accepted to the Astrophysical Journal The Initial Mass Function of Low-Mass Stars and Brown Dwarfs in Young Clusters 1,2 (2000)
BibTeX
@MISC{Luhman00acceptedto,
author = {K. L. Luhman and G. H. Rieke and Erick T. Young and Angela S. Cotera and H. Chen and Marcia J. Rieke and Glenn Schneider and Rodger I. Thompson},
title = {accepted to the Astrophysical Journal The Initial Mass Function of Low-Mass Stars and Brown Dwarfs in Young Clusters 1,2},
year = {2000}
}
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Abstract
We have obtained images of the Trapezium Cluster (140 ′ ′ × 140 ′ ′ ; 0.3 pc × 0.3 pc) with the Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). Combining these data with new ground-based K-band spectra (R = 800) and existing spectral types and photometry, we have constructed an H-R diagram and used it and other arguments to infer masses and ages. To allow comparison with the results of our previous studies of IC 348 and ρ Oph, we first use the models of D’Antona & Mazzitelli. With these models, the distributions of ages of comparable samples of stars in the Trapezium, ρ Oph, and IC 348 indicate median ages of ∼ 0.4 Myr for the first two regions and ∼ 1-2 Myr for the latter. The low-mass IMFs in these sites of clustered star formation are similar over a wide range of stellar densities (ρ Oph, n = 0.2-1×10 3 pc −3; IC 348, n = 1 × 10 3 pc −3; Trapezium, n = 1-5 × 10 4 pc −3) and other environmental conditions (e.g., presence or absence of OB stars). With current data, we cannot rule out modest variations in the substellar mass functions among these clusters. We then make the best estimate of the true form of the IMF in the Trapezium by using the evolutionary models of Baraffe et al. and an empirically adjusted temperature scale and compare this mass function to recent results for the Pleiades and the field. All of these 1 Based on observations made with the Multiple Mirror Telescope operated by the Smithsonian Astrophysical
Keyphrases
initial mass function low-mass star brown dwarf young cluster astrophysical journal clustered star formation ob star temperature scale hubble space telescope near-infrared camera stellar density h-r diagram true form 1-2 myr indicate median age recent result smithsonian astrophysical multi-object spectrometer previous study spectral type mass function antona mazzitelli low-mass imf trapezium cluster evolutionary model environmental condition multiple mirror telescope current data wide range comparable sample new ground-based k-band spectrum modest variation substellar mass function
