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Topic: Brown dwarf

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In the News (Mon 18 Mar 19)

  brown dwarf
By this criterion, brown dwarfs are held to form in the same way as stars, as condensations in an interstellar gas cloud (see stars, evolution).
The more massive a brown dwarf, the higher its surface temperature, though a typical value is about 1000 K. The first brown dwarf to be confirmed, in 1995, on the basis of a combination of mass determination, spectroscopic studies, and direct imaging was Gliese 229B.
At the high-mass, high-temperature end of the brown dwarf scale are the ultra-cool dwarfs, with dusty atmospheres and a spectral type of M7 or later.
www.daviddarling.info /encyclopedia/B/browndwarf.html   (1232 words)

 Wikinfo | Brown dwarf   (Site not responding. Last check: 2007-10-18)
Brown dwarfs are a special type of low-mass star (approximately 13-70 Jupiter masses) that never fuse hydrogen into helium in their cores, as do stars on the main sequence.
Early in their development most brown dwarf stars do have lithium and deuterium fusion in their cores, and a lack of lithium is a test for low-mass objects that are suspected of being brown dwarfs.
Brown dwarfs continue to glow in the red and infrared after their deuterium is exhausted.
www.wikinfo.org /wiki.php?title=Brown_dwarf   (311 words)

 brown dwarf. The Columbia Encyclopedia, Sixth Edition. 2001-05
A year later, several so-called methane dwarfs were discovered; these are thought to be older brown dwarfs that have cooled sufficiently over billions of years so that large amounts of methane could form in their atmospheres.
Observations of 100 young brown dwarfs in the Orion Nebula in 2001 strongly supported the theory that they originate as failed stars; many of the brown dwarfs were surrounded by disks of dust and gas that conceivably could condense and conglomerate to create planets orbiting them.
Brown dwarfs are believed to play an important role in the process of stellar evolution.
www.bartleby.com /65/br/browndwa.html   (398 words)

 Universe Today - Hubble Pins Down Brown Dwarf Masses
The discovery of the paired brown dwarfs and the critical measurements are reported today in the scientific journal Nature by a team of astronomers: Jeff Valenti of the Space Telescope Science Institute (STScI), Robert Mathieu of the University of Wisconsin-Madison, and Keivan Stassun of Vanderbilt University.
Because old brown dwarfs are smaller and dimmer than true stars, it is only in recent years that improvements in telescope technology have allowed astronomers to catalog hundreds of faint objects that they think may be brown dwarfs.
Brown dwarfs and stars are formed in the same way, from a collapsing cloud of interstellar dust and gas.
www.universetoday.com /am/publish/brown_dwarf_masses.html?1532006   (1083 words)

 Brown Dwarfs   (Site not responding. Last check: 2007-10-18)
A brown dwarf is an object that formed the way stars do, from the collapse of a molecular cloud, but that, because it is not massive enough, does not sustain stable hydrogen fusion in its core.
The first object positively identified as a brown dwarf is the faint companion to the M1 V (low mass, red, Main Sequence) star Gliese 229.
The brown dwarf is known as Gliese 229b.
astrosun.tn.cornell.edu /academics/courses/astro201/bd.htm   (92 words)

 Unraveling Brown Dwarf
Brown dwarfs are not massive enough to be stars, nor are they planets in the traditional sense.
One possibility is that brown dwarfs form as a result of the turbulent fragmentation and contraction of molecular cloud cores--that is, in the same way as stars.
It has not yet been possible to measure the sizes of brown dwarf disks to determine whether they are truncated, but their lifetimes appear to be comparable to those of disks around stars.
www.meta-religion.com /Astronomy/Stars/unraveling_brown_dwarf.htm   (870 words)

 CNN.com - Object near sunlike star caught on camera - January 8, 2002
The distance between the substellar object known as brown dwarf and its parent star is less than that between the planet Uranus and the sun.
Brown dwarfs, middling objects between planets and stars, are considerably more massive than the largest planets but do not have enough mass to ignite the thermonuclear reactions necessary to become stars.
In this composite image, light from the brighter primary star is removed from the region of the brown dwarf, lower left.
archives.cnn.com /2002/TECH/space/01/07/brown.dwarf   (525 words)

 Brown dwarf - Wikipedia, the free encyclopedia
Brown dwarf are sub-stellar objects with a mass below that necessary to maintain hydrogen-burning nuclear fusion reactions in their cores, as do stars on the main sequence, but which have fully convective surfaces and interiors, with no chemical differentiation by depth.
While the discovery of the coolest dwarf was highly significant at the time it was debated whether GD 165B would be classified as a brown dwarf or simply a very low mass star since observationally it is very difficult to distinguish between the two.
The use of lithium to distinguish candidate brown dwarfs from low-mass stars is commonly referred to as the lithium test, and was pionereed by Rafael Rebolo and colleagues.
en.wikipedia.org /wiki/Brown_dwarf   (2713 words)

