- ID:
- ivo://CDS.VizieR/J/ApJS/251/26
- Title:
- CO outflow cand. toward W3/4/5 complex. II.
- Short Name:
- J/ApJS/251/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To date, few studies have focused on protostellar outflow feedback at scales larger than several parsecs. To address this paucity of research, we investigate the effects of feedback from CO outflow candidates on their parent clouds over ~110deg^2^ toward the W3/4/5 complex and its surroundings. Our search identified 265 ^13^CO clouds with radii being ~0.04-17.12pc. We estimate the turbulent support and potential disruptive effect of the outflow activities through analyzing physical properties of outflow candidates and their host clouds in terms of turbulence and gravitational binding energy. We find that (1) clouds of larger size might be less affected by feedback; (2) the possible scale break is >~4.7pc for both turbulent support and potential disruptive effect; (3) if outflows couple to dense gas where stars are forming, for clouds in the Perseus arm, a scale <~0.2-0.4pc is sufficient for the energy and momentum injected by outflow activity to maintain turbulence, while for clouds in the Local arm, the scale is <~0.1-0.2pc; and (4) for clouds in the Perseus arm, a scale <~0.3-1.0pc is needed for outflow activity to potentially disperse material away from the natal clouds, while for clouds in the Local arm, the scale is <~0.2-0.6pc. The strength of outflow activity may affect the values in points 3 and 4. Finally, we find that outflow feedback probably possesses the power to alter the line width-size relation.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/472/187
- Title:
- 12CO outflows towards submm cores in Perseus
- Short Name:
- J/A+A/472/187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a search for outflows towards 51 submillimetre cores in Perseus. With consistently derived outflow properties from a large homogeneous dataset within one molecular cloud we can investigate further the mass dependence and time evolution of protostellar mass loss. Of the 51 cores, 37 show broad linewings indicative of molecular outflows. In 13 cases, the linewings could be due to confusion with neighbouring flows but 9 of those sources also have near-infrared detections confirming their protostellar nature. The total fraction of protostars in our sample is 65%. All but four outflow detections are confirmed as protostellar by Spitzer IR detections and only one Spitzer source has no outflow, showing that outflow maps at this sensitivity are equally good at identifying protostars as Spitzer. Outflow momentum flux correlates both with source luminosity and with core mass but there is considerable scatter even within this one cloud despite the homogeneous dataset. We fail to confirm the result of Bontemps et al. (1996A&A...311..858B) that Class I sources show lower momentum fluxes on average than Class 0 sources, with a KS test showing a significant probability that the momentum fluxes for both Class 0s and Class Is are drawn from the same distribution. We find that outflow power may not show a simple decline between the Class 0 to Class I stages. Our sample includes low momentum flux, low-luminosity Class 0 sources, possibly at a very early evolutionary stage. If the only mass loss from the core were due to outflows, cores would last for 10^5^-10^8^years, longer than current estimates of 1.5-4x10^5^years for the mean lifetime for the embedded phase. Additional mechanisms for removing mass from protostellar cores may be necessary.
- ID:
- ivo://CDS.VizieR/J/A+A/607/A110
- Title:
- CO properties of compact group galaxies
- Short Name:
- J/A+A/607/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Compact groups (CGs) provide an environment in which interactions between galaxies and with the intra-group medium enable and accelerate galaxy transitions from actively star forming to quiescent. Galaxies in transition from active to quiescent can be selected, by their infrared (IR) colors, as canyon or infrared transition zone (IRTZ) galaxies. We used a sample of CG galaxies with IR data from the Wide Field Infrared Survey Explorer (WISE) allowing us to calculate the stellar mass and star formation rate (SFR) for each galaxy. Furthermore, we present new CO(1-0) data for 27 galaxies and collect data from the literature to calculate the molecular gas mass for a total sample of 130 galaxies. This data set allows us to study the difference in the molecular gas fraction (Mmol/Mstar) and star formation efficiency (SFE=SFR/Mmol) between active, quiescent, and transitioning (i.e., canyon and IRTZ) galaxies. We find that transitioning galaxies have a mean molecular gas fraction and a mean SFE that are significantly lower than those of