Abstract
In this paper, we present a dust emission map of the starless core TMC-1C taken at 2100 μm. Along with maps at 160, 450, 850, and 1200 μm, we study the dust emissivity spectral index from the (sub)millimeter spectral energy distribution, and find that it is close to the typically assumed value of β = 2. We also map the dust temperature and column density in TMC-1C, and find that at the position of the dust peak (AV ∼ 50) the line-of-sight-averaged temperature is ∼7 K. Employing simple Monte Carlo modeling, we show that the data are consistent with a constant value for the emissivity spectral index over the whole map of TMC-1C.
Highlights
Starless cores are often identified through maps of their dust emission atmillimeter wavelengths, and recent surveys of nearby molecular clouds have increased the number of such objects considerably (e.g., Hatchell et al 2007; Enoch et al 2008; Kauffmann et al 2008; Simpson et al 2008)
Given that an analysis of the flux maps from an idealized core, with line-of-sight temperature variations and noise, gives the correct average emissivity spectral index, we suggest that the value of the emissivity spectral index in TMC-1C is well represented by β 2.2 ± 0.5
We find that the spectral index of the dust emission, as calculated by a variety of related methods, is in the range 1.7 β 2.7
Summary
Starless cores are often identified through maps of their dust emission at (sub)millimeter wavelengths, and recent surveys of nearby molecular clouds have increased the number of such objects considerably (e.g., Hatchell et al 2007; Enoch et al 2008; Kauffmann et al 2008; Simpson et al 2008). The measured (sub)millimeter fluxes are often used in conjunction with assumed values for the dust temperature and/or emissivity to determine core masses, though the systematic errors can be substantial (a factor of a few). Previous studies of the dust emission from TMC-1C at 450, 850, and 1200 μm have determined that it is cold (Td ∼ 6 K) and dense (n ∼ 106 cm−3) at its center, and becomes progressively less dense and warmer at larger radii (Schnee et al 2007b; Schnee & Goodman 2005). Reported mass and temperature profiles for TMC1C are estimated assuming a constant value for the emissivity spectral index (β = 1.8; Schnee et al 2007b). A wide range of values for β in other regions have been measured or
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
