- ID:
- ivo://CDS.VizieR/J/ApJS/248/24
- Title:
- MUSTANG-2 Galactic Plane survey at 3mm (MGPS90)
- Short Name:
- J/ApJS/248/24
- Date:
- 04 Dec 2021
- Publisher:
- CDS
- Description:
- We report the results of a pilot program for a Green Bank Telescope MUSTANG-2 Galactic Plane survey at 3mm (90GHz), MGPS90. The survey achieves a typical 1{sigma} depth of 1-2mJy/beam with a 9" beam. We describe the survey parameters, quality assessment process, cataloging, and comparison with other data sets. We have identified 709 sources over seven observed fields selecting some of the most prominent millimeter-bright regions between 0{deg}<l<50{deg} (total area ~7.5deg^2^). The majority of these sources have counterparts at other wavelengths. By applying flux selection criteria to these sources, we successfully recovered several known hypercompact HII (HCHII) regions but did not confirm any new ones. We identify 126 sources that have mm-wavelength counterparts but do not have cm-wavelength counterparts and are therefore candidate HCHII regions; of these, 10 are morphologically compact and are strong candidates for new HCHII regions. Given the limited number of candidates in the extended area in this survey compared to the relatively large numbers seen in protoclusters W51 and W49, it appears that most HCHII regions exist within dense protoclusters. Comparing the counts of HCHII to ultracompact HII (UCHII) regions, we infer the HCHII region lifetime is 16%-46% that of the UCHII region lifetime. We additionally separated the 3mm emission into dust and free-free emission by comparing with archival 870{mu}m and 20cm data. In the selected pilot fields, most (>~80%) of the 3mm emission comes from plasma, either through free-free or synchrotron emission.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/631/A110
- Title:
- N131 bubble CO (3-2), (2-1) and (1-0) observations
- Short Name:
- J/A+A/631/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- N131 is a typical infrared dust bubble showing an expanding ringlike shell. We study what kinds of CO line ratios can be used to trace the interaction in the expanding bubble. We carry out new CO (3-2) observations towards bubble N131 using JCMT 15-m telescope, and derive line ratios by combining with our previous CO (2-1) and CO (1-0) data from IRAM 30-m observations. To trace the interaction between the molecular gas and the ionized gas in the HII region, we use RADEX to model the dependence of CO line ratios on kinetic temperature and H_2_ volume density, and examine the abnormal line ratios based on other simulations. We present CO (3-2), CO (2-1), and CO (1-0) integrated intensity maps convolved to the same angular resolution (22.5"). The three different CO transition maps show apparently similar morphology. The line ratios of W_CO_(3-2)/W_CO_(2-1) mostly range from 0.2 to 1.2 with a median of 0.54+/-0.12, while the line ratios of W_CO_(2-1)/W_CO_(1-0) range from 0.5 to 1.6 with a median of 0.84+/-0.15. The high CO line ratios W_CO_(3-2)/W_CO_(2-1)>0.8 and W_CO_(2-1)/W_CO_(1-0)>1.2 are beyond the threshold predicted by numerical simulations based on the assumed density-temperature structure for the inner rims of ringlike shell, where are the compressed areas in bubble N131. These high CO integrated intensity ratios, such as W_CO_(3-2)/W_CO_(2-1)>0.8 and W_CO_(2-1)/W_CO_(1-0)>1.2, can be used as a tracer of gas compressed regions with a relatively high temperature and density. This further suggests that the non-Gaussian part of the line-ratio distribution can be used to trace the interaction between the molecular gas and the hot gas in the bubble.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/4512
- Title:
- Nearby Seyfert galaxies FIR emissions
- Short Name:
- J/MNRAS/458/4512
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present far-infrared (FIR) 70-500{mu}m imaging observations obtained with Herschel/Photodetector Array Camera (PACS) and Spectral and Photometric Imaging REceiver (SPIRE) of 33 nearby (median distance of 30Mpc) Seyfert galaxies from the Revised Shapley-Ames (RSA) catalogue. We obtain the FIR nuclear (r=1kpc and r=2kpc) and integrated spectral energy distributions (SEDs). We estimate the unresolved nuclear emission at 70{mu}m and we fit the nuclear and integrated FIR SEDs with a grey body model. We find that the integrated FIR emission of the RSA Seyferts in our sample is dominated by emission from the host galaxy, with dust properties similar to those of normal galaxies (non-AGN). We use four criteria to select galaxies whose nuclear 70{mu}m emission has a significant AGN contribution: (1) elevated 70/160{mu}m flux ratios, (2) spatially resolved, high dust temperature gradient, (3) 70{mu}m excess emission with respect to the fit of the FIR SEDs with a grey body, and (4) excess of nuclear SFR obtained from 70{mu}m over SFR from mid-infrared indicators. 