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
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How we solved a centuries-old mystery by...
on October 10, 2018 at 3:00 pm
A bright new star appeared in the sky in June, 1670. It was seen by the Carthusian monk Père Dom Anthelme in Dijon, France, and astronomer Johannes Hevelius in Gdansk, Poland. Over the next few months, it slowly faded to invisibility. But in March 1671, it reappeared – now even more luminous and among the 100 brightest stars in the sky. Again it faded, and by the end of the summer it was gone. Then in 1672, it put in a third appearance, now only barely visible to the naked eye. […]
When is a nova not a nova? When a white dwarf and...
on October 8, 2018 at 12:55 pm
Researchers from Keele University and an international team of astronomers have reported for the first time that a white dwarf and a brown dwarf collided in a 'blaze of glory' that was witnessed on Earth in 1670. […]
New extremely distant solar system object found...
on October 2, 2018 at 3:00 pm
Carnegie's Scott Sheppard and his colleagues—Northern Arizona University's Chad Trujillo, and the University of Hawaii's David Tholen—are once again redefining our Solar System's edge. They discovered a new extremely distant object far beyond Pluto with an orbit that supports the presence of an even-farther-out, Super-Earth or larger Planet X. […]
Channel Island foxes make a comeback
on October 2, 2018 at 2:50 pm
Visitors of Southern California's Santa Catalina Island in recent years have likely caught sight of what first may appear to be small dogs or half-grown housecats. The docile creatures, sporting bushy salt-and-pepper tails, charcoal and brown camouflage coats and outsized ears, seem ready to overrun the island. […]
Gaia spots stars flying between galaxies
on October 2, 2018 at 2:30 pm
A team of Leiden astronomers used the latest set of data from ESA's Gaia mission to look for high-velocity stars being kicked out of the Milky Way, but were surprised to find stars instead sprinting inwards – perhaps from another galaxy. […]