A5060150671- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Atmospheric Ozone and Climate
- Planetary Science and Exploration
- Radio Astronomy Observations and Technology
- History and Developments in Astronomy
- Calibration and Measurement Techniques
- Chemical and Environmental Engineering Research
- Geophysics and Gravity Measurements
- Geology and Paleoclimatology Research
- Geography and Environmental Studies in Latin America
- Water Quality Monitoring and Analysis
- Geophysics and Sensor Technology
- Regional Development and Innovation
- Environmental and Ecological Studies
- Educational Methods and Psychological Studies
- Archaeological and Geological Studies
- Solar Radiation and Photovoltaics
- Medical Imaging Techniques and Applications
- Language, Linguistics, Cultural Analysis
Fundación Ciencias Exactas y Naturales
2011-2023
University of Buenos Aires
2014-2023
Institute of Astronomy and Space Physics
2014-2023
Consejo Nacional de Investigaciones Científicas y Técnicas
2008-2021
Centro Científico Tecnológico - San Juan
2013-2020
Argentine National Observatory
2013
Ground- and space-based planet searches employing radial velocity techniques transit photometry have detected thousands of planet-hosting stars in the Milky Way. The chemistry these atmospheres is controlled by shape absolute flux stellar spectral energy distribution, however, distributions relatively inactive low-mass are poorly known at present. To better understand exoplanets orbiting stars, we executed a panchromatic (X-ray to mid-IR) study 11 nearby hosting {\it Measurements Ultraviolet...
We present an all-sky catalogue of 2970 nearby (d ≲ 50 pc), bright (J < 9) M- or late K-type dwarf stars, 86 per cent which have been confirmed by spectroscopy. This will be useful for searches Earth-size and possibly Earth-like planets future space-based transit missions ground-based infrared Doppler radial velocity surveys. Stars were selected from the SUPERBLINK proper motion according to absolute magnitudes, spectra, a combination reduced motions photometric colours. From our we...
ABSTRACT Stellar radiation from X-rays to the visible provides energy that controls photochemistry and mass loss exoplanet atmospheres. The important extreme ultraviolet (EUV) region (10–91.2 nm) is inaccessible should be computed a reliable stellar model. It essential understand formation regions physical processes responsible for various emission features predict how spectral distribution varies with age activity levels. We compute state-of-the-art semi-empirical atmospheric model emergent...
There is evidence in the 125-Myr Pleiades cluster, and more recently 5-Myr NGC 2264 that rotation plays a key role Lithium (Li) depletion processes among low-mass stars. Fast rotators appear to be less Li-depleted than equal-mass slow rotators. We intend explore existence of Li - connection beta Pictoris members at an age about 24 Myr, use such correlation either confirm or improve estimate based on Depletion Boundary (LDB) modeling. have photometrically monitored all known association with...
We explore condensation temperature Tc trends in the unique binary system Zet1 Ret - Zet2 Ret, to determine whether there is a depletion of refractories, which could be related planet formation process. The star hosts debris disk was detected by an IR excess and confirmed direct imaging numerical simulations, while does not present nor planets. carried out high-precision abundance determination both components via line-by-line, strictly differential approach. stellar parameters Teff , log g,...
Abstract Characterizing the UV spectral energy distribution (SED) of an exoplanet host star is critically important for assessing its planet’s potential habitability, particularly M dwarfs, as they are prime targets current and near-term characterization efforts atmospheric models predict that their radiation can produce photochemistry on habitable zone planets different from Earth. To derive ground-based proxies emission use when Hubble Space Telescope ( HST ) observations unavailable, we...
M dwarfs are an ideal laboratory for hunting Earth-like planets, and the study of chromospheric activity is important part this task. On one hand, according to short-term their high levels magnetic can affect habitability make it difficult detect exoplanets orbiting around them. other however, long-term studies show whether or not these stars exhibit cyclical behaviour in activity, facilitating detection planets periods low activity. The be detected by studying several spectral lines...
(Abridged) Binary systems with similar components are ideal laboratories which allow several physical processes to be tested, such as the possible chemical pattern imprinted by planet formation process. Aims. We explore probable signature of in remarkable binary system HD 80606 - 80607. The star hosts a giant 4 MJup detected both transit and radial velocity techniques, being one most eccentric planets date. study condensation temperature Tc trends volatile refractory element abundances...
To detect stellar activity cycles and study the possible star-planet interactions (SPI's), we have developed both HK$\alpha$ SPI-HK$\alpha$ projects since 1999 2012 respectively. In this work, present preliminary results of SPI's studying chromospheric look for correlations between stellar/planetary parameters. We find that stars with similar T$_{eff}$, increases mass planet, to previous works. However, ages can also play a role larger sample is needed verify these trends. note some...
