- ID:
- ivo://CDS.VizieR/J/ApJ/658/1006
- Title:
- Radial profiles for 161 face-on spirals
- Short Name:
- J/ApJ/658/1006
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present specific star formation rate (sSFR) radial profiles for a sample of 161 relatively face-on spiral galaxies from the GALEX Atlas of Nearby Galaxies. The sSFR profiles are derived from GALEX and 2MASS (FUV-K) color profiles after a proper SFR calibration of the UV luminosity and K-band mass-to-light ratio are adopted. The (FUV-K) profiles were first corrected for foreground Galactic extinction and later for internal extinction using the ratio of the total-infrared (TIR) to FUV emission. For those objects where TIR-to-FUV ratio radial profiles were not available, the (FUV-NUV) color profiles were used as a measure of the UV slope. The sSFR radial gradients derived from these profiles allow us to quantify the inside-out scenario for the growth of spiral disks for the first time in the local universe.
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- ID:
- ivo://CDS.VizieR/J/ApJ/858/90
- Title:
- Radial profiles of 5 nearby galaxies
- Short Name:
- J/ApJ/858/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use new ALMA observations to investigate the connection between dense gas fraction, star formation rate (SFR), and local environment across the inner region of four local galaxies showing a wide range of molecular gas depletion times. We map HCN(1-0), HCO^+^(1-0), CS(2-1), ^13^CO(1-0), and C^18^O(1-0) across the inner few kiloparsecs of each target. We combine these data with short-spacing information from the IRAM large program EMPIRE, archival CO maps, tracers of stellar structure and recent star formation, and recent HCN surveys by Bigiel+ (2016ApJ...822L..26B) and Usero+ (2015AJ....150..115U). We test the degree to which changes in the dense gas fraction drive changes in the SFR. I_HCN_/I_CO_ (tracing the dense gas fraction) correlates strongly with I_CO_ (tracing molecular gas surface density), stellar surface density, and dynamical equilibrium pressure, P_DE_ (Elmegreen 1989ApJ...338..178E). Therefore, I_HCN_/I_CO_ becomes very low and HCN becomes very faint at large galactocentric radii, where ratios as low as I_HCN_/I_CO_~0.01 become common. The apparent ability of dense gas to form stars, {Sigma}_SFR_/{Sigma}_dense_ (where {Sigma}_dense_ is traced by the HCN intensity and the star formation rate is traced by a combination of H{alpha} and 24{mu}m emission), also depends on environment. {Sigma}_SFR_/{Sigma}_dense_ decreases in regions of high gas surface density, high stellar surface density, and high P_DE_. Statistically, these correlations between environment and both {Sigma}_SFR_/{Sigma}_dense_ and I_HCN_/I_CO_ are stronger than that between apparent dense gas fraction (I_HCN_/I_CO_) and the apparent molecular gas star formation efficiency {Sigma}_SFR_/{Sigma}_mol_. We show that these results are not specific to HCN.
- ID:
- ivo://CDS.VizieR/J/ApJ/838/83
- Title:
- Radial velocities, abundances & membership in TriII
- Short Name:
- J/ApJ/838/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Among the Milky Way satellites discovered in the past three years, Triangulum II has presented the most difficulty in revealing its dynamical status. Kirby+ (2015ApJ...814L...7K) identified it as the most dark-matter-dominated galaxy known, with a mass-to-light ratio within the half-light radius of 3600_-2100_^+3500^M_{sun}_/L_{sun}_. On the other hand, Martin+ (2016ApJ...818...40M) measured an outer velocity dispersion that is 3.5+/-2.1 times larger than the central velocity dispersion, suggesting that the system might not be in equilibrium. From new multi-epoch Keck/DEIMOS measurements of 13 member stars in Triangulum II, we constrain the velocity dispersion to be {sigma}_v_<3.4km/s (90%C.L.). Our previous measurement of {sigma}_v_, based on six stars, was inflated by the presence of a binary star with variable radial velocity. We find no evidence that the velocity dispersion increases with radius. The stars display a wide range of metallicities, indicating that Triangulum II retained supernova ejecta and therefore possesses, or once possessed, a massive dark matter halo. However, the detection of a metallicity dispersion hinges on the membership of the two most metal-rich stars. The stellar mass is lower than galaxies of similar mean stellar metallicity, which might indicate that Triangulum II is either a star cluster or a tidally stripped dwarf galaxy. Detailed abundances of one star show heavily depressed neutron-capture abundances, similar to stars in most other ultra-faint dwarf galaxies but unlike stars in globular clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/430/3453
- Title:
- Radial velocities in A1914
- Short Name:
- J/MNRAS/430/3453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the dynamical state of Abell 1914, a merging cluster hosting a radio halo, quite unusual for its structure. Our study considers spectroscopic data for 119 galaxies obtained with the Italian Telescopio Nazionale Galileo. We select 89 cluster members from spatial and velocity distributions. We also use photometry Canada-France-Hawaii Telescope archives. We compute the mean cluster redshift, <z>=0.168, and the velocity dispersion which shows a high value, {sigma}V=1210^+125^_-110_km/s. From the 2D analysis we find that Abell 1914 has a north-east (NE)-south-west (SW) elongated structure with two galaxy clumps, that mostly merge in the plane of the sky. Our best but very uncertain estimate of the velocity dispersion of the main system is {sigma}V, main ~1000km/s. We estimate a virial mass M_sys_=1.4-2.6x10^15^h^-1^_70_M_{sun}_ for the whole system. We study the merger through a simple two-body model and find that data are consistent with a bound, outgoing substructure observed just after the core crossing. By studying the 2D distribution of the red galaxies, photometrically selected, we show that Abell 1914 is contained in a rich large-scale structure, with two close companion galaxy systems, known to be at z~0.17. The system at SW supports the idea that the cluster is accreting groups from a filament aligned in the NE-SW direction, while that at NW suggests a second direction of the accretion (NW-SE). We conclude that Abell 1914 well fits among typical clusters with radio haloes. We argue that the unusual radio emission is connected to the complex cluster accretion and suggest that Abell 1914 resembles the well-known nearby merging cluster Abell 754 for its particular observed phenomenology.
