Results for "P. J. Amado"

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Preparing the COROT space mission: Building a photometric and variability database of stars in its field of viewDec 22 2003The CNES/European space mission COROT will monitor asteroseismic targets located in selected fields to probe stellar interiors. Therefore, suitable candidate targets have to be searched for in order to optimize the scientific return of the mission. However, ... More
New ground-based observational methods and instrumentation for asteroseismologyJan 27 2012Space instrumentation like SOHO, MOST, CoRoT and Kepler has been and is being built to attain very high precision data to be used for asteroseismic analysis. Nonetheless, there is a very strong need for providing additional information, especially on ... More
Searching for $δ$ Scuti-type pulsation and characterising northern pre-main-sequence field starsJul 01 2014A photometric variability study of a sample of northern field stars, which previously classified as either PMS or Herbig Ae/Be objects, has been undertaken with the purpose of detecting {\delta} Scuti-type pulsations. Determination of physical parameters ... More
Coherent Pion Radiation From Nucleon Antinucleon AnnihilationNov 23 1993A unified picture of nucleon antinucleon annihilation into pions emerges from a classical description of the pion wave produced in annihilation and the subsequent quantization of that wave as a coherent state. When the constraints of energy-momentum and ... More
Seismology of beta Cephei stars: differentially-rotating models for interpreting the oscillation spectrum of nu-EridaniNov 10 2008A method for the asteroseismic analysis of beta Cephei stars is presented and applied to the star nu Eridani. The method is based on the analysis of rotational splittings, and their asymmetries using differentially-rotating asteroseismic models. Models ... More
Frequency ratio method for seismic modeling of Gamma Doradus starsNov 08 2004A method for obtaining asteroseismological information of a Gamma Doradus oscillating star showing at least three pulsation frequencies is presented. This method is based on a first-order asymptotic g-mode expression, in agreement with the internal structure ... More
M dwarf search for pulsations within Kepler GO programOct 22 2014We present the analysis of four M dwarf stars -plus one M giant that seeped past our selection criteria- observed in Cycle 3 of Kepler Guest Observer program (GO3) in a search for intrinsic pulsations. Stellar oscillations in M dwarfs were theoretically ... More
Isospin Recoupling and Bose-Einstein Pion Correlations in Nucleon-Antinucleon AnnihilationsOct 25 1994We study the effect of isospin projections on a two source picture of coherent pions coming from nucleon-antinucleon annihilation. We show that important Hanbury-Brown Twiss correlations among like charge pion pairs compared with unlike arise from these ... More
On the relationship of the scaled phase space and Skyrme-coherent state treatments of proton antiproton annihilation at restAug 24 1995We discuss pion multiplicities and single pion momentum spectra from proton antiproton annihilation at rest. Both the scaled phase space model and the Skyrme-coherent state approach describe these observables well. In the coherent state approach the puzzling ... More
Coherent state formulation of pion radiation from nucleon antinucleon annihilationMar 28 1994We assume that nucleon antinucleon annihilation is a fast process leading to a classical coherent pion pulse. We develop the quantum description of such pion waves based on the method of coherent states. We study the consequences of such a description ... More
The theoretical instability strip of M dwarf starsDec 10 2013The overstability of the fundamental radial mode in M dwarf models was theoretically predicted by Rodr\'iguez-L\'opez et al. (2012). The periods were found to be in the ranges ~25-40 min and ~4-8 h, depending on stellar age and excitation mechanism. We ... More
The Frequency Ratio Method for the seismic modelling of gamma Doradus stars. II The role of rotationAug 23 2005The effect of rotation on the Frequency Ratio Method (Moya et al. 2005) is examined. Its applicability to observed frequencies of rotating gamma Doradus stars is discussed taking into account the following aspects: the use of a perturbative approach to ... More
