Search

[Aims] We present the photometric calibration of the 12 optical passbands for the Javalambre Photometric Local Universe Survey (J-PLUS) third data release (DR3) comprising 1642 pointings of two square degrees each., [Methods] We selected nearly 1.5 million main sequence stars with a signal-to-noise ratio larger than ten in the 12 J-PLUS passbands and available low-resolution (R = 20–80) spectrum from the blue and red photometers (BP/RP) in Gaia DR3. We compared the synthetic photometry from BP/RP spectra with the J-PLUS instrumental magnitudes after correcting for the magnitude and color terms between both systems in order to obtain a homogeneous photometric solution for J-PLUS. To circumvent the current limitations in the absolute calibration of the BP/RP spectra, the absolute color scale was derived using the locus of 109 white dwarfs closer than 100 pc with a negligible interstellar extinction. Finally, the absolute flux scale was anchored to the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) photometry in the r band., [Results] The precision of the J-PLUS photometric calibration estimated from duplicated objects observed in adjacent pointings and by comparison with the spectro-photometric standard star GD 153 is ~12 mmag in u, J0378, and J0395, and it is ~7 mmag in J0410, J0430, ɡ, J0515, r, J0660, i, J0861, and z. The estimated accuracy in the calibration along the surveyed area is better than 1% for all the passbands., [Conclusions] The Gaia BP/RP spectra provide a high-quality, homogeneous photometric reference in the optical range across the full sky in spite of their current limitations as an absolute reference. The calibration method for J-PLUS DR3 reaches an absolute precision and accuracy of 1% in the 12 optical filters within an area of 3284 square degrees.

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. © 2006 The Authors. Journal compilation © 2006 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. We thank the referee Raffaele Gratton for fruitful suggestions that improved the quality of this paper. This work was supported by the Spanish research projects AYA2003–01840 and AYA2004–03059. SOS acknowledges the financial support by the Turkish Scientific and Technical Research Council (TÜBITAK) through the NATO-B2 fellowship and the School of Physics and Astronomy (University of Nottingham). AV is a Ramón y Cajal Fellow of the Spanish Ministry of Education and Science. This research has made use of the SIMBAD data base (operated at CDS, Strasbourg, France), the NASA’s Astrophysics Data System Article Service, and the Hipparcos Input Catalogue. This paper is based on observations obtained at the Isaac Newton Telescope, operated by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. The authors are grateful to the ASTRON-PC and CAT for generous allocation of telescope time., We present a homogeneous set of stellar atmospheric parameters (T-eff, log g, [Fe/H]) for MILES, a new spectral stellar library covering the range lambda lambda 3525-7500 angstrom at 2.3 angstrom (FWHM) spectral resolution. The library consists of 985 stars spanning a large range in atmospheric parameters, from super-metal-rich, cool stars to hot, metal-poor stars. The spectral resolution, spectral type coverage and number of stars represent a substantial improvement over previous libraries used in population synthesis models. The atmospheric parameters that we present here are the result of a previous, extensive compilation from the literature. In order to construct a homogeneous data set of atmospheric parameters we have taken the sample of stars of Soubiran, Katz & Cayrel, which has very well determined fundamental parameters, as the standard reference system for our field stars, and have calibrated and bootstrapped the data from other papers against it. The atmospheric parameters for our cluster stars have also been revised and updated according to recent metallicity scales, colour-temperature relations and improved set of isochrones., Turkish Scientific and Technical Research Council (TÜBITAK), NATO-B2 fellowship, School of Physics and Astronomy (University of Nottingham), Spanish Ministry of Education and Science, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© ESO, 2011. We thank the MAGPOP EU Marie Curie Training Network for financial support for the collaborating research visits and observations that led to this paper. E.T. acknowledges the financial support by the Spanish research project AYA2007-67752-C03-03. We thank Consolider-GTC project for partial financial support. This paper made use of the following public databases: SDSS, NED, HyperLEDA, GOLDMine. We are grateful to the anonymous referee for a critical report that has improved the quality of the paper., We present new medium resolution kinematic data for a sample of 21 dwarf early-type galaxies (dEs) mainly in the Virgo cluster, obtained with the WHT and INT telescopes at the Roque de los Muchachos Observatory (La Palma, Spain). These data are used to study the origin of the dwarf elliptical galaxy population inhabiting clusters. We confirm