The Spitzer Space Telescope mapped the Perseus molecular cloud complex with IRAC and MIPS as part of the c2d Spitzer Legacy project. This paper combines the observations from both instruments giving an overview of low-mass star formation across Perse
us from 3.6 to 70 micron. We provide an updated list of young stellar objects with new classifications and source fluxes from previous works, identifying 369 YSOs in Perseus with the Spitzer dataset. By synthesizing the IRAC and MIPS maps of Perseus and building on the work of previous papers in this series (Jorgensen et al. 2006, Rebull et al. 2007), we present a current census of star formation across the cloud and within smaller regions. 67% of the YSOs are associated with the young clusters NGC 1333 and IC 348. The majority of the star formation activity in Perseus occurs in the regions around the clusters, to the eastern and western ends of the cloud complex. The middle of the cloud is nearly empty of YSOs despite containing regions of high visual extinction. The western half of Perseus contains three-quarters of the total number of embedded YSOs (Class 0+I and Flat SED sources) in the cloud and nearly as many embedded YSOs as Class II and III sources. Class II and III greatly outnumber Class 0+I objects in eastern Perseus and IC 348. These results are consistent with previous age estimates for the clusters. Across the cloud, 56% of YSOs and 91% of the Class 0+I and Flat sources are in areas where Av > 5 mag, indicating a possible extinction threshold for star formation.
Context: Rotationally supported disks are critical in the star formation process. The questions of when do they form and what factors influence or hinder their formation have been studied but are largely unanswered. Observations of early stage YSOs a
re needed to probe disk formation. Aims: VLA1623 is a triple non-coeval protostellar system, with a weak magnetic field perpendicular to the outflow, whose Class 0 component, VLA1623A, shows a disk-like structure in continuum with signatures of rotation in line emission. We aim to determine whether this structure is in part or in whole a rotationally supported disk, i.e. a Keplerian disk, and what are its characteristics. Methods: ALMA Cycle 0 Early Science 1.3 mm continuum and C$^{18}$O (2-1) observations in the extended configuration are presented here and used to perform an analysis of the disk-like structure using PV diagrams and thin disk modelling with the addition of foreground absorption. Results: The PV diagrams of the C$^{18}$O line emission suggest the presence of a rotationally supported component with a radius of at least 50 AU. Kinematical modelling of the line emission shows that the disk out to 180 AU is actually rotationally supported, with the rotation being well described by Keplerian rotation out to at least 150 AU, and the central source mass to be $sim$0.2 M$_{sun}$ for an inclination of 55$^{circ}$. Pure infall and conserved angular momentum rotation models are excluded. Conclusions: VLA1623A, a very young Class 0 source, presents a disk with an outer radius $R_{rm out}$ = 180 AU with a Keplerian velocity structure out to at least 150 AU. The weak magnetic fields and recent fragmentation in this region of rho Ophiuchus may have played a lead role in the formation of the disk.
We used the Submillimeter Array (SMA) to observe the thermal polarized dust emission from the protostellar source NGC 2024 FIR 5. The polarized emission outlines a partial hourglass morphology for the plane-of-sky component of the core magnetic field
. Our data are consistent with previous BIMA maps, and the overall magnetic field geometries obtained with both instruments are similar. We resolve the main core into two components, FIR 5A and FIR 5B. A possible explanation for the asymmetrical field lies in depolarization effects due to the lack of internal heating from FIR 5B source, which may be in a prestellar evolutionary state. The field strength was estimated to be 2.2 mG, in agreement with previous BIMA data. We discuss the influence of a nearby H{sc ii} region over the field lines at scales of $sim 0.01$ pc. Although the hot component is probably compressing the molecular gas where the dust core is embedded, it is unlikely that the radiation pressure exceeds the magnetic tension. Finally, a complex outflow morphology is observed in CO (3 $rightarrow$ 2) maps. Unlike previous maps, several features associated with dust condensations other than FIR 5 are detected.
We present maps of 7.78 square degrees of the Lupus molecular cloud complex at 24, 70, and $160:mu$m. They were made with the Spitzer Space Telescopes Multiband Imaging Photometer for Spitzer (MIPS) instrument as part of the Spitzer Legacy Program, `
`From Molecular Cores to Planet-Forming Disks (c2d). The maps cover three separate regions in Lupus, denoted I, III, and IV. We discuss the c2d pipeline and how our data processing differs from it. We compare source counts in the three regions with two other data sets and predicted star counts from the Wainscoat model. This comparison shows the contribution from background galaxies in Lupus I. We also create two color magnitude diagrams using the 2MASS and MIPS data. From these results, we can identify background galaxies and distinguish them from probable young stellar objects. The sources in our catalogs are classified based on their spectral energy distribution (SED) from 2MASS and Spitzer wavelengths to create a sample of young stellar object candidates. From 2MASS data, we create extinction maps for each region and note a strong corresponence between the extinction and the $160:mu$m emission. The masses we derived in each Lupus cloud from our extinction maps are compared to masses estimated from $^{13}$CO and C$^{18}$O and found to be similar to our extinction masses in some regions, but significantly different in others. Finally, based on our color-magnitude diagrams, we selected 12 of our reddest candidate young stellar objects for individual discussion. Five of the 12 appear to be newly-discovered YSOs.
