We report the second complete molecular line data release from the {\em Census of High- and Medium-mass Protostars} (CHaMP), a large-scale, unbiased, uniform mapping survey at sub-parsec resolution, of mm-wave line emission from 303 massive, dense molecular clumps in the Milky Way. This release is for all $^{12}$CO $J$=1$\rightarrow$0 emission associated with the dense gas, the first from Phase II of the survey, which includes $^{12}$CO, $^{13}$CO, and C$^{18}$O. The observed clump emission traced by both $^{12}$CO and HCO$^+$ (from Phase I) shows very similar morphology, indicating that, for dense molecular clouds and complexes of all sizes, parsec-scale clumps contain $Ξ$ ~ 75% of the mass, while only 25% of the mass lies in extended (>~ 10 pc) or "low density" components in these same areas. The mass fraction of all gas above a density 10$^9$ m$^{-3}$ is $ξ_9$ >~ 50%. This suggests that parsec-scale clumps may be the basic building blocks of the molecular ISM, rather than the standard GMC concept. Using $^{12}$CO emission, we derive physical properties of these clumps in their entirety, and compare them to properties from HCO$^+$, tracing their denser interiors. We compare the standard X-factor converting $I_{CO}$ to $N_{H_2}$ with alternative conversions, and show that only the latter give whole-clump properties that are physically consistent with those of their interiors. We infer that the clump population is systematically closer to virial equilibrium than when considering only their interiors, with perhaps half being long-lived (10s of Myr), pressure-confined entities which only terminally engage in vigorous massive star formation, supporting other evidence along these lines previously published.
We investigate Schmidt's conjecture (i.e., that the star formation rate scales in a power-law fashion with the gas density) for four well-studied local molecular clouds (GMCs). Using the Bayesian methodology we show that a local Schmidt scaling relation of the form Sigma*(A_K) = kappa x (A_K)^{beta} (protostars pc^{-2}) exists within (but not between) GMCs. Further we find that the Schmidt scaling law, by itself, does not provide an adequate description of star formation activity in GMCs. Because the total number of protostars produced by a cloud is given by the product of Sigma*(A_K) and S'(>…
Surveys with the Spitzer and Herschel space observatories are now enabling the discovery and characterization of large samples of protostars in nearby molecular clouds, providing the observational basis for a detailed understanding of star formation in diverse environments. We are pursuing this goal with the Herschel Orion Protostar Survey (HOPS), which targets 328 Spitzer-identified protostars in the Orion molecular clouds, the largest star-forming region in the nearest 500 pc. The sample encompasses all phases of protostellar evolution and a wide range of formation environments, from dense c…
We present the second dust continuum data release in the Census of High- and Medium-mass Protostars (CHaMP), expanding the methodology trialed in Pitts et al. 2019 to the entire CHaMP survey area ($280^{\circ}<l<300^{\circ}$, $-4^{\circ}<b<+2^{\circ}$). This release includes maps of dust temperature ($T_d$), H$_2$ column density ($N_{H_2}$), gas-phase CO abundance, and temperature-density plots for every prestellar clump with Herschel coverage, showing no evidence of internal heating for most clumps in our sample. We show that CO abundance is a strong function of $T_d$, and can be fit with a s…
The Census of High- and Medium-mass Protostars (CHaMP) is the first large-scale, unbiased, uniform mapping survey at sub-parsec scale resolution of 90 GHz line emission from massive molecular clumps in the Milky Way. We present the first Mopra (ATNF) maps of the CHaMP survey region (300°>l>280°) in the HCO+ J=1-0 line, which is usually thought to trace gas at densities up to 10^11 m-3. In this paper we introduce the survey and its strategy, describe the observational and data reduction procedures, and give a complete catalogue of moment maps of the HCO+ J=1-0 emission from the ensemble of 301 …
We present $^{12}$CO, $^{13}$CO, and C$^{18}$O data as the next major release for the CHaMP project, an unbiased sample of Galactic molecular clouds in $l$ = 280$^{\circ}$-300$^{\circ}$. From a radiative transfer analysis, we self-consistently compute 3D cubes of optical depth, excitation temperature, and column density for $\sim$300 massive clumps, and update the $I_{\rm CO}$-dependent CO$\rightarrow$H$_2$ conversion law of Barnes et al (2015). For $N$ $\propto$ $I^p$, we find $p$ = 1.92$\pm$0.05 for the velocity-resolved conversion law aggregated over all clumps. A practical, integrated conv…
(Abridged) The Census of High- and Medium-mass Protostars (CHaMP) is the first large-scale (280 degree<l<300 degree, -4 degree<b<2 degree), unbiased, sub-parsec resolution survey of Galactic molecular clumps and their embedded stars. Barnes et al. (2011) presented the source catalog of ~300 clumps based on HCO+(1-0) emission, used to estimate masses M. Here we use archival mid-infrared to mm continuum data to construct spectral energy distributions. Fitting two-temperature grey-body models, we derive bolometric luminosities, L. We find the clumps have 10Lsun<L<1E6.5Lsun and 0.1<L/M<1E3, consis…
