- ID:
- ivo://CDS.VizieR/J/A+A/417/115
- Title:
- High-mass protostellar candidates
- Short Name:
- J/A+A/417/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present maps of the 850{mu}m and 450{mu}m continuum emission seen towards a sample of 68 high-mass protostellar candidates with luminosities ranging from 10^2.5^L_{sun}_ to ~10^5^L_{sun}_. Most of these candidate high-mass stars are in the earliest stages of evolution, and have not yet developed an ultra-compact HII region. We observe a variety of continuum emission morphologies, from compact symmetric sources through to multiple cores embedded in long filaments of emission. We find on average there is a 65% probability of an IRAS point-source having a companion detection at submillimetre wavelengths. The ratio of integrated flux to peak flux for our detections shows no strong dependence on distance, suggesting the emission we have observed is primarily from scale-free envelopes with power-law density structures. Assuming a near kinematic distance projection, the clumps we detect vary in mass from ~1M_{sun}_ to over 1000M_{sun}_, with a mean clump mass of 330M_{sun}_, column density of 9x10^23cm^-2^ and diameter of ~0.6pc. The high luminosity and low mass of the smallest clumps suggests they are accompanied by a minimal number of stellar companions, while the most massive clumps may be examples of young protogroups and protoclusters. We measure the spectral index of the dust emission ({alpha}) and the spectral index of the dust grain opacity ({beta}) towards each object, finding clumps with morphologies suggestive of strong temperature gradients, and of grain growth in their dense inner regions. We find a mean value for beta of 0.9, significantly smaller than observed towards ultra-compact HII regions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/498/147
- Title:
- High mass protostellar objects physical parameters
- Short Name:
- J/A+A/498/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a previous work (Paper I, Kumar & Grave, 2007A&A...472..155K) a sample of 380 HMPO targets was studied using the GLIMPSE point source catalog and images. A colour-magnitude analysis of the point sources resulted in the identification of infrared counterparts (IRC) of the (sub)mm cores of HMPO candidates which were considered bona fide targets. We aim to estimate and analyse the physical properties of the infrared counterparts of HMPOs by comparing their spectral energy distributions (SED) with those predicted by radiative transfer accretion models of YSOs.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A106
- Title:
- High-redshift candidate Herschel sources
- Short Name:
- J/A+A/622/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of high-redshift candidate Herschel sources. Our sample is obtained after applying a multifrequency filtering method (matched multifilter), which is designed to improve the signal-to-noise ratio (SNR) of faint extragalactic point sources. The method is tested against already-detected sources from the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) and used to search for new high-redshift candidates. The multifilter technique produces also an estimation of the photometric redshift of the sources. When compared with a sample of sources with known spectroscopic redshift, the photometric redshift returned from the multifilter is unbiased in the redshift range 0.8<z<4.3. Using simulated data we reproduce the same unbiased result in roughly the same redshift range and determined the error (and bias above z=4) in the photometric redshifts. Based on the multifilter technique, and a selection based on color, flux, and agreement of fit between the observed photometry and assumed SED, we find 370 robust candidates to be relatively bright high-redshift sources. A second sample with 237 objects focuses on the faint end at high-redshift. These 237 sources were previously near the H-ATLAS detection limit but are now confirmed with our technique as high significance detections. Finally, we look for possible lensed Herschel sources by cross-correlating the first sample of 370 objects with two different catalogs of known low-redshift objects, the redMaPPer Galaxy Cluster Catalog and a catalog of galaxies with spectroscopic redshift from the Sloan Digital Sky Survey Data Release 14. Our search renders a number of candidates to be lensed systems from the SDSS cross-correlation but none from the redMaPPeR confirming the more likely galactic nature of the lenses.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/150
- Title:
- High-res. MIKE obs. of metal-poor stars
- Short Name:
- J/ApJ/898/150
- Date:
- 21 Mar 2022 08:50:22
- Publisher:
- CDS
- Description:
