- ID:
- ivo://CDS.VizieR/J/AJ/160/66
- Title:
- LITTLE THINGS catalog of HI holes in 41 galaxies
- Short Name:
- J/AJ/160/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of holes and shells in the neutral atomic hydrogen (HI) of 41 gas-rich dwarf galaxies in LITTLE THINGS (Local Irregulars That Trace Luminosity Extremes, The HI Nearby Galaxy Survey). We analyzed their properties as part of an investigation into the relation between star formation and structures and kinematics in the HI of small galaxies. We confirmed 306 holes between 38pc (our resolution limit) and 2.3kpc, with expansion velocities up to 30km/s. The global star formation rates (SFRs) measured by H{alpha} and far-UV (FUV) emission are consistent with those estimated from the energy required to create the cataloged holes in our sample. Although we found no obvious correlation between global star forming regions (SFRs) and the HI surface and volume porosities of our sample, two of the four galaxies with the lowest porosity and the two galaxies with the highest porosity have no recent star formation as measured by H{alpha} and FUV emission.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/151/136
- Title:
- LITTLE THINGS dwarf irregular galaxies FUV regions
- Short Name:
- J/AJ/151/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine FUV images of the LITTLE THINGS sample of nearby dwarf irregular (dIrr) and Blue Compact Dwarf galaxies to identify distinct young regions in their far outer disks. We use these data, obtained with the Galaxy Evolution Explorer satellite, to determine the furthest radius at which in situ star formation can currently be identified. The FUV knots are found at distances from the center of the galaxies of 1-8 disk scale lengths and have ages of =<20 Myr and masses of 20 M_{sun}_ to 1x10^5^ M_{sun}_. The presence of young clusters and OB associations in the outer disks of dwarf galaxies shows that dIrrs do have star formation taking place there in spite of the extreme nature of the environment. Most regions are found where the H I surface density is ~1 M_{sun}_/pc^2^, though both the H I and dispersed old stars go out much further. This limiting density suggests a cutoff in the ability to form distinct OB associations and perhaps even stars. We compare the star formation rates in the FUV regions to the average rates expected at their radii and beyond from the observed gas, using the conventional correlation for gas-rich regions. The localized rates are typically 10% of the expected average rates for the outer disks. Either star formation in dIrrs at surface densities <1 M_{sun}_/pc^2^ occurs without forming distinct associations, or the Kennicutt-Schmidt relation over-predicts the rate beyond this point. In the latter case, the stellar disks in the far-outer parts of dIrrs result from scattering of stars from the inner disk.
- ID:
- ivo://CDS.VizieR/J/AJ/144/134
- Title:
- LITTLE THINGS survey of nearby dwarf galaxies
- Short Name:
- J/AJ/144/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present LITTLE THINGS (Local Irregulars That Trace Luminosity Extremes, The HI Nearby Galaxy Survey), which is aimed at determining what drives star formation in dwarf galaxies. This is a multi-wavelength survey of 37 dwarf irregular and 4 blue compact dwarf galaxies that is centered around HI-line data obtained with the National Radio Astronomy Observatory (NRAO) Very Large Array (VLA). The HI-line data are characterized by high sensitivity ({<=}1.1mJy/beam per channel), high spectral resolution ({<=}2.6km/s), and high angular resolution (~6"). The LITTLE THINGS sample contains dwarf galaxies that are relatively nearby ({<=}10.3Mpc; 6" is {<=}300pc), that were known to contain atomic hydrogen, the fuel for star formation, and that cover a large range in dwarf galactic properties. We describe our VLA data acquisition, calibration, and mapping procedures, as well as HI map characteristics, and show channel maps, moment maps, velocity-flux profiles, and surface gas density profiles. In addition to the HI data we have GALEX UV and ground-based UBV and H{alpha} images for most of the galaxies, and JHK images for some. Spitzer mid-IR images are available for many of the galaxies as well. These data sets are available online.
- ID:
- ivo://CDS.VizieR/J/ApJ/690/512
- Title:
- LMXBs and globulars in early-type galaxies. II.
- Short Name:
- J/ApJ/690/512
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an astrometry and photometry catalogue of globular cluster (GC) candidates detected with the Hubble Space Telescope Wide Field Planetary Camera 2 in a sample of 19 early-type galaxies, appropriate for comparison with the low-mass X-ray binary populations observed with Chandra. In a companion paper (Cat. J/ApJ/689/983), we present the Chandra data and investigate the relation between these populations. We demonstrate that, although there is little evidence of a color-magnitude correlation for the GCs, after estimating mass and metallicity from the photometry under the assumption of a single-age simple stellar population, there is a significant positive correlation between mass and metallicity.
- ID:
- ivo://CDS.VizieR/J/ApJ/689/983
- Title:
- LMXBs in early-type galaxies. I. Chandra
- Short Name:
- J/ApJ/689/983
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a Chandra survey of LMXBs in 24 early-type galaxies. Correcting for detection incompleteness, the X-ray luminosity function (XLF) of each galaxy is consistent with a power law with negative logarithmic differential slope, {beta}~2.0. However, {beta} strongly correlates with incompleteness, indicating the XLF flattens at low-L_X_. Although the XLFs are similar, we find evidence of some variation between galaxies. The high-L_X_ XLF slope does not correlate with age, but may correlate with [{alpha}/Fe]. Considering only LMXBs with L_X_>10^37^ergs/s, matching the LMXBs with globular clusters (GCs) identified in HST observations of 19 of the galaxies, we find the probability a GC hosts an LMXB is proportional to L^{alpha}^_GC_Z^{gamma}^_Fe_ where {alpha}=1.01+/-0.19 and {gamma}=0.33+/-0.11. The spatial distribution of LMXBs resembles that of GCs, and the specific frequency of LMXBs is proportional to the GC specific luminosity, consistent with the hypothesis that all LMXBs form in GCs.
