A5072016531- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Atmospheric Ozone and Climate
- High-pressure geophysics and materials
- Chemical Thermodynamics and Molecular Structure
- Atomic and Molecular Physics
- History and Developments in Astronomy
- Astronomical and nuclear sciences
- Physics of Superconductivity and Magnetism
- Geomagnetism and Paleomagnetism Studies
- Crystal Structures and Properties
- Phase-change materials and chalcogenides
- Magnetic Field Sensors Techniques
- Scientific Research and Discoveries
- Geophysics and Sensor Technology
- Pulsars and Gravitational Waves Research
- Spectroscopy and Laser Applications
- Calibration and Measurement Techniques
- Advanced Semiconductor Detectors and Materials
Universidad Nacional de Colombia
2023
Instituto de Ciencias Astronómicas, de la Tierra y del Espacio
2012-2021
National University of San Juan
2008-2021
Centro Científico Tecnológico - San Juan
2003-2020
Consejo Nacional de Investigaciones Científicas y Técnicas
2000-2020
Universitat de Barcelona
2015
Argentine National Observatory
2000-2005
Universidad Abierta
2004
Universidad Nacional de Córdoba
2000-2002
Universidad Nacional Autónoma de México
2002
Context. This work is part of a long-term spectroscopic study sample 30 multiple stars with early-type components. In this second paper we present the results six systems in which new stellar components have been detected. Aims. The main aim to increase knowledge properties and dynamical structure systems. Methods. Using observations taken over time baseline more than 5 years measured RVs by cross-correlations applied spectral disentangling method double-lined Besides discovery objects...
We present an iterative method that allows us to compute the individual spectra and radial velocities of two stellar components spectroscopic binaries. applied this HD 143511 detected occurrence eclipses at conjunction phases. The orbital analysis provides minimum masses with errors 1%. Absolute radii were derived in different ways: a) by combining information provided velocities, rotational spectral line intensities; b) using light curves from ASAS-3 database.
Context. The presence of magnetic fields in O-type stars has been suspected for a long time. discovery these would explain wide range well documented enigmatic phenomena massive stars, particular cyclical wind variability, Hα emission variations, chemical peculiarity, narrow X-ray lines, and non-thermal radio/X-ray emission.
We propose a method for measuring the projected rotational velocity $v sin i$ with high-precision even in spectra blended lines. Though not automatic, our is designed to be applied systematically large numbers of objects without excessive computational requirement. calculate cross correlation function (CCF) object spectrum against zero-rotation template and use Fourier transform (FT) CCF central maximum measure parameter taking limb darkening effect its wavelength dependence into account....
Context. The frequent presence of weak magnetic fields on the surface spotted late-B stars with HgMn peculiarity in binary systems has been controversial during two last decades. Recent studies these using least-squares deconvolution (LSD) technique have failed to detect fields, indicating an upper limit longitudinal field between 8 and 15 G. In LSD studies, assumptions were made that all spectral lines are identical shape can be described by a scaled mean profile.
Theories on the origin of magnetic fields in massive stars remain poorly developed, because properties their field as function stellar parameters could not yet be investigated. To investigate whether are ubiquitous or appear only with a specific spectral classification, certain ages, special environment, we acquired 67 new spectropolarimetric observations for 30 stars. Among observed sample, roughly one third probable members clusters at different whereas remaining known to belong any...
We present the results of a high spectral resolution study eclipsing binary AR Aur. Aur is only known with HgMn primary star exactly on ZAMS and secondary still contracting towards ZAMS. detect for first time in spectra that many elements line profiles are variable over rotation period. The strongest profile variations found Pt, Hg, Sr, Y, Zr, He Nd, while O, Na, Mg, Si, Ca, Ti, Fe show weak distortions slight variability Y also confirmed by another star: alpha And. A preliminary modelling...
The periodic spectroscopic events in η Carinae are now well established and occur near the periastron passage of two massive stars a very eccentric orbit. Several mechanisms have been proposed to explain variations different spectral features, such as an eclipse by wind–wind collision (WWC) boundary, shell ejection from primary star or accretion its wind onto secondary. All them problems explaining all observed phenomena. To better understand nature cyclic events, we performed dense...
(Abridged) Most stellar activity cycles similar to that found in the Sun have been detected by using chromospheric Ca II H&K lines as proxies. However, it is unclear if such could be identified other optical lines. Aims. To detect solar-analog stars and determine these can through lines, Fe Balmer We study star HD 45184. Methods. analyse signatures of 45184 291 HARPS spectra obtained between 2003 2014. In order search for line-core fluxes variations, we focus on H$\alpha$, H$\beta$ which are...
