- ID:
- ivo://CDS.VizieR/J/ApJ/641/389
- Title:
- Millimetric observations of IRDC cores
- Short Name:
- J/ApJ/641/389
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared dark clouds (IRDCs) are dense molecular clouds seen as extinction features against the bright mid-infrared Galactic background. Millimeter continuum maps toward 38 IRDCs reveal extended cold dust emission to be associated with each of the IRDCs. IRDCs range in morphology from filamentary to compact and have masses of 120 to 16000M_{sun}_, with a median mass of 940M_{sun}_. Each IRDC contains at least one compact (0.5pc) dust core and most show multiple cores. We find 140 cold millimeter cores unassociated with MSX 8{mu}m emission.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/895/38
- Title:
- MIR extinction toward Cyg OB2-12 ISM
- Short Name:
- J/ApJ/895/38
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- The sight line toward the luminous blue hypergiant CygOB2-12 is widely used to study interstellar dust on account of its large extinction (AV~10mag) and the fact that this extinction appears to be dominated by dust typical of the diffuse interstellar medium. We present a new analysis of archival Infrared Space Observatory Short Wavelength Spectrometer and Spitzer IRS observations of CygOB2-12 using a model of the emission from the star and its stellar wind to determine the total extinction A{lambda} from 2.4 to 37{mu}m. In addition to the prominent 9.7 and 18{mu}m silicate features, we robustly detect absorption features associated with polycyclic aromatic hydrocarbons, including the first identification of the 7.7{mu}m feature in absorption. The 3.3{mu}m aromatic feature is found to be much broader in absorption than is typically seen in emission. The 3.4 and 6.85{mu}m aliphatic hydrocarbon features are observed with relative strengths that are consistent with observations of these features on sight lines toward the Galactic center. We identify and characterize more than 60 spectral lines in this wavelength range, which may be useful in constraining models of the star and its stellar wind. Based on this analysis, we present an extinction curve A_{lambda}_/A_2.2{mu}m_ that extrapolates smoothly to determinations of the mean Galactic extinction curve at shorter wavelengths and to dust opacities inferred from emission at longer wavelengths, providing a new constraint on models of interstellar dust in the mid-infrared.
- ID:
- ivo://CDS.VizieR/J/ApJ/846/71
- Title:
- M51 ISM structures from the CO maps of PAWS
- Short Name:
- J/ApJ/846/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare the structure of molecular gas at 40pc resolution to the ability of gas to form stars across the disk of the spiral galaxy M51. We break the PdBI Arcsecond Whirlpool Survey (PAWS; Schinnerer+ 2013ApJ...779...42S) into 370pc and 1.1kpc resolution elements, and within each we estimate the molecular gas depletion time ({tau}_Dep_^mol^), the star-formation efficiency per free-fall time ({epsilon}_ff_), and the mass-weighted cloud-scale (40pc) properties of the molecular gas: surface density, {Sigma}, line width, {sigma}, and b={Sigma}/{sigma}^2^{propto}{alpha}_vir_^-1^, a parameter that traces the boundedness of the gas. We show that the cloud-scale surface density appears to be a reasonable proxy for mean volume density. Applying this, we find a typical star-formation efficiency per free-fall time, {epsilon}_ff_(<{Sigma}_40pc_>)~0.3%-0.36%, lower than adopted in many models and found for local clouds. Furthermore, the efficiency per free-fall time anti-correlates with both {Sigma} and {sigma}, in some tension with turbulent star-formation models. The best predictor of the rate of star formation per unit gas mass in our analysis is b={Sigma}/{sigma}^2^, tracing the strength of self-gravity, with {tau}_Dep_^mol^{propto}b^-0.9^. The sense of the correlation is that gas with stronger self-gravity (higher b) forms stars at a higher rate (low {tau}_Dep_^mol^). The different regions of the galaxy mostly overlap in {tau}_Dep_^mol^ as a function of b, so that low b explains the surprisingly high {tau}_Dep_^mol^ found toward the inner spiral arms found by Meidt et al. (2013ApJ...779...45M).