 New Neighbor May Be Closest Known Brown Dwarf
Brown dwarfs are thought to form when an interstellar cloud of gas and dust collapses under the weight of gravity.
Other brown dwarfs have been discovered recently, but their distances have not yet been determined, according to Tom Geballe of the Gemini Observatory.
"If the [prevalence] of brown dwarfs and stars are about the same, then there are over 100 billion brown dwarfs in our galaxy," Geballe said, adding that it would then be logical to assume that at least one would be found at around 4.2 light-years away, the distance to the closest star.
www.space.com /scienceastronomy/astronomy/brown_dwarf_001122.html   (541 words)

 Brown Dwarfs   (Site not responding. Last check: 2007-10-18)
Originally called fl dwarfs (and often called enanas cafe in Mexico), these substellar objects were first conceived of in the early 1960s as dark bodies floating freely in space.
Brown dwarfs lack sufficient mass (about 80 Jupiters) to ignite the fusion of hydrogen in their cores, and thus never become true stars.
Giant planets (such as Jupiter) may be much less massive than brown dwarfs, but are about the same diameter and may contain many of the same molecules in th eir atmospheres.
astron.berkeley.edu /~stars/bdwarfs   (228 words)

 Chandra :: Field Guide to X-ray Sources :: Brown Dwarfs
brown dwarfs inhabited the "undiscovered country" between stars and planets.
Because of their intrinsic faintness and low temperature, brown dwarfs were not discovered until 1995.
After that brown dwarfs glow because of the heat generated by the release of gravitational energy as they slowly contract.
chandra.harvard.edu /xray_sources/browndwarf_fg.html   (245 words)

 Brown Dwarf
Brown Dwarfs are an unusual and exciting class of star/planet that exists on the fine line that separates objects with sufficient mass to become a star, and those objects whose mass falls shy of the density necessary to start the fusion process.
Self-luminous planets and brown dwarfs are expected to show the best contrast against the sky background and the scattered light from their primary stars near their thermal emission peak.
This discovery was later confirmed to be a brown dwarf by emission-line spectroscopy using the four-meter telescope at the Cerro Tololo Interamerican Observatory in Chile.
business.fortunecity.com /rowling/167/SuperNovae/BrownDwarf.html   (4793 words)

 cool brown dwarf
Brown dwarfs are objects 15-70 times more massive than Jupiter, which is 318 times as massive as Earth.
Due to this brown dwarf's small size and relatively cool temperature, any new, habitable planet would need to be much closer than the distance between Earth and its white hot sun, 93 million miles.
Brown dwarfs, also known as "failed stars," are not unusual in the Milky Way and, presumably, in other galaxies.
www.meta-religion.com /Astronomy/Stars/cool_brown_dwarf.htm   (837 words)

 Brown dwarf may someday harbour habitable planets - space - 08 February 2005 - New Scientist
Brown dwarfs are "failed" stars with masses of about 15 to 70 times that of Jupiter.
Earlier studies had shown that several medium-sized brown dwarfs are surrounded by discs of material that could clump together to form planets, just as planets like Earth emerged in a disc of debris around the young Sun.
He adds that the new result suggests brown dwarfs could prove to be fertile hunting grounds for planets, and it might be possible to image these planets directly - without being blinded by the glare that shines out from regular stars.
www.newscientist.com /article.ns?id=dn6977   (725 words)

 Brown dwarf Gliese 229B - press release
Brown dwarfs are a mysterious class of long-sought object that forms the same way stars do, that is, by condensing out of a cloud of hydrogen gas.
Brown dwarfs, like full-fledged stars, would have fragmented and gravitationally collapsed out of a large cloud of hydrogen but were not massive enough to sustain fusion reactions at their cores.
Their lack of success is partly due to the fact that as brown dwarfs age they become cooler, fainter, and more difficult to see.
helios.augustana.edu /~dr/text/95-48.html   (1078 words)

 A Brown Dwarf Solar Flare
Although brown dwarfs are similar in size to Jupiter, they are much more dense and produce their own light whereas Jupiter shines with reflected light from the Sun.
The energy emitted in the brown dwarf flare was comparable to a small solar flare, and was a billion times greater than observed X-ray flares from Jupiter.
Brown dwarfs have too little mass to sustain significant nuclear reactions in their cores.
science.nasa.gov /headlines/y2000/ast12jul_1m.htm?list   (821 words)

