Iglesias-Paramo J.,Institute Astrofisica Of Andalucia Csic |
Iglesias-Paramo J.,CSIC - Estacion Experimental De Zonas Aridas |
Vilchez J.M.,Institute Astrofisica Of Andalucia Csic |
Rosales-Ortega F.F.,National Institute of Astrophysics, Optics and Electronics |
And 27 more authors.
Astrophysical Journal | Year: 2016
This paper aims to provide aperture corrections for emission lines in a sample of spiral galaxies from the Calar Alto Legacy Integral Field Area Survey (CALIFA) database. In particular, we explore the behavior of the log([O iii] λ5007/Hβ)/([N ii] λ6583/Hα) (O3N2) and log[N ii] λ6583/Hα (N2) flux ratios since they are closely connected to different empirical calibrations of the oxygen abundances in star-forming galaxies. We compute the median growth curves of Hα, Hα/Hβ, O3N2, and N2 up to 2.5R 50 and 1.5 disk . These distances cover most of the optical spatial extent of the CALIFA galaxies. The growth curves simulate the effect of observing galaxies through apertures of varying radii. We split these growth curves by morphological types and stellar masses to check if there is any dependence on these properties. The median growth curve of the Hα flux shows a monotonous increase with radius with no strong dependence on galaxy inclination, morphological type, and stellar mass. The median growth curve of the Hα/Hβ ratio monotonically decreases from the center toward larger radii, showing for small apertures a maximum value of ≈10% larger than the integrated one. It does not show any dependence on inclination, morphological type, and stellar mass. The median growth curve of N2 shows a similar behavior, decreasing from the center toward larger radii. No strong dependence is seen on the inclination, morphological type, and stellar mass. Finally, the median growth curve of O3N2 increases monotonically with radius, and it does not show dependence on the inclination. However, at small radii it shows systematically higher values for galaxies of earlier morphological types and for high stellar mass galaxies. Applying our aperture corrections to a sample of galaxies from the SDSS survey at 0.02 ≤ z ≤ 0.3 shows that the average difference between fiber-based and aperture-corrected oxygen abundances, for different galaxy stellar mass and redshift ranges, reaches typically to ≈11%, depending on the abundance calibration used. This average difference is found to be systematically biased, though still within the typical uncertainties of oxygen abundances derived from empirical calibrations. Caution must be exercised when using observations of galaxies for small radii (e.g., below 0.5 ) given the high dispersion shown around the median growth curves. Thus, the application of these median aperture corrections to derive abundances for individual galaxies is not recommended when their fluxes come from radii much smaller than either R 50 or Reff. © 2016. The American Astronomical Society. All rights reserved. Source
Minniti D.,University of Santiago de Chile |
Hempel M.,University of Santiago de Chile |
Toledo I.,University of Santiago de Chile |
Ivanov V.D.,European Southern Observatory |
And 14 more authors.
Astronomy and Astrophysics | Year: 2011
Context. It is not known how many globular clusters may remain undetected towards the Galactic bulge. Aims. One of the aims of the VISTA Variables in the Via Lactea (VVV) Survey is to accurately measure the physical parameters of the known globular clusters in the inner regions of the Milky Way and search for new ones, hidden in regions of large extinction. Methods. From deep near-infrared images, we derive deep JHKS-band photometry of a region surrounding the known globular cluster UKS 1 and reveal a new low-mass globular cluster candidate that we name VVV CL001. Results. We use the horizontal-branch red clump to measure E(B - V) ∼ 2.2 mag, (m - M)0 = 16.01 mag, and D = 15.9 kpc for the globular cluster UKS 1. On the basis of near-infrared colour - magnitude diagrams, we also find that VVV CL001 has E(B - V) ∼ 2.0, and that it is at least as metal-poor as UKS 1, although its distance remains uncertain. Conclusions. Our finding confirms the previous projection that the central region of the Milky Way harbours more globular clusters. VVV CL001 and UKS 1 are good candidates for a physical cluster binary, but follow-up observations are needed to decide if they are located at the same distance and have similar radial velocities. © 2011 ESO. Source
Aquilano R.,CONICET |
Navone H.,Observatorio Astronomico
Advanced Studies in Theoretical Physics | Year: 2010
We analyze a type of self-gravitating object, described by a soliton to the coupled system of the Einstein equation and a matter field equation. The existence of such objects could have important connotations in astrophysics, specially by high density stars. Source
Cano-Diaz M.,National Autonomous University of Mexico |
Sanchez S.F.,National Autonomous University of Mexico |
Zibetti S.,National institute for astrophysics |
Ascasibar Y.,Autonomous University of Madrid |
And 23 more authors.
Astrophysical Journal Letters | Year: 2016
The "main sequence of galaxies" - defined in terms of the total star formation rate ψ versus the total stellar mass M ∗ - is a well-studied tight relation that has been observed at several wavelengths and at different redshifts. All earlier studies have derived this relation from integrated properties of galaxies. We recover the same relation from an analysis of spatially resolved properties, with integral field spectroscopic (IFS) observations of 306 galaxies from the CALIFA survey. We consider the SFR surface density in units of log(M o yr-1 Kpc-2) and the stellar mass surface density in units of log(M o Kpc-2) in individual spaxels that probe spatial scales of 0.5-1.5 Kpc. This local relation exhibits a high degree of correlation with small scatter (σ = 0.23 dex), irrespective of the dominant ionization source of the host galaxy or its integrated stellar mass. We highlight (i) the integrated star formation main sequence formed by galaxies whose dominant ionization process is related to star formation, for which we find a slope of 0.81 ± 0.02; (ii) for the spatially resolved relation obtained with the spaxel analysis, we find a slope of 0.72 ± 0.04; and (iii) for the integrated main sequence, we also identified a sequence formed by galaxies that are dominated by an old stellar population, which we have called the retired galaxies sequence. © 2016. The American Astronomical Society. All rights reserved.. Source
Mottola S.,German Aerospace Center |
Di Martino M.,National institute for astrophysics |
Erikson A.,German Aerospace Center |
Gonano-Beurer M.,German Aerospace Center |
And 7 more authors.
Astronomical Journal | Year: 2011
We present the results of a Jupiter Trojans' light curve survey aimed at characterizing the rotational properties of Trojans in the approximate size range 60-150km. The survey, which was designed to provide reliable and unbiased estimates of rotation periods and amplitudes, resulted in light curves for a total of 80 objects, 56 of which represent the first determinations published to date and nine of which supersede previously published erroneous values. Our results more than double the size of the existing database of rotational properties of Jovian Trojans in the selected size range. The analysis of the distributions of the rotation periods and light curve amplitudes is the subject of companion papers. © 2011. The American Astronomical Society. All rights reserved. Source