A5074926114- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- GNSS positioning and interference
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Superconducting and THz Device Technology
- Galaxies: Formation, Evolution, Phenomena
- History and Developments in Astronomy
- Solar and Space Plasma Dynamics
- Advanced Frequency and Time Standards
- Antenna Design and Optimization
- Calibration and Measurement Techniques
- Ionosphere and magnetosphere dynamics
- Geophysics and Sensor Technology
- Psychology Research and Bibliometrics
- Atmospheric Ozone and Climate
- Quantum optics and atomic interactions
Universitat de València
2014-2023
Parc Científic de la Universitat de València
2013-2023
Aalto University
2022
Max Planck Society
2015
Max Planck Institute for Radio Astronomy
2014-2015
Mbarara University of Science and Technology
2009
University of Arizona
2005
Universidad de Granada
2002
Instituto Nacional de Técnica Aeroespacial
2000
Jet Propulsion Laboratory
1995-1998
We report deep EVN and eMERLIN observations of the Type Ia SN 2014J in nearby galaxy M82. Our represent, together with JVLA SNe 2011fe 2014J, most sensitive radio studies ever. By combining data a proper modeling emission, we constrain mass-loss rate from progenitor system to (for wind speed 100 km s−1). If medium around supernova is uniform, then nISM ≲ 1.3 cm−3, which stringent limit for (uniform) density SN. upper limits favor double-degenerate (DD) scenario—involving two WD stars—for as...
Ultra-high angular resolution in astronomy has always been an important vehicle for making fundamental discoveries. Recent results direct imaging of the vicinity supermassive black hole nucleus radio galaxy M87 by millimeter VLBI system Event Horizon Telescope and various pioneering Space mission RadioAstron provided new momentum high astrophysics. In both mentioned cases, reached values about 10-20 microrcseconds. Further developments toward at least order magnitude "sharper" are dictated...
We have studied the growth of shell-like radio structure supernova SN1993J in M81 from September 1993 through October 2003 with very-long-baseline interferometry (VLBI) observations at wavelengths 3.6, 6, and 18cm. For this purpose, we developed a method to accurately determine outer radius (R) any circularly symmetric compact like SN1993J. The source remains (with deviations circularity under 2%) over almost 4000 days. characterize decelerated expansion SN 1993J approximately day 1500 after...
(See the complete and formatted abstract in paper). We report on VLBI monitoring of low-luminosity AGN (LLAGN) M81 at 1.7, 2.3, 5, 8.4GHz. These observations are phase-referenced to supernova SN1993J (located same galaxy) cover from late 1993 2005. The source consists all frequencies a slightly resolved core small jet extension towards north-east direction (position angle ~65 degrees) agreement with previous publications. find that position intensity peak images 8.4GHz is very stable...
This paper presents the ESA Voyage 2050 White Paper for a concept of TeraHertz Exploration and Zooming-in Astrophysics (THEZA). It addresses science case some implementation issues space-borne radio interferometric system ultra-sharp imaging celestial sources at level angular resolution down to (sub-) microarcseconds. THEZA focuses millimetre sub-millimetre wavelengths (frequencies above $\sim$300~GHz), but allows operations longer too. The rationale is focused on physics spacetime in...
Ultracool dwarfs (UCDs) are a category of astronomical objects that includes brown and very-low-mass stars. Radio observations UCDs have measured their brightness as function time (light curves) spectral energy distributions, providing insight into magnetic fields. We present spatially resolved radio the dwarf LSR J1835+3259 using very-long-baseline interferometry showing extended emission. The detected morphology is consistent with presence radiation belt. Comparison models indicates belt...
A rarity among supernova, SN 1993J in M81 can be studied with high spatial resolution. Its radio power and distance permit VLBI observations to monitor the expansion of its angular structure. This structure was previously revealed shell-like undergoing a self-similar at constant rate. From wavelengths 3.6 6 cm period 6-42 months after explosion, we have discovered that is decelerating. Our measurement this deceleration yields estimates density profiles supernova ejecta circumstellar material...
Stellar radio emission can measure a star’s magnetic field strength and structure, plasma density, dynamics, the stellar wind pressure impinging on exoplanet atmospheres. However, properly interpreting data often requires temporal baselines that cover rotation of stars, orbits their planets, any longer-term activity cycles. Here we present our monitoring campaign young, active M dwarf AU Microscopii with Australia Telescope Compact Array between 1.1 3.1 GHz. With over 250 h observations,...