actively star-forming galaxies. The molecular gas fraction is higher than that of quiescent galaxies, whereas the SFE is similar. These results indicate that the transition from actively star-forming to quiescent in CG galaxies goes along with a loss of molecular gas, possibly due to tidal forces exerted from the neighboring galaxies or a decrease in the gas density. In addition, the remaining molecular gas loses its ability to form stars efficiently, possibly owing to turbulence perturbing the gas, as seen in other, well-studied examples such as Stephan's Quintet and HCG 57. Thus, the amount and properties of molecular gas play a crucial role in the environmentally driven transition of galaxies from actively star forming to quiescent.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A66
- Title:
- CORE high-mass star-forming regions
- Short Name:
- J/A+A/648/A66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Characterizing the physical and chemical properties of forming massive stars at the spatial resolution of individual high-mass cores lies at the heart of current star formation research. We use sub-arcsecond resolution (~0.4arcsec) observations with the NOrthern Extended Millimeter Array at 1.37mm to study the dust emission and molecular gas of 18 high-mass star-forming regions. With distances in the range of 0.7-5.5kpc this corresponds to spatial scales down to 300-2300au that are resolved by our observations. We combine the derived physical and chemical properties of individual cores in these regions to estimate their ages. The temperature structure of these regions are determined by fitting H_2_CO and CH_3_CN line emission. The density profiles are inferred from the 1.37mm continuum visibilities. The column densities of 11 different species are determined by fitting the emission lines with XCLASS. Within the 18 observed regions, we identify 22 individual cores with associated 1.37mm continuum emission and with a radially decreasing temperature profile. We find an average temperature power-law index of q=0.4+/-0.1 and an average density power-law index of p=2.0+/-0.2 on scales on the order of several 1000au. Comparing these results with values of p derived in the literature suggest that the density profiles remain unchanged from clump to core scales. The column densities relative to N(C18O) between pairs of dense gas tracers show tight correlations. We apply the physical-chemical model MUlti Stage ChemicaL codE (MUSCLE) to the derived column densities of each core and find a mean chemical age of ~60000yrs and an age spread of 20000-100000yrs. With this paper we release all data products of the CORE project available at https://www.mpia.de/core. The CORE sample reveals well constrained density and temperature power-law distributions. Furthermore, we characterize a large variety in molecular richness that can be explained by an age spread confirmed by our physical-chemical modeling. The hot molecular cores show the most emission lines, but we also find evolved cores at an evolutionary stage, in which most molecules are destroyed and thus the spectra appear line-poor again.
- ID:
- ivo://CDS.VizieR/J/ApJ/862/105
- Title:
- Core mass function across Gal. env. II. IRDC clumps
- Short Name:
- J/ApJ/862/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the core mass function (CMF) within 32 dense clumps in seven infrared dark clouds (IRDCs) with the Atacama Large Millimeter/submillimeter Array via 1.3mm continuum emission at a resolution of ~1". We have identified 107 cores with the dendrogram algorithm, with a median radius of about 0.02pc. Their masses range from 0.261 to 178M_{sun}_. After applying completeness corrections, we fit the combined IRDC CMF with a power law of the form dN/d.logM{propto}M^-{alpha}^ and derive an index of {alpha}~0.86+/-0.11 for M>=0.79M_{sun}_ and {alpha}~0.70+/-0.13 for M>=1.26M_{sun}_, which is a significantly more top-heavy distribution than the Salpeter stellar initial mass function index of 1.35. We also make a direct comparison of these IRDC clump CMF results to those measured in the more evolved protocluster G286 derived with similar methods, which have {alpha}~1.29+/-0.19 and 1.08+/-0.27 in these mass ranges, respectively. These results provide a hint that, especially for the M>=1.26M_{sun}_ range where completeness corrections are modest, the CMF in high pressure, early-stage environments of IRDC clumps may be top-heavy compared to that in the more evolved, global environment of the G286 protoclusters. However, larger samples of cores probing these different environments are needed to better establish the robustness of this potential CMF variation.
- ID:
- ivo://CDS.VizieR/J/ApJS/196/18
- Title:
- CO survey of galactic molecular clouds. II.