- Extensive progress has recently been made in our understanding of heavy-element production via the r-process in the universe, specifically with the first observed neutron star binary merger (NSBM) event associated with the gravitational-wave signal detected by LIGO, GW170817. The chemical abundance patterns of metal-poor r-process-enhanced stars provide key evidence for the dominant site(s) of the r-process and whether NSBMs are sufficiently frequent or prolific r-process sources to be responsible for the majority of r-process material in the universe. We present atmospheric stellar parameters (using a nonlocal thermodynamic equilibrium analysis) and abundances from a detailed analysis of 141 metal-poor stars carried out as part of the R-Process Alliance (RPA) effort. We obtained high-resolution "snapshot" spectroscopy of the stars using the MIKE spectrograph on the 6.5m Magellan Clay telescope at Las Campanas Observatory in Chile. We find 10 new highly enhanced r-II (with [Eu/Fe]>+1.0), 62 new moderately enhanced r-I (+0.3<[Eu/Fe]<~+1.0), and 17 new limited-r ([Eu/Fe]<+0.3) stars. Among those, we find 17 new carbon-enhanced metal-poor (CEMP) stars, of which five are CEMP-no. We also identify one new s-process-enhanced ([Ba/Eu]>+0.5) and five new r/s (0.0<[Ba/Eu]<+0.5) stars. In the process, we discover a new ultra-metal-poor (UMP) star at [Fe/H]=-4.02. One of the r-II stars shows a deficit in {alpha} and Fe-peak elements, typical of dwarf galaxy stars. Our search for r-process-enhanced stars by RPA efforts has already roughly doubled the known r-process sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/864/8
- Title:
- High resolution NIR observations of z>~1 galaxies
- Short Name:
- J/ApJ/864/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present images taken using the Gemini South Adaptive Optics Imager (GSAOI) with the Gemini Multi-conjugate Adaptive Optics System (GeMS) in three 2arcmin^2^ fields in the Spitzer Extragalactic Representative Volume Survey. These GeMS/GSAOI observations are among the first ~0.1" resolution data in the near-infrared spanning extragalactic fields exceeding 1.5' in size. We use these data to estimate galaxy sizes, obtaining results similar to those from studies with the Hubble Space Telescope, though we find a higher fraction of compact star-forming galaxies at z>2. To disentangle the star-forming galaxies from active galactic nuclei (AGNs), we use multiwavelength data from surveys in the optical and infrared, including far-infrared data from Herschel, as well as new radio continuum data from the Australia Telescope Compact Array and Very Large Array. We identify ultraluminous infrared galaxies (ULIRGs) at z~1-3, which consist of a combination of pure starburst galaxies and AGN/starburst composites. The ULIRGs show signs of recent merger activity, such as highly disturbed morphologies and include a rare candidate triple-AGN. We find that AGNs tend to reside in hosts with smaller scale sizes than purely star-forming galaxies of similar infrared luminosity. Our observations demonstrate the potential for MCAO to complement the deeper galaxy surveys to be made with the James Webb Space Telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A23
- Title:
- HII-chi-mistry-IR. Abundances
- Short Name:
- J/A+A/652/A23
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We provide a new method to derive heavy element abundances based on the unique suite of nebular lines in the mid- to far-infrared (IR) range. Using grids of photo-ionisation models that cover a wide range in O/H and N/O abundances, and ionisation parameter, our code HII-CHI-MISTRY-IR (HCm-IR) provides model-based abundances based on extinction free and temperature insensitive tracers, two significant advantages over optical diagnostics. The code is probed using a sample of 56 galaxies observed with Spitzer and Herschel covering a wide range in metallicity, 7.2~<12+log(O/H)~<8.9. The IR model-based metallicities obtained are robust within a scatter of 0.03dex when the hydrogen recombination lines, which are typically faint transitions in the IR range, are not available. When compared to the optical abundances obtained with the direct method,model- based methods, and strong-line calibrations, HCm-IR estimates show a typical dispersion of ~0.2dex, in line with previous studies comparing IR and optical abundances, a do not introduce a noticeable systematic above 12+log(O/H)>7.6. This accuracy can be achieved using the lines [SIV]10.5um, [SIII]18.7,33.5um, [NeIII]15.6um and [NeII]12.8um. Additionally, HCm-IR provides an independent N/O measurement when the [OIII]52,88um and [NIII]57um transitions are measured, and therefore the derived abundances in this case do not rely on particular assumptions in the N/O ratio. Large uncertainties (~0.4dex) may affect the abundance determinations of galaxies at sub- or over-solar metallicities when a solar-like N/O ratio is adopted. Finally, the code has been applied to 8 galaxies located at 1.8<z<7.5 with ground-based detections of far-IR lines redshifted in the submm range, revealing solar-like N/O and O/H abundances in agreement with recent studies.
