Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dusty old star offers window to our future, astronomers report

12.09.2005


Astronomers have glimpsed dusty debris around an essentially dead star where gravity and radiation should have long ago removed any sign of dust -- a discovery that may provide insights into our own solar system’s eventual demise several billion years from now.



The results are based on mid-infrared observations made with the Gemini 8-meter Frederick C. Gillett Telescope (Gemini North) on Hawaii’s Mauna Kea. The Gemini observations reveal a surprisingly high abundance of dust orbiting an ancient stellar ember named GD 362.

"This is not an easy one to explain," said Eric Becklin, UCLA astronomer and principle investigator for the Gemini observations. "Our best guess is that something similar to an asteroid or possibly even a planet around this long-dead star is being ground up and pulverized to feed the star with dust. The parallel to our own solar system’s eventual demise is chilling."


"We now have a window to the future of our own planetary system," said Benjamin Zuckerman, UCLA professor of physics and astronomy, member of NASA’s Astrobiology Institute, and a co-author on the Gemini-based paper. "For perhaps the first time, we have a glimpse into how planetary systems like our own might behave billions of years from now."

"The reason why this is so interesting is that this particular white dwarf has by far the most metals in its atmosphere of any known white dwarf," Zuckerman added. "This white dwarf is as rich in calcium, magnesium and iron as our own sun, and you would expect none of these heavier elements. This is a complete surprise. While we have made a substantial advance, significant mysteries remain."

The research team includes scientists from UCLA, Carnegie Institution and Gemini Observatory. The results are scheduled for publication in an upcoming issue of the Astrophysical Journal. The results will be published concurrently with complementary near-infrared observations made by a University of Texas team led by Mukremin Kilic at the NASA Infrared Telescope Facility, also on Mauna Kea.

"We have confirmed beyond any doubt that dust never does sleep!" quips Gemini Observatory’s Inseok Song, a co-author of the paper. "This dust should only exist for hundreds of years before it is swept into the star by gravity and vaporized by high temperatures in the star’s atmosphere. Something is keeping this star well stocked with dust for us to detect it this long after the star’s death."

"There are just precious few scenarios that can explain so much dust around an ancient star like this," said UCLA professor of physics and astronomy Michael Jura, who led the effort to model the dust environment around the star. "We estimate that GD 362 has been cooling now for as long as five billion years since the star’s death-throes began and in that time any dust should have been entirely eliminated."

Jura likens the disk to the familiar rings of Saturn and thinks that the dust around GD 362 could be the consequence of the relatively recent gravitational destruction of a large "parent body" that got too close to the dead star.

GD 362 is a white dwarf star. It represents the end-state of stellar evolution for stars like the sun and more massive stars like this one’s progenitor, which had an original mass about seven times the sun’s. After undergoing nuclear reactions for millions of years, GD 362’s core ran out of fuel and could no longer create enough heat to counterbalance the inward push of gravity. After a short period of instability and mass loss, the star collapsed into a white-hot corpse. The remains are cooling slowly over many billions of years as the dying ember makes its slow journey into oblivion.

Based on its cooling rate, astronomers estimate that between two billion to five billion years have passed since the death of GD 362.

"This long time frame would explain why there is no sign of a shell of glowing gas known as a planetary nebula from the expulsion of material as the star died," said team member and Gemini astronomer Jay Farihi.

During its thermonuclear decline, GD 362 went through an extensive period of mass loss, going from a mass of about seven times that of the sun to a smaller, one-solar-mass shadow of its former self.

Although about one-quarter of all white dwarfs contain elements heaver than hydrogen in their atmospheres, only one other white dwarf is known to contain dust. The other dusty white dwarf, designated G29-38, has about 100 times less dust density than GD 362.

The Gemini observations were made with the MICHELLE mid-infrared spectrograph on the Gemini North telescope on Mauna Kea, Hawaii.

"These data are phenomenal," said Alycia Weinberger of the Carnegie Institution. "Observing this star was a thrill! We were able to find the remnants of a planetary system around this star only because of Gemini’s tremendous sensitivity in the mid-infrared. Usually you need a spacecraft to do this well."

The Gemini mid-infrared observations were unique in their ability to confirm the properties of the dust responsible for the "infrared excess" around GD 362. The complementary Infrared Telescope Facility near-infrared observations and paper by the University of Texas team provided key constraints on the environment around the star.

University of Texas astronomer and co-author Ted von Hippel describes how the Infrared Telescope Facility (IRTF) observations complement the Gemini results: "The IRTF spectrum rules out the possibility that this star could be a brown dwarf as the source of the ’infrared excess,’" von Hippel said. "The combination of the two data sets provides a convincing case for a dust disk around GD 362."

Stuart Wolpert | EurekAlert!
Further information:
http://www.college.ucla.edu

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>