that dEs are not dark matter dominated galaxies, at least not up to the half-light radius. We also find that the observed galaxies in the outer parts of the cluster are mostly rotationally supported systems with disky morphological shapes. Rotationally supported dEs have rotation curves similar to those of star-forming galaxies of similar luminosity and follow the Tully-Fisher relation. This is expected if dE galaxies are the descendants of low-luminosity star-forming systems that have recently entered the cluster environment and lost their gas due to a ram-pressure stripping event, quenching their star formation activity and transforming into quiescent systems, but conserving their angular momentum., Ministerio de Ciencia e Innovación (MICINN), Marie Curie Actions (UE), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. © 2003 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. We are indebted to the anonymous referee for very useful suggestions. This work was supported by the Spanish research project No. AYA2000-977., We present new relations between recently defined line-strength indices in the near-infrared (CaT*, CaT, PaT, MgI and sTiO) and central velocity dispersion (sigma(0) ) for a sample of 35 early-type galaxies, showing evidence for significant anti-correlations between Ca ii triplet indices (CaT* and CaT) and log sigma(0). These relations are interpreted in the light of our recent evolutionary synthesis model predictions, suggesting the existence of important Ca underabundances with respect to Fe and/or an increase of the dwarf to giant stars ratio along the mass sequence of elliptical galaxies., Spanish research project, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2002 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. The authors are indebted to the referee G. Da Costa for useful comments and suggestions. JC acknowledges the Comunidad de Madrid for a Formación de Personal Investigador fellowship. AV acknowledges the support of the PPARC rolling grant ‘Extragalactic Astronomy and Cosmology in Durham 1998-2002’. This research has made use of the NASA’s Astrophysics Data System Article Service. This work was supported by the Spanish Programa Sectorial de Promoción del Conocimiento (PB96-610) and Programa Nacional de Astronomía y Astrofísica (AYA2000-977) and, in part, by a British Council grant within the British/Spanish Joint Research Programme (Acciones Integradas)., Using a near-infrared stellar library of 706 stars with a wide coverage of atmospheric parameters, we study the behaviour of the Call triplet strength in terms of effective temperature, surface gravity and metallicity. Empirical fitting functions for recently defined line-strength indices, namely CaT*, CaT and PaT, are provided. These functions can be easily implemented into stellar population models to provide accurate predictions for integrated Ca II strengths. We also present a thorough study of the various error sources and their relation to the residuals of the derived fitting functions. Finally, the derived functional forms and the behaviour of the predicted Ca II are compared with those of previous works in the field., PPARC rolling grant Extragalactic Astronomy and Cosmology, Spanish Programa Sectorial de Promoción del Conocimiento, Programa Nacional de Astronomía y Astrofísica, British Council, British/Spanish Joint Research Programme (Acciones Integradas), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© ESO 2011. We would like to thank H. Kuntschner and M. Cappellari for reporting some of the questions addressed in this research note. We also thank the referee for very constructive comments. We are grateful to F. Valdes for his assistance clarifying the spectral resolution of the Indo-US library, and C. Allende Prieto for useful discussions. J.F.B. and P. S. B. acknowledge support from the Ramón y Cajal Program financed by the Spanish Ministry of Science and Innovation. P. S. B. also acknowledges an E.R.C. grant within the 6th European Community Framework Programme. This research has been supported by the Spanish Ministry of Science and Innovation (MICINN) under grants AYA2009-10368, AYA2010-21322-C03-02 and AYA2010-21322-C03-03. This paper is based on observations obtained at the Isaac Newton Telescope, operated by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias., We present a number of improvements to the MILES library and stellar population models. We correct some small errors in the radial velocities of the stars, measure the spectral resolution of the library and models more accurately, and give a better absolute flux calibration of the models. Methods. We use cross-correlation techniques to correct the radial velocities of the offset stars and the penalised pixel-fitting method, together with different sets of stellar templates, to re-assess the spectral resolution of the MILES stellar library and models. We have also re-calibrated the zero-point flux level of the models using a new calibration scheme. Results. The end result is an even more homogeneously calibrated stellar library than the