- ID:
- ivo://CDS.VizieR/J/A+A/489/533
- Title:
- M83 volume densities of giant molecular clouds
- Short Name:
- J/A+A/489/533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using observed GALEX far-ultraviolet (FUV) fluxes and VLA images of the 21-cm HIcolumn densities, along with estimates of the local dust abundances, we measure the volume densities of a sample of actively star-forming giant molecular clouds (GMCs) in the nearby spiral galaxy M83 on a typical resolution scale of 170 pc. Our approach is based on an equilibrium model for the cycle of molecular hydrogen formation on dust grains and photodissociation under the influence of the FUV radiation on the cloud surfaces of GMCs. We find a range of total volume densities on the surface of GMCs in M83, namely 0.1-400cm^-3^ inside R_25_, 0.5-50cm^-3^ outside R_25_. Our data include a number of GMCs in the HI-ring surrounding this galaxy. Finally, we discuss the effects of observational selection, which may bias our results.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/771/105
- Title:
- MWA Stokes I 189MHz sources
- Short Name:
- J/ApJ/771/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a Stokes I, Q and U survey at 189MHz with the Murchison Widefield Array 32 element prototype covering 2400deg^2^. The survey has a 15.6' angular resolution and achieves a noise level of 15mJy/beam. We demonstrate a novel interferometric data analysis that involves calibration of drift scan data, integration through the co-addition of warped snapshot images, and deconvolution of the point-spread function through forward modeling. We present a point source catalog down to a flux limit of 4Jy. We detect polarization from only one of the sources, PMN J0351-2744, at a level of 1.8%+/-0.4%, whereas the remaining sources have a polarization fraction below 2%. Compared to a reported average value of 7% at 1.4GHz, the polarization fraction of compact sources significantly decreases at low frequencies. We find a wealth of diffuse polarized emission across a large area of the survey with a maximum peak of ~13K, primarily with positive rotation measure values smaller than +10rad/m2. The small values observed indicate that the emission is likely to have a local origin (closer than a few hundred parsecs). There is a large sky area at {alpha}>=2^h^30^m^ where the diffuse polarized emission rms is fainter than 1K. Within this area of low Galactic polarization we characterize the foreground properties in a cold sky patch at ({alpha},{delta})=(4^h^,-27.6{deg}) in terms of three-dimensional power spectra.
953. MWC 480 ALMA image
- ID:
- ivo://CDS.VizieR/J/A+A/622/A75
- Title:
- MWC 480 ALMA image
- Short Name:
- J/A+A/622/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gap-like structures in protoplanetary disks are likely related to planet formation processes. In this work, we present and analyze high-resolution 1.3mm ALMA continuum observations of the protoplanetary disk around the Herbig Ae star MWC 480. Our observations show for the first time a gap centered at ~74AU with a width of ~23AU, surrounded by a bright ring centered at ~98AU from the central star. Detailed radiative transfer modeling of the ALMA image and the broadband spectral energy distribution is used to constrain the surface density profile and structural parameters of the disk. If the width of the gap corresponds to 4-8 times the Hill radius of a single forming planet, then the putative planet would have a mass of 0.4~3M_J_. We test this prediction by performing global three-dimensional smoothed particle hydrodynamic gas/dust simulations of disks hosting a migrating and accreting planet. We find that the dust emission across the disk is consistent with the presence of an embedded planet with a mass of ~2.3M_J_ at an orbital radius of ~78AU. Given the surface density of the best-fit radiative transfer model, the amount of depleted mass in the gap is higher than the mass of the putative planet, which satisfies the basic condition for the formation of such a planet.
- ID:
- ivo://CDS.VizieR/VIII/61
- Title:
- NAIC 611 MHz Survey Source List
- Short Name:
- VIII/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 1000 foot Arecibo reflector was used with a multiple feed system to map the region 0h < RA < 12h, -2d < DEC < +18d at 611 MHz. The observations were made in meridian transit mode using an array of ten line feeds with the electric polarization vector in the east-west plane. The beam power pattern of each feed was approximately Gaussian and circulary symmetric with a half power beam width of about 12.6 arcmin. A source list was produced containing fluxes and positions of 3118 radio sources stronger than 0.35 Jy. The source list is complete for strong, unresolved sources. However it is not intended to be complete for objects highly resolved by the 12.6 arcmin beamsize. The list's lower limit of 0.35 Jy is about 5 times the average sky confusion. The survey was calibrated to the KPW (Kellermann, Pauliny-Toth, and Williams 1969ApJ...157....1K) flux scale. The secondary calibrators were ten sources measured at Arecibo at 606 MHz based on the KPW scale (Condon, Niell and Jauncey 1971). Marked by an asterisk in Table 2, these sources were too few to be used alone to calibrate all of the declination strips. Since a more complete list of good calibration sources did not exist at 611 MHz, the fluxes of 159 additional sources were independently measured accurate to about 7 percent at Arecibo in the Fall of 1973. Table 2 gives their assigned fluxes. These sources were tied to the KPW scale through the ten secondary calibrators.
