Results for "J. A. Caballero"

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A TGAS/Gaia DR1 parallactic distance to the sigma Orionis clusterFeb 20 2017With the new Tycho-Gaia Astrometric Solution, I derive a new parallactic distance to the young sigma Orionis open cluster, which is a cornerstone region for studying the formation and evolution of stars and substellar objects from tens of solar masses ... More
(Sub-)stellar variability: from 20 M$_{\odot}$ to 13 M$_{\rm Jup}$Apr 20 2016Massive early-type stars vary; low-mass late-type brown dwarfs vary, too. I will make a short, but illustrative, summary of my previous studies on stellar and sub-stellar photometric variability (including the discovery of the most variable brown dwarf ... More
The brightest stars of the sigma Orionis clusterJan 03 2007Context: The very young sigma Orionis cluster (about 3 Ma) is a cornerstone for the understanding of the formation of stars and substellar objects down to planetary masses. However, its stellar population is far to be completely known. Aims: This study ... More
Gaia and brown dwarfs from SpainAug 11 2014Gaia will not observe 50000 brown dwarfs, but about 100 times less. However, these <~ 500 brown dwarfs will be benchmarks for many substellar topics. It is possible to identify them in advance and make the list public to all astronomers worldwide through ... More
General study of superscaling in quasielastic $(e,e')$ and $(ν,μ)$ reactions using the relativistic impulse approximationApr 10 2006Jun 27 2006The phenomenon of superscaling for quasielastic lepton induced reactions at energies of a few GeV is investigated within the framework of the relativistic impulse approximation. A global analysis of quasielastic inclusive electron and charged-current ... More
Ultra low-mass star and substellar formation in sigma OrionisNov 07 2005The nearby young sigma Orionis cluster (~360 pc, ~3 Ma) is becoming one of the most important regions for the study of ultra low-mass star formation and its extension down to the mass regimes of the brown dwarfs and planetary-mass objects. Here, I introduce ... More
Stellar and substellar mass function of the young open cluster candidates Alessi 5 and beta MonocerotisNov 03 2010Although the stellar and substellar populations have been studied in various young and old open clusters, additional studies in clusters in the age range from 5 to 100 Myr is crucial (e.g. to give more constrains on initial mass function variation with ... More
A revisit to agglomerates of early-type Hipparcos starsJul 06 2008We study the spatial structure and sub-structure of regions rich in Hipparcos stars with blue B_T-V_T colours. These regions, which comprise large stellar complexes, OB associations, and young open clusters, are tracers of on-going star formation in the ... More
Cool dwarfs in wide multiple systems: Paper 2: A distant M8.5V companion to HD 212168 ABMar 19 2012DENIS J222644.3-750342 is a nearby, very-low-mass, M8.5 V-type star that has been repeatedly targeted by kinematic and activity studies. Thought to be an isolated star, it is actually a wide common-proper-companion at 265 arcsec from the bright G0 V Hipparcos ... More
Young stars and brown dwarfs surrounding Alnilam (eps Ori) and Mintaka (del Ori)Apr 14 2008Aims: We look for new regions for the search of substellar objects. Methods: Two circular areas, 45 arcmin-radius each, centred on the young massive star systems Alnilam and Mintaka in the Orion Belt, have been explored. The regions are very young (less ... More
Music and AstronomyOct 11 2008Oct 16 2008What do Brian May (the Queen's lead guitarist), William Herschel and the Jupiter Symphony have in common? And a white dwarf, a piano and Lagartija Nick? At first glance, there is no connection between them, nor between Music and Astronomy. However, there ... More
New deep XMM-Newton observations to the west of the sigma Orionis clusterSep 05 2008Aims: The objective of this study is to determine the general X-ray properties of the young stars in the external regions of the sigma Orionis cluster (tau ~ 3 Ma, d ~ 385 pc) and yield constraints on the X-ray emission of brown dwarfs. Methods: We carried ... More
Strangeness on the nucleonJan 24 2014Observables from parity violation in elastic electron-nucleon scattering and neutral current quasi-elastic neutrino-nucleus scattering are employed as tools to improve the current knowledge on the strangeness content in the nucleon.
