- ID:
- ivo://CDS.VizieR/J/ApJS/173/85
- Title:
- HI 21cm forbidden-velocity wings
- Short Name:
- J/ApJS/173/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for faint HI 21cm emission line wings at velocities forbidden by Galactic rotation in the Galactic plane using the Leiden/Dwingeloo HI Survey data and the HI Southern Galactic Plane Survey data. These "forbidden-velocity wings" (FVWs) appear as protruding excessive emission in comparison with their surroundings in limited (>~2{deg}) spatial regions over velocity extents of more than ~20km/s in large-scale (l,v) diagrams. Their high velocities imply that there should be some dynamical phenomena associated. We have identified 87 FVWs. We present their catalog and discuss their distribution and statistical properties. We found that 85% of FVWs are not coincident with known supernova remnants (SNRs), galaxies, or high-velocity clouds. Their natures are currently unknown.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/582/A18
- Title:
- HI data cubes of 4 edge-on spiral galaxies
- Short Name:
- J/A+A/582/A18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Edge-on galaxies can offer important insight into galaxy evolution because they are the only systems where the distribution of the different components can be studied both radially and vertically. The HEROES project was designed to investigate the interplay between the gas, dust, stars, and dark matter (DM) in a sample of 7 massive edge-on spiral galaxies. In this second HEROES paper, we present an analysis of the atomic gas content of 6 out of 7 galaxies in our sample. The remaining galaxy was recently analysed according to the same strategy. The primary aim of this work is to constrain the surface density distribution, the rotation curve, and the geometry of the gas disks in a homogeneous way. In addition we identify peculiar features and signs of recent interactions. We have constructed detailed tilted-ring models of the atomic gas disks based on new GMRT 21-cm observations of NGC 973 and UGC 4277 and re-reduced archival HI data of NGC 5907, NGC 5529 IC 2531, and NGC 4217. Potential degeneracies between different models were resolved by requiring good agreement with the data in various representations of the data cubes. From our modelling we find that all but one galaxy are warped along the major axis. In addition, we identify warps along the line of sight in three galaxies. A flaring gas layer is required to reproduce the data for only one galaxy, but (moderate) flares cannot be ruled out for the other galaxies either. A coplanar ring-like structure is detected outside the main disk of NGC 4217, which we suggest could be the remnant of a recent minor merger event. We also find evidence of a radial inflow of 15 +/-5km/s in the disk of NGC 5529, which might be related to the ongoing interaction with two nearby companions. For NGC 5907 the extended, asymmetric, and strongly warped outer regions of the HI disk also suggest a recent interaction. In contrast, the inner disks of these three galaxies (NGC 4217, NGC 5529, and NGC 5907) show regular behaviour and seem largely unaffected by the interactions. Our models further support earlier claims of prominent spiral arms in the disks of IC 2531 and NGC 5529. Finally, we detect a dwarf companion galaxy at a projected distance of 36 kpc from the centre of NGC 973.
- ID:
- ivo://CDS.VizieR/J/A+A/651/A9
- Title:
- HIFI molecular line survey of SgrB2 (M)
- Short Name:
- J/A+A/651/A9
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present a full analysis of a broadband spectral line survey of Sagittarius B2 (Main), one of the most chemically rich regions in the Galaxy located within the giant molecular cloud complex Sgr B2 in the Central Molecular Zone. Our goal is to derive the molecular abundances and temperatures of the high-mass star-forming region Sgr B2(M) and thus its physical and astrochemical conditions. Sgr B2(M) was observed using the Heterodyne Instrument for the Far-Infrared (HIFI) on board the Herschel Space Observatory in a spectral line survey from 480 to 1907GHz at a spectral resolution of 1.1MHz, which provides one of the largest spectral coverages ever obtained toward this high-mass star-forming region in the submillimeter with high spectral resolution and includes frequencies >1THz that are unobservable from the ground. We modeled the molecular emission from the submillimeter to the far-infrared using the XCLASS program, which assumes local thermodynamic equilibrium (LTE). For each molecule, a quantitative description was determined taking all emission and absorption features of that species across the entire spectral range into account. Because of the wide frequency coverage, our models are constrained by transitions over an unprecedented range in excitation energy. Additionally, we derived velocity resolved ortho/para ratios for those molecules for which ortho and para resolved molecular parameters are available. Finally, the temperature and velocity distributions are analyzed and the derived