- ID:
- ivo://CDS.VizieR/J/AJ/124/3042
- Title:
- Narrow-line Seyfert 1 galaxies from SDSS EDR
- Short Name:
- J/AJ/124/3042
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 150 narrow-line Seyfert 1 galaxies (NLS1's) found within the Sloan Digital Sky Survey (SDSS) Early Data Release (EDR) (Stoughton et al., 2002AJ....123..485S), only two of which were previously identified as such. This substantially increases the known number of NLS1's and provides a basic method by which to identify many more with subsequent releases of SDSS data. With its large size and homogeneous, well-defined selection criteria, this sample will help alleviate two major problems that have plagued NLS1 research in the past; namely, their relative rarity and significant differences in selection algorithms between the known samples. Forty-five of these SDSS-selected NLS1's are detected at energies of 0.1-2keV in the ROSAT All-Sky Survey (RASS) and are found to have ultrasoft X-ray spectra with photon indices of {Gamma}>~2, in agreement with previous results for NLS1's. However, about 10-20 of those NLS1's that were not detected by ROSAT have optical properties very similar to the detected objects and so should also have been detected by the RASS. This may be due to either significant intrinsic absorption in many NLS1's, or a significant subclass of NLS1's that have uncharacteristic, intrinsically flatter (hence harder) X-ray spectral energy distributions.
- ID:
- ivo://CDS.VizieR/J/PASP/120/339
- Title:
- Nasu Radio-Transient Search Project
- Short Name:
- J/PASP/120/339
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of two 1.4GHz radio surveys of a +32{deg}<DE<+42{deg} area with four interferometers in the Nasu Radio-Transient Search Project. The observable area was 7.0% of the whole sky. The surveys were carried out between 2004 and 2005. All observed interferometric data were transformed to color images to construct color atlases of the 1.4GHz sky. From these atlases, 144 radio sources were detected by comparison with the 1.4GHz NRAO VLA Sky Survey Catalog, excluding the Cygnus region. The observed data will be used in a transient search alert system.
- 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/VIII/82
- Title:
- 2nd Epoch Molonglo Galactic Plane Survey (MGPS-2)
- Short Name:
- VIII/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The MGPS-2 (second epoch Molonglo Galactic Plane Survey) was carried out with the Molonglo Observatory Synthesis Telescope at a frequency of 843MHz and with a restoring beam of 45"x45"csd|{delta}|, making it he highest resolution large scale radio survey of the southern Galactic plane. It covers the range |b|<10{deg} and 245<l<365{deg}; it is the Galactic counterpart to the SUMSS (Cat. VIII/81) which covers the southern sky ({delta}<-30{deg}, |b|>10{deg}). This catalogue (15-Aug-2007) consists of 48850 compact sources, made by fitting elliptical gaussians in the MGPS-2 mosaics to a limiting peak brightness of 10mJy/beam. We used a custom method (described in the associated publication) to remove extended sources from the catalogue. Positions in the catalogue are accurate to 1-2". See http://www.astrop.physics.usyd.edu.au/mosaics for access to the mosaic images.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A110
- Title:
- Neutral gas in the Milky Way halo
- Short Name:
- J/A+A/542/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an absorption-selected survey of CaII and NaI features located in the halo of the Milky Way using QSO absorption spectroscopy. We made use of the ESO data archive and retrieved all publically available absorption-line data for low- and high-redshift QSOs observed with the Ultraviolet and Visual Echelle Spectrograph (UVES) on the VLT. This enormous data archive (Spectral Quasar Absorption Database, SQUAD; PI: M.T. Murphy) provides high-quality spectral data for ~400 quasars and active galactic nuclei (AGN). Most of these spectra were taken in the UVES standard configuration using the 1" slit, providing a spectral resolution of R~45000 (corresponding to a velocity resolution of ~6.6km/sFWHM). The spectral coverage as well as the signal-to-noise ratio (S/N) varies substantially among the spectra, reflecting the various scientific goals of the original proposals. For several of the sight lines we performed deep (brightness temperature limit, Tb_lim_~30mK, angular resolution: 9' FWHM, spectral resolution: 0.5km/s FWHM) follow-up radio observations using the Effelsberg 100-m telescope to search for HI emission. Furthermore for a large fraction of the sight lines we obtained HI data from the new Galactic All-Sky survey (GASS, Tb_lim_~60mK, angular resolution: 15.6' FWHM, spectral resolution: 0.8km/s FWHM) and the Effelsberg-Bonn HI survey (EBHIS, Tb_lim_~90mK, angular resolution: 10.5' FWHM, spectral resolution: 1.2km/s FWHM). All HI data were corrected for stray radiation using software by P. Kalberla.
- ID:
- ivo://CDS.VizieR/J/ApJS/206/9
- Title:
- New EGOs from Spitzer GLIMPSE II survey. I.
- Short Name:
- J/ApJS/206/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have produced a catalog containing 98 newly identified massive young stellar object (MYSO) candidates associated with ongoing outflows (known as extended green objects, or EGOs). These have been identified from the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) II data set and our new identifications increase the number of known EGOs to ~400 in our Galaxy, adding to the ~300 previously identified EGOs reported by Cyganowski et al. (2008, Cat. J/AJ/136/2391) from the GLIMPSE I survey. The high detection rate (~70%) of 95 GHz class I methanol masers achieved in a survey toward 57 of these new EGOs with the Mopra 22m radio telescope demonstrates that the new EGOs are associated with outflows. Investigations of the mid-infrared properties and physical associations with other star formation tracers (e.g., infrared dark clouds, class I and II methanol masers, and millimeter Bolocam Galactic Plane Survey sources) reveal that the newly identified EGOs are very similar in nature to those in the sample of Cyganowski et al. All of the observational evidence supports the hypothesis that EGOs correspond to MYSOs at the earliest evolutionary stage, with ongoing outflow activity, and active rapid accretion.