Chandra
Orion Ultradeep Project
Brown dwarfs
Brown dwarfs (BDs) are objects with masses below 0.08 Mo, too low to become luminous stars. Born along with more massive stars, they will slowly cool, resembling Jupiter-like planets. Long sought, BDs have only been discovered during the past decade, and the largest known sample is in the Orion Nebula Cluster. COUP establishes that the X-ray properties, indicators of magnetic fields and flares, of Orion BDs closely resemble the X-ray properties of the lower mass M stars. They have hard spectra and show flares, indicating the X-ray emission mechanisms of young BDs are the same as in young stars. But the Orion BDs are very faint in X-rays. Indeed. despite its tremendous sensitivity and success in detecting higher mass stars, COUP detects only 9 of 34 confirmed BDs.
Here is a graph showing the X-ray luminosities (as a fraction of total bolometric luminosities) of the Orion Nebula Cluster brown dwarfs (boxes and arrows on the left side) compared to normal young stars (filled circles on the right side).
The full paper on COUP brown dwarfs is:
X-ray emission from young brown dwarfs in the Orion Nebula Cluster
Thomas Preibisch, Mark J. McCaughrean, Nicolas Grosso, Eric D. Feigelson, Ettore Flaccomio, Konstantin Getman, Lynne A. Hillenbrand,, Gwendolyn Meeus, Giusi Micela, Salvatore Sciortino, Beate Stelzer
Back to the COUP home page
Brown dwarfs
Brown dwarfs (BDs) are objects with masses below 0.08 Mo, too low to become luminous stars. Born along with more massive stars, they will slowly cool, resembling Jupiter-like planets. Long sought, BDs have only been discovered during the past decade, and the largest known sample is in the Orion Nebula Cluster. COUP establishes that the X-ray properties, indicators of magnetic fields and flares, of Orion BDs closely resemble the X-ray properties of the lower mass M stars. They have hard spectra and show flares, indicating the X-ray emission mechanisms of young BDs are the same as in young stars. But the Orion BDs are very faint in X-rays. Indeed. despite its tremendous sensitivity and success in detecting higher mass stars, COUP detects only 9 of 34 confirmed BDs.
Here is a graph showing the X-ray luminosities (as a fraction of total bolometric luminosities) of the Orion Nebula Cluster brown dwarfs (boxes and arrows on the left side) compared to normal young stars (filled circles on the right side).
The full paper on COUP brown dwarfs is:
X-ray emission from young brown dwarfs in the Orion Nebula Cluster
Thomas Preibisch, Mark J. McCaughrean, Nicolas Grosso, Eric D. Feigelson, Ettore Flaccomio, Konstantin Getman, Lynne A. Hillenbrand,, Gwendolyn Meeus, Giusi Micela, Salvatore Sciortino, Beate Stelzer
Back to the COUP home page