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The pre-main sequence (PMS) star ABDorA is the main component of quadruple system ABDoradus. precise determination mass and photometry close companion to ABDorA, ABDorC, has provided an important benchmark for calibration theoretical evolutionary models low-mass stars. limiting factor precision this age system, as both luminosity C are well monitored by other ongoing programs. In paper we present VLTI/AMBER observations which provide a direct measurement size star, 0.96+/-0.06 Rsun. latter...
We add four warmer late-type supergiants to our previous spectro-interferometric studies of red giants and supergiants. V766 Cen (=HR 5171 A) is found be a high-luminosity log(L/L_sun)=5.8+-0.4 source Teff 4290+-760 K radius 1490+-540 Rsun located close both the Hayashi Eddington limits; this consistent with 40 Msun evolutionary track without rotation current mass 27-36 Msun. It exhibits NaI in emission arising from shell 1.5 Rphot photocenter displacement about 0.1 Rphot. shows strong...
A sequence of images from very long baseline interferometry shows that the young radio supernova SN 1993J is expanding with circular symmetry. However, circularly symmetric show emission asymmetries. scenario in which freely ejecta shock mostly isotropic circumstellar material strongly favored. The constitutes first “movie” a supernova.
We report on a simultaneous modelling of the expansion and radio light curves supernova SN1993J. developed simulation code capable generating synthetic supernovae by taking into consideration evolution expanding shock, magnetic fields, relativistic electrons, as well finite sensitivity interferometric arrays used in observations. Our software successfully fits all available data SN 1993J with standard emission model for supernovae, which is extended some physical considerations, such an...
Context: Phase referencing is a standard calibration technique in radio interferometry, particularly suited for the detection of weak sources close to sensitivity limits interferometers. However, effects from changing atmosphere and inaccuracies correlator model may affect phase-referenced images, leading wrong estimates source flux densities positions. A systematic observational study signal decoherence phase referencing, its image plane, has not been performed yet. Aims: We systematically...
We have performed a complete re-calibration and re-analysis of all the available Very-Long-Baseline-Interferometry (VLBI) observations supernova SN1993J, following an homogeneous well-defined methodology. VLBI SN1993J at 69 epochs, spanning 13 years, were by two teams, which used different strategies analysis tools. The results obtained each group are similar, but their conclusions on expansion shape evolution emitting region differ significantly. From our combined set observations, we curve...
Context. The study of pre-main-sequence (PMS) stars with model-independent measurements their masses is essential to check the validity theoretical models stellar evolution. well-known PMS binary AB Dor A/C an important benchmark for this task, since it displays intense and compact radio emission, which makes possible application high-precision astrometric techniques system.
On 28th January 2018, the large Trans-Neptunian Object (TNO) 2002TC302 occulted a m$_v= $15.3 star with ID 130957813463146112 in Gaia DR2 stellar catalog. 12 positive occultation chords were obtained from Italy, France, Slovenia and Switzerland. Also, 4 negative detections near north south limbs. This represents best observed by TNO other than Pluto, terms of number published thus far. From chords, an accurate elliptical fit to instantaneous projection body, compatible misses, can be...
We present an astrometric analysis of the binary systems AB Dor A /AB C and Ba Bb. These two well-known late-type stars are gravitationally associated they constitute quadruple Doradus system. From data available at different wavelengths, we report: (i) a determination orbit C, very low mass companion to A, which confirms estimate 0.090 reported in previous works; (ii) measurement parallax Ba, unambiguously long-suspected physical association between this star A; (iii) evidence orbital...
We report on K-band VLTI/AMBER observations at medium spectral resolution ($\sim$1500) of RS Capricorni, an M6/M7III semi-regular AGB star. From the spectrally-dispersed visibilities, we measure star diameter as a function observing wavelength from 2.13 to 2.47 microns. derive Rosseland angular $7.95 \pm 0.07$ mas, which corresponds effective temperature $3160 160$ K. detect size variations around 10% in CO band heads, indicating strong opacity effects stellar photosphere. also linear...
The star V766 Cen (=HR 5171A) was originally classified as a yellow hypergiant but lately found to more likely be 27-36 Msun red supergiant (RSG). Recent observations indicated close eclipsing companion in the contact or common-envelope phase. Here, we aim at imaging of confirm presence companion. We used near-infrared H -band aperture synthesis three epochs 2014, 2016, and 2017, employing PIONIER instrument Very Large Telescope Interferometer (VLTI). visibility data indicate mean Rosseland...