During the transition phase from a prestellar to a protostellar cloud core, one or several protostars can form within a single gas core. The detailed physical processes of this transition, however, still remain unclear. We present 1.3 mm dust continuum and molecular line observations with the Atacama Large Millimeter/submillimeter Array (ALMA) toward 43 protostellar cores in the Orion Molecular Cloud Complex ($λ$ Orionis, Orion B, and Orion A) with an angular resolution of $\sim$ 0.35" ($\sim$ 140 au). In total, we detect 13 binary/multiple systems. We derive an overall multiplicity frequency …
We present the first census of giant molecular clouds (GMCs) complete down to 10$^6 M_{\odot}$ and within the inner 4 kpc of the nearest giant elliptical and powerful radio galaxy, Centaurus A. We identified 689 GMCs using CO(1--0) data with 1" spatial resolution ($\sim 20$ pc) and 2 km/s velocity resolution obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). The $I$(CO)-$N$(H$_2$) conversion factor based on the virial method is $X_{\rm CO}$ = $(2 \pm 1 )\times10^{20}$ cm$^{-2}$(K km/s)$^{-1}$ for the entire molecular disk, consistent with that of the disks of spiral galaxie…
Chamaeleon I is the most active region in terms of star formation in the Chamaeleon molecular cloud complex. Its population of prestellar and protostellar cores is not known and a controversy exists concerning its history of star formation. Our goal is to characterize the earliest stages of star formation in this cloud. We used the bolometer array LABOCA at APEX to map the cloud in dust continuum emission at 870 micron. The detected sources are analysed by carefully taking into account the spatial filtering inherent in the data reduction process. A search for associations with YSOs is performe…
We present a survey of the Orion A and B molecular clouds undertaken with the IRAC and MIPS instruments onboard Spitzer. In total, five distinct fields were mapped covering 9 sq. degrees in five mid-IR bands spanning 3-24 microns. The survey includes the Orion Nebula Cluster, the Lynds 1641, 1630 and 1622 dark clouds, and the NGC 2023, 2024, 2068 and 2071 nebulae. These data are merged with the 2MASS point source catalog to generate a catalog of eight band photometry. We identify 3479 dusty young stellar objects (YSOs) in the Orion molecular clouds by searching for point sources with mid-IR co…
We present the first census of the interstellar Complex Organic Molecules (iCOMs) in the low-mass Class I protostar SVS13-A, obtained by analysing data from the IRAM-30m Large Project ASAI (Astrochemical Surveys At IRAM). They consist of an high-sensitivity unbiased spectral survey at the 1mm, 2mm and 3mm IRAM bands. We detected five iCOMs: acetaldehyde (CH$_3$CHO), methyl formate (HCOOCH$_3$), dimethyl ether (CH$_3$OCH$_3$), ethanol (CH$_3$CH$_2$OH) and formamide (NH$_2$CHO). In addition we searched for other iCOMs and ketene (H$_2$CCO), formic acid (HCOOH) and methoxy (CH$_3$O), whose only k…
We present new high resolution and dynamic range dust column density and temperature maps of the California Molecular Cloud derived from a combination of Planck and Herschel dust-emission maps, and 2MASS NIR dust-extinction maps. We used these data to determine the ratio of the 2.2 micron extinction coefficient to the 850 micron opacity and found the value to be close to that found in similar studies of the Orion B and Perseus clouds but higher than that characterizing the Orion A cloud, indicating that variations in the fundamental optical properties of dust may exist between local clouds. We…
The Herschel Gould Belt Survey key project mapped the bulk of nearby star-forming molecular clouds in five far-infrared bands with the aim of compiling complete census of prestellar cores and young, embedded protostars. In this paper, we present the catalogue of the dense cores and YSOs/protostars extracted from the Herschel maps of the Lupus I, III, and IV molecular clouds. The physical properties of the detected objects were derived by fitting their spectral energy distributions. A total of 532 dense cores, out of which 103 are presumably prestellar in nature, and 38 YSOs/protostars have bee…
The initial mass function (IMF) of stars is a key quantity affecting almost every field of astrophysics, yet it remains unclear what physical mechanisms determine it. We present the first runs of the STARFORGE project, using a new numerical framework to follow the formation of individual stars in giant molecular clouds (GMCs) using the GIZMO code. Our suite include runs with increasingly complex physics, starting with isothermal ideal magnetohydrodynamic (MHD) and then adding non-isothermal thermodynamics and protostellar outflows. We show that without protostellar outflows the resulting stell…
The interstellar medium has a highly filamentary and hierarchical structure, which may play a significant role in star formation. A systematical study on the large-scale filaments towards their physical parameters, distribution, structures and kinematics will inform us of what kind of filaments have potential to form stars, how the material feed protostars through filaments, and the connection between star formation and Galactic spiral arms. Unlike the traditional "by eyes" searches, we use a customized minimum spanning tree algorithm to identify filaments by linking Galactic clumps from the A…
