Related papers: Time-scales of close-in exoplanet radio emission v…
We reassess the claimed detection of variability in the atmosphere of the hot Jupiter HAT-P-7 b, reported by Armstrong et al. (2016). Although astronomers expect hot Jupiters to have changing atmospheres, variability is challenging to…
All of the solar system gas giants produce electron cyclotron masers, driven by the solar wind impinging on their magnetospheres. Extrapolating to the planet orbiting tau Boo, various authors have predicted that it may be within the…
Owing to technological advances, the number of exoplanets discovered has risen dramatically in the last few years. However, when trying to observe Earth analogs, it is often difficult to test the veracity of detection. We have developed a…
Time-scales of radio emission are studied in PSR J0437-4715 at 327 MHz using almost half a million periods of high quality data from Ooty Radio Telescope. The radio emission in this milli second pulsar occurs on a short (s) time-scale of…
Context. Observing the radio emission from exoplanets is among the most promising methods to detect their magnetic fields and a measurement of an exoplanetary magnetic field will help constrain the planet's interior structure, star-planet…
The successful detection is reported of radial-velocity variations due to orbital motion of the substellar companion of the star tau Bootis, from data obtained with a small aperture (0.4m) telescope and a fibre-fed high-resolution…
Much has been learned about exoplanets and their atmospheres in the last three decades with the help of highly sensitive optical telescopes. Limited observations using X-ray telescopes have revealed the presence of ionospheres with very…
All the giant planets in the solar system generate radio emission via the electron cyclotron maser instability, most notably giving rise to Jupiter's decametric emissions. An interaction with the solar wind is at least partially responsible…
Type II radio bursts are the indicator of adverse space weather in a stellar system. These radio bursts are the consequence of shock wave acceleration due to the coronal mass ejection (CME). In this study, we conduct a series of…
Magnetic fields of exoplanets are important in shielding the planets from cosmic rays and interplanetary plasma. Due to the interaction with the electrons from their host stars, the exoplanetary magnetospheres are predicted to have both…
Existing upper limits on variations in the photospheric radius of the Sun during the solar magnetic activity cycle are at a fractional amplitude of 2x10^{-4}. At that level, the transit duration of a close-in planet around a Sun-like star…
We introduce a model for the orbital period modulation in systems with close-by giant planets based on a spin-orbit coupling that transfers angular momentum from the orbit to the rotation of the planet and viceversa. The coupling is…
Properties of planetary atmospheres, ionospheres, and magnetospheres are difficult to measure from Earth. Radio occultations are a common method for measuring these properties, but they traditionally rely on radio transmissions from a…
We present six epochs of spectropolarimetric observations of the hot-Jupiter-hosting star $\tau$ Bo\"otis that extend the exceptional previous multi-year data set of its large-scale magnetic field. Our results confirm that the large-scale…
The detection of radio emission from an exoplanet would constitute the best way to determine its magnetic field. Indeed, the presence of a planetary magnetic field is a necessary condition for radio emission via the Cyclotron Maser…
Context. Close-in giant extrasolar planets (''Hot Jupiters'') are believed to be strong emitters in the decametric radio range. Aims. We present the expected characteristics of the low-frequency magnetospheric radio emission of all…
Evidence suggesting an observable magnetic interaction between a star and its hot Jupiter appears as a cyclic variation of stellar activity synchronized to the planet's orbit. In this study, we monitored the chromospheric activity of 7…
The magnetic activity of planet-hosting stars is an important factor to estimate the atmospheric stability of close-in exoplanets and the age of their host stars. It has long been speculated that close-in exoplanets can influence the…
We present a study of plasma conditions in the atmospheres of the Hot Jupiters HD 209458b and HD 189733b and for an HD 209458b-like planet at orbit locations between 0.2-1 AU around a Sun-like star. We discuss how these conditions influence…
Physical conditions in the atmospheres of tidally-locked, slowly-rotating hot Jupiters correspond to dynamical circulation regimes with Rhines scales and Rossby deformation radii comparable to the planetary radii. Consequently, the large…