Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Even ’failed stars’ form planets

26.10.2005


An international team of astronomers shows that even brown dwarfs start to form planets



Thus, the process of building planets is more universal and robust than had previously been assumed (Science Express, October 20, 2005).

Brown dwarfs, like more massive normal stars, are formed when interstellar gas and dust clouds collapse. When this happens, a central, dense area builds up, embedded in a rotating disc made of gas and dust. These circumstellar discs produce infrared radiation according to their temperature.


The collapse of gas and dust clouds ends when the increasing pressure, temperature, and density in the central area causes nuclear fusion to start – that is, the burning of hydrogen into helium. This causes the dense area to become its own star. If its mass is too small, however, for the fusion to take place, a brown dwarf is created instead. It will have no further source of energy, and will slowly radiate the compression temperature created by the collapse.

The team of astronomers investigated six young brown dwarfs from the Chamaeleon star-forming region in the direction of the south celestial pole. The objects are between one and three million years old, and their masses are between 40 and 70 times that of Jupiter. The astonomers used SPITZER to record the detailed spectrum of infrared light, from which they derived information about the size of the radiated particles and their minerological composition.

The data analysis showed that in five of the six cases they looked at, dust particles in the circumstellar disc of the ‛failed stars’ stuck together and made larger clumps of olivine, a material made of silicon and crystalline structures. The discs of young normal stars are already known to contain this material. It is also found in comets – the leftover material from the time when our own planetary system was being built. Apparently, the same growth and crystallisation processes take place in the circumstellar discs that we see in normal stars (including the Sun) at the beginning of planet formation.

Futhermore, there was evidence that the circumstellar discs flatten out in a way that one would also expect given how the dust components develop. Daniel Apai, who is doing reserach at the Steward Observatory in Tuscon, Arizona and is a member of the Life and Planets Astrobiology Center NASA´s Astrobiology Institute, says that ‛Using SPITZER, we can investigate planet formation under all different kinds of conditions. Our observations show that the first steps of planet formation are determined to a lesser extent by details than we previously thought’. Kees Dullemond at the Max Planck Instiute for Astronomy stresses that ‛this result is important also because it narrows down theories about planet formation and thus gives us a deeper insight into the process’.

These observational results show that in the future, in projects to find extrasolar planets – like ESA’s DARWIN mission and NASA’s terrestrial planet finder – it could be worth it to look for planets in the neighborhood of brown dwarfs.

We can look at these spectra when we do a wavelength analysis on the light collected in the telescope, similar to the way a drop of water or a prisma turns sunlight into a rainbow. The bright ‛arches’, which appear at different wavelengths, are the ‛fingerprints’ which allow us to read the chemical features (i.e., it contains silicate), the size, and the physical condition (from amorphous to crystalline).

In the picture, the light green vertical stripes indicate the ‛fingerprints’ of crystals which are made primarily of the minieral olivine, which is green, made of silicate, and appears on earth. It seems the spectra of three of the four brown dwarfs have similar components. In interstellar dust, they are unrecognisable. They are most clearly visible in the spectrum of the Hale-Bopp comet. The bigger the dust particles, the wider the ‛arches’ are in their emission spectrum.

Participants in this project: Drs Daniel Apai and Ilaria Pascucci (Steward Observatory, University of Arizona, Tucson), Drs Jeroen Bouwman, Thomas Henning und Cornelis P Dullemond (Max Planck Institute for Astronomy, Heidelberg), and Dr Antonella Natta (Osservatorio Astrofisico di Arcetri, Florence).

Dr Klaus Jäger | EurekAlert!
Further information:
http://www.mpia.de

More articles from Physics and Astronomy:

nachricht SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

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: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>