- ID:
- ivo://CDS.VizieR/J/A+A/623/A171
- Title:
- Mkn 848 MaNGA 3-D data cube
- Short Name:
- J/A+A/623/A171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The characterisation of galaxy-scale outflows in terms of their multi-phase and multi-scale nature, amount, and effects of flowing material is crucial to place constraints on models of galaxy formation and evolution. This study can proceed only with the detailed investigation of individual targets. We present a spatially resolved spectroscopic optical data analysis of Mkn 848, a complex system consisting of two merging galaxies at z~0.04 that are separated by a projected distance of 7.5kpc. Motivated by the presence of a multi-phase outflow in the north-west system revealed by the SDSS integrated spectrum, we analysed the publicly available MaNGA data, which cover almost the entire merging system, to study the kinematic and physical properties of cool and warm gas in detail. Galaxy-wide outflowing gas in multiple phases is revealed for the first time in the two merging galaxies. We also detect spatially resolved resonant NaID emission associated with the outflows. The derived outflow energetics (mass rate, and kinetic and momentum power) may be consistent with a scenario in which both winds are accelerated by stellar processes and AGN activity, although we favour an AGN origin given the high outflow velocities and the ionisation conditions observed in the outflow regions. Further deeper multi-wavelength observations are required, however, to better constrain the nature of these multi-phase outflows. Outflow energetics in the north-west system are strongly different between the ionised and atomic gas components, the latter of which is associated with mass outflow rate and kinetic and momentum powers that are one or two dex higher; those associated with the south-east galaxy are instead similar. Strong kiloparsec-scale outflows are revealed in an ongoing merger system, suggesting that feedback can potentially impact the host galaxy even in the early merger phases. The characterisation of the neutral and ionised gas phases has proved to be crucial for a comprehensive study of the outflow phenomena.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A51
- Title:
- 1.4mm and 3mm interferometry of IRAS 19410+2336
- Short Name:
- J/A+A/545/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The core mass functions (CMFs) of low-mass star-forming regions are found to resemble the shape of the initial mass function (IMF). A similar result is observed for the dust clumps in high-mass star-forming regions, although on spatial scales of clusters that do not resolve the substructure that is found in these massive clumps. The region IRAS 19410+2336 is one exception, having been observed on spatial scales on the order of ~2500AU, which are sufficient to resolve the clump substructure into individual cores. We investigate the protostellar content of IRAS 19410+2336 at high spatial resolution at 1.4mm, determining the temperature structure of the region and deriving its CMF. The massive star-forming region IRAS 19410+2336 was mapped with the PdBI (BCD configurations) at 1.4mm and 3mm in the continuum and several transitions of formaldehyde (H_2_CO) and methyl cyanide (CH_3_CN). The H_2_CO transitions were also observed with the IRAM 30m Telescope. We detect 26 continuum sources at 1.4mm with a spatial resolution as low as ~2200AU, several of them with counterparts at near-infrared and mid-infrared wavelengths, distributed in two (proto)clusters. With the PdBI CH_3_CN and PdBI/IRAM 30m H_2_CO emission, we derive the temperature structure of the region, ranging from 35K to 90K. Using these temperatures, we calculate the core masses of the detected sources, ranging from ~0.7M_{sun}_ to ~8M_{sun}_. These masses are strongly affected by the spatial filtering of the interferometer, which removes a common envelope with ~90% of the single- dish flux. Considering only the detected dense cores and accounting for binning effects as well as cumulative distributions, we derive a CMF, with a power-law index b=~2.3+/-0.2. We resolve the Jeans length of the (proto)clusters by one order of magnitude, and only find a small velocity dispersion between the different subsources. Since we cannot unambiguously differentiate between protostellar and prestellar cores, the derived CMF is not prestellar. Furthermore, because of the large fraction of missing flux, we cannot establish a firm link between the CMF and the IMF. This implies that future high-mass CMF studies will need to complement the interferometer continuum data with the short spacing information, a task suitable for ALMA. We note that the method of extracting temperatures using H_2_CO lines becomes less applicable when reaching the dense core scales of the interferometric observations because most of the H_2_CO appears to originate in the envelope structure.
