- ID:
- ivo://CDS.VizieR/J/A+A/453/493
- Title:
- Line-strength indices in IC 4200
- Short Name:
- J/A+A/453/493
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical spectroscopy, imaging and radio observations of the galaxy IC 4200 are analysed in order to determine the formation history of the galaxy. The two tables available contain informations extracted from the long-slit spectra of IC 4200. The spectra were taken with ESO/NTT/EMMI mounted on the NTT on 12 July 2004, as described in Sec. 3.2 and in Table 4 of the paper. tablec1.dat contains informations on the stellar and ionised-gas kinematics along the optical major and minor axis of the galaxy. The stellar kinematics was determined by fitting Bruzual & Charlot (2003MNRAS.344.1000B) stellar populations synthesis models to the low-S/N 1D bins extracted from the 2D spectrum of IC 4200 (Sec. 3.2.1). The kinematics of the ionised gas was determined by fitting single Gaussians to the Halpha emission line; for this purpose we used IRAF.NOAO.ONEDSPEC.SPLOT. tablec2.dat contains the values of the Lick/IDS indices measured along the optical major and minor axis of IC 4200. The values given are corrected for the effect of velocity dispersion and shifted to the Lick/IDS system.
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- ID:
- ivo://CDS.VizieR/J/ApJ/459/110
- Title:
- Line strengths and gradients in S0 galaxies
- Short Name:
- J/ApJ/459/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Line strengths and their gradients in Mg, Fe, and HBeta have been determined for a sample of 20 S0 galaxies in order to study the stellar populations of their bulges and disks and to investigate their relationship to elliptical galaxies. Data are also presented for the elliptical galaxy NGC 1700 and the E/S0 NGC 3585. We find that S0 galaxies generally follow a similar, though possibly steeper, relationship between central Mg_2 line strength and central velocity dispersion as found for elliptical galaxies. The S0 galaxies show no dependence between Fe line strengths and central velocity dispersion -- similar to the behavior observed in elliptical galaxies. The central Mg/Fe ratios in the luminous S0 galaxies show an overabundance of Mg to Fe with respect to solar element ratios. The magnitudes of the Mg and Fe line-strength gradients within the galaxies are found to be correlated, i.e., objects with steep Mg gradients have correspondingly large Fe gradients. We infer bulge and disk gradients for the nine most edge-on galaxies for which we have both major- and minor-axis profiles. The metal line strengths decrease with radius along the major and minor axes in the bulge-dominated central regions. At larger radii, however, the major-axis metal line strength profiles flatten while the minor-axis bulge profiles fall to lower values. Representative color maps in B-R are presented that display a separation between bulge and disk colors corresponding to the metal line strength profiles. Based on our Mg_2 profiles, the average metal gradient found in the disks of our sub-sample is Delta[Fe/H]/Delta(r/h)=-0.08+/-0.06, which corresponds to a reduction in the mean metallicity of the disk stellar population by <~15% per disk scale length (h). These shallow metallicity gradients are approximately a factor of 2-3 smaller than those derived for the disks of late-type spiral galaxies from H II regions and are consistent with previous investigations that showed a trend for disk metallicity gradients to decrease toward earlier Hubble types. As inferred from our Mg and Fe line strengths, the mean size of the bulge metallicity gradients is Delta[Fe/H]/Delta(log r)=-0.7+/-0.4, which is steeper than typical elliptical galaxy gradients. Our findings do not support formation scenarios in which bulges formed either from heated disk material at late times after disk formation or through dissipationless stellar merging, as neither process includes mechanisms for producing the observed metallicity gradients. Our observations are better explained in terms of formation via dissipative collapse (or merging) at early times.
- ID:
- ivo://CDS.VizieR/J/ApJ/527/573
- Title:
- Line Strengths in Elliptical Galaxies
- Short Name:
- J/ApJ/527/573
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have restudied line-strength gradients of 80 elliptical galaxies. Typical metallicity gradients of elliptical galaxies are {delta}[Fe/H]/{delta}log(r){=~}-0.3, which is flatter than the gradients predicted by monolithic collapse simulations. The metallicity gradients do not correlate with any physical properties of galaxies, including central and mean metallicities, central velocity dispersions {sigma}_0_, absolute B magnitudes M_B_, absolute effective radii R_e_, and dynamical masses of galaxies. By using the metallicity gradients, we have calculated mean stellar metallicities for individual ellipticals. Typical mean stellar metallicities are <[Fe/H]> {=~} -0.3 and range from <[Fe/H]>{=~}-0.8 to +0.3, which is contrary to what Gonzalez & Gorgas (1996) claimed; the mean metallicities of ellipticals are not universal. The mean metallicities correlate well with {sigma}_0{sigma}_ and dynamical masses, though relations for M_B_ and R_e_ include significant scatters.