Quartets of superdeformed bands and supersymmetry breakingOct 22 1992We examine the prediction of supersymmetric quantum mechanics that bands with identical gamma-ray energies occur in quartets. The experimental data suggest that this scenario is actually realized in nature. In the $A=150$ mass region, four known pairs ... More
Asteroseismic determination of the physical characteristics of the planetary system host HR\,8799 ($λ$ Bootis nature and age)Mar 26 2010HR\,8799 is a $\lambda$ Bootis, $\gamma$ Doradus star hosting a planetary system and a debris disk with two rings. This makes this system a very interesting target for asteroseismic studies. In particular, this work is devoted to the determination of ... More
Age determination of the HR8799 planetary system using asteroseismologyMar 30 2010Discovery of the first planetary system by direct imaging around HR8799 has made the age determination of the host star a very important task. This determination is the key to derive accurate masses of the planets and to study the dynamical stability ... More
The planetary system host HR\,8799: On its $λ$ Bootis natureMar 17 2010HR\,8799 is a $\lambda$ Bootis, $\gamma$ Doradus star hosting a planetary system and a debris disk with two rings. This makes this system a very interesting target for asteroseismic studies. This work is devoted to the determination of the internal metallicity ... More
The pre-main sequence star HD 34282: A very short period delta Scuti-type pulsatorJun 04 2004HD 34282 has been found to pulsate during a systematic search for short-term photometric variability in Herbig Ae/Be stars with the goal of determining the position and size of the pre-main sequence instability strip. Simultaneous Stromgren photometry ... More
HD 172189: An eclipsing and spectroscopic binary with a Delta Sct-ttype pulsating component in an open clusterJun 03 2005We present a study based on more than 2500 uvby-measurements collected on HD 172189, a new eclipsing binary system with a Delta Sct-type pulsating component that belongs to the open cluster IC 4756. The great interest of this object lies in that three ... More
Flux tube widening in compact U (1) lattice gauge theory computed at T < Tc with the multilevel method and GPUsSep 16 2013We utilize Polyakov loop correlations to study d=3+1 compact U (1) flux tubes and the static electron-positron potential in lattice gauge theory. With the plaquette field operator, in U(1) lattice gauge theory, we probe directly the components of the ... More
Quasiperiodic patterns in $δ$ Scuti stars: an in-depth study of the CoRoT star HD 174966Jan 27 2016In this work, we have gone one step further from the study presented in the first CoRoT symposium. Our analysis consists on constructing a model database covering the entire uncertainty box of the $\delta$ Sct star HD174966, derived from the usual observables ... More
Short-range effects and magnetization reversal in Co$_{80}$Fe$_{20}$ thin films: a MOKE magnetometry/domain imaging and AMR studyJul 19 2005Jul 29 2006A MOKE magnetometry unit simultaneously sensitive to both in-plane magnetization components, based on an intensity differential detection method, allows us to observe the uniaxial anisotropy impressed during CoFe-deposition and to discriminate the magnetization ... More
Discovery and application of Frequency Ratio Method to the new multiperiodic gamma Dor star HD 218427Jan 19 2006gamma Dor-type oscillations have been discovered in the star HD218427 through simultaneous uvby photometric observations carried out in the year 2003. A few Hbeta-Crawford measurements were also collected for calibration purposes which place this star ... More
Comprehensive transient-state study for CARMENES-NIR high thermal stabilityJul 21 2010CARMENES has been proposed as a next-generation instrument for the 3.5m Calar Alto Telescope. Its objective is finding habitable exoplanets around M dwarfs through radial velocity measurements (m/s level) in the near-infrared. Consequently, the NIR spectrograph ... More
