Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hubble space telescope reveals the aftermath of “Star Wars”

17.04.2007
An Anglo-American team of astronomers have used the Advanced Camera for Surveys on the Hubble Space Telescope (HST) to obtain the first direct optical images of the aftermath of a recent titanic explosion that took place in a star system 5,000 light years from Earth.

In a talk on Tuesday 17 April at the Royal Astronomical Society National Astronomy Meeting in Preston, Professor Michael Bode of Liverpool John Moores University will describe how these unique observations shed new light on the circumstances of such events.

Professor Bode will be speaking on behalf of the team which also comprises Dan Harman and Matt Darnley (Liverpool JMU, UK), Tim O’Brien (Jodrell Bank Observatory, University of Manchester, UK), Howard Bond (Space Telescope Science Institute, USA), Sumner Starrfield (Arizona State University, USA), Nye Evans (University of Keele, UK), Stewart Eyres (University of Central Lancashire, UK) and Michael Shara (American Museum of Natural History, USA).

During the night of 12 February 2006, Japanese amateur astronomers reported that a star in the constellation of Ophiuchus (known as RS Oph for short) had suddenly brightened and become visible even with the unaided eye in the night sky. Although this was the latest in a series of such outbursts of this star that have been spotted over the last hundred years or so, it was the first one since 1985 and gave scientists an opportunity to study it with new, more powerful, telescopes on the ground and in space.

RS Oph consists of a white dwarf, a super-dense dead star about the size of the Earth which was once the core of a star like the Sun and whose outer layers have been lost into space, in close orbit with a much larger, so-called red giant star. The two stars are so close together that the strong gravitational field of the white dwarf continuously pulls hydrogen-rich gas from the outer layers of the red giant. After around 20 years, so much gas builds up that a runaway thermonuclear explosion occurs on the white dwarf's surface. In less than a day, its energy output increases to over 100,000 times that of the Sun, and a quantity of gas equivalent to the mass of the Earth is ejected into space at speeds of several thousand kilometres per second (several million miles per hour).

Explosions such as this on short timescales of decades can only be explained if the white dwarf is near the maximum mass it could have without having collapsed to become an even denser object - a neutron star – during a supernova explosion.

What is also very unusual in RS Oph is that the red giant is losing enormous amounts of gas in a wind that envelops the whole system. As a result, the explosion on the white dwarf occurs effectively “inside” its companion's atmosphere and the ejected gas then slams into it at very high speed. Professor Bode explains “Immediately after the explosion, an observing campaign was set in train that involved most of the major space observatories, and many on the ground. We expected to see emission from the blast waves set up as the ejecta from the white dwarf impacted the red giant wind and we were not disappointed! For example, X-ray observations revealed temperatures in the shocked gas of over 100,000,000 degrees Celsius (around ten times that in the core of the Sun).”

On the ground, radio observations from telescopes spread around the globe also allowed the team to probe the initial stages of the outburst. Professor Bode comments, “Our first observations, made only two weeks after the explosion was reported, showed an expanding blast wave already comparable in size to Saturn’s orbit around the Sun. Over the next few months we were surprised to find our radio observations apparently showing it turning from a ring into a cigar-like shape with two more extended blobs (“jets”) gradually emerging, one on either side.”

In order to determine more precisely what was happening, optical observations with the orbiting Hubble Space Telescope (HST) were made in July 2006. Dr Dan Harman of Liverpool JMU took on the task of analysing the resulting data. “The problem here was that, seen from a distance of 5,000 light years, we were looking for what would appear to be very tiny and very faint features buried within the glare from the bright central star – a bit like trying to read the registration (licence) plate of an approaching car with its headlights on at night. However, after carefully removing the confusing effects of the star we were astounded by the results”.

Professor Bode continues, “Archival images taken before the latest outburst show no extended structure, but our latest HST images clearly show what appear to be two overlapping rings of total extent around 0.4 seconds of arc in size. At a distance of 5,000 light years, that equates to 8 times the diameter of Pluto’s orbit around our Sun and an inferred speed of expansion from the time of the explosion of around 3,200 kilometres per second (over 7 million miles per hour). The overall size and orientation are consistent with continued expansion of the largest structures (so-called “jets”) seen in the later radio images, but the picture is, perhaps unsurprisingly, not the simple one that had been assumed prior to the 2006 outburst.”

What Mike Bode and the team think we may be seeing is emission from the boundary of a rapidly expanding region shaped something like a peanut, but inclined towards us at an angle of around 40 degrees. The central stars orbit around each other in the plane of the “waist” region and the rings we see are a natural consequence of us looking through this inclined structure. They are now working with astronomers in Mexico who have high resolution optical spectra taken from the ground at around the time of the HST observations, and with these they expect to be able to tie down the geometry more precisely. “Further scheduled HST observations should also help in this regard”, says Bode. As Professor Sumner Starrfield adds, “The HST images clearly resolve the effects of high velocity material that has been explosively ejected from the white dwarf and then impacting the environment of the companion star: Star Wars in Action.”

The big question is what causes this shaping in the first place? It is thought unlikely that it originates in the explosion itself. More probable is that the environment into which the material is ejected is denser in some directions (most likely the plane of the binary star orbit) than others. This will have important wider implications for our understanding of the explosion and how jet-like structures are formed in many other astronomical objects.

CONTACTS

Prof Michael F. Bode
Astrophysics Research Institute, Liverpool John Moores University
Tel: +44 (0)151 231 2920 (direct), 2919(secretary)
Mob: +44 (0)796 842 2360
E-mail: mfb@astro.livjm.ac.uk
Dr Daniel Harman
Astrophysics Research Institute, Liverpool John Moores University
United Kingdom
Tel: +44 (0)151 231 2906 (direct), 2919 (secretary)
E-mail: dh@astro.livjm.ac.uk
Dr Stewart Eyres
Centre for Astrophysics
University of Central Lancashire
Tel: +44 (0)1772 893 742
E-mail: spseyres@uclan.ac.uk
Dr Tim O'Brien
Jodrell Bank Observatory
University of Manchester
Tel: +44 (0)1477 571321
E-mail: tob@jb.man.ac.uk
Prof Sumner Starrfield
School of Earth and Space Exploration
Arizona State University
Tel: +1 480 965 7569
E-mail: sumner.starrfield@asu.edu

Robert Massey | alfa
Further information:
http://www.ras.org.uk
http://www.nam2007.uclan.ac.uk/press.php

More articles from Physics and Astronomy:

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Nagoya physicists resolve long-standing mystery of structure-less transition

21.08.2017 | Materials Sciences

Chronic stress induces fatal organ dysfunctions via a new neural circuit

21.08.2017 | Health and Medicine

Scientists from the MSU studied new liquid-crystalline photochrom

21.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>