We present 6 new transits of the system WASP-4. Together with 28 light curves published in literature, we perform an homogeneous study its parameters and search for variations transit's central times. The final values agree those previously reported, except a slightly lower inclination. find no significant long-term $i$ or $R_{P}/R_{\star}$. $O-C$ mid-transit times do not show signs TTVs greater than 54 s.
Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magneto-hydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter chemistry planetary atmospheres, a quantitative description evolution NUV emission from dwarfs is needed when modeling these effects. We investigated luminosity early M-type cross-correlating Lepine & Gaidos (2011) catalog bright with GALEX...
Low-mass members of young stellar associations exhibit a wide spread rotation periods. Such originates from distributions masses and initial However, multiplicity can also play significant role. We investigate the role played by physical companions in shortening primordial disc lifetime. have compiled most extensive list low-mass 25-Myr beta Pictoris association. measured periods about all used updated UVWXYZ components to assess their membership. built period distribution distinguishing...
Abstract M dwarf stars are excellent candidates around which to search for exoplanets, including temperate, Earth-sized planets. To evaluate the photochemistry of planetary atmosphere, it is essential characterize UV spectral energy distribution planet’s host star. This wavelength regime important because molecules in atmosphere such as oxygen and ozone have highly wavelength-dependent absorption cross sections that peak (900–3200 Å). We seek provide a broadly applicable method estimating...
Solar forcing on climate has been reported in several studies although the evidence so far remains inconclusive. Here, we analyze stream flow of one largest rivers world, Paraná southeastern South America. For last century, find a strong correlation with sunspot number, multidecadal time scales, and larger solar activity corresponding to flow. The coefficient is r=0.78, significant 99% level. In shorter scales El Niño. These results are step toward flood prediction, which might have great...
We intended to compile the most complete catalog of bona fide members and candidate beta Pictoris association, measure their rotation periods basic properties from our own observations, public archives, exploring literature. carried out a multi-observatories campaign get photometric time series collected all archived data for stars in catalog. Each was analyzed with Lomb-Scargle CLEAN periodograms search stellar periods. complemented measured rotational detailed information on multiplicity,...
(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...
M stars are ideal targets to search for Earth-like planets. However, they usually have high levels of magnetic activity, which could affect their habitability and make difficult the detection exoplanets orbiting around them. Unfortunately, long-term variability dM has not been extensively studied, due low intrinsic brightness. For this reason, in 1999 we started HKalpha project, systematically observes spectra a large number stars, particular at Complejo Astronomico El Leoncito (CASLEO). In...
Stellar ultraviolet (UV) radiation drives photochemistry, and extreme-ultraviolet (EUV) mass loss in exoplanet atmospheres. However, the UV flux is partly unobservable due to interstellar absorption, particularly EUV range (100--912 A). It therefore necessary reconstruct spectra order characterize environment of exoplanets. In present work, we use a radiative transfer code SSRPM build one-dimensional semi-empirical models two M dwarf hosts, GJ 832 581, synthesize their spectra. equipped with...
Context. The largest dataset of stellar activity measurements available at present is the one obtained Mount Wilson Observatory, where high-precision H+K fluxes have been measured from 1966 for about 2200 stars. Since h and k lines λ2800 Å are formed in a similar way to emission lines, they also good indicators chromospheric structure. International Ultraviolet Explorer (IUE) provides large database UV spectra band 1150-3350 1978 1995, which can be used study activity.
We compile a list of 121 RS CVn type stars from the bibliography in southern hemisphere, to search for activity cycles, covering large range luminosities and rotation periods. For each system list, we obtain photometric data All Sky Automated Survey (ASAS), complement it with our own photometry, obtained Optical Robotic Observatory (ORO). analyze this Generalized Lomb-Scargle periodogram determine period possible cycles system. found periods 102 systems 91 systems. From statistical analysis...
Several late-type stars present activity cycles similar to that of the Sun. However, these have been mostly studied in F K stars. Due their small intrinsic brightness, M dwarfs are not usually targets long-term observational studies stellar activity, and variability is generally known. In this work, we study two dwarf stars: Gl 229 A (M1/2) 752 (M2.5). We employ medium-resolution echelle spectra obtained at 2.15 m telescope Argentinian observatory CASLEO between 2000 2010, photometric...
Context. The IUE database provides a large number of UV high and low-resolution spectra RS CVn-type stars from 1978 to 1996. In particular, many these were monitored continuously during several seasons by IUE. Aims. Our main purpose is study the short long-term chromospheric activity CVn systems most observed IUE: HD 22468 (V711 Tau, HR 1099, K1IV+G5V), 21242 (UX Ari, K0IV+G5V) 224085 (II Peg, K2IV). Methods. We first obtain Mount Wilson index S spectra. Secondly, we analyse with...