An Overview of the 4m International Liquid Mirror Telescope
Kuntal Misra (ARIES India)

The 4m International Liquid Mirror Telescope (ILMT) is the first optical survey telescope in Devasthal, India. The telescope achieved its first light on 29 April 2022. The primary mirror is made of liquid mercury, continuously spinning to achieve a paraboloid shape. It constantly scans a 22 arcmin wide strip of the zenithal sky and records the images in three broadband filters (g', r' and i') using a 4k X 4k CCD camera in Time Delay Integration (TDI) mode. In about 10-12 hours of observations during a single night, approximately 15 GB of data volume is generated. To process this data, different automated pipelines are developed to perform the astrometric and photometric calibration, image subtraction to detect new transients and machine learning based tools to classify these transients. In this talk, I will give a brief overview of the ILMT and its science drivers, the initial results and the availability of data to the users.

The wonders of X-ray polarimetry
Frédéric Marin (CNRS, Observatoire de Strasbourg)

The Imaging X-ray Polarimetry Explorer (IXPE) is the first satellite dedicated to observing the polarization of X-rays from almost any cosmic source. Since its launch in December 2021, IXPE has revolutionized our understanding of high-energy physics, from the structure and composition of relativistic jets to surface models of magnetars, from the topology of magnetic fields in supernova remnants to the geometry of X-ray coronas around black holes, and even probing the accretion cycle of our own galaxy’s supermassive black hole. In this talk, I will review these results and highlight the major discoveries made by this modest satellite that are paving the way for many more to come.

The TROY project: Do trojan exoplanets really exist?
Olga Balsalobre (Center for Astrobiology, Madrid)

The existence of co-orbital (or trojan) planets has been theorized for over two decades. These are pairs of planets sharing the orbital path around their star. Hydrodynamical simulations suggest that co-orbitals could be a natural by-product of planet formation. Recently, this hypothesis has gained observational support with the discovery of co-orbital gas and dust in a handful of young systems. Yet, the absence of confirmed trojan planets in mature systems remains an open question. A dedicated search for these configurations is crucial to dermine whether current detection techniques are systematically overlooking them, or if trojans are disrupted as the planetary systems evolve. In this talk, I will present the multi-technique approach we follow in the TROY project. We search for co-orbital candidates across different evolutionary stages of planetary systems combining Radial Velocities, Transits, and Direct Imaging.

Exploring the X-ray activity of M Dwarfs: a focus on the benchmark planet host Proxima Centauri
Enza Magaudda (University of Tübingen)

The magnetic activity of the Sun and solar-like stars is driven by an αΩ-dynamo, where differential rotation and convection regenerate the magnetic field, producing strong optical, UV, and X-ray emissions. M dwarfs are also magnetically active, though the underlying mechanism remains unclear, and their X-ray emission significantly impacts the evolution of orbiting planets.

This talk explores the X-ray activity of M dwarfs, examining its dependence on mass and rotation using the largest and most uniform dataset of new X-ray observations and rotation periods, supplemented by literature data. Additionally, I present a detailed study of Proxima Centauri, a benchmark planet host and known flare star. Using XMM-Newton and eROSITA data, I derived for the first time the relation between coronal temperature and X-ray luminosity based on the variability of a single star. Compared to solar-type stars, Proxima Centauri exhibits higher coronal temperatures, and a temperature spread at a given X-ray luminosity, likely due to variations in electric currents shaping its magnetic loops. These findings enhance our understanding of stellar magnetic activity and its role in shaping planetary atmospheres and habitability.

Treatment of magnetic activity effects in an era of high-precision asteroseismology
Jérôme Bétrisey ('Université d'Uppsala.)