originally released one, with a measured spectral resolution of similar to 2.5 angstrom, almost constant with wavelength, for both the MILES stellar library and models. Furthermore, the new absolute flux calibration for the spectra excellently agrees with predictions based on independent photometric libraries. Conclusions. This improved version of the MILES library and models (version 9.1) is available at the project's website (http://miles.iac.es)., Spanish Ministry of Science and Innovation, E.R.C. within European Community, Spanish Ministry of Science and Innovation (MICINN), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. The authors acknowledge the referee's comments, which led to improvements in this work. They also thank Carlos Hernández Monteagudo for his very useful advice. LADG acknowledges support from the 'Caja Rural de Teruel' to develop this research. AJC is a Ramón y Cajal Fellow of the Spanish Ministry of Economy and Competitiveness. This work was supported by the 'Programa Nacional de Astronomía y Astrofísica' of the Spanish Ministry of Economy and Competitiveness under grants AYA2012-30789, AYA2010-21322-C03-02, AYA2009-10368 and AYA2009-07723-E. This work made use of the Rainbow Cosmological Surveys Database, which is operated by the Universidad Complutense de Madrid (UCM)., Using a compilation of 379 massive (stellar mass M ≳ 10^11 M_⊙) spheroid-like galaxies from the near-infrared Palomar/DEEP-2 survey, we investigated, up to z ∼ 1, whether the presence of companions depends on the size of the host galaxy. We explored the presence of companions for mass ratios with respect to the central massive galaxy down to 1 : 10 and 1 : 100, and within projected distances of 30, 50 and 100 kpc of these objects. We found evidence that these companions are equally distributed around both compact and extended massive spheroid-like galaxies. This suggests that, at least since z ∼ 1, the merger activity in these objects is nearly homogeneous across the whole population and that the merger history is not affected by the size of the host galaxy. Our results could indicate that compact and extended massive spheroid-like galaxies are increasing in size at the same rate., Ministerio de Economía y Competitividad (MINECO), Caja Rural de Teruel, Programa Nacional de Astronomía y Astrofísica (PNAyA), España, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. © 2009 The Authors. Journal compilation. © 2009 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. We acknowledge an anonymous referee for his/her very useful comments. AJC is a Juan de la Cierva Fellow of the Spanish Ministry of Science and Innovation. This work has been funded by the Spanish Ministry of Science and Innovation through grants AYA2007-67752-C03-01 and AYA2006-15698-C02-02., Using the near-infrared spectral stellar library of Cenarro et al., the behaviour of the Mg i line at 8807 A and nearby TiO bands is analyzed in terms of the effective temperature, surface gravity and metallicity of the library stars. New spectroscopic indices for both spectral features - namely MgI and sTiO - are defined, and their sensitivities to different signal-to-noise ratios, spectral resolutions, flux calibrations and sky emission-line residuals are characterized. The two new indices exhibit interesting properties. In particular, MgI is a good indicator of the Mg abundance, whereas sTiO is a powerful dwarf-to-giant discriminator for cold spectral types. Empirical fitting polynomials that reproduce the strength of the new indices as a function of the stellar atmospheric parameters are computed, and a fortran routine with the fitting function predictions is made available. A thorough study of several error sources, non-solar [Mg/Fe] ratios and their influence on the fitting function residuals is also presented. From this analysis, an [Mg/Fe] underabundance of similar to -0.04 is derived for the Galactic open cluster M67., Spanish Ministry of Science and Innovation, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© ESO 2003. Valuable discussions with A. Vazdekis, and J. J. González are gratefully acknowledged. The data employed in Appendix A was obtained with the 1m JKT, 2.5m INT and the 4.2m WHT at La Palma Observatory, and with the 3.5m Telescope at Calar Alto Observatory. The JKT, INT and WHT are operated on the island of La Palma by the Royal Greenwich Observatory at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. The Calar Alto Observatory is operated jointly by the Max-Planck-Institute fur Astronomie, Heidelberg, and the Spanish Comisión Nacional de Astronomía. This work was supported by the Spanish Programa Nacional de Astronomía y Astrofísica under grant AYA2000-977., It is well known that, when analyzed in the light of current synthesis model predictions, variations in the physical properties of single stellar populations (e.g. age, metallicity, initial mass function, element abundance ratios) may have a similar effect in their integrated spectral energy distributions. The confusion is even worsened when more realistic scenarios, i.e. composite star formation