- ID:
- ivo://CDS.VizieR/J/A+A/568/L5
- Title:
- HH 212 CO, CS and 850um ALMA images
- Short Name:
- J/A+A/568/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We wish to exploit the unmatched combination of high angular resolution, high sensitivity, high-imaging fidelity, and spectral coverage provided by ALMA to shed light on the complex kinematics of the innermost central regions of HH212 protostellar system. We mapped the inner 10" (4500AU) of the HH212 system at ~0.5" resolution in several molecular tracers and in the 850um dust continuum using the ALMA interferometer in band 7 in the extended configuration of the Early Science Cycle 0 operations. Within a single ALMA spectral set-up, we simultaneously identify all the crucial ingredients known to be involved in the star formation recipe: (i) the fast, collimated bipolar SiO jet driven by the protostar; (ii) the large-scale swept-up CO outflow; (iii) the flattened rotating and infalling envelope, with bipolar cavities carved by the outflow (in C^17^O(3-2)); and (iv) a rotating wide-angle flow that fills the cavities and surrounds the axial jet (in C^34^S(7-6)). In addition, the compact high-velocity C^17^O emission (+/-1.9-3.5km/s from systemic) shows a velocity gradient along the equatorial plane consistent with a rotating disk of ~0.2"=90AU around a ~0.3+/-0.1M_{sun}_ source. The rotating disk is possibly Keplerian. HH212 is the third Class 0 protostar with possible signatures of a Keplerian disk of radius >=30AU. The warped geometry in our CS data suggests that this large Keplerian disk might result from misaligned magnetic and rotation axes during the collapse phase. The wide-angle CS flow suggests that disk winds may be present in this source.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/394/1857
- Title:
- H_2_/HI ratio in galaxies
- Short Name:
- J/MNRAS/394/1857
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We revisit the mass ratio {eta}_galaxy_ between molecular hydrogen (H2) and atomic hydrogen (HI) in different galaxies from a phenomenological and theoretical viewpoint.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A82
- Title:
- HH83 outflow spectrally select. structures pm
- Short Name:
- J/A+A/652/A82
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We continue our program of investigation of the proper motions of spectrally separated structures in the Herbig-Haro outflows with the aid of Fabry-Perot scanning interferometry. This work mainly focuses on the physical nature of various structures in the jets. The aim of the present study is to measure the proper motions of the previously discovered kinematically separated structures in the working surface of the HH 83 collimated outflow. We used observations from two epochs separated by 15 years, which were performed on the 6m telescope with Fabry-Perot scanning interferometer. We obtained images corresponding to different radial velocities for the two separate epochs, and used them to measure proper motions. In the course of our data analysis, we discovered a counter bow-shock of HH 83 flow with positive radial velocity, which makes this flow a relatively symmetric bipolar system. The second epoch observations confirm that the working surface of the flow is split into two structures with an exceptionally large (250km/s) difference in radial velocity. The proper motions of these structures are almost equal, which suggests that they are physically connected. The asymmetry of the bow shock and the turning of proper motion vectors suggests a collision between the outflow and a dense cloud. The profile of the H{alpha} line for the directly invisible infrared source HH 83 IRS, obtained by integration of the data within the reflection nebula, suggests it to be of P Cyg type with a broad absorption component characteristic of the FU Ori-like objects. If this object underwent an FU Ori type outburst, which created the HH 83 working surfaces, its eruption took place about 1500 years ago according to the kinematical age of the outflow.
