- ID:
- ivo://CDS.VizieR/J/AJ/141/23
- Title:
- HI holes in THINGS galaxies
- Short Name:
- J/AJ/141/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the properties of HI holes detected in 20 galaxies that are part of "The HI Nearby Galaxy Survey." We detected more than 1000 holes in total in the sampled galaxies. Where they can be measured, their sizes range from about 100pc (our resolution limit) to about 2kpc, their expansion velocities range from 4 to 36km/s, and their ages are estimated to range between 3 and 150Myr. The holes are found throughout the disks of the galaxies, out to the edge of the HI disk; 23% of the holes fall outside R25. We find that shear limits the age of holes in spirals (shear is less important in dwarf galaxies) which explains why HI holes in dwarfs are rounder, on average than in spirals.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/506/677
- Title:
- HI in Local Supercluster dwarf galaxies
- Short Name:
- J/A+A/506/677
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed 71 dwarf galaxies of low surface brightness using the 100-m radio telescope at Effelsberg in a search for new members of 27 northern galaxy groups with characteristic distances of 8 to 15Mpc. We present radial velocities, HI-fluxes, and HI line widths for 17 detected galaxies as well as upper limits for the remaining undetected objects.
- ID:
- ivo://CDS.VizieR/J/A+A/481/645
- Title:
- HII regions in interacting galaxies
- Short Name:
- J/A+A/481/645
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of interacting galaxies have shown that dwarf galaxies may be produced in tidal tails during collisions. Numerical simulations suggest that the total detachment of the tidal dwarf requires the companion's mass to be comparable to or higher than that of the parent galaxy. This would imply that minor mergers (interaction between unequal mass galaxies) might not form tidal dwarf galaxies (TDGs). The objectives of the paper is to analyse the main properties of a sample of 116 HII regions previously selected from H{alpha} images of 11 minor mergers of galaxies and discuss the nature of these regions comparing their properties with those observed in HII regions in normal and isolated galaxies and TDG candidates. Individual parameters such as: blue absolute magnitude, MB, H{alpha} luminosity, L(H{alpha}), star formation rate, SFR(H{alpha}) and mass, M/M_{sun}_ of these regions were derived and compared with those of the HII regions in normal isolated galaxies, as well as in tidal dwarf candidates.
- ID:
- ivo://CDS.VizieR/J/A+A/428/837
- Title:
- HII regions in minor mergers of galaxies
- Short Name:
- J/A+A/428/837
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the B, V and I photometry of eleven southern minor mergers. The total apparent B magnitude, integrated B-V and V-I colours were measured. We built B, V, and I equivalent profiles for each galaxy and decomposed them into bulge and disk components when possible. From H{alpha}+N[II] images we have estimated the basic photometric parameters of the HII regions, such as position, size, B-V and V-I colours, H{alpha}+[NII] luminosity and EW(H{alpha}+[NII]) equivalent width.
- ID:
- ivo://CDS.VizieR/J/AJ/141/113
- Title:
- HII regions of M51 and NGC 4449
- Short Name:
- J/AJ/141/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used images from the Advanced Camera for Surveys on the Hubble Space Telescope in H{alpha}, and in the neighboring continuum, to produce flux-calibrated images of the large spiral galaxy M51 and the dwarf irregular NGC 4449. From these images, we have derived the absolute luminosities in H{alpha}, the areas, and the positions with respect to the galactic centers as reference points of over 2600 HII regions in M51 and over 270 HII regions in NGC 4449.
- ID:
- ivo://CDS.VizieR/J/MNRAS/416/2401
- Title:
- HI morphology of 28 THINGS galaxies
- Short Name:
- J/MNRAS/416/2401
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxy evolution is driven to a large extent by interactions and mergers with other galaxies and the gas in galaxies is extremely sensitive to the interactions. One method to measure such interactions uses the quantified morphology of galaxy images. Well-established parameters are Concentration, Asymmetry, Smoothness, Gini and M20 of a galaxy image. Thus far, the application of this technique has mostly been restricted to rest-frame ultraviolet and optical images. However, with the new radio observatories being commissioned [South African Karoo Array Telescope (MeerKAT), Australian SKA Pathfinder (ASKAP), Extended Very Large Array (EVLA), Westerbork Synthesis Radio Telescope/APERture Tile In Focus instrument (WSRT/APERTIF) and ultimately the Square Kilometer Array (SKA)], a new window on the neutral atomic hydrogen gas (HI) morphology of large numbers of galaxies will open up. The quantified morphology of gas discs of spirals can be an alternative indicator of the level and frequency of interaction. The HI in galaxies is typically spatially more extended and more sensitive to low-mass or weak interactions.