histories, are considered. This is, in fact, one of the major problems when facing the study of stellar populations in star clusters and galaxies. Typically, the observational efforts have aimed to find the most appropriate spectroscopic indicators in order to avoid, as far as possible, degeneracies in the parameter space. However, from a practical point of view, the most suited observables are not, necessarily, those that provide more orthogonality in that parameter space, but those that give the best balance between parameter degeneracy and sensitivity to signal-to-noise ratio per Angstrom, S/N(Angstrom). In order to achieve the minimum combined total error in the derived physical parameters, this work discusses how the functional dependence of typical line-strength indices and colors on S/N(Angstrom) allows to define a suitability parameter which helps to obtain more realistic combinations of spectroscopic data. As an example, we discuss in more detail the problem of breaking the well known age-metallicity degeneracy in relatively old stellar populations, comparing the suitability of different spectroscopic diagrams for a simple stellar population of solar metallicity and of 12 Gyr in age., Spanish Programa Nacional de Astronomía y Astrofísica, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2009. The American Astronomical Society. All rights reserved. We thank the MAGPOP EU Marie Curie Training and Research Network for financial support and the anonymous referee for useful comments. E. T. and A. G. d. P. thank the Spanish research projects AYA2007-67752-C03-03 and AYA2006-02358, respectively. A. J. C. is Juan de la Cierva Fellow of the Spanish Ministry of Science and Innovation. This Letter made use of the following public databases: SDSS, NED, HyperLEDA ( Paturel et al. 2003), GOLDMine ( Gavazzi et al. 2003)., We present new observational results on the kinematical, morphological, and stellar population properties of a sample of 21 dEs located both in the Virgo Cluster and in the field, which show that 52% of the dEs (1) are rotationally supported, (2) exhibit structural signs of typical rotating systems such as disks, bars, or spiral arms, (3) are younger (~3 Gyr) than non-rotating dEs, and (4) are preferentially located either in the outskirts of Virgo or in the field. This evidence is consistent with the idea that rotationally supported dwarfs are late-type spirals or irregulars that recently entered the cluster and lost their gas through a ram pressure stripping event, quenching their star formation and becoming dEs through passive evolution. We also find that all, but one, galaxies without photometric hints for hosting disks are pressure supported and are all situated in the inner regions of the cluster. This suggests a different evolution from the rotationally supported systems. Three different scenarios for these non-rotating galaxies are discussed (in situ formation, harassment, and ram pressure stripping)., Unión Europea. FP6, Ministerio de Ciencia e Innovación (MICINN), Programa Juan de la Cierva (MICINN), Multi-wavelength analysis of galaxy populations (MAGPOP) Marie Curie Training and Research Network, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2001 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. We are indebted to the anonymous referee for very useful suggestions. Work on writing this paper was partially developed while AJC was a visitor at the Department of Physics (University of Durham) and at the School of Physics and Astronomy (University of Nottingham), whose hospitality is acknowledged gratefully. This research has made use of the Simbad data base (operated at CDS, Strasbourg, France), the NASAs Astrophysics Data System Article Service, and the Hipparcos Input Catalog. AV acknowledges the support of the PPARC rolling grant ‘Extragalactic Astronomy and Cosmology in Durham 1998–2002’. This work was supported in part by a British Council grant within the British/Spanish Joint Research Programme (Acciones Integradas). AJC acknowledges the Comunidad de Madrid for a Formación de Personal Investigador fellowship. This work was supported by the Spanish Programa Sectorial de Promoción del Conocimiento under grants No. PB96-610 and AYA2000-977, We present a homogeneous set of stellar atmospheric parameters (T-eff, log g, [Fe/H]) for a sample of about 700 field and cluster stars which constitute a new stellar library in the near-IR developed for stellar population synthesis in this spectral region (lambda 8350-9020). Having compiled the available atmospheric data in the literature for field stars, we have found systematic deviations between the atmospheric parameters from different bibliographic references. The Soubiran, Katz & Cayrel sample of stars with very well determined fundamental parameters has been taken as our standard reference system, and other papers have been calibrated and bootstrapped against it. The obtained transformations are provided in this paper. Once most of the data sets were on the same system, final parameters were derived by performing error weighted means. Atmospheric