abundances are compared with those obtained for Sgr B2(N) from a similar HIFI survey. A total of 92 isotopologues were identified, arising from 49 different molecules, ranging from free ions to complex organic compounds and originating from a variety of environments from the cold envelope to hot and dense gas within the cores. Sulfur dioxide, methanol, and water are the dominant contributors. Vibrationally excited HCN (v2=1) and HNC (v2=1) are detected as well. For the ortho/para ratios, we find deviations from the high temperature values between 37 and 180%. In total 14% of all lines remain unidentified. Compared to Sgr B2(N), we found less complex molecules such as CH_3_OCH_3_, CH_3_NH_2_, or NH_2_CHO, but more simple molecules such as CN, CCH, SO, and SO_2_. However some sulfur bearing molecules such as H_2_CS, CS, NS, and OCS are more abundant in N than in M. The derived molecular abundances can be used for comparison to other sources and for providing further constraints for astrochemical models.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A114
- Title:
- Hi-GAL cluster candidates physical properties
- Short Name:
- J/A+A/597/A114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aims are to investigate the clustering of the far-infrared sources from the Herschel infrared Galactic Plane Survey (Hi-GAL) in the Galactic longitude range of -71 to 67{deg}. These clumps, and their spatial distribution, are an imprint of the original conditions within a molecular cloud. This will produce a catalogue of over-densities. The minimum spanning tree (MST) method was used to identify the over-densities in two dimensions. The catalogue was further refined by folding in heliocentric distances, resulting in more reliable over-densities, which are cluster candidates. We found 1633 over-densities with more than ten members. Of these, 496 are defined as cluster candidates because of the reliability of the distances, with a further 1,137 potential cluster candidates. The spatial distributions of the cluster candidates are different in the first and fourth quadrants, with all clusters following the spiral structure of the Milky Way. The cluster candidates are fractal. The clump mass functions of the clustered and isolated are statistically indistinguishable from each other and are consistent with Kroupa's initial mass function.
- ID:
- ivo://CDS.VizieR/J/ApJ/772/45
- Title:
- Hi-GAL obs.: star formation in the third quadrant
- Short Name:
- J/ApJ/772/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first Herschel PACS and SPIRE photometric observations in a portion of the outer Galaxy (216.5{deg}<~l<~225.5{deg} and -2{deg}<~b<~0{deg}) as a part of the Hi-GAL survey. The maps between 70 and 500{mu}m, the derived column density and temperature maps, and the compact source catalog are presented. NANTEN CO(1-0) line observations are used to derive cloud kinematics and distances so that we can estimate distance-dependent physical parameters of the compact sources (cores and clumps) having a reliable spectral energy distribution that we separate into 255 proto-stellar and 688 starless sources. Both typologies are found in association with all the distance components observed in the field, up to ~5.8kpc, testifying to the presence of star formation beyond the Perseus arm at these longitudes. Selecting the starless gravitationally bound sources, we identify 590 pre-stellar candidates. Several sources of both proto- and pre-stellar nature are found to exceed the minimum requirement for being compatible with massive star formation based on the mass-radius relation. For the pre-stellar sources belonging to the Local arm (d<~1.5kpc) we study the mass function whose high-mass end shows a power law N(logM){propto}M^-1.0+/-0.2^. Finally, we use a luminosity versus mass diagram to infer the evolutionary status of the sources, finding that most of the proto-stellar sources are in the early accretion phase (with some cases compatible with a Class I stage), while for pre-stellar sources, in general, accretion has not yet started.
- ID:
- ivo://CDS.VizieR/J/other/JApA/25.143
- Title:
- High galactic latitude HI absorption survey
- Short Name:
- J/other/JApA/25.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Giant Meterwave Radio Telescope (GMRT) to measure the Galactic HI 21-cm line absorption towards 102 extragalactic radio continuum sources, located at high (|b|>15{deg}) Galactic latitudes. The Declination coverage of the present survey is DE~-45{deg}. With a mean rms optical depth of ~0.003, this is the most sensitive Galactic HI 21-cm line absorption survey to date. To supplement the absorption data, we have extracted the HI 21-cm line emission profiles towards these 102 lines of sight from the Leiden Dwingeloo Survey of Galactic neutral hydrogen. We have carried out a Gaussian fitting analysis to identify the discrete absorption and emission components in these profiles. In this paper, we present the spectra and the components. A subsequent paper will discuss the interpretation of these results.
