February 14, 2013
Ultra-cool Dwarf Secrets To Be Revealed By Gaia Mission
April Flowers for redOrbit.com - Your Universe Online
There are small subsets of stars among the hundred billion in the Milky Way called ultra-cool dwarfs, which have a temperature below 2500 Kelvin. Both ultra-cool dwarfs and brown dwarfs exist at these lower temperatures. The lower temperatures indicate that these are some of the most ancient objects in our Galaxy, leading scientists to examine them for information on primitive chemical composition. The Gaia mission, which will be launched by the European Space Agency (ESA) at the end of 2013, seeks to study these compositions, among other things.
Brown dwarfs and ultra-cool dwarfs seem quite similar under observation; however, there are clear differences. For example, brown dwarfs do not reach the necessary temperature to produce nuclear reactions that characterize ultra-cool dwarfs. Some refer to brown dwarfs as "failed stars" because they lack mass.
Gaia is a satellite, currently under trial, which will conduct a census of a thousand million stars in our galaxy. The satellite will monitor each of its target stars approximately 70 times over the course of the five-year mission, precisely charting their positions, distances, movements, and changes in brightness.
The National University of Distance Education (UNED), the Institute of Cosmos Sciences of the UB (ICCUB), the Astrobiology Center (CSIC-INTA), the University of CÃ¡diz, and the German-Spanish Calar Alto Observatory have collaborated in a new study to develop a method that will allow Gaia to detect ultra-cool dwarfs in the Milky Way. The method to estimate physical parameters of these objects, detailed in the journal Astronomy & Astrophysics, has been validated by data mining techniques. The researchers used this data mining to make estimations while taking into account Gaia's measurement parameters and design characteristics.
The accuracy of data has been highly improved by this new method, assuring that the estimation of ultra-cool dwarfs' temperature will have a small margin of error. This will also considerably increase the number of ultra-cool dwarfs detected, although only a few tens of those showing a temperature lower than 1500K and weak bright in the wavelengths observed by Gaia could be detected.