On the variability of HD 170699 - a possible COROT targetSep 23 2008We present the analysis of the variability of HD 170699, a COROT star showing the characteristics of a non evolutionary Delta Scuti star with high rotational velocity. There is a clear period of 10.45 c/d with 5.29 mmag amplitude in the y filter. From ... More
CARMENES. I. A radial-velocity survey for terrestrial planets in the habitable zones of M dwarfs. A historical overviewOct 19 2012CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs) is a next generation instrument being built for the 3.5-m telescope at the Calar Alto Observatory by a consortium of eleven ... More
Fano-Rashba effect in quantum dotsMar 05 2008We consider the electronic transport through a Rashba quantum dot coupled to ferromagnetic leads. We show that the interference of localized electron states with resonant electron states leads to the appearance of the Fano-Rashba effect. This effect occurs ... More
Two Skyrmion Dynamics with Omega MesonsSep 17 1999We present our first results of numerical simulations of two skyrmion dynamics using an $\omega$-meson stabilized effective Lagrangian. We consider skyrmion-skyrmion scattering with a fixed initial velocity of $\beta=0.5$, for various impact parameters ... More
Magnetically-driven colossal supercurrent enhancement in InAs nanowire Josephson junctionsJan 12 2016The Josephson effect is a fundamental quantum phenomenon consisting in the appearance of a dissipationless supercurrent in a weak link between two superconducting (S) electrodes. While the mechanism leading to the Josephson effect is quite general, i.e., ... More
MOST observations of the Herbig Ae δ-Scuti star HD 34282Oct 17 2012Oct 19 2012MOST observations and model analysis of the Herbig Ae star HD 34282 (V1366 Ori) reveal {\delta}-Scuti pulsations. 22 frequencies are observed, 10 of which confirm those previously identified by Amado et al. (2006), and 12 of which are newly discovered ... More
Asteroseismology with the WIRE satellite. I. Combining Ground- and Space-based Photometry of the Delta Scuti Star Epsilon CepheiOct 18 2006We have analysed ground-based multi-colour Stromgren photometry and single-filter photometry from the star tracker on the WIRE satellite of the delta scuti star Epsilon Cephei. The ground-based data set consists of 16 nights of data collected over 164 ... More
Efficient scheduling of astronomical observations. Application to the CARMENES radial-velocity surveyJul 19 2017Jun 06 2018Targeted spectroscopic exoplanet surveys face the challenge of maximizing their planet detection rates by means of careful planning. The number of possible observation combinations for a large exoplanet survey, i.e., the sequence of observations night ... More
CoRoT photometry and high-resolution spectroscopy of the interacting eclipsing binary AU MonSep 08 2009Analyses of very accurate CoRoT space photometry, past Johnson V photoelectric photometry and high-resolution \'echelle spectra led to the determination of improved and consistent fundamental stellar properties of both components of AU Mon. We derived ... More
CARMENES input catalogue of M dwarfs II. High-resolution imaging with FastCamAug 29 2016Aims: We search for low-mass companions of M dwarfs and characterize their multiplicity fraction with the purpose of helping in the selection of the most appropriate targets for the CARMENES exoplanet survey. Methods: We obtained high-resolution images ... More
CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOSFeb 26 2015Context. CARMENES is a stabilised, high-resolution, double-channel spectrograph at the 3.5 m Calar Alto telescope. It is optimally designed for radial-velocity surveys of M dwarfs with potentially habitable Earth-mass planets. Aims. We prepare a list ... More
HD 51106 and HD 50747: an ellipsoidal binary and a triple system observed with CoRoTSep 28 2009We present an analysis of the observations of HD 51106 and HD 50747 by the satellite CoRoT, obtained during its initial run, and of the spectroscopic preparatory observations. AIMS: We complete an analysis of the light curve, extract the main frequencies ... More
Multisite photometry of the pulsating Herbig Ae star V346 OriMar 26 2009CONTEXT: The study of pulsation in Pre--Main--Sequence intermediate-mass stars represents an important tool for deriving information on fundamental stellar parameters and internal structure, as well as for testing current theoretical models. Interest ... More
