Among the hundred billion stars which can be observed in the Milky Way, there is a group of stars, the so-named ultra-cool dwarfs, defined as stars with a temperature below 2500 K, which includes ultra-cool dwarfs and brown dwarfs. It is a really interesting group: they are the most ancient objects in our Galaxy and, therefore, they can provide information about its primitive chemical composition. This is one of the objectives of Gaia mission which will be launched at the end of 2013 by the European Space Agency.
When observing them, they seem quite similar, but there are clear differences between brown dwarfs and ultra-cool dwarfs: brown dwarfs do not reach the temperature they need to produce the nuclear reactions which characterize ultra-cool dwarfs. It could be said that brown dwarfs are failed stars because they lack mass.
A study published on the journal Astronomy & Astrophysics, led by the National University of Distance Education (UNED) and in which researchers from the Institute of Cosmos Sciences of the UB (ICCUB) participated, has developed a method that will allow Gaia to detect tens of ultra-cool dwarfs in the Milky Way. The method to estimate physical parameters of these objects, such as temperature or gravity, has also been validated. Researchers have used data mining techniques to make estimations taking into account the parameters that Gaia can measure and its design characteristics.
Astronomers at the California Institute of Technology (Caltech) have discovered that the dwarf planet 2007 OR10—nicknamed Snow White—is an icy world, with about half its surface covered in water ice that once flowed from ancient, slush-spewing volcanoes. The new findings also suggest that the red-tinged dwarf planet may be covered in a thin layer of methane, the remnants of an atmosphere that’s slowly being lost into space.
Full Story: http://news.caltech.edu/press_releases/13445