- ID:
- ivo://CDS.VizieR/J/AJ/131/2114
- Title:
- Radial velocities in Fornax dSph
- Short Name:
- J/AJ/131/2114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocity results for 176 stars in the Fornax dwarf spheroidal galaxy, of which at least 156 are probable Fornax members. We combine with previously published data to obtain a radial velocity sample with 206 stars, of which at least 176 are probable Fornax members.
- ID:
- ivo://CDS.VizieR/J/ApJ/399/353
- Title:
- Radial velocities in Hickson compact groups
- Short Name:
- J/ApJ/399/353
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocities have been observed for 457 galaxies in the 100 Hickson compact groups (Hickson =1982ApJ...255..382H; catalog <VII/85>). Brighter galaxies were observed over the period 1984-1986, using the 1.5m telescope of the F.L. Whipple Observatory on Mt. Hopkins, Arizona, in wavelength range 470-710nm; the remaining fainter galaxies were observed with the Canada-France-Hawaii Telescope (CFHT). These velocities are listed in table2. Dynamical parameters were derived for 92 of the 100 groups, which are listed in table3; Hubble constant was assumed to be Ho=100km/s/Mpc.
- ID:
- ivo://CDS.VizieR/J/AJ/95/284
- Title:
- Radial velocities in 14 rich clusters
- Short Name:
- J/AJ/95/284
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Heliocentric radial velocities accurate to <~50km/s are given for 1267 galaxies in the fields of 14 rich clusters from the Dressler (1980, Cat. <VII/174>) catalog (instead of 1268 velocities in 15 clusters as indicated in the title).
- ID:
- ivo://CDS.VizieR/J/AJ/139/216
- Title:
- Radial velocities in UGC 842 and NGC 6034
- Short Name:
- J/AJ/139/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new insight on NGC 6034 and UGC 842, two groups of galaxies previously reported in the literature as being fossil groups. The study is based on optical photometry and spectroscopy obtained with the CTIO Blanco telescope and Sloan Digital Sky Survey archival data.
- ID:
- ivo://CDS.VizieR/J/A+A/330/881
- Title:
- Radial velocities of Cartwheel Galaxy
- Short Name:
- J/A+A/330/881
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on high spectral and spatial resolution kinematic observations of H{alpha} emission from the Cartwheel system obtained with a scanning Fabry-Perot interferometer. Velocity fields for two galaxies were measured, for the main galaxy of the system, the Cartwheel galaxy, and for a spiral companion ~25h^-1^kpc to the north. The velocity field and the rotation curve of the spiral companion shows classical differential rotation and indicates the mass of the galaxy to be in the range 2.9-4.8x10^9^M{sun}. The Cartwheel galaxy contains strong H{alpha} in emission asymmetrically distributed along its outer ring, with some faint emission detected inside it. The velocity field and the rotation curve of the Cartwheel galaxy is clearly dominated by differential rotation although second-order effects cause distortions which can be understood in a scenario where expansion and density-wave motions are also considered. Our best model-fit to the observed velocity field of the Cartwheel galaxy includes three components for the kinematic of its outer ring: a circular velocity of 217km/s, an expansion velocity of 13-30+/-10km/s and a sinusoidal perturbation with an amplitude of 20+/-5km/s. This expansion velocity, lower than found in previous studies, implies that the ring could be older than previously thought. The rotation curve of the Cartwheel galaxy is consistent with a progenitor which had the morphology of a late-type spiral galaxy. Our measurements support the collisional models of ring galaxy formation and should impose strong constraints to simulations.
- ID:
- ivo://CDS.VizieR/J/AJ/137/3100
- Title:
- Radial velocities of 4 dSph galaxies
- Short Name:
- J/AJ/137/3100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic data for individual stars observed from 2004 March through 2008 August as part of our Michigan/MIKE Fiber System (MMFS) survey of four dwarf spheroidal (dSph) galaxies: Carina, Fornax, Sculptor, and Sextans. Using MMFS at the Magellan/Clay Telescope at Las Campanas Observatory, we have acquired 8855 spectra from 7103 red-giant candidates in these Galactic satellites. We list measurements of each star's line-of-sight velocity (median error +/-2.1km/s) and spectral line indices for iron and magnesium absorption features.