Abstract The system AR Aur is a young late B-type double-lined eclipsing binary with primary star of HgMn peculiarity. We applied the Doppler imaging method to reconstruct distribution Fe and Y over surface using spectroscopic time series obtained in 2005 from 2008 October 2009 February. results show remarkable evolution element overabundances. Measurements magnetic field moment technique several elements reveal presence longitudinal order few hundred gauss both stellar components quadratic...
<i>Aims. <i/>We gathered about 100 high-resolution spectra of three typical HgMn (mercury-manganese) stars, HD 11753, 53244, and 221507, to search for slowly pulsating B-like pulsations surface inhomogeneous distribution various chemical elements. <i>Methods. <i/>Classical frequency analysis methods were used detect line profile variability determine the variation period. Doppler imaging reconstruction was performed obtain abundance maps elements on stellar surface. <i>Results. <i/>For which...
Context. Despite the importance of magnetic fields to a full understanding properties accreting Herbig Ae/Be stars, these have scarcely been studied until now over rotation cycle. One reason for paucity observations is lack knowledge their periods. The sharp-lined young Ae star HD 101412 with strong surface field has become in past few years one most well-studied targets among stars.
Aims: Time series of high-resolution spectra the late B-type star HD 11753 exhibiting HgMn chemical peculiarity are used to study surface distribution different elements and their temporal evolution. Methods: High-resolution high signal-to-noise ratio were obtained using CORALIE spectrograph at La Silla in 2000, 2009, 2010. Surface maps YII, SrII, TiII, CrII calculated Doppler imaging technique. The results also compared equivalent width measurements. evolution spots both on short long time...
HD 65949 is a late B star with exceptionally strong Hg ii λ3984, but it not typical HgMn star. The Re spectrum of extraordinary strength. Abundances or upper limits are derived here for 58 elements based on model Teff= 13 100 K and log (g) = 4.0. Even-Z through nickel show minor deviations from solar abundances. Anomalies among the odd-Z copper mostly small. Beyond iron peak, huge scatter found. Enormous enhancements found rhenium mercury (Z= 75–80). We note presence Th iii in spectrum....
Abstract Recently, we performed a complete study of the SB2 system HD 161701 with an orbital period 12.5 d, consisting HgMn primary and classical Ap secondary. Since this is first identified particular combination peculiar stars, presence magnetic field in both components considerable interest to astronomers studying stellar magnetism impact binary systems. Apart from 161701, only one other close systems component, 98088, currently known. Using high accuracy radial velocity planet searcher...
Aims. Recent magnetic field surveys in O- and B-type stars revealed that about 10% of the core-hydrogen-burning massive host large-scale fields. The physical origin these fields is highly debated. To identify model processes responsible for generation stars, it important to establish whether are found very young star-forming regions or they formed close interacting binary systems.
Context. θ Carinae belongs to a group of peculiar early-type stars (OBN) with enhanced nitrogen and carbon deficiency. It is also known as binary system, but it not clear yet whether the chemical anomalies can be explained by mass transfer between two components. On basis previously reported spectral variability few metal lines may expected that Car possesses weak magnetic field.
We obtained high-resolution, high signal-to-noise UVES and a few lower quality HARPS spectra revealing the presence of resolved magnetically split lines. HD101412 is first Herbig Ae star for which rotational Doppler effect was found to be small in comparison magnetic splitting. The measured mean field modulus varies from 2.5 3.5kG, while quadratic vary range 3.5 4.8kG. To determine period variations, we used radial velocity, equivalent width, line asymmetry measurements variable spectral...
Abstract We present the results of our observations eight magnetic Herbig Ae/Be stars obtained with X‐shooter spectrograph mounted on UT2 at VLT. provides a simultaneous, medium‐resolution and high‐sensitivity spectrum over entire wavelength range from 300 to 2500 nm. estimate mass accretion rates ( Ṁ acc ) targets 13 different spectral diagnostics using empiric calibrations derived previously for T Tauri‐type brown dwarfs. have estimated targets, which 2 × 10 –9 –7 M ⊙ yr –1 . Furthermore,...
Abstract The B fields in OB stars (BOB) survey is an ESO large programme collecting spectropolarimetric observations for a number of early-type order to study the occurrence rate, properties, and ultimately origin magnetic massive stars. As July 2014, total 98 objects were observed over 20 nights with FORS2 HARPSpol. Our preliminary results indicate that fraction organised, detectable field low. This conclusion, now independently reached by two different surveys, has profound implications...
Aims. Only for very few β Cephei stars has the behaviour of magnetic field been studied over rotation cycle. During past two years we have obtained multi-epoch polarimetric spectra star V1449 Aql with SOFIN at Nordic Optical Telescope to search a period and constrain geometry field.