parameters for cluster stars have also been revised and updated according to recent metallicity scales and colour-temperature relations., PPARC rolling grant Extragalactic Astronomy and Cosmology, British Council, British/Spanish Joint Research Programme (Acciones Integradas), Spanish Programa Sectorial de Promoción del Conocimiento, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© ESO 2008. This work was supported by the Spanish research projects AYA2006-14318, AYA2006-15698-C02-02, AYA2007-67752C03-03. E. M. Q. acknowledges the Spanish Ministry of Education and Science and the European Social Found for a Formación de Personal Investigador fellowship under the project AYA2003-01840. A.J.C. is a Juan de la Cierva Fellow of the Spanish Ministry of Education and Science. This research was supported by a Marie Curie Intra-European Fellowship within the 6th European Community Framework Program. Based on observations collected at the Centro Astronomico Hispano Aleman (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut fur Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This research made use of the SIMBAD database (operated at CDS, Strasbourg, France), the NASA's Astrophysiscs Data System Bibliographic Services, and the Hipparcos Input Catalogue. The authors are grateful to the allocation time committees for the generous concession of observing time. We finally thank the anonymous referee for very useful comments and suggestions., The analysis of unresolved stellar populations demands evolutionary synthesis models with realistic physical ingredients and extended wavelength coverage. Aims. We quantitatively describe the first CO bandhead at 2.3 mu m to allow stellar population models to provide improved predictions in this wavelength range. Methods. We observed a new stellar library with a better coverage of the stellar atmospheric parameter space than in earlier works. We performed a detailed analysis of the robustness of previous CO index definitions with spectral resolution, wavelength calibration, signal-to-noise ratio, and flux calibration. Results. We define a new line-strength index for the first CO bandhead at 2.3 mu m, DCO, better suited for stellar population studies than previous index definitions. We derive empirical fitting functions for the CO feature as a function of the stellar parameters (T(eff), log g and [Fe/H]), showing a detailed quantitative metallicity dependence., Spanish research projects, Marie Curie Intra-European Fellowship, Ministerio de Educación y Ciencia, European Social Found for a Formacion de Personal Investigador, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. © 2008 The Authors. Journal compilation © 2008 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. We would like to thank Scott Trager, Ignacio Trujillo and an anonymous referee for valuable comments and discussion. DM thanks the MAGPOP EU Marie Curie Training and Research Network for financial support. The Network also provided financial support for collaborating research visits during which part of this paper was done. Based on observations made with the NOT, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. The data presented here have been taken using ALFOSC, which is owned by the Instituto de Astrofísica de Andalucía (IAA) and operated at the NOT under agreement between IAA and the NBIfAFG of the Astronomical Observatory of Copenhagen. This paper made use of the following public data bases: SDSS, NED, HyperLEDA, GOLDMine., Dwarf galaxies, as the most numerous type of galaxy, offer the potential to study galaxy formation and evolution in detail in the nearby universe. Although they seem to be simple systems at first view, they remain poorly understood. In an attempt to alleviate this situation, the MAGPOP EU Research and Training Network embarked on a study of dwarf galaxies named MAGPOP-ITP. In this paper, we present the analysis of a sample of 24 dwarf elliptical galaxies (dEs) in the Virgo cluster and in the field, using optical long-slit spectroscopy. We examine their stellar populations in combination with their light distribution and environment. We confirm and strengthen previous results that dEs are, on average, younger and more metal-poor than normal elliptical galaxies, and that their [alpha/Fe] abundance ratios scatter around solar. This is in accordance with the downsizing picture of galaxy formation where mass is the main driver for the star formation history. We also find new correlations between the luminosity-weighted mean age, the large-scale asymmetry, and the projected Virgocentric distance. We find that environment plays an important role in the termination of the star formation activity by ram-pressure stripping of the gas in short time-scales, and in the transformation of discy dwarfs to more spheroidal objects by harassment over longer time-scales. This points towards a continuing infalling scenario for the evolution of dEs., MAGPOP EU Marie Curie Training and Research Network, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. © 2003 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. We