A5008362602- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Calibration and Measurement Techniques
- Organometallic Complex Synthesis and Catalysis
- Astronomical and nuclear sciences
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Inorganic and Organometallic Chemistry
- Metal complexes synthesis and properties
- Scientific Research and Discoveries
- Impact of Light on Environment and Health
- Molecular Junctions and Nanostructures
- Crystal Structures and Properties
- Radio Astronomy Observations and Technology
- Space Exploration and Technology
Universidad Andrés Bello
2015-2024
Vatican Observatory
2015-2024
Universidade Federal de Santa Catarina
2022-2024
Vatican Secret Archives
2010-2024
Millennium Institute of Astrophysics
2014-2022
Pontificia Universidad Católica de Chile
2011-2021
University of Chile
2017
Princeton University
2011-2015
European Southern Observatory
2011-2015
University of Alicante
2015
We report on our search for microlensing towards the Large Magellanic Cloud (LMC). Analysis of 5.7 years photometry 11.9 million stars in LMC reveals 13 - 17 events. This is significantly more than $\sim$ 2 to 4 events expected from lensing by known stellar populations. The timescales ($\that$) range 34 230 days. estimate optical depth with $2 < \that 400$ days be 1.2 ^{+0.4}_ {-0.3} \ten{-7}$, an additional 20% 30% systematic error. spatial distribution mildly inconsistent LMC/LMC disk...
Doppler measurements from Subaru and Keck have revealed radial velocity variations in the V=8.15, G0IV star HD 149026 consistent with a Saturn-Mass planet 2.8766 day orbit. Photometric observations at Fairborn Observatory detected three complete transit events depths of 0.003 mag predicted times conjunction. is now second brightest transiting extrasolar planet. The mass star, based on interpolation stellar evolutionary models, 1.3 +/- 0.1 solar masses; together amplitude, K=43.3 m s^-1, we...
We determine the iron distribution function (IDF) for bulge field stars, in three different fields along Galactic minor axis and at latitudes b=-4 deg, b=-6 b=-12 deg. A fourth including NGC6553 is also included discussion. About 800 K giants were observed with GIRAFFE spectrograph of FLAMES@VLT spectral resolution R~20,000. Several them again UVES R~45,000 to insure accuracy measurements. The LTE abundance analysis yielded stellar parameters abundances that allowed us construct an IDF that,...
Context. The ESO public survey VISTA variables in the Vía Láctea (VVV) started 2010. VVV targets 562 sq. deg Galactic bulge and an adjacent plane region is expected to run for about five years.
Context. The Milky Way bulge is the nearest galactic and most readily accessible laboratory for studies of stellar populations in spheroids based on individual abundances kinematics. These are challenged by strongly variable often large extinction a small spatial scale.
We combine high-resolution spectroscopic data from APOGEE-2 Survey Data Release 16 (DR16) with broad-band photometric several sources, as well parallaxes {\it Gaia} 2 (DR2). Using the Bayesian isochrone-fitting code {\tt StarHorse}, we derive distances, extinctions and astrophysical parameters for around 388,815 APOGEE stars, achieving typical distance uncertainties of $\sim 6\%$ giants, 2\%$ dwarfs, extinction 0.07$ mag when all information is available, 0.17$ if optical photometry missing....
Galactic haloes in a $\Lambda$-CDM universe are predicted to host today swarm of debris resulting from cannibalised dwarf galaxies. The chemo-dynamical information recorded their stellar populations helps elucidate nature, constraining the assembly history Galaxy. Using data APOGEE and \textit{Gaia}, we examine chemical properties various halo substructures, considering elements that sample nucleosynthetic pathways. systems studied Heracles, \textit{Gaia}-Enceladus/Sausage (GES), Helmi...
ABSTRACT A key event in the history of Milky Way is formation bar. This affects subsequent structural and dynamical evolution entire Galaxy. When bar formed, gas was likely rapidly funnelled to centre Galaxy settling a star-forming nuclear disc. The can then be dated by considering age distribution oldest stars formed stellar In this highly obscured crowded region, reliable tracers are limited, but bright, high-amplitude Mira variables make useful indicators as they follow period–age...
We present K-band imaging observations of ten gamma-ray burst (GRB) host galaxies for which an optical and/or radio afterglow associated with the GRB event was clearly identified.Data were obtained Very Large Telescope and New Technology at ESO (Chile), Gemini-North telescope Mauna Kea (Hawaii).Adding to our sample nine other hosts photometry determined redshifts published in literature, we compare their observed absolute K magnitudes as well R -K colours those distant sources detected...