Cool dwarfs in wide multiple systems. Paper 4: a common-proper-motion pair of two identical mid-M dwarfs separated by about 10000 AUJul 22 2012LSPM J0651+1843 and LSPM J0651+1845 are two high-proper-motion stars recently claimed to form a binary system, FMR 83, by Rica (2012). Here we characterize the system in detail, using astrometric and photometric data, and find that the pair consists of ... More
Music and astronomy. II. unitedsoundsofcosmosNov 18 2016We have been congratulated on the stage by a Nobel laureate (he was our curtain raiser), played our music in planetariums, museums, observatories throughout Spain and at the end of the meeting of the ESO telescopes time allocation committee, shocked audiences ... More
HRC-I/Chandra X-ray observations towards sigma OrionisJun 21 2010Aims: We investigated the X-ray emission from young stars and brown dwarfs in the sigma Orionis cluster (tau~3 Ma, d~385 pc) and its relation to mass, presence of circumstellar discs, and separation to the cluster centre by taking advantage of the superb ... More
Contamination by field late-M, L and T dwarfs in deep surveysMay 29 2008Jun 01 2008Context: Deep photometric surveys for substellar objects in young clusters and for high-redshift quasars are affected by contaminant sources at different heliocentric distances.If not correctly taken into account, the contamination may have a strong effect ... More
Analysis of Meson Exchange and Isobar Currents in (e,e'p) Reactions from O-16Apr 12 1999Apr 13 1999An analysis of the effects of meson exchange and isobar currents in exclusive (e,e'p) processes from O-16 under quasi-free kinematics is presented. A model that has probed its feasibility for inclusive quasi-elastic (e,e') processes is considered. Sensitivity ... More
Uncorrelated scattering approximation revisitedMay 21 2004May 24 2004The formalism to describe the scattering of a weakly bound projectile nucleus by a heavy target is investigated, using the Uncorrelated Scattering Approximation. The main assumption involved is to neglect the correlation between the fragments of the projectile ... More
One dimensional scattering of a two body interacting system by an infinite wallOct 24 2010The one-dimensional scattering of a two body interacting system by an infinite wall is studied in a quantum-mechanical framework. This problem contains some of the dynamical features present in the collision of atomic, molecular and nuclear systems. The ... More
Uncorrelated scattering approximation for the scattering and break-up of weakly bound nuclei on heavy targetsMay 07 2001The scattering of a weakly bound (halo) projectile nucleus by a heavy target nucleus is investigated. A new approach, called the Uncorrelated Scattering Approximation, is proposed. The main approximation involved is to neglect the correlation between ... More
Skewed recoil polarization in (e,e'p) reactions from polarized nucleiNov 11 2004The general formalism describing $\vec{A}(\vec{e},e'\vec{p})B$ reactions, involving polarization of the electron beam, target and ejected proton, is presented within the framework of the relativistic plane wave impulse approximation for medium and heavy ... More
A third massive star component in the σ Orionis AB systemAug 23 2011We report on the detection of a third massive star component in the \sigma\ Orionis AB system, traditionally considered as a binary system. The system has been monitored by the IACOB spectroscopic survey of Northern Massive stars program, obtaining 23 ... More
Relativistic descriptions of quasielastic charged-current neutrino-nucleus scattering: application to scaling and superscaling ideasMar 03 2011May 20 2011The analysis of the recent experimental data on charged-current neutrino-nucleus scattering cross sections measured at MiniBooNE requires fully relativistic theoretical descriptions also accounting for the role of final state interactions. In this work ... More
Induced Nucleon Polarization and Meson-Exchange Currents in (e,e'p) ReactionsFeb 02 2004May 11 2004Nucleon recoil polarization observables in $(e,e'\vec{p})$ reactions are investigated using a semi-relativistic distorted-wave model which includes one- and two-body currents with relativistic corrections. Results for the induced polarization asymmetry ... More
Meson Exchange Currents in (e,e'p) recoil polarization observablesMay 26 2003Jul 31 2003A study of the effects of meson-exchange currents and isobar configurations in $A(\vec{e},e'\vec{p})B$ reactions is presented. We use a distorted wave impulse approximation (DWIA) model where final-state interactions are treated through a phenomenological ... More