are indebted to the Padova group for making available their isochrones calculations.We are grateful to R. Schiavon for providing us with a set of synthetic spectra of SSPs and stars, as well as for very interesting discussions. This work was supported in part by a British Council grant within the British/Spanish Joint Research Programme (Acciones Integradas) and by the Spanish Programa Nacional de Astronomía y Astrofísica under grant no AYA2000-974. This work is based on observations at the JKT, INT and WHT on the island of La Palma operated by the Isaac Newton Group at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias., We present a new evolutionary stellar population synthesis model, which predicts spectral energy distributions for single-age single-metallicity stellar populations (SSPs) at resolution 1.5 Angstrom (FWHM) in the spectral region of the near-infrared Ca II triplet feature. The main ingredient of the model is a new extensive empirical stellar spectral library that has been recently presented by Cenarro et al., which is composed of more than 600 stars with an unprecedented coverage of the stellar atmospheric parameters. Two main products of interest for stellar population analysis are presented. The first is a spectral library for SSPs with metallicities -1.7<[Fe/H]<+0.2, a large range of ages (0.1-18 Gyr) and initial mass function (IMF) types. They are well suited to modelling galaxy data, since the SSP spectra, with flux-calibrated response curves, can be smoothed to the resolution of the observational data, taking into account the internal velocity dispersion of the galaxy, allowing the user to analyse the observed spectrum in its own system. We also produce integrated absorption-line indices (namely CaT*, CaT and PaT) for the same SSPs in the form of equivalent widths. We find the following behaviour for the Ca II triplet feature in old-aged SSPs: (i) the strength of the CaT* index does not change much with time for all metallicities for ages larger than similar to3 Gyr; (ii) this index shows a strong dependence on metallicity for values below [M/H]similar to-0.5; and (iii) for larger metallicities this feature does not show a significant dependence either on age or on the metallicity, being more sensitive to changes in the slope of power-like IMF shapes. The SSP spectra have been calibrated with measurements for globular clusters by Armandroff & Zinn, which are well reproduced, probing the validity of using the integrated Ca II triplet feature for determining the metallicities of these systems. Fitting the models to two early-type galaxies of different luminositie, British Council grant within the British/Spanish Joint Research Programme (Acciones Integradas), Spanish Programa Nacional de Astronomía y Astrofísica, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2001 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. We thank Guy Worthey for providing us with a list of candidate stars at the beginning of this project. Ayvur Peletier’s help is acknowledged with the observations and the web page design. AJC acknowledges the hospitality of the Department of Physics (University of Durham) and the School of Physics and Astronomy (University of Nottingham). We also thank S. Pedraz and A. Gil de Paz for helpful suggestions. The JKT, INT and WHT are operated on the island of La Palma by the Royal Greenwich Observatory at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. The Calar Alto Observatory is operated jointly by the Max-Planck Institute für Astronomie, Heidelberg, and the Spanish Comisión Nacional de Astronomía. This research has made use of the Simbad data base (operated at CDS, Strasbourg, France), the NASAs Astrophysics Data System Article Service, and the Hipparcos Input Catalogue. AJC acknowledges the Comunidad de Madrid for a Formación de Personal Investigador fellowship. AV acknowledges the support of the PPARC rolling grant ‘Extragalactic Astronomy and Cosmology in Durham 1998-2002’ and of a British Council grant within the British/Spanish Joint Research Programme (Acciones Integradas). This work was supported by the Spanish Programa Sectorial de Promoción del Conocimiento under grant No. PB96-610., A new stellar library at the near-IR spectral region developed for the empirical calibration of the Ca II triplet and stellar population synthesis modelling is presented. The library covers the range lambda lambda 8348-9020 at 1.5-Angstrom (FWHM) spectral resolution, and consists of 706 stars spanning a wide range in atmospheric parameters. We have defined a new set of near-IR indices, CaT*, CaT and PaT, which mostly overcome the limitations of previous definitions, the former being specially suited for the measurement of the Ca II triplet strength corrected for the contamination from Paschen lines. We also present a comparative study of the new and the previous Ca indices, as well as the corresponding transformations between the different systems. A thorough analysis of the sources of index errors and the procedure to calculate them is given. Finally, index and error