James Liebert et al. 2003 The Astronomical Journal 125 343 doi:10.1086/345514
James Liebert1, J. Davy Kirkpatrick2, K. L. Cruz3, I. Neill Reid3,4, Adam Burgasser5, C. G. Tinney6 and John E. Gizis7
Show affiliationsTime series spectrophotometry of the L5 dwarf 2MASS J01443536-0716142 showed strong Hα emission that declined by nearly 75% in four consecutive exposures. The line was not detected in emission on a spectrum obtained 11 months later. This behavior contrasts with that of 2MASSI J1315309-264951, an L5 dwarf that has shown even stronger Hα emission on four separate occasions. The observational database suggests that L dwarfs can be found in such strong flares only occasionally, with a duty cycle on the order of 1%. In contrast, the few, continuously strong Hα emitters, including PC 0025+0447 and 2MASSI J1237392+652615, must either be (1) objects no older than 10–100 Myr with continuously active accretion and/or chromospheres, but which apparently formed in isolation from known young stellar clusters and associations, or (2) objects empowered by a different but unknown mechanism for the Hα energy.
stars: chromospheres; stars: individual (2MASS J01443536-0716142, 2MASSI J1315309-264951, PC 0025+0447, 2MASSI J1237392+652615); stars: low-mass, brown dwarfs
Issue 1 (2003 January)
Received 2002 August 28, accepted for publication 2002 October 10
James Liebert et al. 2003 The Astronomical Journal 125 343
Adam J. Burgasser et al. 2000 The Astronomical Journal 120 473
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