2014ApJ...796..119S -
Astrophys. J., 796, 119 (2014/December-1)
The impact of chromospheric activity on observed initial mass functions.
STASSUN K.G., SCHOLZ A., DUPUY T.J. and KRATTER K.M.
Abstract (from CDS):
Using recently established empirical calibrations for the impact of chromospheric activity on the radii, effective temperatures, and estimated masses of active low-mass stars and brown dwarfs, we reassess the shape of the initial mass function (IMF) across the stellar/substellar boundary in the Upper Sco star-forming region (age ∼ 5-10 Myr). We adjust the observed effective temperatures to warmer values using the observed strength of the chromospheric Hα emission, and redetermine the estimated masses of objects using pre-main-sequence evolutionary tracks in the H-R diagram. The effect of the activity-adjusted temperatures is to shift the objects to higher masses by 3%-100%. While the slope of the resulting IMF at substellar masses is not strongly changed, the peak of the IMF does shift from ~0.06 to ~0.11 M☉. Moreover, for objects with masses ≲ 0.2 M☉, the ratio of brown dwarfs to stars changes from ∼80% to ∼33%. These results suggest that activity corrections are essential for studies of the substellar mass function, if the masses are estimated from spectral types or from effective temperatures.
Abstract Copyright:
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Journal keyword(s):
brown dwarfs - stars: activity - stars: fundamental parameters - stars: low-mass - stars: luminosity function, mass function
Simbad objects:
1
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