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 Major discovery in controlling quantum states of single atoms
20.02.2018 | Institute for Basic Science

nachricht Observing and controlling ultrafast processes with attosecond resolution
20.02.2018 | Technische Universität München

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: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

'Lipid asymmetry' plays key role in activating immune cells

20.02.2018 | Life Sciences

MRI technique differentiates benign breast lesions from malignancies

20.02.2018 | Medical Engineering

Major discovery in controlling quantum states of single atoms

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>