Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Glasgow astronomers explain hot star disks

01.11.2002


Astronomers have been puzzled for decades as to how the rings of hot gas surrounding certain types of star are formed. Now a team of scientists from the Universities of Glasgow and Wisconsin believe they have found the answer. The team studied a type of young, hot star, known as a "Be star", that has a disk of glowing gas around it, similar to the rings surrounding Saturn. Until now, no one has been able to account for how these rings form but in a paper published this month*, the team suggest an answer.


Artist’s impression of a Be Star



The gas ring surrounding a Be Star may appear and then disappear, possibly reforming at a later time. Material in the disk is attracted back towards the star by the pull of gravity, but if it has enough energy it can escape into space, contributing to the stellar wind.

The new theory reveals why this material is held in a disk at some distance from the star instead of either being pulled closer or flying away into space.


Deborah Telfer of Glasgow University explains
"Our model relies on the existence of a magnetic field around Be stars producing a ‘Magnetically Torqued Disk’. Magnetic field lines channel stellar wind material leaving the surface of the star down towards the equatorial plane. A disk then forms in the region where particles have sufficient angular velocity to balance gravity. In the outer regions, the weaker magnetic field lines should burst open allowing particles to form part of the general stellar wind."

Previously, the Wind Compressed Disk Model (Bjorkman and Cassinelli, 1993) was regarded as one of the most successful explanations of circumstellar disks. However, it predicts disks that are out-flowing (i.e. the material moves from the star to the disk and then away into space) and expanding. Yet Be stars are observed to have circumstellar Keplerian disks, meaning that the disks are supported against gravity by rotation rather than gas or radiation pressure.

Deborah has been working with Joseph Cassinelli of Wisconsin on the new model for Be star disks and they are delighted at the success of their results.

These suggest that only a narrow range of types of star would form a detectable Magnetically Torqued Disk and be seen as Be stars.

Heavier stars would require an unreasonably large magnetic field while lighter stars would produce disks too small to be detected. More work is needed to explain every aspect of observational evidence but we may finally be reaching an understanding of what
produces these Saturn-like stars.

Julia Maddock | alfa

More articles from Physics and Astronomy:

nachricht APEX takes a glimpse into the heart of darkness
25.05.2018 | Max-Planck-Institut für Radioastronomie

nachricht First chip-scale broadband optical system that can sense molecules in the mid-IR
24.05.2018 | Columbia University School of Engineering and Applied Science

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: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

If solubilty is the problem - Mechanochemistry is the solution

25.05.2018 | Life Sciences

Investigating cell membranes: researchers develop a substance mimicking a vital membrane component

25.05.2018 | Interdisciplinary Research

When corals eat plastics

24.05.2018 | Ecology, The Environment and Conservation

VideoLinks
Science & Research
Overview of more VideoLinks >>>