A5082974229- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- History and Developments in Astronomy
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Space Exploration and Technology
- Particle physics theoretical and experimental studies
- Spectroscopy and Laser Applications
- Nuclear Physics and Applications
- Astrophysical Phenomena and Observations
- Target Tracking and Data Fusion in Sensor Networks
- Scientific Research and Discoveries
- Advanced Statistical Methods and Models
- High-Energy Particle Collisions Research
- Astronomical and nuclear sciences
- Radiation Detection and Scintillator Technologies
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Multilevel Inverters and Converters
University of Chile
2015-2024
Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
2012-2024
European Southern Observatory
1997-2023
Federico Santa María Technical University
2016-2022
Universidade de Santiago de Compostela
2022
Universidad Complutense de Madrid
2021
George Washington University
2020
University of Concepción
2016-2017
Duke University
2017
Georgia State University
2017
Astrometric measurements for 25 red dwarf systems are presented, including the first definitive trigonometric parallaxes 20 within 10 pc of Sun, horizon RECONS sample. The three nearest that had no previous (other than perhaps rough preliminary efforts) SO 0253+1652 (3.84 ± 0.04 pc, 23rd system), SCR 1845-6357 AB (3.85 0.02 24th nearest), and LHS 1723 (5.32 56th nearest). In total, seven reported here rank among 100 stellar systems. Supporting photometric spectroscopic observations have been...
We present UBVRIz' optical images taken with MOSAIC on the CTIO 4 m telescope of 0.32 deg2 Extended Hubble Deep Field-South. This is one four fields comprising MUSYC survey, which optimized for study galaxies at z = 3, active galactic nucleus (AGN) demographics, and Galactic structure. Our methods used astrometric calibration, weighted image combination, photometric calibration in AB magnitudes are described. calculate corrected aperture photometry its uncertainties find through tests that...
The results of speckle interferometric observations at the Southern Astrophysical Research Telescope (SOAR) telescope in 2014 are given. A total 1641 were taken, yielding 1636 measurements 1218 resolved binary and multiple stars 577 non-resolutions 441 targets. We for first time 56 pairs, including some nearby astrometric or spectroscopic binaries ten new subsystems previously known visual binaries. calibration data is checked by linear fits to positions 41 wide observed SOAR over several...
Eighteen RR Lyrae variables (RRLs) that lie in the "124 clump" identified by Quasar Equatorial Survey Team (QUEST) have been observed spectroscopically to measure their radial velocities and metal abundances. Ten blue horizontal branch (BHB) stars Sloan Digital Sky (SDSS) were added this sample. Six of nine densest region clump a mean velocity Galactic rest frame (Vgsr) 99.8 σ = 17.3 km s-1, which is slightly smaller than average error measurements. The whole sample contains eight RRLs five...
We present stellar metallicities derived from Ca ii triplet spectroscopy in over 350 red giant branch stars 13 fields distributed different positions the Small Magellanic Cloud, ranging ∼1° to ∼4° its center. In innermost fields, average metallicity is [Fe/H] ∼−1. This value decreases when we move away toward outermost regions. first detection of a spectroscopic gradient this galaxy. show that related an age gradient, sense more metal-rich stars, which are also younger, concentrated central regions
We present accurate trigonometric parallaxes for 20 new members of the 25 pc white dwarf (WD) sample as part Discovery and Evalution Nearby Stellar Embers (DENSE) project.7 Previously, there were a total 112 WD systems with placing them within these, 99 have known to better than 10%. Thus, presented in this work represent 20% increase number WDs accurately be pc. In addition, we updated seven 10 that been observed Astrometric Search Planets Encircling Stars initiative monitor nearby southern...
We estimated the dynamical surface mass density Σ at solar position between Z = 1.5 and 4 kpc from Galactic plane, as inferred kinematics of thick disk stars. The formulation is exact within limit validity a few basic assumptions. resulting trend Σ(Z) matches expectations visible alone, no dark component required to account for observations. extrapolate matter (DM) in neighborhood 0 ± 1 mM☉ pc−3, all current models spherical DM halo are excluded confidence level higher than 4σ. A detailed...