- Short Name:
- J/ApJS/196/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present fully sampled 38" resolution maps of the CO and ^13^CO J=2-1 lines in the molecular clouds toward the HII region complex W3. The maps cover a 2.0{deg}x1.67{deg} section of the galactic plane and span -70 to -20km/s (LSR) in velocity with a resolution of ~1.3km/s. The velocity range of the images includes all the gas in the Perseus spiral arm. We also present maps of CO J=3-2 emission for a 0.5{deg}x0.33{deg} area containing the HII regions W3 Main and W3(OH). The J=3-2 maps have velocity resolution of 0.87km/s and 24" angular resolution. Color figures display the peak line brightness temperature, the velocity-integrated intensity, and velocity channel maps for all three lines, and also the (CO/^13^CO) J=2-1 line intensity ratios as a function of velocity. The line intensity image cubes are made available in standard FITS format as electronically readable files. We compare our molecular line maps with the 1.1mm continuum image from the BOLOCAM Galactic Plane Survey (BGPS). From our ^13^CO image cube, we derive kinematic information for the 65 BGPS sources in the mapped field, in the form of Gaussian component fits.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/39
- Title:
- CO survey of molecular clouds. III. Serpens
- Short Name:
- J/ApJS/209/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We mapped ^12^CO and ^13^CO J=2-1 emission over 1.04deg^2^ of the Serpens molecular cloud with 38" spatial and 0.3km/s spectral resolution using the Arizona Radio Observatory Heinrich Hertz Submillimeter Telescope. Our maps resolve kinematic properties for the entire Serpens cloud. We also compare our velocity moment maps with known positions of young stellar objects (YSOs) and 1.1 mm continuum emission. We find that ^12^CO is self-absorbed and ^13^CO is optically thick in the Serpens core. Outside of the Serpens core, gas appears in filamentary structures having LSR velocities which are blueshifted by up to 2km/s relative to the 8km/s systemic velocity of the Serpens cloud. We show that the known Class I, flat, and Class II YSOs in the Serpens core most likely formed at the same spatial location and have since drifted apart. The spatial and velocity structure of the ^12^CO line ratios implies that a detailed three-dimensional radiative transfer model of the cloud will be necessary for full interpretation of our spectral data. The "starless cores" region of the cloud is likely to be the next site of star formation in Serpens.
- ID:
- ivo://CDS.VizieR/J/ApJS/214/7
- Title:
- CO survey of molecular clouds. IV. NGC 1333
- Short Name:
- J/ApJS/214/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We mapped the NGC 1333 section of the Perseus Molecular Cloud in the J=2-1 emission lines of ^12^CO and ^13^CO over a 50'x60' region (3.4x4.1pc at the cloud distance of 235pc), using the Arizona Radio Observatory Heinrich Hertz Submillimeter Telescope. The angular resolution is 38" (0.04pc) and velocity resolution is 0.3km/s. We compare our velocity moment maps with known positions of young stellar objects (YSOs) and (sub)millimeter dust continuum emission. The CO emission is brightest at the center of the cluster of YSOs, but is detected over the full extent of the mapped region at >=10xrms. The morphology of the CO channel maps shows a kinematically complex structure, with many elongated features extending from the YSO cluster outward by ~1pc. One notable feature appears as a narrow serpentine structure that curves and doubles back, with a total length of ~3pc. The ^13^CO velocity channel maps show evidence for many low-density cavities surrounded by partial shell-like structures, consistent with previous studies. Maps of the velocity moments show localized effects of bipolar outflows from embedded YSOs, as well as a large-scale velocity gradient around the central core of YSOs, suggestive of large-scale turbulent cloud motions determining the location of current star formation. The CO/^13^CO intensity ratios show the distribution of the CO opacity, which exhibits a complex kinematic structure. Identified YSOs are located mainly at the positions of greatest CO opacity.
- ID:
- ivo://CDS.VizieR/J/PASJ/56/313
- Title:
- 13CO survey of Mon & CMa molecular clouds
- Short Name:
- J/PASJ/56/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Through a large-scale 13^CO (J=1-0) survey toward a region in Monoceros and Canis Major, we have identified in total 115 clouds.
- ID:
- ivo://CDS.VizieR/J/ApJS/252/20
- Title:
- CO survey of the CMa OB1 complex
- Short Name:
- J/ApJS/252/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Purple Mountain Observatory 13.7m millimeter telescope at Delingha in China, we have conducted a large-scale simultaneous survey of ^12^CO, ^13^CO, and C^18^O (J=1-0) toward the CMa OB1 complex with a sky coverage of 16.5deg^2^ (221.5{deg}<=l<=227{deg}, -2.5{deg}<=b<=0.5{deg}). Emission from the CMa OB1 complex is found in the range 7km/s<=V_LSR_<=25km/s. The large-scale structure, physical properties, and chemical abundances of the molecular clouds are presented. A total of 83 C^18^O molecular clumps are identified with the GaussClumps algorithm within the mapped region. We find that 94% of these C18O molecular clumps are gravitationally bound. The relationship between their size and mass indicates that none of the C^18^O clumps has the potential to form high-mass stars. Using a semiautomatic IDL algorithm, we newly discover 85 CO outflow candidates in the mapped area, including 23 bipolar outflow candidates. Additionally, a comparative study reveals evidence for a significant variety of physical properties, evolutionary stages, and levels of star formation activity in different subregions of the CMa OB1 complex.
