Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

‘Deep impact’ of pulsar around companion star

01.03.2006


Astronomers have witnessed a never-seen-before event in observations by ESA’s XMM-Newton spacecraft - a collision between a pulsar and a ring of gas around a neighbouring star.


Pulsar 1259-63 orbits a star (SS 2883) which is bright and visible to amateur astronomers



The rare passage, which took the pulsar plunging into and through this ring, illuminated the sky in gamma- and X-rays. It has revealed a remarkable new insight into the origin and content of ‘pulsar winds’, which has been a long-standing mystery. The scientists described the event as a natural but ‘scaled-up’ version of the well-known Deep Impact satellite collision with Comet Tempel 1.

Their final analysis is based on a new observation from XMM-Newton and a multitude of archived data which will lead to a better understanding of what drives well-known ‘pulsar nebulae’, such as the colourful Crab and Vela pulsars.


"Despite countless observations, the physics of pulsar winds have remained an enigma," said lead author Masha Chernyakova, of the Integral Science Data Centre, Versoix, Switzerland.

"Here we had the rare opportunity to see pulsar wind clashing with stellar wind. It is analogous to smashing something open to see what’s inside."

A pulsar is a fast-spinning core of a collapsed star that was once about 10 to 25 times more massive than our Sun. The dense core contains about a solar mass compacted in a sphere about 20 kilometres across.

The pulsar in this observation, called PSR B1259-63, is a radio pulsar, which means most of the time it emits only radio waves. The binary system lies in the general direction of the Southern Cross about 5000 light-years away.

Pulsar wind comprises material flung away from the pulsar. There is ongoing debate about how energetic the winds are and whether these winds consist of protons or electrons. What Chernyakova’s team has found, although surprising, ties in neatly with other recent observations.

The team observed PSR B1259-63 orbiting a ‘Be’ star named SS 2883, which is bright and visible to amateur astronomers. ‘Be’ stars, so named because of certain spectral characteristics, tend to be a few times more massive than our Sun and rotate at astonishing speeds.

They rotate so fast that their equatorial region bulges and they become flattened spheres. Gas is consistently flung off such a star and settles into an equatorial ring around the star, with an appearance somewhat similar to the planet Saturn and its rings.

The pulsar plunges into the Be star’s ring twice during its 3.4-year elliptical orbit; but the plunges are only a few months apart, just before and after ‘periastron’, the point when the two objects in orbit are closest to each other. It is during the plunges that X-rays and gamma rays are emitted, and XMM-Newton detects the X-rays.

"For most of the 3.4-year orbit, both sources are relatively dim in X-rays and it is not possible to identify characteristics in the pulsar wind," said co-author Andrii Neronov. "As the two objects draw closer together, sparks begin to fly."

The new XMM-Newton data was collected nearly simultaneously with a HESS observation. HESS, the High Energy Stereoscopic System, is a new ground-based gamma-ray telescope in Namibia.

Announced last year, the HESS observation was puzzling in that the gamma-ray emission fell to a minimum at periastron and had two maximums, just before and after the periastron, the opposite of what scientists were expecting.

The XMM-Newton observation supports the HESS observation by showing how the maximums were generated by the double plunging into the Be star’s ring. By combining these two observations with radio observations from the last periastron event, the scientists now have a complete picture of this system.

Tracing the rise and fall of X-rays and gamma rays day after day as the pulsar dug through the Be star’s disk, the scientists could conclude that the wind of electrons at an energy level of 10-100 MeV is responsible for the observed X-ray light. (1 MeV represents one million electron volts.)

Although 10-100 MeV is energetic, this is about 1000 times less than the expected energy level of 100 TeV. Even more puzzling is the multi-TeV gamma-ray emission, which, although surely emanating from the 10-100 TeV wind electrons, seems to be produced differently to how it was thought before.

"The only fact that is crystal clear at the moment is that this is the pulsar system to watch if we want to understand pulsar winds," said Chernyakova.

"Never have we seen pulsar wind in such detail. We are continuing with theoretical models now. We have some good explanation of the radio-to-TeV-gamma-ray behaviour of this funny system, but it is still ‘under construction.’"

Monica Talevi | alfa
Further information:
http://www.esa.int/esaSC/SEMK6HMVGJE_index_0.html

More articles from Physics and Astronomy:

nachricht MSU astronomers discovered supermassive black hole in an ultracompact dwarf galaxy
14.08.2018 | Lomonosov Moscow State University

nachricht ASU astrophysicist helps discover that ultrahot planets have starlike atmospheres
13.08.2018 | Arizona State University

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: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

'Building up' stretchable electronics to be as multipurpose as your smartphone

14.08.2018 | Information Technology

During HIV infection, antibody can block B cells from fighting pathogens

14.08.2018 | Life Sciences

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>