 BBC NEWS | Science/Nature | 'Failed star' found nearby
The brown dwarf was discovered from its rapid motion across the sky.
It is a dwarf star and with a surface temperature of about 4,000 C, somewhat cooler than the Sun.
Brown Dwarfs are thought to form in much the same way as stars, by the gravitational collapse of clumps of cold gas and dust in dense molecular clouds.
news.bbc.co.uk /2/hi/science/nature/2660953.stm   (408 words)

 BBC News | SCI/TECH | 'Failed star' delights astronomers
A brown dwarf is too big to be a planet but too small to be a star and although a great many have been detected before, this is the first time one has been directly imaged so close to its companion.
Because brown dwarfs are intermediate objects between planets and stars, they are often described as "failed stars"; they are more massive than Jupiter, the largest planet in our Solar System, but fall short of the minimum mass needed to sustain nuclear fusion.
The research team behind the discovery estimate the mass of the brown dwarf to be 55 to 78 times the mass of planet Jupiter.
news.bbc.co.uk /1/hi/sci/tech/1749477.stm   (663 words)

 Brown Dwarfs
It appears that numerically, brown dwarfs may be nearly as common as stars (though they do not contain a dynamically interesting amount of mass).
The dark bands are hypothetical; although dust does form in the atmospheres of brown dwarfs, it is unclear how non-uniform their appearance is. The banding is reasonable, since they usually rotate very fast (in hours; like Jupiter).
A couple of magnetic "spots" are also shown; there is evidence of magnetic fields at least on the younger brown dwarfs (although it doesn't give rise to the same atmospheric heating and activity as on stars).
astro.berkeley.edu /~basri/bdwarfs   (528 words)

 ScienceDaily: Discovery Of The First X-Ray Emitting Brown Dwarf
Brown dwarfs are objects intermediate between stars and planets.
It is precisely their very low luminosity what makes brown dwarfs so difficult to detect: it was not until late 1995 that the first bona-fide brown dwarf was identified.
Brown dwarf -- Brown dwarfs were originally called fl dwarfs, a classification for dark substellar objects floating freely in space which were too low in mass to sustain stable hydrogen...
www.sciencedaily.com /releases/1998/10/981013075810.htm   (2567 words)

 LOT of digital editing and rearranging, they slowly merged into one somewhat spurious whole.   (Site not responding. Last check: 2007-10-18)
Contrariwise, brown dwarfs at the high end of their mass range can be hot enough to deplete dwarf their lithium when they are young.
Dwarfs, along with a few other dwarf Warhammer races, are by nature tinkerers.Thus the centre of the star contracts liberating gravitational energy which heats dwarf the gas and provides short term stability.Snowmobile Map for the White Mts.
The density of a white dwarf is approximately siberian dwarf hamster a ton per cubic centimeter..
debtpop.sitesled.com   (2803 words)

 Brown dwarf identity crisis: star or planet?   (Site not responding. Last check: 2007-10-18)
A brown dwarf is a star that doesn't have quite enough mass to ignite the full-scale hydrogen fusion reactions that power stars such as our sun.
Luhman has long studied brown dwarfs and, with the advent of new instruments such as the Spitzer, in recent years has begun searching for smaller solar systems in hopes of better understanding the diversity of stars and planetary systems.
The brown dwarf is only about 2 million years old and the swirl of dust and gas surrounding it eventually might give birth to a very small solar system.
www.post-gazette.com /pg/05339/617278.stm   (934 words)

 Scientists Snap First Images of Brown Dwarf in Planetary System | Eberly College of Science
The gravity of the distant brown dwarf companion may be reponsible for the distorted shape of the inner planet's orbit.
Brown dwarfs are small stars that are not massive enough to burn hydrogen, like our Sun does.
These brown dwarfs have masses of only 20 and 50 times the mass of Jupiter and have orbits that are more than 10 times larger than Pluto's orbit.
www.science.psu.edu /alert/Luhman9-2006-2.htm   (1011 words)

 White Dwarfs
A white dwarf is what stars like our Sun become when they have exhausted their nuclear fuel.
Since a white dwarf has no way to keep itself hot unless it is accreting matter from a nearby star (see Cataclysmic Variables), it cools down over the course of the next billion years or so.
Because a white dwarf is no longer able to create internal pressure, gravity unopposedly crushes it down until even the very electrons that make up a white dwarf's atoms are mashed together.
imagine.gsfc.nasa.gov /docs/science/know_l2/dwarfs.html   (762 words)

 What is a brown dwarf?
In order to understand what is a brown dwarf, we need to understand the difference between a star and a planet.
Brown dwarfs are objects which have a size between that of a giant planet like Jupiter and that of a small star.
It is possible that a great deal of the mass in the Universe is in the form of brown dwarfs, and since they do not give off much light, they could constitute part of the "missing mass" problem faced by cosmology.
starchild.gsfc.nasa.gov /docs/StarChild/questions/question62.html   (429 words)

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