An Aladin-based search for proper-motion companions to young stars in the Local Association, Tucana-Horologium and beta PictorisJan 20 2012We have used the Aladin sky atlas of the Virtual Observatory to look for new common proper-motion pairs in three young stellar kinematic groups: Local Association (~10-120 Ma), Tucana-Horologium (~30 Ma) and ? Pictoris (~12 Ma). We have found 9 new and ... More
Generalized scattering-matrix approach for magneto-optics in periodically patterned multilayer systemsFeb 07 2012We present here a generalization of the scattering-matrix approach for the description of the propagation of electromagnetic waves in nanostructured magneto-optical systems. Our formalism allows us to describe all the key magneto-optical effects in any ... More
Analysis of the MINERvA antineutrino double-differential cross sections within the SuSAv2-MEC modelJul 27 2018Oct 16 2018We compare the results of the SuSAv2 model including meson-exchange currents (MEC) with the recent measurement of the quasielastic-like double differential antineutrino cross section on hydrocarbon performed by the MINERvA Collaboration. The relativistic ... More
Parity violation and dynamical relativistic effects in $(\vec{e},e'N)$ reactionsJan 17 2015It is well known that coincidence quasielastic $(\vec{e},e'N)$ reactions are not appropriate to analyze effects linked to parity violation due the presence of the fifth electromagnetic (EM) response $R^{TL'}$. Nevertheless, in this work we develop a fully ... More
Cool dwarfs in wide multiple systems. Paper 6: A curious quintuple system of a compact Sun-like triple and a close pair of an M dwarf and a very cool white dwarf at a wide separationAug 17 2018The system WDS 16329+0315 is an old, nearby quintuple physical system in the thick Galactic disc formed by a close-resolved, triple primary of solar metallicity, namely HD 149162, and a very wide, common proper motion, secondary pair, formed by the mid-M ... More
Wide sigma Orionis binaries resolved by UKIDSSJul 03 2017In spite of its importance for the study of star formation at all mass domains, the nearby young sigma Orionis cluster still lacks a comprehensive survey for multiplicity. We try to fill that observational gap by looking for wide resolved binaries with ... More
Identification of blue high proper motion objects in the Tycho-2 and 2MASS catalogues using Virtual Observatory toolsSep 17 2010May 23 2011With available Virtual Observatory tools, we looked for new bright blue high proper motion objects in the entire sky: white dwarfs, hot subdwarfs, runaway OB stars, and early-type stars in nearby young moving groups. We performed an all-sky cross-match ... More
Global analysis of parity-violating asymmetry data for elastic electron scatteringMar 20 2014Jul 18 2014We perform a statistical analysis of the full set of parity-violating asymmetry data for elastic electron scattering including the most recent high precision measurement from $Q$-weak. Given the basis of the present analysis, our estimates appear to favor ... More
Using electron scattering to constrain the axial-vector form factorJan 16 2015We present an analysis of elastic and quasielastic parity-violating (PV) electron scattering processes. These reactions can help to constrain the weak neutral current form factors of the nucleon that play an essential role in the description of neutrino ... More
Cool dwarfs in wide multiple systems. Paper 5: New astrometry of 54 wide pairs with M dwarfsJan 21 2015We investigate the membership in double, triple or higher-order-multiplicity systems of 54 pairs with at least one bright M dwarf in the solar neighbourhood. These M dwarfs are potential targets of radial-velocity surveys for exoplanets. We measure angular ... More
Parity Violation in Elastic Electron-Nucleon Scattering: Strangeness Content in the NucleonNov 29 2011Oct 05 2012Parity violation in elastic electron-nucleon scattering is studied with the basic goal of improving the understanding of electroweak hadronic structure with special emphasis on the strangeness content in the nucleon. Models for the parity-violating (PV) ... More
Kinematical relativistic effects in $(\vec{e},e'\vec{N})$ reactionsJan 03 2002Apr 05 2002Kinematical relativistic effects are analyzed within the plane-wave impulse approximation for outgoing nucleon polarized responses in coincidence electron scattering. Following recent approaches for non-relativistic reductions of the electromagnetic current ... More