- ID:
- ivo://CDS.VizieR/J/A+A/575/A44
- Title:
- HI absorption in flux-selected radio AGNs
- Short Name:
- J/A+A/575/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the HI 21cm absorption in a sample of 101 flux-selected radio AGN (S_1.4GHz_>50mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect HI absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis on the radio sources, while here we characterize the absorption spectra of the individual detections using the recently presented busy function. The HI absorption spectra show a broad variety of widths, shapes, and kinematical properties. The full width half maximum (FWHM) of the busy function fits of the detected HI lines lies in the range 32km/s<FWHM<570km/s, whereas the full width at 20% of the peak absorption (FW20) lies in the range 63km/s<FW20<825km/s. The width and asymmetry of the profiles allows us to identify three groups: narrow lines (FWHM<100km/s), intermediate widths (100km/s<FWHM<200km/s), and broad profiles (FWHM>200km/s). We study the kinematical and radio source properties of each group, with the goal of identifying different morphological structures of HI. Narrow lines mostly lie at the systemic velocity and are likely produced by regularly rotating HI disks or gas clouds. More HI disks can be present among galaxies with lines of intermediate widths; however, the HI in these sources is more unsettled. We study the asymmetry parameter and blueshift/redshift distribution of the lines as a function of their width. We find a trend for which narrow profiles are also symmetric, while broad lines are the most asymmetric. Among the broadest lines, more lines appear blueshifted than redshifted, similarly to what was found by previous studies. Interestingly, symmetric broad lines are absent from the sample. We argue that if a profile is broad, it is also asymmetric and shifted relative to the systemic velocity because it is tracing unsettled HI gas. In particular, besides three of the broadest (up to FW20=825km/s) detections, which are associated with gas-rich mergers, we find three new cases of profiles with blueshifted broad wings (with FW20>500km/s) in high radio power AGN. These detections are good candidates for being HI outflows. Together with the known cases of outflows already included in the sample (3C 293 and 3C 305), the detection rate of HI outflows is 5% in the total radio AGN sample. Because of the effects of spin temperature and covering factor of the outflowing gas, this fraction could represent a lower limit. However, if the relatively low detection rate is confirmed by more detailed observations, it would suggest that, if outflows are a characteristic phenomenon of all radio AGN, they would have a short depletion timescale compared to the lifetime of the radio source. This would be consistent with results found for some of the outflows traced by molecular gas. Using stacking techniques, in our previous paper we showed that compact radio sources have higher {tau}, FWHM, and column density than extended sources. In addition, here we find that blueshifted and broad/asymmetric lines are more often present among compact sources. In good agreement with the results of stacking, this suggests that unsettled gas is responsible for the larger stacked FWHM detected in compact sources. Therefore in such sources the HI is more likely to be unsettled. This may arise as a result of jet-cloud interactions, as young radio sources clear their way through the rich ambient gaseous medium.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/696
- Title:
- HI absorption in nearby radio galaxies
- Short Name:
- J/MNRAS/440/696
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using archival data from the Hi Parkes All-Sky Survey (HIPASS), we have searched for 21cm line absorption in 204 nearby radio and star-forming galaxies with continuum flux densities greater than S_1.4_~250mJy within the redshift range 0<cz<12000km/s. By applying a detection method based on Bayesian model comparison, we successfully detect and model absorption against the radio-loud nuclei of four galaxies, of which the Seyfert 2 galaxy 2MASX J130804201-2422581 was previously unknown. All four detections were achieved against compact radio sources, which include three active galactic nuclei (AGNs) and a nuclear starburst, exhibiting high dust and molecular gas content. Our results are consistent with the detection rate achieved by the recent ALFALFA (Arecibo Legacy Fast Arecibo L-band Feed Array) Hi absorption pilot survey by Darling et al. and we predict that the full ALFALFA survey should yield more than three to four times as many detections as we have achieved here. Furthermore, we predict that future all-sky surveys on the Square Kilometre Array precursor telescopes will be able to detect such strong absorption systems associated with type 2 AGNs at much higher redshifts, providing potential targets for detection of H_2_O megamaser emission at cosmological redshifts.
