- ID:
- ivo://CDS.VizieR/J/AJ/161/71
- Title:
- Paramaters for 40 LITTLE THINGS galaxies
- Short Name:
- J/AJ/161/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar, gaseous and young stellar disks in the LITTLE THINGS sample of nearby dwarf irregular galaxies are fitted with functions to search for correlations between the parameters. We find that the HI radial profiles are generally flatter in the center and fall faster in the outer regions than the V-band profiles, while young stars are more centrally concentrated, especially if the HI is more centrally flat. This pattern suggests that the HI is turning into molecules in the center, and the molecular clouds are forming stars and FUV. A model that assumes the molecular surface density is proportional to the total gas surface density to a power of 1.5 or 2, in analogy with the Kennicutt-Schmidt relation, reproduces the relationship between the ratio of the visible to the HI scale length and the HI Sersic index. The molecular fraction is estimated as a function of radius for each galaxy by converting the FUV to a molecular surface density using conventional calibrations. The average molecular fraction inside 3RD is 23%{+/-}17%. However, the break in the stellar surface brightness profile has no unified tracer related to star formation.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/899/15
- Title:
- Parameters for the 58 {tau}HI(v) sightlines
- Short Name:
- J/ApJ/899/15
- Date:
- 14 Mar 2022 07:09:23
- Publisher:
- CDS
- Description:
- Resolving the phase structure of neutral hydrogen (HI) is crucial for understanding the life cycle of the interstellar medium (ISM). However, accurate measurements of HI temperature and density are limited by the availability of background continuum sources for measuring HI absorption. Here we test the use of deep learning for extracting HI properties over large areas without optical depth information. We train a 1D convolutional neural network using synthetic observations of 3D numerical simulations of the ISM to predict the fraction (f_CNM_) of cold neutral medium (CNM) and the correction to the optically thin HI column density for optical depth (R_H_I__) from 21cm emission alone. We restrict our analysis to high Galactic latitudes (|b|>30{deg}), where the complexity of spectral line profiles is minimized. We verify that the network accurately predicts f_CNM_ and R_H_I__ by comparing the results with direct constraints from 21cm absorption. By applying the network to the GALFA-HI survey, we generate large-area maps of f_CNM_ and R_H_I__. Although the overall contribution to the total HI column of CNM-rich structures is small (~5%), we find that these structures are ubiquitous. Our results are consistent with the picture that small-scale structures observed in 21cm emission aligned with the magnetic field are dominated by CNM. Finally, we demonstrate that the observed correlation between HI column density and dust reddening (E(B-V)) declines with increasing R_H_I__, indicating that future efforts to quantify foreground Galactic E(B-V) using HI, even at high latitudes, should increase fidelity by accounting for HI phase structure.
- ID:
- ivo://CDS.VizieR/J/A+A/486/755
- Title:
- Parameters of galaxies in 8 Abell clusters
- Short Name:
- J/A+A/486/755
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper is a continuation of an ongoing study of the evolutionary processes affecting cluster galaxies. Both CCD R band and Halpha narrow-band imaging was used to determine photometric parameters (m_r_, r_24_, Halpha flux, and equivalent width) and derive star formation rates for 227 CGCG galaxies in 8 low-redshift clusters. The galaxy sample is a subset of CGCG galaxies in an objective prism survey (OPS) of cluster galaxies for Halpha emission. It is found that detection of emission-line galaxies in the OPS is 85%, 70%, and 50% complete at the mean surface brightness values of 1.25x10^-19^, 5.19x10^-20^, and 1.76x10^-20^W/m^2^/arcsec^2^, respectively, measured within the R band isophote of 24mag/arcsec^2^ for the galaxy. The CCD data, together with matched data from a recent Halpha galaxy survey of UGC galaxies within 3000km/s, will be used for a comparative study of R band and Halpha surface photometry between cluster and field spirals.
- ID:
- ivo://CDS.VizieR/J/ApJS/107/97
- Title:
- Parameters of 2447 southern spirals
- Short Name:
- J/ApJS/107/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I-band luminosities, rotational velocities, and redshifts of 1092 spiral galaxies have been measured by CCD photometry and Halpha spectroscopy using the 1m and 2.3m telescopes at Siding Spring Observatory, respectively. The results are tabulated. Luminosity profiles and Halpha rotation curves are given for the galaxies. When these results are combined with similar data for 1355 spiral galaxies published previously (Mathewson, Ford, & Buchhorn, hereafter Paper I, 1992ApJS...81..413M), it provides a large, uniform, and unique data set with which to measure, via the Tully-Fisher relation, the peculiar velocities of galaxies in the local universe to a distance of 11,000km/s (Mathewson & Ford, in Proc. Heron Island Workshop on Peculiar Velocities in the Universe). Taking advantage of the opportunity for publishing this data in machine-readable form, in the CD-ROM, we have also published similar data for the 1355 galaxies in Paper I.