The high-energy emission from GX 339-4 as seen with INTEGRAL and XMM-NewtonDec 07 2008GX 339--4 is a well-known microquasar. In this contribution we show the obtained results with the INTEGRAL and XMM-Newton observatories of the outburst undertaken on 2007. The observations cover spectral evolution from the hard, soft intermediate states ... More
Rubidium resonant squeezed light from a diode-pumped optical-parametric oscillatorJul 27 2008We demonstrate a diode-laser-pumped system for generation of quadrature squeezing and polarization squeezing. Due to their excess phase noise, diode lasers are challenging to use in phase-sensitive quantum optics experiments such as quadrature squeezing. ... More
Parity violation in quasielastic electron-nucleus scattering within the relativistic impulse approximationJan 17 2015We study parity violation in quasielastic (QE) electron-nucleus scattering using the relativistic impulse approximation. Different fully relativistic approaches have been considered to estimate the effects associated with the final-state interactions. ... More
Kinematical versus dynamical relativistic effects in A(\vec{e},e'\vec{p})BJul 30 2001The relativistic mean field approach is applied to the description of coincidence $A(e,e'p)B$ reactions where both the incident electron beam and knockout proton are polarized. Effects introduced by the dynamical enhancement of the lower components of ... More
RPWIA analysis of dynamical relativistic contributions in $^{16}O(\vec{e},e'\vec{p})$ reactionsJan 03 2002Apr 05 2002Coincidence scattering of polarized electrons from nuclei with polarization transfer to outgoing nucleons is studied within the context of relativistic mean field theory. Effects introduced by the dynamical enhancement of the lower components of the bound ... More
X-ray pulsars: a reviewJun 14 2012Accreting X-ray pulsars are among the most luminous objects in the X-ray sky. In highly magnetized neutron stars (B~10^12 G), the flow of matter is dominated by the strong magnetic field. The general properties of accreting X-ray binaries are presented, ... More
Stellar multipilicity in the σ Orionis cluster: a reviewAug 10 2014The nearby, young, extinction-free {\sigma} Orionis cluster is acknowledged as a cornerstone for studying the stellar and substellar formation and evolution, especially at very low masses. However, the relatively limited knowledge of multiplicity in the ... More
Gaia and sigma Orionis from 20 Msol to 3 MJup: the most complete and precise Initial Mass Function with a parallax determination?Dec 03 2011The sigma Orionis cluster is to date the star-forming region with the largest number of confirmed brown dwarfs and substellar objects below the deuterium burning mass limit. The most massive star, sigma Ori Aa, just in the cluster centre, is the \sim20Msol-mass ... More
Reaching the boundary between stellar kinematic groups and very wide binaries. The Washington Double Stars with the widest angular separationsAug 19 2009Aims. I look for and characterise very wide binaries and multiple systems with projected physical separations larger than s = 0.1 pc, which is generally believed to be a sharp upper limit to the distribution of wide binay semimajor axes. Methods. I investigated ... More
Stars and brown dwarfs, spatial distribution, multiplicity, X-rays, discs, and the complete mass function of the sigma Orionis clusterOct 11 2008The young sigma Orionis cluster in the Orion Belt is an incomparable site for studying the formation and evolution of high-mass, solar-like, and low-mass stars, brown dwarfs, and substellar objects below the deuterium burning mass limit. The first version ... More
Parallactic distances and proper motions of virtually all stars in the sigma Orionis cluster or: How I learned to get the most out of TOPCAT and love Gaia DR2May 14 2018May 18 2018Parallactic distances and proper motions of virtually all stars in the sigma Orionis cluster or: How I learned to get the most out of TOPCAT and love Gaia DR2
Formation, evolution and multiplicity of brown dwarfs and giant exoplanetsOct 11 2008This proceeding summarises the talk of the awardee of the Spanish Astronomical Society award to the the best Spanish thesis in Astronomy and Astrophysics in the two-year period 2006-2007. The thesis required a tremendous observational effort and covered ... More