Close-up of primary and secondary asteroseismic CoRoT targets and the ground-based follow-up observationsOct 22 2007Nov 10 2008To optimise the science results of the asteroseismic part of the CoRoT satellite mission a complementary simultaneous ground-based observational campaign is organised for selected CoRoT targets. The observations include both high-resolution spectroscopic ... More
Spectroscopic characterisation of CARMENES target candidates from FEROS, CAFE and HRS high-resolution spectraJul 29 2016CARMENES (Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrographs) started a new planet survey on M-dwarfs in January this year. The new high-resolution spectrographs are operating in the visible ... More
Pulsation spectrum of Delta Sct stars: the binary HD 50870 as seen with CoRoT and HARPSMar 01 2012We present the results obtained with the CoRoT satellite for HD 50870, a Delta Sct star which was observed for 114.4 d. The 307,570 CoRoT datapoints were analysed with different techniques. The photometric observations were complemented over 15 nights ... More
The variability of the CoRoT target HD171834: gamma Dor pulsations and/or activity?Nov 08 2011We present the preliminary results of a frequency and line-profile analysis of the CoRoT gamma Dor candidate HD171834. The data consist of 149 days of CoRoT light curves and a ground-based dataset of more than 1400 high-resolution spectra, obtained with ... More
Asteroseismic analysis of the CoRoT δ-Scuti star HD174936Aug 18 2009We present an analysis of the \delta-Scuti star object HD 174936 (ID 7613) observed by CoRoT during the first short run SRc01 (27 days). A total number of 422 frequencies we are extracted from the light curve using standard prewhitening techniques. This ... More
The double-mode nature of the HADS star GSC 00144-03031 and the Petersen diagram of the classJun 13 2005The double--mode pulsation of GSC 00144-03031 has been detected when searching for COROT targets. A very large dataset composed of 4722 photometric measurements was collected at six observatories in Europe and America. There is no hint of the excitation ... More
High-cadence spectroscopy of M-dwarfs. I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+BApr 18 2016Understanding the sources of instrumental systematic noise is a must to improve the design of future spectrographs. In this study, we alternated observations of the well-suited pair of M-stars GJ 725A+B to delve into the sub-night HARPS-N response. Besides ... More
The CARMENES search for exoplanets around M dwarfs - Photospheric parameters of target stars from high-resolution spectroscopyFeb 08 2018The new CARMENES instrument comprises two high-resolution and high-stability spectrographs that are used to search for habitable planets around M dwarfs in the visible and near-infrared regime via the Doppler technique. Characterising our target sample ... More
Pb/InAs nanowire Josephson junction with high critical current and magnetic flux focusingNov 04 2014Mar 25 2015We have studied mesoscopic Josephson junctions formed by highly $n$-doped InAs nanowires and superconducting Ti/Pb source and drain leads. The current-voltage properties of the system are investigated by varying temperature and external out-of-plane magnetic ... More
The CARMENES search for exoplanets around M dwarfs. Period search in H$α$, Na I D, and Ca II IRT linesJan 16 2019We use spectra from CARMENES, the Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs, to search for periods in chromospheric indices in 16 M0 to M2 dwarfs. We measure spectral indices in ... More
Multiplicity of solutions for fractional Hamiltonian systems with Liouville-Weyl fractional derivativeSep 02 2014In this paper, we investigate the existence of infinitely many solutions for the following fractional Hamiltonian systems: \begin{eqnarray}\label{eq00} _{t}D_{\infty}^{\alpha}(_{-\infty}D_{t}^{\alpha}u(t)) + L(t)u(t) = & \nabla W(t,u(t))\\ u\in H^{\alpha}(\mathbb{R}, ... More
CARMENES input catalogue of M dwarfs IV. New rotation periods from photometric time seriesOct 08 2018Aims. The main goal of this work is to measure rotation periods of the M-type dwarf stars being observed by the CARMENES exoplanet survey to help distinguish radial-velocity signals produced by magnetic activity from those produced by exoplanets. Rotation ... More