We present the first set of definitive trigonometric parallaxes and proper motions from Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI). Full astrometric reductions for program are discussed, including methods reference stars selection, differential color refraction corrections, conversion relative to absolute parallax. Using data acquired at 0.9-m CTIO, full solutions $VRIJHK_s$ photometry presented 36 red white dwarf stellar systems with faster than 1\farcs0/yr. Of...
Trigonometric parallaxes, proper motions and VJ(RI)KC photometry are given for 25 stars (of which one is a zero-parallax control field) targeted by the Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI), widely scoped program aimed at discovering characterizing nearby stars. The trigonometric parallaxes presented last that were obtained with CTIO 1.5 m telescope, fainter subset of CTIOPI input list. First 22 systems, within 10 pc (DENIS 0255-4700), between pc. At...
We present trigonometric parallaxes of 64 stellar systems with proper motions between 0\farcs5 yr$^{-1}$ and 1\farcs0 from the ongoing RECONS (Research Consortium On Nearby Stars) parallax program at CTIO (the Cerro Tololo Interamerican Observatory). All are south DEC $= +30$, 58 had no previous parallaxes. In addition to for systems, we motions, Johnson-Kron-Cousins $VRI$ photometry, variability measurements, spectral types. Nine multiple; results their components, three which new...
We report measurements of the photon beam asymmetry $\Sigma$ for reactions $\vec{\gamma}p\to p\pi^0$ and p\eta $ from GlueX experiment using a 9 GeV linearly-polarized, tagged incident on liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as function proton momentum transfer, possess greater precision than previous $\pi^0$ are first $\eta$ this energy regime. results compared with theoretical predictions based $t$-channel, quasi-particle exchange constrain...
The discovery and subsequent detailed study of T dwarfs have provided many surprises pushed the physics modelling cool atmospheres in unpredicted directions. Distance is a critical parameter for studies these objects to determine intrinsic luminosities, test binarity measure their motion Galaxy. We describe new observational programme distances across full range T-dwarf subtypes using New Technology Telescope (NTT)/SOFI telescope/instrument combination. present preliminary results ten...
The GlueX experiment at Jefferson Lab ran with its first commissioning beam in late 2014 and the spring of 2015. Data were collected on both plastic liquid hydrogen targets, much detector has been commissioned. All systems are now performing or near design specifications events being fully reconstructed, including exclusive production π0, η ω mesons. Linearly-polarized photons successfully produced through coherent bremsstrahlung polarization transfer to ρ observed.
view Abstract Citations (152) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The 1993 Multiwavelength Campaign on 3C 279: Radio to Gamma-Ray Energy Distribution in Low State Maraschi, L. ; Grandi, P. Urry, C. M. Wehrle, A. E. Madejski, G. Fink, H. Ghisellini, Hartman, R. Koratkar, von Montigny, Pian, Thomas, Treves, Aller, F. D. Bailyn, Balonek, T. J. Bock, Collmar, W. Glass, I. S. Litchfield, McHardy, Mendez, Pesce, Reuter, Robson, Steppe,...
Trigonometric parallaxes, proper motions, and VJ(RI)KC photometry are presented for 31 stars targeted by the Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI), a program of wide scope aimed at discovering characterizing nearby stars. The data given first that have been obtained with CTIO 1.5 m telescope, targeting fainter subset CTIOPI input list. We present trigonometric parallaxes 21 systems, which one is within 10 pc (LP 647-013 9.59 ± 0.22 pc) six between 25 pc....
We present a quantitative analysis of the star formation history (SFH) 12 fields in Small Magellanic Cloud (SMC) based on unprecedented deep [(B − R), R] color–magnitude diagrams (CMDs). Our reach down to oldest main-sequence turnoff with high photometric accuracy, which is vital for obtaining accurate SFHs, particularly at intermediate and old ages. use IAC-pop code obtain SFH, using synthetic CMDs generated IAC-star. SFH as function ψ(t, z) age metallicity. also consider several auxiliary...
