improving our understanding of this important object."

Lisa De Nike | EurekAlert!
Further information:
http://www.jhu.edu/
http://fuse.pha.jhu.edu/~wpb/cyglpstar.html ´

More articles from Physics and Astronomy:

nachricht A better way to weigh millions of solitary stars
15.12.2017 | Vanderbilt University

nachricht A chip for environmental and health monitoring
15.12.2017 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>