The CARMENES search for exoplanets around M dwarfs: Radial-velocity variations of active stars in visual-channel spectraMar 06 2018Previous simulations predicted the activity-induced radial-velocity (RV) variations of M dwarfs to range from $\sim1$ cm/s to $\sim1$ km/s, depending on various stellar and activity parameters. We investigate the observed relations between RVs, stellar ... More
The gamma Dor CoRoT target HD49434. I-Results from the ground-based campaignJul 06 2008Context: We present the results of an extensive ground-based photometric and spectroscopic campaign on the gamma Dor CoRoT target HD49434. This campaign was preparatory to the CoRoT satellite observations, which took place from October 2007 to March 2008. ... More
Ground-based observations of the beta Cephei CoRoT main target HD 180642: abundance analysis and mode identificationJun 19 2009The known beta Cephei star HD 180642 was observed by the CoRoT satellite in 2007. From the very high-precision light curve, its pulsation frequency spectrum could be derived for the first time (Degroote and collaborators). In this paper, we obtain additional ... More
Tuning the electron-phonon coupling in multilayer graphene with magnetic fieldsJul 31 2009Magneto Raman scattering study of the E$_{2g}$ optical phonons in multi-layer epitaxial graphene grown on a carbon face of SiC are presented. At 4.2K in magnetic field up to 33 T, we observe a series of well pronounced avoided crossings each time the ... More
CARMENES input catalogue of M dwarfs: III. Rotation and activity from high-resolution spectroscopic observationsFeb 06 2018CARMENES is a spectrograph for radial velocity surveys of M dwarfs with the aim of detecting Earth-mass planets orbiting in the habitable zones of their host stars. To ensure an optimal use of the CARMENES Guaranteed Time Observations, in this paper we ... More
HD172189: another step in furnishing one of the best laboratories known for asteroseismic studiesSep 18 2009HD172189 is a spectroscopic eclipsing binary system with a rapidly-rotating pulsating delta Scuti component. It is also a member of the open cluster IC4756. These combined characteristics make it an excellent laboratory for asteroseismic studies. To date, ... More
The Delta Scuti star FG Vir. V. The 2002 photometric multisite campaignApr 07 2004A high-accuracy multisite campaign was carried out from 2002 January to May with a photometric coverage of 398 hours at five observatories. The concentration on a few selected sites gives better consistency and accuracy than collecting smaller amounts ... More
Plateau insulator transition in grapheneJul 09 2009Mar 30 2010The quantum Hall effect in a single-layer graphene sample is studied in strong magnetic fields up to 28 T. Our measurements reveal the existence of a metal- insulator transition from filling factor $\nu=-2$ to $\nu=0$. The value of the universal scaling ... More
Preparing the COROT space mission: new variable stars in the galactic Anticenter directionFeb 22 2005The activities related to the preparation of the asteroseismic, photometric space mission COROT are described. Photoelectric observations, wide--field CCD photometry, uvbyB calibrations and further time--series have been obtained at different observatories ... More
The CARMENES search for exoplanets around M dwarfs. Activity indicators at visible and near-infrared wavelengthsJan 25 2019The CARMENES survey is searching for Earth-like planets orbiting M dwarfs using the radial velocity method. Studying the stellar activity of the target stars is important to avoid false planet detections and to improve our understanding of the atmospheres ... More
VSOP: The Variable Star One-shot Project I. Project presentation and first data releaseMay 29 2007The Variable Star One-shot Project (VSOP) is aimed at (1) providing the variability type and spectral type of all unstudied variable stars, (2) process, publish, and make the data available as automatically as possible, and (3) generate serendipitous ... More
The Variable Star One-shot Project, and its little child: WikimbadMay 15 2007The Variable Star One-shot Project (VSOP) aimed at providing to the world-wide stellar community the necessary one-shot spectrum of unstudied variable stars, too often classified as such by an analysis of photometric data only. The VSOP has established ... More