- ID:
- ivo://CDS.VizieR/J/ApJS/182/378
- Title:
- HI and OVI absorbers in nearby Universe
- Short Name:
- J/ApJS/182/378
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze intergalactic HI and OVI absorbers with {nu}<5000km/s in Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer spectra of 76 active galactic nuclei. The baryons traced by HI/OVI absorption are clearly associated with the extended surroundings of galaxies; for impact parameters <400kpc they are 2-4 times more numerous as those inside the galaxies. This large reservoir of matter likely plays a major role in galaxy evolution. We tabulate the fraction of absorbers having a galaxy of a given luminosity within a given impact parameter ({rho}) and velocity difference ({Delta}v), as well as the fraction of galaxies with an absorber closer than a given {rho} and {Delta}v. We identify possible "void absorbers" ({rho}>3Mpc to the nearest L_*_ galaxy), although at v<2500km/s all absorbers are within 1.5Mpc of an L>0.1L_*_ galaxy. The absorber properties depend on {rho}, but the relations are not simple correlations.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A130
- Title:
- HI and 250um images of the Virgo cirrus
- Short Name:
- J/A+A/597/A130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the correlation between far-infrared/submm dust emission and atomic gas column density in order to derive the properties of the high Galactic latitude, low density, Milky Way cirrus in the foreground of the Virgo cluster of galaxies. Dust emission maps from 60 to 850um are obtained from SPIRE observations carried out within the Herschel Virgo Cluster Survey, complemented by IRAS-IRIS and Planck-HFI maps. Data from the Arecibo legacy Fast ALFA Survey is used to derive atomic gas column densities for two broad velocity components, low and intermediate velocity clouds. Dust emissivities are derived for each gas component and each far-infrared/submm band. For the low velocity clouds, we measure an average emissivity {epsilon]_{nu}^LVC=(0.79+/-0.08)*10^-20^MJy.cm^2^/sr at 250um. After fitting a modified blackbody to the available bands, we estimated a dust absorption cross-section {tau}_{nu}^LVC/N_HI_=(0.49+/-0.13)*10^-25cm^2^/H at 250um (with dust temperature T=20.4+/-1.5K and spectral index {beta}=1.53+/-0.17). The results are in excellent agreement with those obtained by Planck over a much larger coverage of the high Galactic latitude cirrus (50% of the sky vs 0.2% in our work). For dust associated with intermediate velocity gas, we confirm earlier Planck results and find a higher temperature and lower emissivity and cross-section. After subtracting the modelled components, we find regions at scales smaller than 20' where the residuals deviate significantly from the average, cosmic-infrared-background dominated, scatter. These large residuals are most likely due to local variations in the cirrus dust properties (and/or the dust/atomic-gas correlation) or to high-latitude molecular clouds with average N_H2_<~10^20^cm^-2^. We find no conclusive evidence for intracluster dust emission in Virgo.
- ID:
- ivo://CDS.VizieR/J/ApJ/842/133
- Title:
- HI-bearing ultra-diffuse ALFALFA galaxies
- Short Name:
- J/ApJ/842/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 115 very low optical surface brightness, highly extended, HI-rich galaxies carefully selected from the ALFALFA survey that have similar optical absolute magnitudes, surface brightnesses, and radii to recently discovered "ultra-diffuse" galaxies (UDGs). However, these systems are bluer and have more irregular morphologies than other UDGs, are isolated, and contain significant reservoirs of HI. We find that while these sources have normal star formation rates for HI-selected galaxies of similar stellar mass, they have very low star formation efficiencies. We further present deep optical and HI-synthesis follow-up imaging of three of these HI-bearing ultra-diffuse sources. We measure HI diameters extending to ~40kpc, but note that while all three sources have large HI diameters for their stellar mass, they are consistent with the HI mass-HI radius relation. We further analyze the HI velocity widths and rotation velocities for the unresolved and resolved sources, respectively, and find that the sources appear to inhabit halos of dwarf galaxies. We estimate spin parameters, and suggest that these sources may exist in high spin parameter halos, and as such may be potential HI-rich progenitors to the ultra-diffuse galaxies observed in cluster environments.
- ID:
- ivo://CDS.VizieR/J/A+A/428/823
- Title:
- HI catalog of low surface brightness galaxies
- Short Name:
- J/A+A/428/823
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using both the Arecibo 305m and the Nancay decimetric 100-m class radio telescopes, we have observed the H I line of 116 Low Surface Brightness (LSB) galaxies from the Bothun et al. (1985AJ.....90.2487B) subset of LSB galaxies in the Uppsala General Catalog. Combining our results with previous studies done on the Bothun et al. (1985AJ.....90.2487B) catalog results in a well-defined catalog of H I properties of 526 LSB galaxies ranging in redshift space from 0<=z<=0.1. With this catalog in hand, we have been able to explore the parameter space occupied by LSB galaxies more completely than has been previously possible.
- ID:
- ivo://CDS.VizieR/J/A+A/565/A25
- Title:
- Hickson compact groups Herschel observations
- Short Name:
- J/A+A/565/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a Herschel far-infrared and sub-millimetre (sub-mm) study of a sample of 120 galaxies in 28 Hickson compact groups (HCGs). Fitting their UV to sub-mm spectral energy distributions with the model of da Cunha et al. (2008MNRAS.388.1595C), we accurately estimate the dust masses, luminosities, and temperatures of the individual galaxies.