- ID:
- ivo://CDS.VizieR/J/AJ/113/905
- Title:
- HI observations of galaxies
- Short Name:
- J/AJ/113/905
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present H I 21-cm line observations of 543 galaxies at low galactic latitude in the Galactic Anticenter region of the Zone of Avoidance (4h<={alpha}<=8h, 0{deg}=<{delta}=<37{deg}). The sample comprises 147 catalogued objects (from UGC, CGCG, MCG, and IRAS) still missing a redshift measurement and a list of 369 objects selected from an extensive optical compilation of galaxy candidates in this area. The spectra were acquired using the 305-m Arecibo telescope and cover a velocity range from -350 to +13800km/s at a resolution of about 16km/s. 196 galaxies were detected,59 of the catalogued ones and 137 from the optical compilation. The H I derived properties are presented, as is a discussion regarding the redshift distribution in this region. Our data seem to be consistent with a link across the Zone of Avoidance between the Pisces-Perseus supercluster and Abell 569.
- ID:
- ivo://CDS.VizieR/J/A+A/442/137
- Title:
- HI observations of WHISP disk galaxies
- Short Name:
- J/A+A/442/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present HI observations of 68 early-type disk galaxies from the WHISP survey. They have morphological types between S0 and Sab and absolute B-band magnitudes between -14 and -22. These galaxies form the massive, high surface-brightness extreme of the disk galaxy population, few of which have been imaged in HI before. The HI properties of the galaxies in our sample span a large range; the average values of MHI/LB and DHI/D25 are comparable to the ones found in later-type spirals, but the dispersions around the mean are larger. No significant differences are found between the S0/S0a and the Sa/Sab galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/450/2025
- Title:
- HIPASS-ZoA HII regions
- Short Name:
- J/MNRAS/450/2025
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a Radio Recombination Line (RRL) survey of the Galactic plane from the Hi Parkes All-sky Survey and associated Zone of Avoidance survey, which mapped the region l=196{deg}-0{deg}-52{deg} and |b|<=5{deg} at 1.4GHz and 14.4-arcmin resolution. We combine three RRLs, H168{alpha}, H167{alpha}, and H166{alpha} to derive fully sampled maps of the diffuse ionized emission along the inner Galactic plane. The velocity information, at a resolution of 20km/s, allows us to study the spatial distribution of the ionized gas and compare it with that of the molecular gas, as traced by CO. The longitude-velocity diagram shows that the RRL emission is mostly associated with CO gas from the molecular ring and is concentrated within the inner 30{deg} of longitude. A map of the free-free emission in this region of the Galaxy is derived from the line-integrated RRL emission, assuming an electron temperature gradient with Galactocentric radius of 496+/-100K/kpc. Based on the thermal continuum map, we extracted a catalogue of 317 compact (<~15-arcmin) sources, with flux densities, sizes, and velocities. We report the first RRL observations of the southern ionized lobe in the Galactic Centre. The line profiles and velocities suggest that this degree-scale structure is in rotation. We also present new evidence of diffuse ionized gas in the 3-kpc arm. Helium and carbon RRLs are detected in this survey. The He line is mostly observed towards HII regions, whereas the C line is also detected further away from the source of ionization. These data represent the first observations of diffuse C RRLs in the Galactic plane at a frequency of 1.4GHz.
- ID:
- ivo://CDS.VizieR/J/A+A/324/877
- Title:
- HI properties of spiral and irregular galaxies
- Short Name:
- J/A+A/324/877
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of neutral hydrogen properties of 108 galaxies, based on short 21-cm observations with the Westerbork Synthesis Radio Telescope (WSRT). The results of two HI surveys are analysed to investigate the existence of relations between optical and HI properties, like diameters, hydrogen masses and average surface densities. For all galaxies in our sample we find that the HI diameter, defined at a surface density level of 1M_{sun}_/pc^2^, is larger than the optical diameter, defined at the 25^th^mag/arcsec^2^ isophotal level. The Hi-to-optical-diameter ratio does not depend on morphological type or luminosity. The strongest, physically meaningful, correlation for the sample of 108 galaxies is the one between logM_HI_ and logD_HI_, with a slope of 2. This implies that the HI surface density averaged over the whole HI disc is constant from galaxy to galaxy, independent of luminosity or type. The radial HI surface density profiles are studied using the technique of principal component analysis. We find that about 81% of the variation in the density profiles of galaxies can be explained by two dimensions. The most dominant component can be related to "scale" and the second principal component accounts for the variance in the behaviour of the radial profile in the central parts of galaxies (i.e. "peak or depression") . The third component accounts for 7% of the variation and is most likely responsible for bumps and wiggles in the observed density profiles.