- ID:
- ivo://CDS.VizieR/J/ApJ/709/424
- Title:
- HII regions identified with WMAPS and GLIMPSE
- Short Name:
- J/ApJ/709/424
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Wilkinson Microwave Anisotropy Probe (WMAP) maximum entropy method foreground emission map combined with previously determined distances to giant HII regions to measure the free-free flux at Earth and the free-free luminosity of the Galaxy. We find a total flux f_{nu}_=54211Jy and a flux from 88 sources of f_{nu}_=36043Jy. The bulk of the sources are at least marginally resolved, with mean radii ~60pc, electron density n_e_~9cm^-3^, and filling factor {Phi}HII~0.005 (over the Galactic gas disk). We use GLIMPSE and Midcourse Space Experiment (MSX) 8um images to show that the bulk of the free-free luminosity is associated with bubbles having radii r~5-100pc, with a mean of ~20pc. These bubbles are leaky, so that ionizing photons emitted inside the bubble escape and excite free-free emission beyond the bubble walls, producing WMAP sources that are larger than the 8um bubbles. We suggest that the WMAP sources are the counterparts of the extended low density HII regions described by Mezger (1978A&A....70..565M). The 18 most luminous WMAP sources emit half the total Galactic ionizing flux.
- ID:
- ivo://CDS.VizieR/J/MNRAS/387/954
- Title:
- H2 imaging of NGC 1333, L1455, L1448 and B1
- Short Name:
- J/MNRAS/387/954
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss wide-field near-infrared (near-IR) imaging of the NGC 1333, L1448, L1455 and B1 star-forming regions in Perseus. The observations have been extracted from a much larger narrow-band imaging survey of the Taurus-Auriga-Perseus complex. These H_2_ 2.122um observations are complemented by broad-band K imaging, mid-IR imaging and photometry from the Spitzer Space Telescope, and published submillimetre CO J=3-2 maps of high-velocity molecular outflows. We detect and label 85 H_2_ features and associate these with 26 molecular outflows.
- ID:
- ivo://CDS.VizieR/J/A+A/505/29
- Title:
- HI observations of 2MASS galaxies in ZoA
- Short Name:
- J/A+A/505/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A pilot survey has been made to obtain 21cm HI emission line profiles for 197 objects in the zone of avoidance (ZoA) that were classified as galaxies in the 2MASS all-sky near-infrared Extended Source Catalog (2MASX), as well as a further 16 2MASS pre-release working database sources that did not make it into 2MASX. One hundred sixteen of the 2MASX sources and the 16 working database sources were observed using the Nancay radio telescope, usually in the 325 to 11825km/s range, and the other 81 2MASX sources were observed with the Arecibo radio telescope in the -500 to 11000km/s range, and for 9 also in the 9500 to 21000km/s range.
- ID:
- ivo://CDS.VizieR/J/AJ/127/3235
- Title:
- HIRES atlas of all RBGS galaxies
- Short Name:
- J/AJ/127/3235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution 12, 25, 60, and 100{mu}m images of 106 interacting galaxy systems contained in the IRAS Revised Bright Galaxy Sample (RBGS, Sanders et al., Cat. <J/AJ/126/1607>), a complete sample of all galaxies having a 60{mu}m flux density greater than 5.24Jy. These systems were selected to have at least two distinguishable galaxies separated by less than three average galactic diameters, and thus we have excluded very widely separated systems and very advanced mergers. Additionally, some systems have been included that are more than three galactic diameters apart, yet have separations less than 4 and are thus likely to suffer from confusion in the RBGS. The new complete survey has the same properties as the prototype survey of Surace et al., 1993AJ....105..864S.