CAB-LAEFF ::

Brown Dwarfs

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	Image composition in Orion.
	We have extensively studied the Sigma Orionis cluster, located between Orion's Belt and sword and West of the Head Nebulae. In this region we have discovered several dozens of Brown Dwarfs and isolated planetary mass objects.

What is a Brown Dwarf?

A Brown Dwarf is a quasi-stellar object unable to fuse hydrogen in a stable manner. This happens because its mass is so small (about seven percent of the solar mass, or seventy five the mass of Jupiter) that its core never gets hot and dense enough to initiate this nuclear reaction. Therefore, since its only source of energy is from its gravitational potential, a Brown Dwarf contracts and cools down with age, becoming fainter.

Our work at LAEFF

We are conducting several research proyects in this area, including the discovery and characterization of the Brown Dwarf properties located in the field and in young stellar associations. One of our main targets has been the nearby young cluster associated to the Sigma Orionis star (about 5 million year old) and the Orion's Head (Lambda Orionis or Collinder 69), of similar age.

A key problem is the formation mechanism of brown dwarfs. They might form either in similar fashion as stars or as planets. See the webpage of the Star Formation group or the formation and evolution of planetary systems. We are dealing with this problem from different persespectives, such as substellar Initial Mass Function or the spatial distribution in an open cluster.

Brown Dwarfs with accreting disks. In the last months, we have confirmed the presence of accreting disks around several young brown dwarfs.

The Age Scale based on the bottom of the Main Sequence.

The Dynamical Masses of Brown Dwarfs.

Class I and brown dwarfs (protoBDs)

Who are we

Our team is composed by two researchers, David Barrado y Navascués and Nuria Huélamo, and two students, María Morales Calderón y Amelia Bayo.

We also collaborate with other teams in Spain (at the IAC, including Rafael Rebolo, Eduardo Martín, María Rosa Zapatero Osorio, Victor Béjar and José Caballero; and at UAM, Carlos Eiroa), in Europe (Reinhard Mundt, Jochen Eisloeffel, Jerome Bouvier, Simon Hosgkin), in ESO (Itziar de Gregorio and Claudio Melo and in USA (John Stauffer, Ray Jayawardhana, Subu Mohanty and Herve Bouy).