ABSTRACT The results of speckle interferometric observations at the Southern Astrophysical Research Telescope in 2015 are provided, totaling 1303 measurements 924 resolved binary and multiple stars, non-resolutions 260 targets. separations range from 12 mas to 3.″37 (median 0.″17); maximum measured magnitude difference is 6.7 mag. We 27 pairs for first time, including 10 as inner or outer subsystems previously known binaries, e.g., 50 pair ϵ Cha. Newly commented upon. discuss three...
The results of speckle interferometric observations at the 4.1 m SOAR telescope in 2016 and 2017 are given, totaling 2483 measurements 1570 resolved pairs 609 non-resolutions. We describe briefly recent changes instrument observing method quantify accuracy pixel scale position angle calibration. Comments given on 44 here for first time. Orbital motion newly subsystem BU~83 Aa,Ab roughly agrees with its 36 year astrometric orbit proposed by J.~Dommanget. Most Tycho binaries examined turned...
The speckle interferometry program at the 4.1 m Southern Astrophysical Research Telescope (SOAR), started in 2008, now accumulated over 30,300 individual observations of 12,700 distinct targets. Its main goal is to monitor orbital motion close binaries, including members high-order hierarchies and low-mass dwarfs solar neighborhood. results from 2021 are published here, totaling 2,623 measurements 2,123 resolved pairs non-resolutions 763 median measured separation 0.21", 75 were closer than...
Background: Energetic quarks in nuclear DIS propagate through the medium. Processes that are believed to occur inside nuclei include quark energy loss medium-stimulated gluon bremsstrahlung and intra-nuclear interactions of forming hadrons. More data required gain a more complete understanding these effects. Purpose: To test theoretical models parton transport hadron formation, we compared their predictions for kinematic dependence pion production nuclei. Methods: We have measured...
Abstract We present measurements in the context of a survey southern hemisphere binary and multiple stellar systems observed with Zorro Speckle dual diffraction-limited optical imaging camera on 8.1 m Gemini South telescope carried out between 2019 2023. The overall motivation our some initial results these observations are outlined to demonstrate capabilities—and limitations—of Zorro. report astrometric characterization instrument terms precision accuracy provide details custom-made data...
We describe the Yale/San Juan Southern Proper Motion (SPM) Catalog 1.0, which provides positions, absolute proper motions, and photographic BV photometry for 58,880 objects at South Galactic pole. The sky coverage of SPM 1.0 is about 720 deg2 in magnitude range 5 < V 18.5. About 55% all catalog stars are randomly chosen, whereas remainder contains numerous astrophysically interesting drawn from various lists databases. accuracy positions motions 40–150 mas 3–8 yr-1, respectively, depending...
The variation of the kinematical properties Galactic thick disk with height Z are studied by means 412 red giants observed in direction south pole up to 4.5 kpc from plane. We confirm non-null mean radial motion toward anticenter found other authors, but we find that it changes sign at |Z|=3 kpc, and proposed inward LSR alone cannot explain these observations. rotational velocity decreases |Z| -30 km/s/kpc, data better represented a power-law index 1.25, similar analysis SDSS data. All...
To explore the complex halo substructure that has been reported in direction of Virgo constellation, radial velocities and metallicities have measured for 82 RR Lyrae stars (RRLS) were identified by QUEST survey. These are distributed over 90 square degrees sky, lie from 4 to 23 kpc Sun. Using an algorithm finding groups phase space modeling smooth component region, we 5 most significant RRLS groups, some which previously known or suspected. We examined SEKBO Catalina catalog (with available...
Context. In 2012, we applied a three-dimensional formulation to kinematic measurements of the Galactic thick disk and derived surprisingly low dark matter density at solar position. This result was challenged by Bovy & Tremaine (2012, ApJ, 756, 89), who claimed that observational data are consistent with expected local if one-dimensional approach is adopted.