Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Extrasolar Planet News: Superplanet Or Brown Dwarf?

30.11.2004


New observations of an oddball planetary system 150 light-years from Earth may force astronomers to rethink the textbook definition of a planet and the accepted idea about how such a body forms. The observations suggest that either some planets are superheavy or that planets can form from disks of gas and dust that encircle not just a single star but two starlike objects.



Two years ago, when astronomers at the Geneva Observatory in Sauverny, Switzerland, reported their findings on the sunlike star HD 202206, nothing seemed out of the ordinary. The team announced that a body at least 17.4 times as heavy as Jupiter orbits the star. The unseen body resides at an average distance from the star of 0.82 times the Earth-sun distance.

The same team, led by Alexandre Correia of the University of Aveiro in Portugal, has now found evidence for a second unseen body orbiting HD 202206. This object is at least 2.4 times as heavy as Jupiter and resides at an average distance from the star of 2.55 times the Earth-sun distance, the researchers report (http://xxx.lanl.gov/abs/ astro-ph/0411512).


According to International Astronomical Union standards, the heavier body is a failed star known as a brown dwarf. By the union’s definition, brown dwarfs range from 13 to about 75 times the mass of Jupiter. That’s heavy enough to burn deuterium at their cores but too light to burn any other nuclear fuel, as bona fide stars do.

In contrast, the lighter object would be classified as a planet, as long as it weighs less than the 13-Jupiter-mass cutoff, as the scientists strongly suspect. In that case, it would have formed from gas and dust coalescing within a disk of material that surrounded the star in its youth. This would make it the first planet known to orbit a pair of objects— goes around the star five times, the outer body goes around exactly once. This particular synchrony has never before been observed in a planetary system. Synchrony keeps objects in an especially powerful gravitational embrace.

Synchrony can’t happen by chance, Correia says. The team suggests that the two bodies are birds of a feather, born in the same way and at the same time.

In that case, the heavier object orbiting HD 202206 wouldn’t be a brown dwarf after all, but the heaviest planet known. If so, the disk from which the two planets arose would have to have been two to four times as heavy as expected, Correia told Science News.

Moreover, if the heavier body is a superplanet, “we have to rethink our definition of what is a brown dwarf and what is a planet,” says Correia. Some objects massive enough to burn deuterium may be brown dwarfs, while others may be planets, he notes. “Somewhat odd systems like this . . . challenge our overall thinking about the formation of giant planets and brown dwarfs,” says Alan P. Boss of the Carnegie Institution of Washington (D.C.).

It’s possible that the heavier object is a brown dwarf but that theorists haven’t yet been clever enough to figure out why it’s in sync with the outer planet, cautions Adam S. Burrows of the University of Arizona in Tucson.

Published in the Nov. 27 issue of Science News, a weekly news magazine.

| newswise
Further information:
http://www.sciencenews.org

More articles from Physics and Astronomy:

nachricht Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas

nachricht Calculating quietness
22.09.2017 | Forschungszentrum MATHEON ECMath

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: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>