Reaching the boundary between stellar kinematic groups and very wide binaries. II. alpha Lib + KU Lib: a common proper motion system in Castor separated by 1.0 pcJan 29 2010Feb 22 2010Aims: I investigate the gravitational binding of a nearby common proper motion system in the young Castor moving group (tau ~ 200 Ma), formed by the bright quadruple star alpha Lib (Zubenelgenubi) and the young solar analog KU Lib. The system has an exceptionally ... More
From 1000 AU to 1000 pc: high proper-motion stars in the solar neighbourhood, radio sources in the sigma Orionis cluster, and new X-ray stars surrounding AlnilamJan 18 2009Jan 20 2009The Virtual Observatory is useful. I summarise some of my works where I extensively use the Aladin sky atlas. Topics cover from the search and common proper motion confirmation of very low-mass stars and brown dwarfs in wide (rho > 1000 AU) binaries and ... More
A near-infrared/optical/X-ray survey in the centre of sigma OrionisMay 07 2007Because of the intense brightness of the OB-type multiple star system sigma Ori, the low-mass stellar and substellar populations close to the centre of the very young sigma Orionis cluster is poorly know. I present an IJHKs survey in the cluster centre, ... More
Cool dwarfs in wide multiple systems: Paper I: Two mid-M dwarfs in a loosely-bound common-proper-motion pairDec 03 2011Mar 19 2012This is the first of a series of works devoted to investigate cool dwarfs in wide multiple systems. Here, I present Koenigstuhl 4 A and B, two bright, intermediate M dwarfs with a common high proper-motion and separated by 299 arcsec. At the most probable ... More
Spatial distribution of stars and brown dwarfs in sigma OrionisOct 05 2007I have re-visited the spatial distribution of stars and high-mass brown dwarfs in the sigma Orionis cluster (~3 Ma, ~360 pc). The input was a catalogue of 340 cluster members and candidates at separations less than 30 arcmin to sigma Ori AB. Of them, ... More
Stars and brown dwarfs in the sigma Orionis cluster. II. A proper motion studyJan 20 2010Feb 22 2010Aims: I seek to fully know the stellar and substellar populations in the young sigma Orionis open cluster, which is a benchmark for star-forming studies. Because of the very low proper motion of the cluster, late-type dwarfs with appreciable proper motion ... More
Dynamical parallax of sigma Ori AB: mass, distance and ageOct 18 2007The massive OB-type binary sigma Ori AB is in the centre of the very young sigma Orionis cluster. I have computed the most probable distances and masses of the binary for several ages using a dynamical parallax-like method. It incorporates the BVRIH-band ... More
The widest ultracool binaryDec 08 2006Aims: I test the ejection scenario of formation of brown dwarfs and very low-mass stars through the detection of a very wide ultracool binary. Methods: LEHPM 494 (M6.0 +/- 1.0 V) and DENIS-P J0021.0-4244 (M9.5 +/- 0.5 V) are separated by 1.3 arcmin and ... More
A review on substellar objects beyond the deuterium burning mass limit: planets, brown dwarfs or what?Aug 23 2018"Free-floating, non-deuterium-burning, substellar objects" are isolated bodies of a few Jupiter masses found in very young open clusters and associations, nearby young moving groups and in the immediate vicinity of the Sun. They are neither brown dwarfs ... More
The occultation events of the Herbig Ae/Be star V1247 OriFeb 22 2010Aims: I study new deep (DeltaV ~ 1.20-1.65 mag) occultation events of the delta Scuti, Herbig Ae/Be star V1247 Ori in the Ori OB1 b association. Methods: I use the V-band ASAS light curve of V1247 Ori, which covers the last nine years, together with photometric ... More
Stars and brown dwarfs in the sigma Orionis cluster: the Mayrit catalogueOct 31 2007The young sigma Orionis cluster is an indispensable basis for understanding the formation and evolution of stars, brown dwarfs and planetary-mass objects. Our knowledge of its stellar population is, however, incomplete. I present the Mayrit catalogue, ... More
Recent Developments in relativistic models for exclusive (e,e'p) reactionsSep 26 2001A comparison of impulse approximation calculations for the (e,e'p) reaction, based on the Dirac equation and the Schrodinger one is presented. Trivial (kinematics) differences are indicated, as well as how to remove them from the standard nonrelativistic ... More
Superscaling and Charge-changing Neutrino Cross SectionsSep 09 2005Sep 12 2005The superscaling function extracted from inclusive electron scattering data is used to predict high energy charge-changing neutrino cross sections in the quasi-elastic and $\Delta$ regions.
