arXiv subjects

A. García-Muñoz

Publications and source records attributed to A. García-Muñoz.

4 recordsLinked to original sources

arXiv2026

Star-Planet Interactions: Observational Techniques and Methods

This chapter summarizes the techniques and methods used to study star-planet interaction (SPI) from the observational point of view. SPI can produce a wide range of observational signatures, from localized stellar activity enhancements to changes in planetary atmospheric escape and transmission spectra. This chapter reviews the main observational techniques used to detect and characterize SPI, emphasizing the methodological challenges involved in separating planet-induced signals from intrinsic stellar variability. We discuss radial-velocity diagnostics, including cross-correlation, template matching, line-by-line methods, and activity indicators, highlighting their sensitivity to line-profile distortions and chromatic variability. We then review precision photometry as a tool to search for orbit-locked variability, flare modulation, and active-region occultations during planetary transits. Chromospheric diagnostics, including Ca II, Halpha, He I, and Na II lines, are presented as tracers of magnetic variability at different atmospheric heights and as potential probes of intermittent SPI signatures. We also discuss transmission spectroscopy as a complementary approach, since planetary atmospheric tracers such as H I Lyalpha, Balmer lines, C II, and He I can encode information about the stellar high-energy environment, stellar wind, and magnetic coupling. In addition, radio observations provide a promising avenue to probe magnetic SPI directly through coherent emission mechanisms. Finally, we examine time-series analysis techniques commonly employed in SPI searches, including generalized Lomb-Scargle periodograms, rolling periodograms, harmonic analyses, and bootstrap-based significance estimation. (abridged)

astro-ph.SR↗

arXiv2024

Multilayer hazes over Saturn's hexagon from Cassini ISS limb images

In June 2015, Cassini high-resolution images of Saturn's limb southwards of the planet's hexagonal wave revealed a system of at least six stacked haze layers above the upper cloud deck. Here, we characterize those haze layers and discuss their nature. Vertical thickness of layers ranged from 7 to 18 km, and they extended in altitude approx 130 km, from pressure level 0.5 bar to 0.01 bar. Above them, a thin but extended aerosol layer reached altitude approx 340 km (0.4 mbar). Radiative transfer modeling of spectral reflectivity shows that haze properties are consistent with particles of diameter 0.07- 1.4 \{mu}m and number density 100 - 500 cm -3. The nature of the hazes is compatible with their formation by condensation of hydrocarbon ices, including acetylene and benzene at higher altitudes. Their vertical distribution could be due to upward propagating gravity waves generated by dynamical forcing by the hexagon and its associated eastward jet.

astro-ph.EP↗

arXiv2018

Stationary waves and slowly moving features in the night upper clouds of Venus

At the cloud top level of Venus (65-70 km altitude) the atmosphere rotates 60 times faster than the underlying surface, a phenomenon known as superrotation. Whereas on Venus's dayside the cloud top motions are well determined and Venus general circulation models predict a mean zonal flow at the upper clouds similar on both day and nightside, the nightside circulation remains poorly studied except for the polar region. Here we report global measurements of the nightside circulation at the upper cloud level. We tracked individual features in thermal emission images at 3.8 and 5.0 $\mathrm{μm}$ obtained between 2006 and 2008 by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS-M) onboard Venus Express and in 2015 by ground-based measurements with the Medium-Resolution 0.8-5.5 Micron Spectrograph and Imager (SpeX) at the National Aeronautics and Space Administration Infrared Telescope Facility (NASA/IRTF). The zonal motions range from -110 to -60 m s$^{-1}$, consistent with those found for the dayside but with larger dispersion. Slow motions (-50 to -20 m s$^{-1}$) were also found and remain unexplained. In addition, abundant stationary wave patterns with zonal speeds from -10 to +10 m s$^{-1}$ dominate the night upper clouds and concentrate over the regions of higher surface elevation.

astro-ph.EP↗

arXiv2013

On the effects of the evolution of microbial mats and land plants on the Earth as a planet. Photometric and spectroscopic light curves of paleo-Earths

Understanding the spectral and photometric variability of the Earth and the rest of the solar system planets has become of the utmost importance for the future characterization of rocky exoplanets. As this is not only interesting at present times but also along the planetary evolution, we studied the effect that the evolution of microbial mats and plants over land has had on the way our planet looks from afar. As life evolved, continental surfaces changed gradually and non- uniformly from deserts through microbial mats to land plants, modifying the reflective properties of the ground and most probably the distribution of moisture and cloudiness. Here, we used a radiative transfer model of the Earth, together with geological paleo-records of the continental distribution and a reconstructed cloud distribution, to simulate the visible and near-IR radiation reflected by our planet as a function of Earth's rotation. We found that the evolution from deserts to microbial mats and to land plants produces detectable changes in the globally-averaged Earth's reflectance. The variability of each surface type is located in different bands and can induce reflectance changes of up to 40% in period of hours. We conclude that using photometric observations of an Earth- like planet at different photometric bands, it would be possible to discriminate between different surface types. While recent literature proposes the red edge feature of vegetation near 0.7 μm as a signature for land plants, observations in near-IR bands can be equally or even better suited for this purpose.

astro-ph.EP↗