- ID:
- ivo://CDS.VizieR/J/ApJ/662/525
- Title:
- LMXBs in globular clusters of 5 galaxies
- Short Name:
- J/ApJ/662/525
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of LMXBs and GCs in five early-type galaxies using Chandra X-ray and HST optical data. Of the 186 LMXBs within the optical fields of view, 71 are in GCs, confirming that LMXBs are formed particularly efficiently in clusters due to dynamical interactions.
- ID:
- ivo://CDS.VizieR/J/A+A/468/49
- Title:
- LMXBs in the bulge of M31
- Short Name:
- J/A+A/468/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the population of X-ray point sources in the bulge of M31 to contrast properties of various subpopulations, such as persistent and transient sources and primordial LMXBs and dynamically formed ones. Based on the data from 26 archival Chandra observations we study the source content and properties of various subpopulations of X-ray sources to a maximum distance of 12' from the centre of M 31.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A38
- Title:
- Local galaxies dust properties
- Short Name:
- J/A+A/631/A38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derived the dust properties for 753 local galaxies and examine how these relate to some of their physical properties. We present the derived dust emission properties, including model spectral energy distribution (SEDs), star formation rates (SFRs) and stellar masses, as well as their relations. We modelled the global dust-SEDs for 753 galaxies, treated statistically as an ensemble within a hierarchical Bayesian dust-SED modelling approach, so as to derive their infrared (IR) emission properties. To create the observed dust-SEDs, we used a multi-wavelength set of observations, ranging from near-IR to far-IR-to-submillimeter wavelengths. The model-derived properties are the dust masses (Mdust), the average interstellar radiation field intensities (Uav), the mass fraction of very small dust grains ("QPAH" fraction), as well as their standard deviations. In addition, we used mid-IR observations to derive SFR and stellar masses, quantities independent of the dust-SED modelling. We derive distribution functions of the properties for the galaxy ensemble and as a function of galaxy type. The mean value of Mdust for the early-type galaxies (ETGs) is lower than that for the late-type and irregular galaxies (LTGs and Irs, respectively), despite ETGs and LTGs having stellar masses spanning across the whole range observed. The U_av_ and "QPAH" fraction show no difference among different galaxy types. When fixing Uav to the Galactic value, the derived "QPAH" fraction varies across the Galactic value (0.071). The specific SFR increases with galaxy type, while this is not the case for the dust-specific SFR (SFR/M_dust_), showing an almost constant star formation efficiency per galaxy type. The galaxy sample is characterised by a tight relationship between the dust mass and the stellar mass for the LTGs and Irs, while ETGs scatter around this relation and tend towards smaller dust masses. While the relation indicates that Mdust may fundamentally be linked to M*, metallicity and U_av_ are the second parameter driving the scatter, which we investigate in a forthcoming work. We used the extended Kennicutt-Schmidt (KS) law to estimate the gas mass and the gas-to-dust mass ratio (GDR). The gas mass derived from the extended KS law is on average ~20% higher than that derived from the KS law, and a large standard deviation indicates the importance of the average star formation present to regulate star formation and gas supply. The average GDR for the LTGs and Irs is 370, and including the ETGs gives an average of 550.
- ID:
- ivo://CDS.VizieR/J/MNRAS/330/547
- Title:
- Local galaxy ages and metallicities
- Short Name:
- J/MNRAS/330/547
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have assembled a catalogue of relative ages, metallicities and abundance ratios for about 150 local galaxies in field, group and cluster environments. The galaxies span morphological types from cD and ellipticals, to late-type spirals. Ages and metallicities were estimated from high-quality published spectral line indices using Worthey & Ottaviani (1997, Cat. <J/ApJS/111/377>) single stellar population evolutionary models. The identification of galaxy age as a fourth parameter in the fundamental plane (Forbes, Ponman & Brown, 1998ApJ...508L..43F) is confirmed by our larger sample of ages. We investigate trends between age and metallicity, and with other physical parameters of the galaxies, such as ellipticity, luminosity and kinematic anisotropy. We demonstrate the existence of a galaxy age-metallicity relation similar to that seen for local galactic disc stars, whereby young galaxies have high metallicity, while old galaxies span a large range in metallicities. We also investigate the influence of environment and morphology on the galaxy age and metallicity, especially the predictions made by semi-analytic hierarchical clustering models (HCM). We confirm that non-cluster ellipticals are indeed younger on average than cluster ellipticals as predicted by the HCM models. However we also find a trend for the more luminous galaxies to have a higher [Mg/Fe] ratio than the lower luminosity galaxies, which is opposite to the expectation from HCM models.
- ID:
- ivo://CDS.VizieR/J/A+A/398/479
- Title:
- Local galaxy flows within 5 Mpc
- Short Name:
- J/A+A/398/479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope/WFPC2 images of sixteen dwarf galaxies as part of our snapshot survey of nearby galaxy candidates. We derive their distances from the luminosity of the tip of the red giant branch stars with a typical accuracy of ~12%.