HD 50844: the new look of Delta Sct stars from CoRoT space photometryJun 15 2009It has also been suggested that the detection of a wealth of very low amplitude modes in Delta Sct stars was only a matter of signal--to--noise ratio. Access to this treasure, impossible from the ground, is one of the scientific aims of the space mission ... More
Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicatorsOct 27 2017Context: The CARMENES survey is a high-precision radial velocity (RV) programme that aims to detect Earth-like planets orbiting low-mass stars. Aims: We develop least-squares fitting algorithms to derive the RVs and additional spectral diagnostics implemented ... More
An in-depth study of HD 174966 with CoRoT photometry and HARPS spectroscopy. Large separation as a new observable for δSct starsJul 10 2013The aim of this work was to use a multi-approach technique to derive the most accurate values possible of the physical parameters of the \delta Sct star HD174966. In addition, we searched for a periodic pattern in the frequency spectra with the goal of ... More
The CARMENES search for exoplanets around M dwarfs: Wing asymmetries of H$α$, Na I D, and He I linesJan 31 2018Stellar activity is ubiquitously encountered in M dwarfs and often characterised by the H$\alpha$ line. In the most active M dwarfs, H$\alpha$ is found in emission, sometimes with a complex line profile. Previous studies have reported extended wings and ... More
Quantum critical point in heavy fermionsDec 13 2004The concept that heavy fermions are close to a quantum critical point and that this proximity determines their physical behavior, has opened new perspectives in the study of these systems. It has provided a new paradigm for understanding and probing the ... More
Black brane steady statesJan 07 2015Aug 02 2015We follow the evolution of an asymptotically AdS black brane with a fixed temperature gradient at spatial infinity until a steady state is formed. The resulting energy density and energy flux of the steady state in the boundary theory are compared to ... More
Asteroseismology of the Beta Cephei star Nu Eridani: photometric observations and pulsational frequency analysisJan 13 2005We undertook a multisite photometric campaign for the Beta Cephei star Nu Eridani. More than 600 hours of differential photoelectric uvyV photometry were obtained with 11 telescopes during 148 clear nights. The frequency analysis of our measurements shows ... More
Effect of a magnetic field on the two-phonon Raman scattering in grapheneJan 11 2010May 21 2010We have studied, both experimentally and theoretically, the change of the so-called 2D band of the Raman scattering spectrum of graphene (the two-phonon peak near 2700 cm-1) in an external magnetic field applied perpendicular to the graphene crystal plane ... More
A Minimal Supersymmetric Kink ModelJun 05 2014Aug 19 2014In this paper we investigate a minimal supersymmetric soliton model, $\mathcal{N}=1$, in ($1+1$) dimensions in which the bosonic part of the potential presents a $\lambda \phi^4$ coupling. In this system a fermion field is coupled to a pseudoscalar field ... More
Magneto-Raman scattering of graphene on graphite: Electronic and phonon excitationsJan 10 2011Jul 11 2011Magneto-Raman scattering experiments from the surface of graphite reveal novel features associated to purely electronic excitations which are observed in addition to phonon-mediated resonances. Graphene-like and graphite domains are identified through ... More
The asteroseismic ground-based observational counterpart of CoRoTJul 20 2009We present different aspects of the ground-based observational counterpart of the CoRoT satellite mission. We give an overview of the selected asteroseismic targets, the numerous instruments and observatories involved, and the first scientific results. ... More
Domains of Disoriented Chiral CondensateAug 06 1996The probability distribution of neutral pion fraction from independent domains of disoriented chiral condensate is characterized. The signal for the condensate is clear for a small number of domains but is greatly reduced for more than three.