measurements for the whole stellar library are provided together with the final spectra., PPARC rolling grant ‘Extragalactic Astronomy and Cosmology, British Council, British/Spanish Joint Research Programme (Acciones Integradas), Spanish Programa Sectorial de Promoción del Conocimiento, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2010 The Authors © 2010 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. We are indebted to the Padova group for making available their isochrone calculations. We are grateful to P. Coelho, J. L. Cervantes, I. G. de la Rosa, M. Koleva, E. Ricciardelli and J. González Hernández for very useful discussions. We would also like to thank J. A. Pérez Prieto for helping us in the construction of the web page for the models. We thank the referee for pointing out relevant aspects that were useful for improving the original manuscript. The MILES library was observed at the INT on the island of La Palma, operated by the Isaac Newton Group at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This research has made an extensive use of the SIMBAD data base ( operated at CDS, Strasbourg, France), the NASA's Astrophysics Data System Article Service and the Hipparcos Input Catalogue. PSB acknowledges the support of a Marie Curie Intra-European Fellowship within the 6th European Community Framework Programme. JFB acknowledges support from the Ramón y Cajal Program financed by the Spanish Ministry of Science and Innovation. AJC is a Ramón y Cajal Fellow of the Spanish Ministry of Science and Innovation. This work has been supported by the Programa Nacional de Astronomía y Astrofísica of the Spanish Ministry of Science and Innovation under grants AYA2007-67752-C03-01, AYA2007-67752-C03-02 and AYA2006-15698-C02-02., We present synthetic spectral energy distributions (SEDs) for single-age, single-metallicity stellar populations (SSPs) covering the full optical spectral range at moderately high resolution [full width at half-maximum (FWHM) = 2.3 A]. These SEDs constitute our base models, as they combine scaled-solar isochrones with an empirical stellar spectral library [Medium resolution INT Library of Empirical Spectra (MILES)], which follows the chemical evolution pattern of the solar neighbourhood. The models rely as much as possible on empirical ingredients, not just on the stellar spectra, but also on extensive photometric libraries, which are used to determine the transformations from the theoretical parameters of the isochrones to observational quantities. The unprecedented stellar parameter coverage of the MILES stellar library allowed us to safely extend our optical SSP SED predictions from intermediate- to very-old-age regimes and the metallicity coverage of the SSPs from super-solar to [M/H] = -2.3. SSPs with such low metallicities are particularly useful for globular cluster studies. We have computed SSP SEDs for a suite of initial mass function shapes and slopes. We provide a quantitative analysis of the dependence of the synthesized SSP SEDs on the (in)complete coverage of the stellar parameter space in the input library that not only shows that our models are of higher quality than those of other works, but also in which range of SSP parameters our models are reliable. The SSP SEDs are a useful tool to perform the analysis of stellar populations in a very flexible manner. Observed spectra can be studied by means of full spectrum fitting or by using line indices. For the latter, we propose a new line index system to avoid the intrinsic uncertainties associated with the popular Lick/IDS system and provide more appropriate, uniform, spectral resolution. Apart from constant resolution as a function of wavelength, the system is also based on flux-calibrated spectra. Dat, Spanish Ministry of Science and Innovation, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2009. The American Astronomical Society. The authors acknowledge the referee, Bahram Mobasher, for his useful comments. E. M.-Q. acknowledges the SMES for a FPI PhD fellowship. This work has been partially supported by the SMES through the research project AYA2007-67752-C0301. N. C. also acknowledges financial support from the research project AYA2006-15698-C02-02. P. S.-B. acknowledges the financial support from a Marie Curie European Reintegration Grant within the 7th European Community Framework Programme., The study of stellar populations in early-type galaxies in different environments is a powerful tool for constraining their star formation histories. This study has been traditionally restricted to the optical range, where dwarfs around the turn-off and stars at the base of the red giant branch dominate the integrated light at all ages. The near-infrared spectral range is especially interesting since in the presence of an intermediate-age population, asymptotic giant branch stars are the main contributors. In this Letter, we measure the near-infrared indices Na I and D(CO) for a sample of 12 early-type galaxies in low-density environments and compare them with the Fornax galaxy sample presented by Silva et al.. The analysis