- ID:
- ivo://CDS.VizieR/J/ApJ/727/46
- Title:
- Highly ionized plasmas in the Milky Way
- Short Name:
- J/ApJ/727/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The cooling transition temperature gas in the interstellar medium (ISM), traced by the high ions, SiIV, CIV, NV, and OVI, helps to constrain the flow of energy from the hot ISM with T>10^6^K to the warm ISM with T<2x10^4^K. We investigate the properties of this gas along the lines of sight to 38 stars in the Milky Way disk using 1.5-2.7km/s resolution spectra of SiIV, CIV, and NV absorption from the Space Telescope Imaging Spectrograph, and 15km/s resolution spectra of OVI absorption from the Far Ultraviolet Spectroscopic Explorer. The absorption by SiIV and CIV exhibits broad and narrow components while only broad components are seen in NV and OVI. The narrow components imply gas with T<7x10^4^K and trace two distinct types of gas.
- ID:
- ivo://CDS.VizieR/J/A+A/620/A158
- Title:
- High-mass IR-dark clumps MALT90 molecular content
- Short Name:
- J/A+A/620/A158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High mass stars form in groups or clusters in dense molecular clumps with sizes of 1pc and masses of 200M_{sun}_. Infrared-dark clumps and the individual cores within them with sizes <0.1pc and masses <100M_{sun}_ are important laboratories for high-mass star formation in order to study the initial conditions. We investigate the physical and chemical properties of high-mass clumps in order to better understand the early evolutionary stages and find targets which show star formation signs such as infall motions or outflows. We selected the high-mass clumps from ATLASGAL survey that were identified as dark at 8/24um wavelengths. We use MALT90 Survey data which provides a molecular line set (HCO^+^, HNC, HCN, N^13^CH^+^, H^13^CO^+^, HN^13^C (1-0), SiO) to investigate the physical and chemical conditions in early stages of star formation. Results. (1) Eleven sources have significant SiO detection (over 3{sigma}) which usually indicates outflow activity. (2) Thirteen sources are found with blue profiles in both/either HCO+ and/or HNC lines and clump mass infall rates are estimated to be in the range of 0.2x10^-3^M_{sun}_/yr-1.8x10^-2^M_{sun}_/yr. (3) The excitation temperature is obtained as <24K for all sources. (4) The column densities for optically thin lines of H^13^CO^+^ and HN^13^C (1-0) are in the range of 0.4-8.8(x10^12^)cm^-2^, and 0.9-11.9(x10^12^)cm^-2^, respectively, while it is in the range of 0.1-7.5(x10^14^)cm^-2^ for HCO^+^ and HNC lines. The column densities for N^13^CH^+^ were ranging between 4.4-275.7(x10^12^)cm^-2^ as expected from cold dense regions. (5) Large line widths of N^13^CH^+^ might indicate turbulence and large line widths of HCO^+^, HNC, and SiO indicate outflow activities. (6) Mean optical depths are 20.32, and 23.19 for optically thick HCO^+^ and HCN lines, and 0.39 and 0.45 for their optically thin isotopologues H^13^CO^+^ and HN^13^C (1-0), respectively. This study reveals the physical and chemical properties of 30 high-mass IR-dark clumps and the interesting targets among them based on their emission line morphology and kinematics.
- ID:
- ivo://CDS.VizieR/J/ApJ/867/167
- Title:
- High-mass outflows from the COHRS CO(3-2) survey
- Short Name:
- J/ApJ/867/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An unbiased search of molecular outflows within the region of the CO High Resolution survey has identified 157 high-mass outflows from a sample of 770 APEX Telescope Large Area Survey of the Galaxy clumps with a detection rate of 20%. The detection rate of outflows increases for clumps with higher M_clump_, L_bol_, L_bol_/M_clump_,N_H2_, and T_dust_ compared to the clumps with no outflow. The detection rates of the outflow increase from protostellar (8%) to young stellar object clump (17%) to massive star-forming clump (29%). The detection rate 26% for quiescent clump is preliminary, because the sample of quiescent clumps is small. A statistical relation between the outflow and clump masses for our sample is log(M_out_/M_{sun}_)=(-1.1+/-0.21)+(0.9+/-0.07)log(M_clump_/M_{sun}_). The detection rate of outflows and the outflow mass-loss rate show an increase with increasing M_clump_, L_bol_, N_H_2_, and T_dust_, which indicates that clumps with outflow with higher parameter values are at a more advanced evolutionary stage. The outflow mechanical force increases with increasing bolometric luminosities. No clear evidence has yet been found that higher-mass outflows have different launching conditions than low-mass outflows.
- 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.