Nucleon-Antinucleon Interaction from the Skyrme ModelJun 04 1996We calculate the nucleon-antinucleon static potential in the Skyrme model using the product ansatz and including some finite $N_C$ (number of colors) corrections. The mid and long range part of the spin-spin and tensor force are correctly given in both ... More
GAUDI: a preparatory archive for the COROT missionSep 30 2004The GAUDI database (Ground-based Asteroseismology Uniform Database Interface, is a preparatory archive for the COROT (COnvection, ROtation and planetary Transits, mission developed ... More
The CARMENES search for exoplanets around M dwarfs: A low-mass planet in the temperate zone of the nearby K2-18May 02 2018May 04 2018K2-18 is a nearby M2.5 dwarf, located at 34 pc and hosting a transiting planet which was first discovered by the {\it K2} mission and later confirmed with {\it Spitzer Space Telescope} observations. With a radius of $\sim 2 \, R_{\oplus}$ and an orbital ... More
Asteroseismology of the Beta Cephei star 12 (DD) Lacertae: photometric observations, pulsational frequency analysis and mode identificationOct 11 2005We report a multisite photometric campaign for the Beta Cephei star 12 Lacertae. 750 hours of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with 9 telescopes during 190 nights. Our frequency ... More
A terrestrial planet candidate in a temperate orbit around Proxima CentauriSep 12 2016At a distance of 1.295 parsecs, the red-dwarf Proxima Centauri ($\alpha$ Centauri C, GL 551, HIP 70890, or simply Proxima) is the Sun's closest stellar neighbor and one of the best studied low-mass stars. It has an effective temperature of only $\sim$ ... More
The CARMENES search for exoplanets around M dwarfs. Chromospheric modeling of M2-3 V stars with PHOENIXFeb 11 2019Chromospheric modeling of observed differences in stellar activity lines is imperative to fully understand the upper atmospheres of late-type stars. We present one-dimensional parametrized chromosphere models computed with the atmosphere code PHOENIX ... More
Preparing the COROT space mission: incidence and characterisation of pulsation in the Lower Instability StripApr 23 2003By pursuing the goal to find new variables in the COROT field-of-view we characterised a sample of stars located in the lower part of the instability strip. Our sample is composed of stars belonging to the disk population in the solar neighbourhood. We ... More
The 2003-4 multisite photometric campaign for the Beta Cephei and eclipsing star 16 (EN) Lacertae with an Appendix on 2 Andromedae, the variable comparison starAug 21 2015A multisite photometric campaign for the Beta Cephei and eclipsing variable 16 Lacertae is reported. 749 h of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with ten telescopes during 185 nights. ... More
Multiple water band detections in the CARMENES near-infrared transmission spectrum of HD 189733 bNov 21 2018Aims: We explore the capabilities of CARMENES for characterizing hot-Jupiter atmospheres by targeting multiple water bands, in particular, those at 1.15 and 1.4 $\mu$m. Hubble Space Telescope observations suggest that this wavelength region is relevant ... More
The CARMENES search for exoplanets around M dwarfs - The enigmatic planetary system GJ 4276: One eccentric planet or two planets in a 2:1 resonance?Jan 07 2019We report the detection of a Neptune-mass exoplanet around the M4.0 dwarf GJ 4276 (G 232-070) based on radial velocity (RV) observations obtained with the CARMENES spectrograph. The RV variations of GJ 4276 are best explained by the presence of a planetary ... More
The CARMENES search for exoplanets around M dwarfs: Nine new double-line spectroscopic binary starsAug 21 2018Context. The CARMENES spectrograph is surveying ~300 M dwarf stars in search for exoplanets. Among the target stars, spectroscopic binary systems have been discovered, which can be used to measure fundamental properties of stars. Aims. Using spectroscopic ... More
The CARMENES search for exoplanets around M dwarfs: The warm super-Earths in twin orbits around the mid-type M dwarfs Ross 1020 (GJ 3779) and LP 819-052 (GJ 1265)Oct 17 2018We announce the discovery of two planetary companions orbiting around the low mass stars Ross 1020 (GJ 3779, M4.0V) and LP 819-052 (GJ 1265, M4.5V). The discovery is based on the analysis of CARMENES radial velocity observations in the visual channel ... More
Detection and Doppler monitoring of EPIC 246471491, a system of four transiting planets smaller than NeptuneAug 01 2018The Kepler extended mission, also known as K2, has provided the community with a wealth of planetary candidates that orbit stars typically much brighter than the targets of the original mission. These planet candidates are suitable for further spectroscopic ... More