16 galaxies (48 per cent of the initial sample) satisfy at least one of these conditions, whereas 10 satisfy half or more. After careful examination of these, we select six bona fide candidates (18 per cent of the initial sample) and estimate that ~40-70 per cent of their nuclear (r=1-2kpc) 70{mu}m emission is contributed by dust heated by the AGN.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/1523
- Title:
- New young stellar cluster towards IRAS 04186+5143
- Short Name:
- J/MNRAS/452/1523
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a new young stellar cluster in the outer Galaxy located at the position of an IRAS Point Source Catalog source that has been previously misidentified as an external galaxy. The cluster is seen in our near-infrared imaging towards IRAS 04186+5143 and in archive Spitzer images confirming the young stellar nature of the sources detected. There is also evidence of subclustering seen in the spatial distributions of young stars and of gas and dust. Near- and mid-infrared photometry indicates that the stars exhibit colours compatible with reddening by interstellar and circumstellar dust and are likely to be low- and intermediate-mass young stellar objects (YSOs) with a large proportion of Class I YSOs. Ammonia and CO lines were detected, with the CO emission well centred near the position of the richest part of the cluster. The velocity of the CO and NH3 lines indicates that the gas is Galactic and located at a distance of about 5.5kpc, in the outer Galaxy. Herschel data of this region characterize the dust environment of this molecular cloud core where the young cluster is embedded. We derive masses, luminosities, and temperatures of the molecular clumps where the young stars reside and discuss their evolutionary stages.
- ID:
- ivo://CDS.VizieR/J/A+A/656/A60
- Title:
- NGC1808 ALMA datacubes
- Short Name:
- J/A+A/656/A60
- Date:
- 21 Mar 2022 07:01:58
- Publisher:
- CDS
- Description:
- We report on Atacama Large Millimeter Array (ALMA) observations of CO(3-2) emission in the Seyfert2/starburst galaxy NGC 1808, at a spatial resolution of 4pc. Our aim is to investigate the morphology and dynamics of the gas inside the central 0.5kpc and to probe the nuclear feeding and feedback phenomena. We discovered a nuclear spiral of radius 1"=45pc. Within it, we found a decoupled circumnuclear disk or molecular torus of a radius of 0.13"=6pc. The HCN(4-3) and HCO^+^(4-3) and CS(7-6) dense gas line tracers were simultaneously mapped and detected in the nuclear spiral and they present the same misalignment in the molecular torus. At the nucleus, the HCN/HCO^+^ and HCN/CS ratios indicate the presence of an active galactic nucleus (AGN). The molecular gas shows regular rotation, within a radius of 400pc, except for the misaligned disk inside the nuclear spiral arms. The computations of the torques exerted on the gas by the barred stellar potential reveal that the gas within a radius of 100pc is feeding the nucleus on a timescale of five rotations or on an average timescale of ~60Myr. Some non-circular motions are observed towards the center, corresponding to the nuclear spiral arms. We cannot rule out that small extra kinematic perturbations could be interpreted as a weak outflow attributed to AGN feedback. The molecular outflow detected at >=250pc in the NE direction is likely due to supernovae feedback and it is connected to the kpc-scale superwind.
- ID:
- ivo://CDS.VizieR/J/ApJ/671/605
- Title:
- NGC 2264 and ONC PMS stars in the infrared
- Short Name:
- J/ApJ/671/605
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of pre-main-sequence star rotation periods reveal slow rotators in young clusters of various ages, indicating that angular momentum is somehow removed from these rotating masses. The mechanism by which spin-up is regulated as young stars contract has been one of the longest standing problems in star formation. Attempts to observationally confirm the prevailing theory that magnetic interaction between the star and its circumstellar disk regulates these rotation periods have produced mixed results. In this paper, we use the unprecedented disk identification capability of the Spitzer Space Telescope to test the star-disk interaction paradigm in two young clusters, NGC 2264 and the Orion Nebula Cluster (ONC).
