- ID:
- ivo://CDS.VizieR/J/AJ/138/703
- Title:
- Deep MIPS observations of IC 348 nebula
- Short Name:
- J/AJ/138/703
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe new, deep MIPS photometry and new high signal-to-noise optical spectroscopy of the 2.5Myr old IC 348 Nebula. To probe the properties of the IC 348 disk population, we combine these data with previous optical/infrared photometry and spectroscopy to identify stars with gas accretion, to examine their mid-IR colors, and to model their spectral energy distributions.
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- ID:
- ivo://CDS.VizieR/J/A+A/619/A52
- Title:
- Dense cores and YSOs in Lupus complex
- Short Name:
- J/A+A/619/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the catalogue of the dense cores and YSOs/protostars of the Lupus I, Lupus III, and Lupus IV molecular clouds. Sources were extracted from the far-infrared photometric maps at 70, 160, 250, 350 and 500um acquired with the Spectral and Photometric Imaging Receiver (SPIRE) and the Photodetector Array Camera and Spectrometer (PACS) instruments onboard the Herschel Space Observatory, within the Herschel Gould Belt Survey project. A total of 532 dense cores, out of which 103 are presumably prestellar in nature, and 38 YSOs/protostars have been detected in the three clouds. The physical properties of the objects were derived by fitting their spectral energy distributions. Almost all the prestellar cores are associated with filaments against only about one third of the unbound cores and YSOs/ protostars. Prestellar core candidates are found even in filaments that are on average thermally sub-critical and over a background column density lower than that measured in other star forming regions so far. The core mass function of the prestellar cores peaks between 0.2 and 0.3 solar masses and it is compatible with the log-normal shape found in other regions. Herschel data reveal several, previously undetected, protostars and new candidates of Class 0 and Class II with transitional disks. We estimate the evolutionary status of the YSOs/protostars using two independent indicators: the {alpha} index and the fitting of the spectral energy distribution from near- to far-infrared wavelengths. For 70% of the objects, the evolutionary stages derived with the two methods are in agreement.
- ID:
- ivo://CDS.VizieR/J/ApJ/710/1247
- Title:
- Dense cores in Gould Belt clouds
- Short Name:
- J/ApJ/710/1247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using data from the SCUBA Legacy Catalogue (850um) and Spitzer Space Telescope (3.6-70um), we explore dense cores in the Ophiuchus, Taurus, Perseus, Serpens, and Orion molecular clouds. We develop a new method to discriminate submillimeter cores found by Submillimeter Common-User Bolometer Array (SCUBA) as starless or protostellar, using point source photometry from Spitzer wide field surveys. First, we identify infrared sources with red colors associated with embedded young stellar objects (YSOs). Second, we compare the positions of these YSO candidates to our submillimeter cores. With these identifications, we construct new, self-consistent starless and protostellar core mass functions (CMFs) for the five clouds. We find best-fit slopes to the high-mass end of the CMFs of -1.26+/-0.20, -1.22+/-0.06, -0.95+/-0.20, and -1.67+/-0.72 for Ophiuchus, Taurus, Perseus, and Orion, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/668/1042
- Title:
- Dense cores in Perseus molecular cloud
- Short Name:
- J/ApJ/668/1042
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We survey the kinematics of over 150 candidate (and potentially star-forming) dense cores in the Perseus molecular cloud with pointed N_2_H^+^(1-0) and simultaneous C^18^O(2-1) observations. Our detection rate of N_2_H^+^ is 62%, rising to 84% for SCUBA-selected targets. In agreement with previous observations, we find that the dense N_2_H^+^ targets tend to display nearly thermal line widths, particularly those that appear to be starless (using Spitzer data), indicating that turbulent support on the small scales of molecular clouds is minimal. For those N_2_H^+^ targets that have an associated SCUBA dense core, we find that their internal motions are more than sufficient to provide support against the gravitational force on the cores.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/342
- Title:
- Dense cores in Taurus L1495 cloud
- Short Name:
- J/MNRAS/459/342
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of dense cores in a ~4{deg}x2{deg} field of the Taurus star-forming region, inclusive of the L1495 cloud, derived from Herschel SPIRE and PACS observations in the 70{mu}m, 160{mu}m, 250{mu}m, 350{mu}m, and 500{mu}m continuum bands. Estimates of mean dust temperature and total mass are derived using modified blackbody fits to the spectral energy distributions. We detect 525 starless cores of which ~10-20 per cent are gravitationally bound and therefore presumably prestellar. Our census of unbound objects is ~85 per cent complete for M>0.015M_{sun}_ in low-density regions (A_V_<~5mag), while the bound (prestellar) subset is ~85 per cent complete for M>0.1M_{sun}_ overall. The prestellar core mass function (CMF) is consistent with lognormal form, resembling the stellar system initial mass function, as has been reported previously. All of the inferred prestellar cores lie on filamentary structures whose column densities exceed the expected threshold for filamentary collapse, in agreement with previous reports. Unlike the prestellar CMF, the unbound starless CMF is not lognormal, but instead is consistent with a power-law form below 0.3M_{sun}_ and shows no evidence for a low-mass turnover. It resembles previously reported mass distributions for CO clumps at low masses (M<~0.3M_{sun}_). The volume density PDF, however, is accurately lognormal except at high densities. It is consistent with the effects of self-gravity on magnetized supersonic turbulence. The only significant deviation from lognormality is a high-density tail which can be attributed unambiguously to prestellar cores.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/1560
- Title:
- Dense core survey in the Orion B cloud
- Short Name:
- J/ApJ/691/1560