Structural properties of thin-film ferromagnetic topological insulatorsJun 06 2017We present a comprehensive study of the crystal structure of the thin-film, ferromagnetic topological insulator (Bi, Sb)$_{2-x}$V$_x$Te$_3$. The dissipationless quantum anomalous Hall edge states it manifests are of particular interest for spintronics, ... More
Classical and Quantum Coherent State Description of Nucleon-Antinucleon Annihilation at Rest in the Skyrme Model with Omega MesonsMay 22 1994We model the $N\bar{N}$ system at rest as a baryon number zero lump in the Skyrme model including the $\omega$ field. We integrate the classical equations of motion from the highly non-perturbative annihilation region into the non-interacting radiation ... More
AdS black holes as reflecting cavitiesJul 15 2008Jul 23 2008We use the identification between null singularities of correlators in the bulk with time singularities in the boundary correlators to study the analytic structure of time-dependent thermal Green functions using the eikonal approximation for classical ... More
Branching Ratios in Proton Antiproton Annihilation at Rest from Large Nc QCDApr 21 1995We use classical or large Nc QCD to describe the mesons (pion, rho, omega) coming from proton-antiproton annihilation at rest as classical fields, which we then quantize as coherent states. This treatment gives a nearly parameter free account of the pion ... More
Nucleon-Antinucleon Annihilation in Large Nc QCD with rho and omega MesonsMay 16 1995We use classical/large Nc (number of colors) QCD to study nucleon--antinucleon annihilation at rest. We include pion, rho and omega fields in the classical dynamics, starting from the nonlinear sigma model. We begin with a spherical blob of pionic matter ... More
Lifshitz black holes in string theoryMay 24 2011Jun 03 2011We provide the first black hole solutions with Lifshitz asymptotics found in string theory. These are expected to be dual to models enjoying anisotropic scale invariance with dynamical exponent z=2 at finite temperature. We employ a consistent truncation ... More
Pion correlation from Skyrmion-AntiSkyrmion annihilationJul 13 1995We study two pion correlations from Skyrmion and antiSkyrmion collision, using the product ansatz and an approximate random grooming method for nucleon projection. The spatial-isospin coupling inherent in the Skyrme model, along with empirical averages, ... More
Anomalous transport coefficients from Kubo formulas in HolographyFeb 22 2011May 24 2011In the presence of dense matter quantum anomalies give rise to two new transport phenomena. An anomalous current is generated either by an external magnetic field or through vortices in the fluid carrying the anomalous charge. The associated transport ... More
Skyrmions and the Nuclear ForceOct 20 1992The derivation of the nucleon-nucleon force from the Skyrme model is reexamined. Starting from previous results for the potential energy of quasistatic solutions, we show that a calculation using the Born-Oppenheimer approximation properly taking into ... More
Quantum Phenomenology for the Disoriented Chiral CondensateJul 07 1994We consider the quantum state describing theDisoriented Chiral Condensate (DCC), which may be produced in high energy collisions. We show how a mean field treatment of the quantum equations corresponding to the classical linear sigma model leads to a ... More
High-cadence spectroscopy of M-dwarfs - II. Searching for stellar pulsations with HARPSMay 12 2017Stellar oscillations appear all across the Hertzsprung-Russell diagram. Recent theoretical studies support their existence also in the atmospheres of M dwarfs. These studies predict for them short periodicities ranging from 20~min to 3~h. Our Cool Tiny ... More
Hydrodynamics of Holographic SuperconductorsMar 12 2009Jun 17 2009We study the poles of the retarded Green functions of a holographic superconductor. The model shows a second order phase transition where a charged scalar operator condenses and a U(1) symmetry is spontaneously broken. The poles of the holographic Green ... More
Detection of He I $\lambda10830$ Å absorption on HD 189733 b with CARMENES high-resolution transmission spectroscopyDec 06 2018We present three transit observations of HD 189733 b obtained with the high-resolution spectrograph CARMENES at Calar Alto. A strong absorption signal is detected in the near-infrared He I triplet at 10830 \AA{} in all three transits. During mid-transit, ... More
Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69bDec 07 2018Hot gas giant exoplanets can lose part of their atmosphere due to strong stellar irradiation, affecting their physical and chemical evolution. Studies of atmospheric escape from exoplanets have mostly relied on space-based observations of the hydrogen ... More
Gliese 49: Activity evolution and detection of a super-EarthMar 12 2019Small planets around low-mass stars often show orbital periods in a range that corresponds to the temperate zones of their host stars which are therefore of prime interest for planet searches. Surface phenomena such as spots and faculae create periodic ... More