Following the success of missions like CoRoT, Kepler, and TESS, asteroseismic modelling is poised to play a pivotal role in upcoming space-based missions such as PLATO, CubeSpec, and Roman. Despite remarkable achievements, asteroseismology has also revealed significant discrepancies between observed data and theoretical stellar models, leading to non-negligible biases in stellar characterisation in our era of high-precision asteroseismology. In the past decades, magnetic activity effects were typically neglected in asteroseismic modelling of solar-type stars, assuming that these effects could be accounted for in the parametrisation of the so-called ‘surface effects’. This picture has, however, been challenged in recent years, as it was demonstrated that magnetic activity can have a significant impact on the asteroseismic characterisation using both forward and inverse methods. In this presentation, I will present these results and show that magnetic activity effects cannot be suppressed with standard methods employed to mitigate surface effects. Subsequently, I will also discuss how magnetic activity effects are averaged with longer observations and what conclusions can be drawn for future photometry missions.

Influence of a subsurface ocean on the rotation variations of large icy satellites
Alexis Coyette (UNamur)

We use an angular momentum approach to study the Cassini states (CS) of large natural satellites such as the Galilean satellites and Titan. Unlike classical approaches where obliquity is the solution of a trigonometric equation, our approach allows us to identify not only the mean obliquity of satellites, but also their nutation in space as well as their polar motion (PM) with respect to the solid surface. Triaxiality of the satellite has a significant effect on the mean obliquities of CSI, CSII and CSIV. We assess the stability of the Cassini states over a wide range of free and forced precession frequency ratios and find that CSI and CSIII are always stable. Even if the different Galilean Moons are thought to occupy CSI, we therefore also analytically study CSIII. We here solve the dynamic equations governing CSI and CSIII up to order two in small quantities and without averaging the external torque over the mean anomaly to obtain the time-variable obliquity and polar motion (at long-period and short-period). By extending the system of equations governing CSI, including gravitational and pressure couplings between misaligned layers, we predict the orientation of the spin axes of the outer shell, internal ocean and solid interior for an ocean-bearing body.

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Violeta Gamez-Rosas (STAR)

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Morgan Deal (Université de Montpellier)

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Yoshiki Hatta (Graduate School of Advanced Studies, SOKENDAI, Tokyo)

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Plasma conditions at the orbits of Io, Europa, and Ganymede derived from the lead angle of the satellite auroral footprints observed by Juno-UVS
Shinnosuke Satoh (Tohoku University)

Io, Europa, and Ganymede act as an obstacle to the corotating plasma in the Jovian magnetosphere. Through the electrodynamic interaction at the moons (e.g., Kivelson et al., 2004), Alfvén waves are launched and propagate along the magnetic field. Auroral electrons are accelerated toward/away from Jupiter's atmosphere by the Alfvén waves and ultimately induce multiple satellite auroral footprints and a diffuse auroral tail in Jupiter's atmosphere (e.g., Clarke et al., 2002; Bonfond et al., 2008).

The Alfvén velocity depends on the local magnetic field magnitude and the local plasma mass density. The position of satellite auroral footprints is detemined by the Alfvén wave propagation time. The angular separation between the satellite body and the auroral footprint is called the lead angle. The footprint lead angle has been proven to be useful to investigate temporal variations of plasma parameters in the Io plasma torus (Moirano et al., 2023) and the plasma disc at Europa's orbit (Satoh et al., 2024). Both studies traced the Alfvén waves from the moon to the MAW spot in the plasma sheet with various plasma parameters and estimated the lead angle to find the best fit parameters. Estimation of the plasma parameters at the orbits of the icy moons is important because the magnetospheric plasma controls source and loss of neutral atmospheres in the icy moons.

Now, using the same fitting procedure as Satoh et al. (2024), we’re trying to derive the three ion parameters (atomic mass, number density, and temperature) at the orbits of Io, Europa, and Ganymede, from the footprint lead angle measured by Juno-UVS. In addition to the MAWs, we also use the lead angle of the Transhemispheric Electron Beam (TEB) spot (Bonfond et al., 2008). The TEB spot is generated by the electrons accelerated away from Jupiter in the other hemisphere. Hence, the TEB spot in one hemisphere is strongly associated with the other hemisphere's MAW spot. Using the TEB spot, we can trace the Alfvén waves that have different propagation paths than the ones corresponding to the MAW spot observed in the same hemisphere at the same time, which is expected to add another constraint for the estimation of ion parameters.