Binary Brown Dwarf Kelu-1

This pair of NASA Hubble Space Telescope images of the binary brown dwarf Kelu-1 trace the orbital motion of the two stars over a seven-year span as photographed by the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on Hubble.

In 1998, the "stars" were too close together to be resolved by Hubble. By 2005, they had moved apart to a separation of 520 million miles. The projected maximum separation is 550 million miles.

Binary systems allow astronomers to estimate the mass of companion objects. The brown dwarfs are 61 and 50 times the mass of Jupiter. They are therefore too small to burn as stars, but too large to have formed as planets. Based on the total estimated mass of the system, astronomers suspect there is a third brown dwarf member that has not yet been resolved.

About the data

This image was created from HST data from proposals 7952 : E. Martin (Institute for Astrophysics, Canary Islands) and G. Basri (University of California, Berkeley); and 10208 : W. Brandner, E. Masciadri, and V. Joergens (Max-Planck-Institute for Astronomy, Heidelberg), R. Koehler (Heidelberg-Königstuhl State Observatory, Heidelberg), M. Kasper (European Southern Observatory, Germany), and H. Bouy (Institute for Astrophysics, Canary Islands). M. Stumpf, of the Max-Planck-Institute for Astronomy in Heidelberg, is also on the science team.