The impact of chromospheric activity on observed initial mass functions
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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
Stassun , K G , Scholz , A , Dupuy , T J & Kratter , K M 2014 , ' The impact of chromospheric activity on observed initial mass functions ' Astrophysical Journal , vol 796 , no. 2 , 119 . DOI: 10.1088/0004-637X/796/2/119
© 2014. The American Astronomical Society. All rights reserved.
K.G.S. acknowledges NSF grants PAARE AST-0849736 and AAG AST-1109612. The work of A.S. for this paper has been supported by the Science Foundation Ireland through the grant 10/RFP/AST278.
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