Abstract
We have created new dust temperature and column density maps of Perseus, Ophiuchus, and Serpens using 60 and 100 μm data from the Improved Reprocessing of the IRAS Survey (IRIS) recalibration of Infrared Astronomical Satellite (IRAS) data. We describe an optimized method for finding the dust temperature, emissivity spectral index, and optical depth using optical and near-infrared extinction maps. The creation of these temperature and extinction maps (covering tens of square degrees of molecular clouds) is one of the first results from the ongoing Coordinated Molecular Probe Line Extinction Thermal Emission (COMPLETE) Survey of Star-Forming Regions. However, while the extinctions derived from the IRIS emission maps are globally accurate, we warn that far-infrared emission is not a good proxy for extinction on the scale of 1 pixel (~5'). In addition to describing the global dust properties of these clouds, we have found two particularly interesting features in the column density and temperature maps. In the Ophiuchus dark cloud complex, the new dust temperature map shows a little-known warm (25 K) dust ring with a 2 pc diameter. This shell is approximately centered on the B star ρ Ophiuchus, 1° north of the well-studied ρ Oph star-forming cluster. In Perseus, the column density map shows a 10 pc diameter ring, a feature not apparent in the filamentary chain of clouds seen in molecular gas. These rings are further discussed in detail in our companion papers.
Highlights
The goal of the COMPLETE Survey is to use a carefully chosen set of observing techniques to fully sample the density, temperature, and velocity structure of three of the five large starforming complexes observed in the NASA-sponsored Spitzer Legacy Survey ‘‘From Molecular Cores to Planet-forming Disks’’ described in Evans et al (2003).The c2d Survey, started in late 2003, is producing highresolution infrared spectroscopy and near- through far-infrared (NIR, FIR) images of each of its 5 pc scale target complexes
In this paper we present new temperature and extinction maps of the Perseus, Serpens, and Ophiuchus star-forming regions, produced from 60 and 100 m flux density maps obtained from Improved Reprocessing of the Infrared Astronomical Satellite (IRAS) Survey (IRIS) and normalized using optical/NIR extinction maps generated by J
Vol 634 where Nd represents column density of dust grains, is a constant that relates the flux to the optical depth of the dust, is the emissivity spectral index, and i is the solid angle subtended at ki by the detector
Summary
The goal of the COMPLETE Survey is to use a carefully chosen set of observing techniques to fully sample the density, temperature, and velocity structure of three of the five large starforming complexes observed in the NASA-sponsored Spitzer Legacy Survey ‘‘From Molecular Cores to Planet-forming Disks’’ (cores to disks [c2d]) described in Evans et al (2003). COMPLETE is providing fully sampled millimeter spectral line, extinction, and thermal emission maps for the same regions, at arcminute resolution or better (Goodman 2004). The SFD98 maps were based on low-resolution temperature data and optimized for low-extinction regions. It has been established that the SFD98 maps lose accuracy at AV > 0:5 mag (Arce & Goodman 1999a; Cambresy et al 2005), so they are not adequate for mapping column density in the high-extinction areas targeted in the COMPLETE survey. Earlier releases of the IRAS data did not have the appropriate zero-point calibration, which can have serious consequences on the derived dust temperature and column density (Arce & Goodman 1999a, 1999b). We find that values of the free parameters are consistent with zero and provide independent evidence that the zero-point calibrations of the IRIS data at 60 and 100 m are correct
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