We seek to constrain the formation of Galactic bulge by means analysing detailed chemical composition a large sample red clump stars in Baade's window. measure [Fe/H] 219 from R=20000 resolution spectra obtained with FLAMES/GIRAFFE at VLT, using an automatic procedure, differentially metal-rich local reference star muLeo. For subsample 162 stars, we also derive [Mg/H] spectral synthesis around MgI triplet 6319A. The Fe and Mg metallicity distributions are both asymmetric, median values +0.16...
We present extensive optical and infrared photometry of the afterglow gamma-ray burst (GRB) 030329 its associated supernova (SN) 2003dh over first two months after detection (2003 March 30-May 29 UT). Optical spectroscopy from a variety telescopes is shown and, when combined with photometry, allows an unambiguous separation between SN contributions. The GRB initially power-law continuum but shows significant color variations during week that are unrelated to presence SN. early light curve...
The EROS and MACHO collaborations have each published upper limits on the amount of planetary mass dark matter in Galactic Halo obtained from gravitational microlensing searches. In this paper two are combined to give a much stronger constraint abundance low MACHOs.
Two main scenarios for the formation of Galactic bulge are invoked, first one through gravitational collapse or hierarchical merging subclumps, second secular evolution disc. We aim to constrain studies correlation between kinematics and metallicities in Baade's Window (l=1, b=-4) two other fields along minor axis (l=0, b=-6 b=-12). combine radial velocity [Fe/H] measurements obtained with FLAMES/GIRAFFE at VLT a spectral resolution R=20000, plus field OGLE-II proper motions, compare these...
Characterizing the nature and spatial distribution of lensing objects that produce previously measured microlensing optical depth toward Large Magellanic Cloud (LMC) remains an open problem. We present appraisal ability SuperMACHO Project, a next-generation survey directed LMC, to discriminate between various proposed populations. consider two scenarios: by uniform foreground screen self-lensing LMC stars. have carried out extensive simulations, based upon data obtained during first year...
Aims. We present the analysis of [α/Fe] abundance ratios for a large number stars at several locations in Milky Way bulge with aim constraining its formation scenario.
We present stellar proper motions in the Galactic bulge from Sagittarius Window Eclipsing Extrasolar Search (SWEEPS) project using ACS WFC on HST. Proper are extracted for more than 180,000 objects, with >81,000 measured to accuracy better 0.3 mas yr−1 both coordinates. report several results based these measurements: (1) Kinematic separation of disk allows a sample >15,000 objects be ≥6 σ detections motion, <0.2% contamination disk. This includes first detection candidate blue straggler...
We have used HST imaging of the central regions globular cluster 47 Tucanae (=NGC 104), taken with WFPC2 and ACS instruments between 1995 2002, to derive proper motions U- V-band magnitudes for 14,366 stars within 100'' (about 5 core radii) center. This represents largest set member velocities collected any cluster. The involved range in brightness from just fainter than horizontal branch more 2.5 mag below main-sequence turnoff. In course obtaining these kinematic data, we also use a recent...
We re-analyze 4 years of HARPS spectra the nearby M1.5 dwarf GJ 667C available through European Southern Observatory public archive. The new radial velocity (RV) measurements were obtained using a data analysis technique that derives Doppler measurement and other instrumental effects least-squares approach. Combining these 143 with 41 additional RVs from Magellan/Planet Finder Spectrograph Keck/High Resolution Echelle Spectrometer spectrometers reveals three signals beyond previously...
Aims.This paper investigates the peculiar behaviour of light even (alpha-elements) and odd atomic number elements in red giants galactic bulge, both terms chemical evolution possible deep-mixing mechanisms these evolved stars.
We present the first microlensing candidate for a free-floating exoplanet–exomoon system, MOA-2011-BLG-262, with primary lens mass of Mhost ∼ 4 Jupiter masses hosting sub-Earth moon. The argument an exomoon hinges on system being relatively close to Sun. data constrain product MLπrel where ML is and πrel lens–source relative parallax. If nearby (large πrel), then small (a few masses) companion sub-Earth-mass exomoon. best-fit solution has large proper motion, μrel = 19.6 ± 1.6 mas yr−1,...
We have combined optical and near-infrared data of known RR Lyrae (RRL) stars in the bulge order to study spatial distribution its metal-poor component by measuring precise reddening values distances 7663 fundamental-mode RRL with high-quality photometry. obtain a distance Galactic center R0 = 8.33 ± 0.05 0.14 kpc. find that differs from structures traced predominantly metal-rich red clump (RC) stars. Unlike RC stars, do not trace strong bar, but more spheroidal, centrally concentrated...