- ID:
- ivo://CDS.VizieR/J/A+A/645/A94
- Title:
- NGC 2264 clumps column densities
- Short Name:
- J/A+A/645/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mass segregation of stellar clusters could be primordial rather than dynamical. Despite the abundance of studies of mass segregation for stellar clusters, those for stellar progenitors are still scarce, so the question on the origin and evolution of mass segregation is still open. Our goal is to characterize the structure of the NGC 2264 molecular cloud and compare the populations of clumps and young stellar objects (YSOs) in this region whose rich YSO population has shown evidence of sequential star formation. We separated the Herschel column density map of NGC 2264 in three subregions and compared their cloud power spectra using a multiscale segmentation technique. We identified in the whole NGC 2264 cloud a population of 256 clumps with typical sizes of ~0.1pc and masses ranging from 0.08M_{sun}_ to 53M_{sun}_. Although clumps have been detected all over the cloud, the central subregion of NGC 2264 concentrates most of the massive, bound clumps. The local surface density and the mass segregation ratio indeed indicate a strong degree of mass segregation for the 15 most massive clumps, with a median Sigma_6 _three time that of the whole clumps population and Lambda_MSR_ about 8. We showed that this cluster of massive clumps is forming within a high-density cloud ridge, itself formed and probably still fed by the high concentration of gas observed on larger scales in the central subregion. The time sequence obtained from the combined study of the clump and YSO populations in NGC 2264 suggests that the star formation started in the northern subregion, that it is now actively developing at the center and will soon start in the southern subregion. Taken together, the cloud structure and the clump and YSO populations in NGC 2264 argue for a dynamical scenario of star formation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/420/2884
- Title:
- NGC 1960 IRAC and MIPS photometry
- Short Name:
- J/MNRAS/420/2884
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of Spitzer IRAC (3.6-8um) and MIPS (24um) imaging of members of the 16^+10^_-5_ Myr old open cluster NGC 1960 (M36). Models of terrestrial planet formation indicate that rocky planets are likely to achieve their final masses at around 10-30Myr, and thus this cluster is at an interesting epoch for planet formation. We find 21 B-F5 type stars and 14 F6-K9 type stars which have 24um excess emission, and thus determine that >30 per cent of B-F5 type stars and >23 per cent of F6-K9 type stars in this cluster have 24um excess emission. These excess frequencies are similar to those observed in other clusters of similar age. Three early-type stars have excesses at near-infrared wavelengths. Analysis of their spectral energy distributions confirms that these are true debris discs and not remnant primordial or transitional discs. None of the 61 Sun-like stars has confirmed near-infrared excess, and we can place a limit on the frequency of 8um excess emission around Sun-like stars of <7 per cent. All of the detected excesses are consistent with emission from debris discs and are not primordial.
- ID:
- ivo://CDS.VizieR/J/A+A/563/L1
- Title:
- NGC1333-IRAS2A CALYPSO IRAM-PdBI 1mm and 3mm maps
- Short Name:
- J/A+A/563/L1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The structure and kinematics of Class 0 protostars on scales of a few hundred AU is poorly known. Recent observations have revealed the presence of Keplerian disks with a diameter of 150-180AU in L1527-IRS and VLA1623A, but it is not clear if such disks are common in Class 0 protostars. Here we present high-angular-resolution observations of two methanol lines in NGC1333-IRAS2A. We argue that these lines probe the inner envelope, and we use them to study the kinematics of this region. Our observations suggest the presence of a marginal velocity gradient normal to the direction of the outflow. However, the position velocity diagrams along the gradient direction appear inconsistent with a Keplerian disk. Instead, we suggest that the emission originates from the infalling and perhaps slowly rotating envelope, around a central protostar of 0.1-0.2M_{sun}_. If a disk is present, it is smaller than the disks of L1527-IRS and VLA1623A, perhaps suggesting that NGC1333-IRAS2A is younger.
- ID:
- ivo://CDS.VizieR/J/A+A/563/L2
- Title:
- NGC1333-IRAS2A CALYPSO IRAM-PdBI 1mm maps
- Short Name:
- J/A+A/563/L2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the origin of complex organic molecules (COMs) in the gas phase around the low-mass Class 0 protostar NGC 1333-IRAS2A, to determine if the COM emission lines trace an embedded disk, shocks from the protostellar jet, or the warm inner parts of the protostellar envelope. In the framework of the CALYPSO IRAM Plateau de Bure survey, we obtained large bandwidth spectra at sub-arcsecond resolution towards NGC 1333-IRAS2A. We identify the emission lines towards the central protostar and perform Gaussian fits to constrain the size of the emitting region for each of these lines, tracing various physical conditions and scales.