- ID:
- ivo://CDS.VizieR/J/MNRAS/425/2741
- Title:
- Parameters of Spiral galaxies from SDSS 7
- Short Name:
- J/MNRAS/425/2741
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have compiled a sample of 3041 spiral galaxies with multiband gri imaging from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7; Abazajian et al., 2009ApJS..182..543A) and available galaxy rotational velocities, V, derived from HI linewidths. We compare the data products provided through the SDSS imaging pipeline with our own photometry of the SDSS images, and use the velocities, V, as an independent metric to determine ideal galaxy sizes (R) and luminosities (L). Our radial and luminosity parameters improve upon the SDSS DR7 Petrosian radii and luminosities through the use of isophotal fits to the galaxy images. This improvement is gauged via VL (Vmag-Luminosity) and RV relations whose respective scatters are reduced by ~8 and ~30% with our parameters compared to similar relations built with SDSS parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/505/1049
- Title:
- Parkes HI observations behind Milky Way II
- Short Name:
- J/A+A/505/1049
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of our programme to map the large-scale distribution of galaxies behind the southern Milky Way, we observed 314 optically-selected, partially-obscured galaxies in the Zone of Avoidance (ZOA) in the Crux and Great Attractor (GA) regions. An additional 29 galaxies were observed in the Vela ZOA survey region (because of the small numbers they are not discussed any further). The observations were conducted with the Parkes 64m (210 ft) radio telescope, in a single-pixel pointed mode, reaching an rms noise level of typically 2-6mJy over the velocity search range of 400<v<10500km/s. A total of 162 galaxies were detected (plus 14 galaxies in the Vela region). The detection rate is slightly higher than for the Hydra/Antlia region (52% versus 45%) observed in the same way.
- ID:
- ivo://CDS.VizieR/J/MNRAS/405/783
- Title:
- Passive red spirals in Galaxy Zoo
- Short Name:
- J/MNRAS/405/783
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the spectroscopic properties and environments of red (or passive) spiral galaxies found by the Galaxy Zoo project. By carefully selecting face-on disc-dominated spirals, we construct a sample of truly passive discs (i.e. they are not dust reddened spirals, nor are they dominated by old stellar populations in a bulge). As such, our red spirals represent an interesting set of possible transition objects between normal blue spiral galaxies and red early types, making up ~6 per cent of late-type spirals. We use optical images and spectra from Sloan Digital Sky Survey to investigate the physical processes which could have turned these objects red without disturbing their morphology.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/1909
- Title:
- Passive spiral galaxies quench
- Short Name:
- J/MNRAS/474/1909
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the properties of a sample of 35 nearby passive spiral galaxies in order to determine their dominant quenching mechanism(s). All five low-mass (M*<1x10^10^M_{sun}_) passive spiral galaxies are located in the rich Virgo cluster. This is in contrast to low-mass spiral galaxies with star formation, which inhabit a range of environments. We postulate that cluster-scale gas stripping and heating mechanisms operating only in rich clusters are required to quench low-mass passive spirals, and ram-pressure stripping and strangulation are obvious candidates. For higher mass passive spirals, while trends are present, the story is less clear. The passive spiral bar fraction is high: 74+/-15 per cent, compared with 36+/-5 per cent for a mass, redshift and T-type matched comparison sample of star-forming spiral galaxies. The high mass passive spirals occur mostly, but not exclusively, in groups, and can be central or satellite galaxies. The passive spiral group fraction of 74+/-15 per cent is similar to that of the comparison sample of star-forming galaxies at 61+/-7 per cent. We find evidence for both quenching via internal structure and environment in our passive spiral sample, though some galaxies have evidence of neither. From this, we conclude no one mechanism is responsible for quenching star formation in passive spiral galaxies - rather, a mixture of mechanisms is required to produce the passive spiral distribution we see today.
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/L11
- Title:
- Passive spiral galaxy cand. multi-phot.
- Short Name:
- J/MNRAS/462/L11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified a population of passive spiral galaxies from photometry and integral field spectroscopy. We selected z<0.035 spiral galaxies that have WISE colours consistent with little mid-infrared emission from warm dust. Matched aperture photometry of 51 spiral galaxies in ultraviolet, optical and mid-infrared show these galaxies have colours consistent with passive galaxies. Six galaxies form a spectroscopic pilot study and were observed using the Wide-Field Spectrograph (WiFeS) to check for signs of nebular emission from star formation. We see no evidence of substantial nebular emission found in previous red spiral samples. These six galaxies possess absorption line spectra with 4000{AA} breaks consistent with an average luminosity-weighted age of 2.3Gyr. Our photometric and IFU spectroscopic observations confirm the existence of a population of local passive spiral galaxies, implying that transformation into early-type morphologies is not required for the quenching of star formation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/344/181
- Title:
- PDS versus Markarian starburst galaxies
- Short Name:
- J/MNRAS/344/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The characteristics of the starburst galaxies from the Pico dos Dias Survey (PDS, Coziol et al., 1998ApJS..119..239C) are compared with those of the nearby ultraviolet (UV) bright Markarian starburst galaxies, having the same limit in redshift (v_h_<7500km/s) and absolute B magnitude (M_B_<18). An important difference is found: the Markarian galaxies are generally undetected at 12 and 25um in IRAS. This is consistent with the UV excess shown by these galaxies and suggests that the youngest star-forming regions dominating these galaxies are relatively free of dust.