Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The Beautiful Death: the Halos of Planetary Nebulae Revealed

11.09.2008
Stars without enough mass to turn into exploding supernovae end their lives blowing away most of their mass in a non-explosive, but intense stellar wind.

Only a hot stellar core remains in the form of a white dwarf; the rest of the star is dispersed into the interstellar medium, enriching it with chemically processed elements, such as carbon, that is found in all living organisms on Earth.

These elements were cooked in the stellar furnace during a stellar life span covering billions of years. The high-energy radiation from the hot white dwarf makes the blown gas to shine for a short period of time, and the result is one of the most colourful and beautiful astronomical objects: a planetary nebula.

The complex history of mass loss

The events which lead to the formation of a planetary nebula develop in two phases that finally induce a structure composed of a denser, inner region –the planetary nebula itself– and an external fainter halo, that consists of the ionized stellar wind. All together, the blowing of this material is performed in a relatively short time, in astronomical terms, and the planetary nebula is visible only during a few thousand years. For this reason there are not many of these objects available for study.

External halos of planetary nebulae are faint and difficult to study, but they can provide a wealth of information on the physical properties of the final mass loss stage of the dying star. Although there is progress in understanding both stellar evolution and mass loss theoretically, observational details of, in particular, the last phase of the mass loss process have remained obscure. Classical astronomical spectrographs and other instruments are able to study only a few points of such faint and extended objects, making the analysis of these halos an extremely cumbersome, or even impossible task.

Integral field spectroscopy to the rescue

Through the new technique of integral field spectroscopy it is possible to obtain hundreds of spectra across a relatively large area of the sky, and this opens new prospects for the analysis of extended objects, such as planetary nebulae. Calar Alto Observatory has one of the world's best integral field spectrographs, PMAS (Potsdam Multi-Aperture Spectrophotometer), attached to its 3.5 m telescope.

In a research article, that was just published in the journal Astronomy and Astrophysics, a research team from the Astrophysical Institute in Potsdam, lead by C. Sandin, has used PMAS to study the two-dimensional structure of a selected set of five planetary nebulae in our Galaxy: the Blue Snowball Nebula (NGC 7662), M2-2, IC 3568, the Blinking Planetary Nebula (NGC 6826) and the Owl Nebula (NGC 3587).

The halos of planetary nebulae revealed

For four of these objects the research team derived a temperature structure, which extended all the way from the central star and out into the halo, and found, in three cases, that the temperature increases steeply in the inner halo. According to Sandin, "The appearance of such hot halos can be readily explained as a transient phenomenon which occurs when the halo is being ionized." Another remarkable result of this study is that it has been possible, for the first time, to measure the mass loss history of the final evolution of the stars which produced the planetary nebulae.

Sandin says that "In comparison to other methods which measure mass loss rates, our estimates are made directly on the gas component of the stellar wind." The results allow important insights on how mass is lost in time, and the researchers found that "the mass loss rate increases by a factor of about 4-7 during the final, say, 10 000 years of mass loss."

The research team plans to continue with this study of the final evolutionary phases of low mass stars, and have observed planetary nebulae in the Magellanic Clouds. As the authors argue "on the theoretical side the results of our studies should provide a challenging basis for further improvement of models of stellar winds."

David Galadi-Enriquez | alfa
Further information:
http://www.caha.es
http://www.caha.es/the-beautiful-death_en.html

More articles from Physics and Astronomy:

nachricht Study offers new theoretical approach to describing non-equilibrium phase transitions
27.04.2017 | DOE/Argonne National Laboratory

nachricht SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>