National Aeronautics and Space Administration Logo
Follow this link to skip to the main content NASA Banner
Solar System Exploration
News & Events
Where is the Gas in Interstellar Space?
Where is the Gas in Interstellar Space?
18 Apr 2007
(Source: Royal Astronomical Society)

A team of astronomers led by Professor Martin Barstow of the University of Leicester have searched for the hot gas thought to be present in the interstellar space around the Sun but found it just isn't there. Speaking at the Royal Astronomical Society National Astronomy Meeting in Preston on Tuesday 17 April, Professor Barstow will present a map of the local interstellar medium, the gas lying between the stars out to distances of about 300 light years from the Sun, made using the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite.

Professor Barstow and his team used FUSE to observe a group of white dwarf stars (compact remnants of stars like our Sun will be at the end of its life). The scientists intended to probe the structure of interstellar space in the vicinity of the Sun by searching for the imprint of oxygen in the ultraviolet light from the stars. However, all the oxygen detected was found to be in the atmospheres of the stars and no interstellar oxygen was found. This implies that, rather than being full of tenuous ionized gas, as expected, this region of interstellar space (the Local Cavity) is actually empty and was probably swept clear by an ancient supernova explosion a few million years ago.

Our present picture of the local interstellar medium is that the Sun and Solar system are embedded in and near the edge of a wispy diffuse cloud, known as the Local Cloud (or Local Fluff). This cloud, which is only 20-30 light years across, is itself in a larger much less dense region called the Local Bubble or Local Cavity.

The gas in the Local Cavity was expected to bear the scars of recent nearby events, such as supernova explosions, and radiation from hot young stars. These would make the cavity gas hot and ionized, with the electrons stripped from the constituent atoms, and should be detected by FUSE. The hot gas should emit also X-rays that are detected as a diffuse background in X-ray telescopes. However, if there is no hot gas present, then we need to find another explanation for this X-ray background. One novel suggestion is that it arises from the exchange of charged particles at the boundary between the Sun?s magnetic field and interstellar space.

CONTACT:

Professor Martin Barstow University of Leicester Tel: +44 (0)116 252 3492 E-mail: mab@star.le.ac.uk

IMAGES:

Images can be found at: http://nam2007.uclan.ac.uk/press.php

News Archive Search  Go!
Show  results per page
 
 
Awards and Recognition   Solar System Exploration Roadmap   Contact Us   Site Map   Print This Page
NASA Official: Kristen Erickson
Advisory: Dr. James Green, Director of Planetary Science
Outreach Manager: Alice Wessen
Curator/Editor: Phil Davis
Science Writer: Autumn Burdick
Producer: Greg Baerg
Webmaster: David Martin
> NASA Science Mission Directorate
> Budgets, Strategic Plans and Accountability Reports
> Equal Employment Opportunity Data
   Posted Pursuant to the No Fear Act
> Information-Dissemination Policies and Inventories
> Freedom of Information Act
> Privacy Policy & Important Notices
> Inspector General Hotline
> Office of the Inspector General
> NASA Communications Policy
> USA.gov
> ExpectMore.gov
> NASA Advisory Council
> Open Government at NASA
Last Updated: 18 Apr 2007