Class I protostars are a bridge between Class 0 protostars, and Class II protoplanetary disks. Recent studies show gaps and rings in the dust distribution of disks younger than 1 Myr, suggesting that planet formation may start already at the Class I stage. To understand what chemistry planets will inherit, it is crucial to characterize the chemistry of Class I sources and to investigate how chemical complexity evolves from Class 0 protostars to protoplanetary disks. The goal is twofold: to obtain a census of the molecular complexity in a sample of four Class I protostars, and to compare it wit…
We conduct a census of the high-mass protostellar population of the $\sim70,000\:M_\odot$ Infrared Dark Cloud (IRDC) G028.37+00.07, identifying 35 sources based on their $70\:μ$m emission, as reported in the {\it Herschel} Hi-GAL catalog of Molinari et al. (2016). We perform aperture photometry to construct spectral energy distributions (SEDs), which are then fit with the massive protostar models of Zhang & Tan (2018). We find that the sources span a range of isotropic luminosities from $\sim$20 to 4,500$\:L_\odot$. The most luminous sources are predicted to have current protostellar masses of…
Cyanopolyynes are chains of carbon atoms with an atom of hydrogen and a CN group on either side. They are detected almost everywhere in the ISM, as well as in comets. In the past, they have been used to constrain the age of some molecular clouds, since their abundance is predicted to be a strong function of time. We present an extensive study of the cyanopolyynes distribution in the solar-type protostar IRAS16293-2422 based on TIMASSS IRAM-30m observations. The goals are (i) to obtain a census of the cyanopolyynes in this source and of their isotopologues; (ii) to derive how their abundance va…
We present and discuss the results of the Herschel Gould Belt survey observations in a ~11 deg^2 area of the Aquila molecular cloud complex at d~260 pc, imaged with the SPIRE/PACS cameras from 70 to 500 micron. We identify a complete sample of starless dense cores and embedded protostars in this region, and analyze their global properties and spatial distributions. We find a total of 651 starless cores, ~60% of which are gravitationally bound prestellar cores, and they will likely form stars in the future. We also detect 58 protostellar cores. The core mass function (CMF) derived for the prest…
We report a new analysis protocol for HCN hyperfine data, based on the PYSPECKIT package, and results of using this new protocol to analyse a sample area of seven massive molecular clumps from the Census of High- and Medium-mass Protostars (CHaMP) survey, in order to derive maps of column density for this species. There is a strong correlation between the HCN integrated intensity, IHCN, and previously reported IHCO+ in the clumps, but IN2H+ is not well correlated with either of these other two "dense gas tracers". The four fitted parameters from PYSPECKIT in this region fall in the range of VL…
H2D+ is a primary ion which dominates the gas-phase chemistry of cold dense gas. Therefore it is hailed as a unique tool in probing the earliest, prestellar phase of star formation. Observationally, its abundance and distribution is however just beginning to be understood in low-mass prestellar and cluster-forming cores. In high mass star forming regions, H2D+ has been detected only in two cores, and its spatial distribution remains unknown. Here we present the first map of the 372 GHz ortho-H2D+ and N2H+ 4-3 transition in the DR21 filament of Cygnus-X with the JCMT, and N2D+ 3--2 and dust con…
We used FIR and submillimeter continuum data from Herschel and the Atacama Pathfinder EXperiment (APEX) to fit pixel-by-pixel modified Planck SEDs to prestellar and protostellar clumps in the Census of High- and Medium-mass Protostars (CHaMP) ($280^{\circ}<\ell<300^{\circ}$, $-4^{\circ}<b<+2^{\circ}$). We present maps of dust temperature ($T_{\text{d}}$) and H$_2$ column density (\ncol) for molecular clumps in the Carina Nebula complex (Regions 9 through 11), and surrounding RCW 64 (Region 26). We compare the column densities of CO and H$_2$ to chart regional variations in their correspondence…
During the embedded phase of pre-main sequence stellar evolution, a disk forms from the dense envelope while an accretion-driven outflow carves out a cavity within the envelope. Highly excited H2O emission in spatially unresolved Spitzer/IRS spectra of a low-mass Class 0 object, NGC 1333 IRAS 4B, has previously been attributed to the envelope-disk accretion shock but could instead be produced in an outflow. As part of the survey of low-mass sources in the Water in Star Forming Regions with Herschel (WISH-LM) program, we used Herschel/PACS to obtain a far-IR spectrum and several Nyquist-sampled…
We present a 1.1~mm census of dense cores in the Mon~R2 Giant Molecular Cloud with the AzTEC instrument on the Large Millimeter Telescope (LMT). We detect 295 cores (209 starless, and 86 with protostars) in a two square degree shallow survey. We also carry out a deep follow-up survey of 9 regions with low to intermediate ($3<A_V<7$) gas column densities and detect 60 new cores in the deeper survey which allows us to derive a completeness limit. After performing corrections for low signal-to-noise cores, we find a median core mass of $\sim 2.1 \text{M}_{\odot}$ and a median size of $ 0.08$~pc. …
