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 single photon reveals quantum entanglement of 16 million atoms
16.10.2017 | Université de Genève

nachricht On the generation of solar spicules and Alfvenic waves
16.10.2017 | Instituto de Astrofísica de Canarias (IAC)

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: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

Im Focus: New nanomaterial can extract hydrogen fuel from seawater

Hybrid material converts more sunlight and can weather seawater's harsh conditions

It's possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. UCF...

Im Focus: Small collisions make big impact on Mercury's thin atmosphere

Mercury, our smallest planetary neighbor, has very little to call an atmosphere, but it does have a strange weather pattern: morning micro-meteor showers.

Recent modeling along with previously published results from NASA's MESSENGER spacecraft -- short for Mercury Surface, Space Environment, Geochemistry and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

Conference Week RRR2017 on Renewable Resources from Wet and Rewetted Peatlands

28.09.2017 | Event News

 
Latest News

A single photon reveals quantum entanglement of 16 million atoms

16.10.2017 | Physics and Astronomy

The melting ice makes the sea around Greenland less saline

16.10.2017 | Earth Sciences

On the generation of solar spicules and Alfvenic waves

16.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>