- ID:
- ivo://CDS.VizieR/J/AJ/135/2424
- Title:
- Line strengths of early-type galaxies
- Short Name:
- J/AJ/135/2424
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present measurements of velocity dispersions and Lick indices for 509 galaxies in the local universe, based on high signal-to-noise, long-slit spectra obtained with the 1.52m ESO telescope at La Silla.
- ID:
- ivo://CDS.VizieR/J/A+A/462/81
- Title:
- L_IR_-T_dust_ relation in galaxies
- Short Name:
- J/A+A/462/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRAS observations show the existence of a correlation between the infrared luminosity L_IR_ and dust temperature T_d_ in star-forming galaxies, in which larger L_IR_ leads to higher dust temperature. The L_IR_-T_d_ relation is commonly seen as reflecting the increase in dust temperature in galaxies with higher star formation rate (SFR). Even though the correlation shows a significant amount of dispersion, a unique relation has been commonly used to construct spectral energy distributions (SEDs) of galaxies in distant universe studies, such as source number counting or photometric redshift determination. In this work, we introduce a new parameter, namely the size of the star-forming region r_IR_ and lay out the empirical and modelled relation between the global parameters L_IR_, T_d_ and r_IR_ of IR-bright non-AGN galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/3766
- Title:
- List of galaxies with star forming regions
- Short Name:
- J/MNRAS/462/3766
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first study of GALEX far-ultraviolet (FUV) luminosity functions of individual star-forming regions within a sample of 258 nearby galaxies spanning a large range in total stellar mass and star formation properties. We identify ~65000 star-forming regions (i.e. FUV sources), measure each galaxy's luminosity function, and characterize the relationships between the luminosity function slope ({alpha}) and several global galaxy properties. A final sample of 82 galaxies with reliable luminosity functions are used to define these relationships and represent the largest sample of galaxies with the largest range of galaxy properties used to study the connection between luminosity function properties and galaxy environment. We find that {alpha} correlates with global star formation properties, where galaxies with higher star formation rates and star formation rate densities ({Sigma}_SFR_) tend to have flatter luminosity function slopes. In addition, we find that neither stochastic sampling of the luminosity function in galaxies with low-number statistics nor the effects of blending due to distance can fully account for these trends. We hypothesize that the flatter slopes in high {Sigma}_SFR_ galaxies is due to higher gas densities and higher star formation efficiencies which result in proportionally greater numbers of bright star-forming regions. Finally, we create a composite luminosity function composed of star-forming regions from many galaxies and find a break in the luminosity function at brighter luminosities. However, we find that this break is an artefact of varying detection limits for galaxies at different distances.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/3130
- Title:
- Lists of arm and interarm supernovae
- Short Name:
- J/MNRAS/459/3130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 215 supernovae (SNe), we analyse their positions relative to the spiral arms of their host galaxies, distinguishing grand-design (GD) spirals from non-GD (NGD) galaxies. We find that: (1) in GD galaxies, an offset exists between the positions of Ia and core-collapse (CC) SNe relative to the peaks of arms, while in NGD galaxies the positions show no such shifts; (2) in GD galaxies, the positions of CC SNe relative to the peaks of arms are correlated with the radial distance from the galaxy nucleus. Inside (outside) the corotation radius, CC SNe are found closer to the inner (outer) edge. No such correlation is observed for SNe in NGD galaxies nor for SNe Ia in either galaxy class; (3) in GD galaxies, SNe Ibc occur closer to the leading edges of the arms than do SNe II, while in NGD galaxies they are more concentrated towards the peaks of arms. In both samples of hosts, the distributions of SNe Ia relative to the arms have broader wings. These observations suggest that shocks in spiral arms of GD galaxies trigger star formation in the leading edges of arms affecting the distributions of CC SNe (known to have short-lived progenitors). The closer locations of SNe Ibc versus SNe II relative to the leading edges of the arms supports the belief that SNe Ibc have more massive progenitors. SNe Ia having less massive and older progenitors, have more time to drift away from the leading edge of the spiral arms.
- 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.
- 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.