Using Electron Scattering Superscaling to predict Charge-changing Neutrino Cross Sections in NucleiSep 30 2004Dec 06 2004Superscaling analyses of few-GeV inclusive electron scattering from nuclei are extended to include not only quasielastic processes, but now also into the region where $\Delta$-excitation dominates. It is shown that, with reasonable assumptions about the ... More
Relativistic pionic effects in quasielastic electron scatteringJun 15 2001The impact of relativistic pionic correlations and meson-exchange currents on the response functions for electromagnetic quasielastic electron scattering from nuclei is studied in detail. Results in first-order perturbation theory are obtained for one-particle ... More
Relativistic effects in electromagnetic nuclear responses in the quasi-elastic delta regionMay 18 1999A new non-relativistic expansion in terms of the nucleon's momentum inside nuclear matter of the current for isobar electro-excitation from the nucleon is performed. Being exact with respect to the transferred energy and momentum, this yields new current ... More
Relativistic Effects in Electromagnetic Meson-Exchange Currents for One-Particle Emission ReactionsJun 04 1998Oct 26 1998Following recent studies of non-relativistic reductions of the single-nucleon electromagnetic current operator, here we extend the treatment to include meson exchange current operators. We focus on one-particle emission electronuclear reactions. In contrast ... More
Preliminary results on a Virtual Observatory search for companions to Luyten starsOct 11 2008The Aladin sky atlas of the Virtual Observatory has shown to be a powerful and easy-handling tool for the discovery, confirmation, and characterisation of high proper-motion, multiple stellar systems of large separation in the solar vicinity. Some of ... More
Relativistic models for electron and neutrino-nucleus scatteringSep 03 2009Relativistic models developed for the exclusive and inclusive quasielastic (QE) electron scattering have been extended to charged-current (CC) and neutral-current (NC) neutrino-nucleus scattering. Different descriptions of final-state interactions (FSI) ... More
Relativistic mean field approximation to the analysis of 16O(e,e'p)15N data at |Q^2|\leq 0.4 (GeV/c)^2Jan 18 2001May 30 2001We use the relativistic distorted wave impulse approximation to analyze data on 16O(e,e'p)15N at |Q^2|\leq 0.4 (GeV/c)^2 that were obtained by different groups and seemed controversial. Results for differential cross-sections, response functions and A_TL ... More
Momentum distribution of relativistic nuclei with Hartree-Fock mesonic correlationsJun 05 2002Sep 26 2002The impact of Hartree-Fock correlations on the nuclear momentum distribution is studied in a fully relativistic one boson exchange model. Hartree-Fock equations are exactly solved to first order in the coupling constants. The renormalization of the Dirac ... More
Consistent one-pion exchange currents in electron scattering from a relativistic Fermi gasJul 26 2001A set of fully relativistic one-pion-exchange electromagnetic operators is developed for use in one-particle emission reactions induced by electrons. To preserve the gauge invariance of the theory additional pionic correlation operators are required beyond ... More
Relativistic Models of Quasielastic Electron and Neutrino-Nucleus ScatteringOct 06 2009Relativistic models developed for the exclusive and inclusive quasielastic (QE) electron scattering have been extended to charged-current (CC) and neutral-current (NC) neutrino-nucleus scattering. Different descriptions of final-state interactions (FSI) ... More
Gauge and Lorentz invariant one-pion exchange currents in electron scattering from a relativistic Fermi gasApr 01 2002A consistent analysis of relativistic pionic correlations and meson-exchange currents for electroweak quasielastic electron scattering from nuclei is carried out. Fully-relativistic one-pion-exchange electromagnetic operators are developed for use in ... More
Nuclear transparencies in relativistic A(e,e'p) modelsJan 20 2004Relativistic and unfactorized calculations for the nuclear transparency extracted from exclusive A(e,e'p) reactions for 0.3 \leq Q^2 \leq 10 (GeV/c)^2 are presented for the target nuclei C, Si, Fe and Pb. For Q^2 \geq 0.6 (GeV/c)^2, the transparency results ... More