- ID:
- ivo://CDS.VizieR/J/A+A/447/609
- Title:
- 1.2mm continuum observations in rho Oph cloud
- Short Name:
- J/A+A/447/609
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a wide field survey for dust sources at 1.2-millimetres in the rho Ophiuchi molecular cloud, covering more than 1 square degree in an unbiased fashion. We detect a number of previously unknown sources, ranging from extended cores over compact, starless cores to envelopes surrounding young stellar objects of Class 0, Class I, and Class II type. We analyse the mass distribution, spatial distribution and the potential equilibrium of the cores.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/2222
- Title:
- 1.1mm dust continuum emission along Gal. plane
- Short Name:
- J/MNRAS/473/2222
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Sensitive, imaging observations of the {lambda}1.1mm dust continuum emission from a 1deg^2^ area collected with the AzTEC bolometer camera on the Large Millimeter Telescope are presented. A catalogue of 1545 compact sources is constructed based on a Wiener-optimization filter. These sources are linked to larger clump structures identified in the Bolocam Galactic Plane Survey. Hydrogen column densities are calculated for all sources and mass and mean volume densities are derived for the subset of sources for which kinematic distances can be assigned. The AzTEC sources are localized, high-density peaks within the massive clumps of molecular clouds and comprise 5-15 per cent of the clump mass. We examine the role of the gravitational instability in generating these fragments by comparing the mass of embedded AzTEC sources to the Jeans mass of the parent BGPS object. For sources with distances less than 6kpc the fragment masses are comparable to the clump Jeans mass, despite having isothermal Mach numbers between 1.6 and 7.2. AzTEC sources linked to ultra compact HII regions have mass surface densities greater than the critical value implied by the mass-size relationship of infrared dark clouds with high-mass star formation, while AzTEC sources associated with Class II methanol masers have mass surface densities greater than 0.7gcm^-2^ that approaches the proposed threshold required to form massive stars.
- ID:
- ivo://CDS.VizieR/J/A+A/548/A24
- Title:
- 1.3mm observations of CrA cluster
- Short Name:
- J/A+A/548/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The importance of the physical environment in the evolution of newly formed low-mass stars remains an open question. In particular, radiation from nearby more massive stars may affect both the physical and chemical structure of these kinds of young stars. We constrain the physical characteristics of a group of embedded low-mass protostars in Corona Australis in the vicinity of the young luminous Herbig Be star R CrA.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A146
- Title:
- M33 molecular clouds and young stellar clusters
- Short Name:
- J/A+A/601/A146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the association between giant molecular clouds (GMCs) and young stellar cluster candidates (YSCCs) to shed light on the time evolution of local star formation episodes in the nearby galaxy M33. The CO (J=2-1) IRAM all-disk survey was used to identify and classify 566 GMCs with masses between 2x10^4^ and 2x10^6^M_{sun}_ across the whole star-forming disk of M33. In the same area, there are 630 YSCCs that we identified using Spitzer-24um data. Some YSCCs are embedded star-forming sites, while the majority have GALEX-UV and H{alpha} counterparts with estimated cluster masses and ages. The GMC classes correspond to different cloud evolutionary stages: inactive clouds are 32% of the total and classified clouds with embedded and exposed star formation are 16% and 52% of the total, respectively. Across the regular southern spiral arm, inactive clouds are preferentially located in the inner part of the arm, possibly suggesting a triggering of star formation as the cloud crosses the arm. The spatial correlation between YSCCs and GMCs is extremely strong, with a typical separation of 17pc. This is less than half the CO (2-1) beam size and illustrates the remarkable physical link between the two populations. GMCs and YSCCs follow the HI filaments, except in the outermost regions, where the survey finds fewer GMCs than YSCCs, which is most likely due to undetected clouds with low CO luminosity. The distribution of the non-embedded YSCC ages peaks around 5Myr, with only a few being as old as 8-10Myr. These age estimates together with the number of GMCs in the various evolutionary stages lead us to conclude that 14Myr is the typical lifetime of a GMC in M33 prior to cloud dispersal. The inactive and embedded phases are short, lasting about 4 and 2Myr, respectively. This underlines that embedded YSCCs rapidly break out from the clouds and become partially visible in H{alpha} or UV long before cloud dispersal.
- ID:
- ivo://CDS.VizieR/J/ApJ/638/293
- Title:
- 1.1mm sources in the Perseus Molecular Cloud
- Short Name:
- J/ApJ/638/293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have completed a 1.1mm continuum survey of 7.5{deg}^2^ of the Perseus Molecular Cloud using Bolocam at the Caltech Submillimeter Observatory. This represents the largest millimeter or submillimeter continuum map of Perseus to date. Our map covers more than 30,000 31" (FWHM) resolution elements to a 1{sigma} rms of 15mJy/beam. We detect a total of 122 cores above a 5{sigma} point-source mass detection limit of 0.18M_{sun}_, assuming a dust temperature of T_D_=10K, 60 of which are new millimeter or submillimeter detections.