of these indices in combination with Lick/IDS indices in the optical range reveals that (1) the Na I index is a metallicity indicator as good as C4668 in the optical range, and (2) D(CO) is a tracer of intermediate-age stellar populations. We find that low-mass galaxies in low-density environments show higher Na I and D(CO) than those located in the Fornax cluster, which points toward a late stage of star formation for the galaxies in less dense environments, in agreement with results from other studies using independent methods., SMES, Marie Curie European Reintegration Grant, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2004. The American Astronomical Society. All rights reserved. The authors are indebted to the referee, S. M. Faber, for useful comments and suggestions. A. J. C. acknowledges financial support from a Universidad Complutense de Madrid Fundación del Amo Fellowship. The William Herschel Telescope is operated on the island of La Palma by the Royal Greenwich Observatory at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This work was supported by the Spanish research project AYA2003-01840., We present measurements of the Ca II triplet and the Ca4227 Lick index for a sample of early-type galaxies in the Coma Cluster, deriving, for the first time, their corresponding relationships with velocity dispersion. Compared with a similar subsample of elliptical galaxies in the field, Coma galaxies with velocity dispersions in the range approximate to180-270 km s(-1) exhibit significant differences in the strengths of the Ca features, suggesting an influence of the environment on the star formation histories of these galaxies. We argue that the main scenarios previously proposed to explain the relatively low Ca II triplet of galaxies are not able by themselves to simultaneously reconcile the strengths of the two Ca indices in both environments., Universidad Complutense de Madrid, Fundación del Amo, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Astrophysical surveys rely heavily on the classification of sources as stars, galaxies, or quasars from multiband photometry. Surveys in narrow-band filters allow for greater discriminatory power, but the variety of different types and redshifts of the objects present a challenge to standard template-based methods. In this work, which is part of a larger effort that aims at building a catalogue of quasars from the miniJPAS survey, we present a machine learning-based method that employs convolutional neural networks (CNNs) to classify point-like sources including the information in the measurement errors. We validate our methods using data from the miniJPAS survey, a proof-of-concept project of the Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS) collaboration covering ∼1 deg2 of the northern sky using the 56 narrow-band filters of the J-PAS survey. Due to the scarcity of real data, we trained our algorithms using mocks that were purpose-built to reproduce the distributions of different types of objects that we expect to find in the miniJPAS survey, as well as the properties of the real observations in terms of signal and noise. We compare the performance of the CNNs with other well-established machine learning classification methods based on decision trees, finding that the CNNs improve the classification when the measurement errors are provided as inputs. The predicted distribution of objects in miniJPAS is consistent with the putative luminosity functions of stars, quasars, and unresolved galaxies. Our results are a proof of concept for the idea that the J-PAS survey will be able to detect unprecedented numbers of quasars with high confidence.

In this series of papers, we employ several machine learning (ML) methods to classify the point-like sources from the miniJPAS catalogue, and identify quasar candidates. Since no representative sample of spectroscopically confirmed sources exists at present to train these ML algorithms, we rely on mock catalogues. In this first paper, we develop a pipeline to compute synthetic photometry of quasars, galaxies, and stars using spectra of objects targeted as quasars in the Sloan Digital Sky Survey. To match the same depths and signal-to-noise ratio distributions in all bands expected for miniJPAS point sources in the range 17.5 ≤ r < 24, we augment our sample of available spectra by shifting the original r-band magnitude distributions towards the faint end, ensure that the relative incidence rates of the different objects are distributed according to their respective luminosity functions, and perform a thorough modelling of the noise distribution in each filter, by sampling the flux variance either from Gaussian realizations with given widths, or from combinations of Gaussian functions. Finally, we also add in the mocks the patterns of non-detections which are present in all real observations. Although the mock catalogues presented in this work are a first step towards simulated data sets that match the properties of the miniJPAS observations, these mocks can be adapted to serve the purposes of other photometric surveys.