Relativistic analyses of quasielastic neutrino cross sections at MiniBooNE kinematicsApr 28 2011Two relativistic approaches are considered to evaluate the quasielastic double-differential and integrated neutrino-nucleus cross sections. One, based on the relativistic impulse approximation, relies on the microscopic description of nuclear dynamics ... More
Relativistic Models for Quasi-Elastic Neutrino-Nucleus ScatteringAug 25 2011Two relativistic approaches to charged-current quasielastic neutrino-nucleus scattering are illustrated and compared: one is phenomenological and based on the superscaling behavior of electron scattering data and the other relies on the microscopic description ... More
Cool dwarfs in wide multiple systems. Paper 3: Two common-proper-motion, late-type stars separated by over 11 arcminMay 24 2012LP 209-28 and LP 209-27 have similar proper motions as tabulated by several catalogues. Using seven astrometric epochs spanning 59 years, we confirm a common tangential velocity by measuring a constant angular separation of rho = 666.62+/-0.09 arcsec. ... More
Scaling and isospin effects in quasielastic lepton-nucleus scattering in the Relativistic Mean Field ApproachMay 10 2007The role of isospin in quasielastic electron scattering and charge-changing neutrino reactions is investigated in the relativistic impulse approximation. We analyze proton and neutron scaling functions making use of various theoretical descriptions for ... More
Final-state interactions and superscaling in the semi-relativistic approach to quasielastic electron and neutrino scatteringDec 13 2006The semi-relativistic approach to electron and neutrino quasielastic scattering from nuclei is extended to include final-state interactions. Starting with the usual non-relativistic continuum shell model, the problem is relativized by using the semi-relativistic ... More
Quaiselastic scattering from relativistic bound nucleons: Transverse-Longitudinal responseMay 14 1999Jun 07 1999Predictions for electron induced proton knockout from the $p_{1/2}$ and $p_{3/2}$ shells in $^{16}$O are presented using various approximations for the relativistic nucleonic current. Results for the differential cross section, transverse-longitudinal ... More
Delta-isobar relativistic meson exchange currents in quasielastic electron scatteringJan 08 2003Mar 24 2003We study the role of the $\Delta$-isobar current on the response functions for high energy inclusive quasielastic electron scattering from nuclei. We consider a general Lagrangian which is compatible with contact invariance and perform a fully relativistic ... More
The IBIS / ISGRI Source Location AccuracyFeb 27 2013We present here results on the source location accuracy of the INTEGRAL IBIS/ISGRI coded mask telescope, based on ten years of INTEGRAL data and on recent developments in the data analysis procedures. Data were selected and processed with the new Off-line ... More
Superscaling analysis of the Coulomb Sum Rule in quasielastic electron-nucleus scatteringDec 22 2009Mar 26 2010The Coulomb sum rule for inclusive quasielastic electron scattering in $^{12}$C, $^{40}$Ca and $^{56}$Fe is analyzed based on scaling and superscaling properties. Results obtained in the relativistic impulse approximation with various descriptions of ... More
Relativistic descriptions of inclusive quasielastic electron scattering: application to scaling and superscaling ideasJun 15 2009An analysis of inclusive quasielastic electron scattering is presented using different descriptions of the final state interactions within the framework of the relativistic impulse approximation. The relativistic Green's function approach is compared ... More
X-ray variability of sigma Orionis young stars with ROSATMar 27 2009We used the Aladin Virtual Obsrvatory tool and High Resolution Imager ROSAT archival data to search for X-ray variability in scale of days in 23 young stars in the sigma Orionis cluster and a background galaxy. Five stars displayed unambiguous flares ... More
Final-State Interactions in the Superscaling Analysis of Neutral-Current Quasielastic Neutrino ScatteringMay 15 2008Effects of strong final-state interactions in the superscaling properties of neutral-current quasielastic neutrino cross sections are investigated using the Relativistic Impulse Approximation as guidance. First- and second-kind scaling are analyzed for ... More
Superscaling in lepton-nucleus scatteringSep 19 2006We suggest that superscaling analyses of few-GeV inclusive electron scattering from nuclei, both in the quasielastic peak and in the region where the $\Delta$-excitation dominates, allow one to make reliable predictions for charge-changing neutrino reactions ... More
