Modeling the Physical Structure of the Low‐Density Pre‐Protostellar Core Lynds 1498

Abstract

Pre-protostellar cores likely represent the incipient stages of low-mass (approximate to 1 M-circle dot) star formation. Lynds 1498 is a pre-protostellar core (PPC) and was one of the initial objects toward which molecular depletion and differentiation was detected. Despite the considerable scrutiny of L1498, there has not been an extensive study of the density and temperature structure as derived from radiative transfer modeling of dust continuum observations. We present deep SCUBA observations of L1498 at 850 and 450 mu m, high-resolution BEARS maps of the N2H+ 1 -> 0 transition, Caltech Submillimeter Observatory observations of the N2H+ 3 -> 2 transition, and Green Bank Telescope observations of the C3S 4 -> 3 transition. We also present a comparison of derived properties between L1498 and nearby PPCs that have been observed at far- infrared and submillimeter wavelengths. The L1498 continuum emission is modeled using a one-dimensional radiative transfer code that self-consistently calculates the temperature distribution and calculates the spectral energy distribution and intensity profiles at 850 and 450 mu m. We present a more realistic treatment of PPC heating that varies the strength of the interstellar radiation field (s(isrf)) and includes attenuation of the ISRF due to dust grains at the outer radius of the core, AV. The best-fit model consists of a Bonner-Ebert sphere with a central density of (1-3) x 10(4) cm(-3), R-0 approximate to 0.29 pc, 0.5