Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid
These are organized by a classification scheme developed exclusively for Cosma. More…
Brown dwarf is a substellar object that occupies the mass range between the heaviest gas giant planets and the lightest stars, having masses between approximately 13 to 75–80 times that of Jupiter (MJ), or approximately 2.5×1028 kg to about 1.5×1029 kg. Below this range are the sub-brown dwarfs, and above it are the lightest red dwarfs (M9 V). Brown dwarfs may be fully convective, with no layers or chemical differentiation by depth.
Unlike the stars in the main sequence, brown dwarfs are not massive enough to sustain nuclear fusion of ordinary hydrogen (1H) to helium in their cores. They are, however, thought to fuse deuterium (2H) and to fuse lithium (7Li) if their mass is above a debated threshold of 13 MJ and 65 MJ, respectively. It is also debated whether brown dwarfs would be better defined by their formation processes rather than by their supposed nuclear fusion reactions.
Stars are categorized by spectral class, with brown dwarfs designated as types M, L, T, and Y.[ Despite their name, brown dwarfs are of different colors. Many brown dwarfs would likely appear magenta to the human eye, or possibly orange/red. Brown dwarfs are not very luminous at visible wavelengths.
There are planets known to orbit brown dwarfs: 2M1207b, MOA-2007-BLG-192Lb, and 2MASS J044144b.
At a distance of about 6.5 light years, the nearest known brown dwarf is Luhman 16, a binary system of brown dwarfs discovered in 2013. HR 2562 b is listed as the most-massive known exoplanet (as of December 2017) in NASA’s exoplanet archive, despite having a mass (30±15 MJ) more than twice the 13-Jupiter-mass cutoff between planets and brown dwarfs. — Wikipedia
Phys.org - latest science and technology news stories Phys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.
A new classification scheme for exoplanet sizes
on September 24, 2018 at 12:50 pm
There are about 4433 exoplanets in the latest catalogs. Their radii have generally been measured by knowing the radius of their host star and then closely fitting the lightcurves as the planet transits across the face of the star. The radius of the host star is thus a key parameter and latest data release of the Gaia mission has enabled astronomers to improve the accuracy of stellar properties in its catalog very significantly – to a precision in radius of about 8 percent—for nearly […]
When is a star not a star? The line that...
on September 17, 2018 at 2:36 pm
The line that separates stars from brown dwarfs may soon be clearer thanks to new work led by Carnegie's Serge Dieterich. Published by the Astrophysical Journal, his team's findings demonstrate that brown dwarfs can be more massive than astronomers previously thought. […]
New binary system showcasing beaming effect found...
on September 5, 2018 at 1:10 pm
An international team of astronomers has discovered a new eclipsing binary system composed of an M-dwarf orbiting a main sequence star. The transiting dwarf star exhibits the so-called relativistic beaming effect. The finding is reported in a paper published August 20 on the arXiv pre-print repository. […]
Mapping trees can help count endangered lemurs
on August 30, 2018 at 5:01 pm
The vast majority of lemur species are on the edge of extinction, experts warn. But not every lemur species faces a grim future. There may be as many as 1.3 million white-fronted brown lemurs still in the wild, for example, and mouse lemurs may number more than 2 million, a Duke-led study has shown. […]
Stellar 'swarms' help astronomers understand the...
on August 28, 2018 at 3:30 pm
New work from Carnegie's Jonathan Gagné and the American Museum of Natural History's Jacqueline Faherty identified nearly a thousand potential members and 31 confirmed members of stellar associations—stars of similar ages and compositions that are drifting together through space—in our own corner of the Milky Way. Their work, published in the Astrophysical Journal, could help astronomers understand the evolution of stars and the properties of future exoplanet discoveries. […]