Scaling Function and Nucleon Momentum DistributionApr 23 2010Scaling studies of inclusive quasielastic electron scattering reactions have been used in the past as a basic tool to obtain information on the nucleon momentum distribution in nuclei. However, the connection between the scaling function, extracted from ... More
Kinematics of M dwarfs in the CARMENES input catalogue: membership in young moving groupsOct 11 2015We present a detailed study of the kinematics of M dwarfs in the CARMENES (Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrographs) input catalog. We have selected all M dwarfs with known parallactic ... More
Neutral current (anti)neutrino scattering: relativistic mean field and superscaling predictionsOct 23 2012We evaluate the neutral current quasi-elastic neutrino cross section within two nuclear models: the SuSA model, based on the superscaling behavior of electron scattering data, and the RMF model, based on relativistic mean field theory. We also estimate ... More
Near-infrared low-resolution spectroscopy of Pleiades L-type brown dwarfsMay 18 2010May 22 2010The fundamental properties of brown dwarfs evolve with age. Models describing the evolution of luminosities and effective temperatures, among other physical parameters, can be empirically constrained using brown dwarfs of various masses in star clusters ... More
Analysis of factorization in (e,e'p) reactions: A survey of the relativistic plane wave impulse approximationOct 16 1997The issue of factorization within the context of coincidence quasi-elastic electron scattering is reviewed. Using a relativistic formalism for the entire reaction mechanism and restricting ourselves to the case of plane waves for the outgoing proton, ... More
Probing Deformed Orbitals with \vec{A}(\vec{e}, e' N)B reactionsNov 11 1994We present results for response functions and asymmetries in the nuclear reactions 37\vec{Ar}(\vec{e},e'n)36Ar and 37\vec{K}(\vec{e},e' p)36Ar at quasifree kinematics. We compare PWIA results obtained using deformed HF wave functions with PWIA and DWIA ... More
Relativistic versus Nonrelativistic Optical Potentials in A(e,e'p)B ReactionsDec 07 1993Apr 27 1995We investigate the role of relativistic and nonrelativistic optical potentials used in the analysis of ($e,e'p$) data. We find that the relativistic calculations produce smaller ($e,e'p$) cross sections even in the case in which both relativistic and ... More
Spectroscopic Factors in $^{40}$Ca and $^{208}$Pb from $(e,e'p)$: Fully Relativistic AnalysisOct 04 1993We present results for spectroscopic factors of the outermost shells in $^{40}$Ca and $^{208}$Pb, which have been derived from the comparison between the available quasielastic ($e,e'p$) data from NIKHEF-K and the corresponding calculated cross-sections ... More
Pionic correlations and meson-exchange currents in two-particle emission induced by electron scatteringAug 04 2010Two-particle two-hole contributions to electromagnetic response functions are computed in a fully relativistic Fermi gas model. All one-pion exchange diagrams that contribute to the scattering amplitude in perturbation theory are considered, including ... More
Inclusive quasielastic scattering of polarized electrons from polarized nucleiApr 16 1998The inclusive quasielastic response functions that appear in the scattering of polarized electrons from polarized nuclei are computed and analyzed for several closed-shell-minus-one nuclei with special attention paid to 39K. Results are presented using ... More
Reaching the boundary between stellar kinematic groups and very wide binaries. III. Sixteen new stars and eight new wide systems in the beta Pictoris moving groupAug 27 2015Aims. We look for common proper motion companions to stars of the nearby young beta Pictoris moving group. Methods. First, we compiled a list of 185 beta Pictoris members and candidate members from 35 representative works. Next, we used the Aladin and ... More
Relativistic descriptions of final-state interactions in charged-current quasielastic neutrino-nucleus scattering at MiniBooNE kinematicsJul 26 2011The results of two relativistic models with different descriptions of the final-state interactions are compared with the MiniBooNE data of charged-current quasielastic cross sections. The relativistic mean field model uses the same potential for the bound ... More