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out an H^13^CO^+^(J=1-0 at 86.75433GHz) core survey in a large area of 1deg^2^, covering most of the dense region in the Orion B molecular cloud, using the Nobeyama 45m radio telescope with the 25-BEam Array Receiver System. We cataloged 151 dense cores using the clumpfind method. The cores have mean radius, velocity width, and mass of 0.10+/-0.02pc, 0.53+/-0.15km/s, and 8.1+/-6.4M_{sun}_, respectively, which are very similar to those in the Orion A cloud. We examined the spatial relation between our H^13^CO^+^ cores and the 850um cores observed by Johnstone and colleagues in 2001 (Cat. J/ApJ/559/307) and 2006 (Cat. J/ApJ/639/259), and found that there are two types of spatial relationships: H^13^CO^+^ cores with and without the 850um cores. Since the mean density of the 850um cores is higher than that of the H^13^CO^+^ cores, we can interpret the H^13^CO^+^ cores with 850um cores as being more centrally concentrated and hence more evolved, compared with those without.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/217
- Title:
- Density distributions for mm-wave line ratios
- Short Name:
- J/ApJ/835/217
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the use of mm-wave emission line ratios to trace molecular gas density when observations integrate over a wide range of volume densities within a single telescope beam. For observations targeting external galaxies, this case is unavoidable. Using a framework similar to that of Krumholz & Thompson (2007ApJ...669..289K), we model emission for a set of common extragalactic lines from lognormal and power law density distributions. We consider the median density of gas that produces emission and the ability to predict density variations from observed line ratios. We emphasize line ratio variations because these do not require us to know the absolute abundance of our tracers. Patterns of line ratio variations have the potential to illuminate the high-end shape of the density distribution, and to capture changes in the dense gas fraction and median volume density. Our results with and without a high-density power law tail differ appreciably; we highlight better knowledge of the probability density function (PDF) shape as an important area. We also show the implications of sub-beam density distributions for isotopologue studies targeting dense gas tracers. Differential excitation often implies a significant correction to the naive case. We provide tabulated versions of many of our results, which can be used to interpret changes in mm-wave line ratios in terms of adjustments to the underlying density distributions.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A109
- Title:
- Draco nebula Herschel 250um map
- Short Name:
- J/A+A/599/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Draco nebula is a high Galactic latitude interstellar cloud observed at velocities corresponding to the intermediate velocity cloud regime. This nebula shows unusually strong CO emission and remarkably high-contrast small-scale structures for such a diffuse high Galactic latitude cloud. The 21cm emission of the Draco nebula reveals that it is likely to have been formed by the collision of a cloud entering the disk of the Milky Way. Such physical conditions are ideal to study the formation of cold and dense gas in colliding flows of diffuse and warm gas. The objective of this study is to better understand the process of structure formation in a colliding flow and to describe the ects of matter entering the disk on the interstellar medium. We conducted Herschel-SPIRE observations of the Draco nebula. The clumpfind algorithm was used to identify and characterize the small-scale structures of the cloud.
- ID:
- ivo://CDS.VizieR/J/ApJ/869/L42
- Title:
- DSHARP. II. Annular substructures data
- Short Name:
- J/ApJ/869/L42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Disk Substructures at High Angular Resolution Project (DSHARP) used the Atacama Large Millimeter/submillimeter Array (ALMA) to map the 1.25mm continuum of protoplanetary disks at a spatial resolution of ~5au. We present a systematic analysis of annular substructures in the 18 single-disk systems targeted in this survey. No dominant architecture emerges from this sample; instead, remarkably diverse morphologies are observed. Annular substructures can occur at virtually any radius where millimeter continuum emission is detected and range in widths from a few astronomical units to tens of astronomical units. Intensity ratios between gaps and adjacent rings range from near-unity to just a few percent. In a minority of cases, annular substructures coexist with other types of substructures, including spiral arms (3/18) and crescent-like azimuthal asymmetries (2/18). No clear trend is observed between the positions of the substructures and stellar host properties. In particular, the absence of an obvious association with stellar host luminosity (and hence the disk thermal structure) suggests that substructures do not occur preferentially near major molecular snowlines. Annular substructures like those observed in DSHARP have long been hypothesized to be due to planet-disk interactions. A few disks exhibit characteristics particularly suggestive of this scenario, including substructures in possible mean-motion resonance and "double gap" features reminiscent of hydrodynamical simulations of multiple gaps opened by a planet in a low-viscosity disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/869/L41
- Title:
- DSHARP I. Sample, ALMA obs. log and overview
- Short Name:
- J/ApJ/869/L41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce the Disk Substructures at High Angular Resolution Project (DSHARP), one of the initial large programs conducted with the Atacama Large Millimeter/submillimeter Array (ALMA). The primary goal of DSHARP is to find and characterize substructures in the spatial distributions of solid particles for a sample of 20 nearby protoplanetary disks, using very high resolution (~0.035", or 5au, Full width half maximum (FWHM)) observations of their 240GHz (1.25mm) continuum emission. These data provide a first homogeneous look at the small-scale features in disks that are directly relevant to the planet formation process, quantifying their prevalence, morphologies, spatial scales, spacings, symmetry, and amplitudes, for targets with a variety of disk and stellar host properties. We find that these substructures are ubiquitous in this sample of large, bright disks. They are most frequently manifested as concentric, narrow emission rings and depleted gaps, although large-scale spiral patterns and small arc-shaped azimuthal asymmetries are also present in some cases. These substructures are found at a wide range of disk radii (from a few astronomical units to more than 100au), are usually compact (<=10au), and show a wide range of amplitudes (brightness contrasts). Here we discuss the motivation for the project, describe the survey design and the sample properties, detail the observations and data calibration, highlight some basic results, and provide a general overview of the key conclusions that are presented in more detail in a series of accompanying articles.
