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Date and Time of the Query: 2019-06-26 T06:54:44 PDT
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For refcode 2004AJ....128.2295L:
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2004AJ....128.2295L Dynamical Mass Estimates for Five Young Massive Stellar Clusters Soren S. Larsen, Jean P. Brodie, and Deidre A. Hunter Abstract. We have obtained high-dispersion spectra for four massive star clusters in the dwarf irregular galaxies NGC 4214 and NGC 4449, using the HIRES spectrograph on the Keck I telescope. Combining the velocity dispersions of the clusters with structural parameters and photometry from images taken with the Hubble Space Telescope, we estimate mass-to-light (M/L) ratios and compare these with simple stellar population models in order to constrain the stellar mass functions (MFs) of the clusters. For all clusters we find M/L values that are similar to or slightly higher than for a Kroupa MF and thereby rule out any MF that is deficient in low-mass stars compared with a Kroupa-type MF. The four clusters have virial masses ranging between 2.1x10^5^ and 1.5x10^6^M_sun_, half-light radii between 3.0 and 5.2 pc, estimated core densities in the range 2x10^3^ to 2x10^5^M_sun_pc^-3^, and ages between 200 and 800 Myr. We also present new high-dispersion near-infrared spectroscopy for a luminous young (~15 Myr) cluster in the nearby spiral galaxy NGC 6946, which we have previously observed with HIRES. The new measurements in the infrared agree well with previous estimates of the velocity dispersion for this cluster, yielding a mass of about 1.7x10^6^M_sun_. Including an improved estimate of the reddening toward this cluster, the new data yield an M/L in excellent agreement with a Kroupa-type MF also for this cluster. The properties of the clusters studied here are all consistent with the clusters being young versions of the old globular clusters found around all major galaxies. Keywords: Galaxies: Irregular, Galaxies: Star Clusters =========================================================================== 2006AJ....131.2362L Erratum: "Dynamical Mass Estimates for Five Young Massive Stellar Clusters" (2004, AJ, 128, 2295) Soren S. Larsen, Jean P. Brodie, and Deidre A. Hunter The broadband colors listed for one of the clusters, NGC 6946-1447, in Table 2 were not corrected for foreground reddening (although the V_0_ magnitude was). The table has been updated with the correct colors. The measurements of structural parameters and dynamical mass are unaffected, but the resulting change in the extinction estimate (internal extinction now appears to be negligible) affects Figure 6 and some of the quantities listed in Table 9 (M/L_V_, M_V_ and {mu}_0_ for this cluster). The increase in M/L_V_ then suggests that the mass function of this cluster may be somewhat bottom-heavy. Data for the four other clusters analyzed in the paper are correct as listed and unaffected by this error. The basic conclusion, i.e., that all the clusters should be capable of long-term survival, remains unchanged. {see text} ===========================================================================
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