ICTS

The discovery of extrasolar planets enables us to tackle millennia old questions about whether the Earth and our Solar System are unique, and how they formed, and whether Life exists beyond the Earth. The 6000 exoplanets now known reveal many of the underlying mechanisms of how planets form and evolve, and the complex interplay between stars and the planets over time in sculpting the atmospheres of planets and the architecture of planetary systems.

In this talk I will discuss the techniques we use to discover exoplanets, the challenges of detecting terrestrial planets like the Earth, capable of hosting liquid water on their surface, and how the coolest most numerous stars in the Galaxy are potentially attractive targets. New precision spectroscopic and photometric instruments are now beginning to discover and characterize rocky planets around the coolest stars, and discovering ways to mitigate the noise from the stars themselves, that currently limits our ability to discover planets like our own around the nearest Sun-like stars.

The talk will also discuss how these discoveries pave the way for NASA's next flagship mission - the Habitable World Observatory, which will be capable of observing these new worlds in reflected light, and analyzing this light to search for biosignatures in their atmosphere. The ability to answer the age-old question of whether Life exists outside the solar system is now within our reach!

The atmosphere of brown dwarfs is very much similar to that of hot giant planets. Therefore, understanding the atmosphere of brown dwarfs provides important insight onto the atmosphere of gas giant extra-solar planets. Depending on their spectra, brown dwarfs are divided into three classes : L, T and Y dwarfs. The indirect evidence for the presence of dust cloud in the atmosphere of L dwarfs comes from the diagnosis of its optical and infra-red spectra. The direct evidence of dust comes from the detection of linear polarization in the optical bands. In the first part of the lecture, I shall discuss the physical and chemical properties of the atmosphere of brown dwarfs derived from the detail theoretical analysis of the observed spectra as well as the observed photo-polarimetric data. The second part of the lecture will describe analysis of atmosphere of exoplanets- both gas giant and telluric by using transmission spectra. It'll be demonstrated that polarisation may serve as a potential tool to probe the atmosphere of exoplanets.

In this pedagogical lecture I will review the main discovery techniques for exoplanets, and their relative strengths and weaknesses. The goal will be to understand what parameter space each discovery technique shines in, and how combinations of some of these techniques can further increase our understanding of exoplanet properties.

The observation of the first hot Jupiters around 3 decades ago has fuel the field of planet formation as the origin of these planets is still unknown at the present day. As such, planet formation models face the challenge to bridge two distinct states within the timeframe of the observations of planetary systems: the protoplanetary disc stage during which the planets form and the final (exo)-planetary system. This implies that models of planet formation need to include the structure and evolution of the protoplanetary discs, the accretion and migration processes of the growing planets as well as their composition. Consequently many different initial parameters of the disc (e.g. disc mass, disc radius, viscosity) and the planet (e.g. starting position and time) can be chosen. However, the number of observational constraints (e.g. planetary mass, final orbital distance) is limited, giving rise to a degeneracy within the models. A promising avenue to extend these observational constraints are measurements of atmospheric abundances, where observations via the JWST provide unprecedented data. In this talk, I will introduce the ingredients of planet formation models and how we can link these models to constraints from exoplanetary atmospheres to reveal the formation location of (hot) giant planets.

All magnetized solar system planets are strong radio emitters. Similar radio emissions have been found in the lowest mass stars and brown dwarfs and searches for radio emission from exoplanets is underway. These emissions are thought to be powered by various mechanisms drawing energy from the rotation of the emitting object, magnetic reconnection and/or magnetized wind impinging on the object. In this talk I will review the fundamentals of the relevant emission mechanisms, the plasma conditions that lead to such emissions, phenomenology of the observed emission and open questions in the field.

We analyze the transit timing variations (TTVs) of the hot Jupiter WASP-12b using 391 transit light curves, including seven new ground-based observations and data from TESS, ETD, ExoClock, and the literature. All light curves were uniformly modeled to obtain precise mid-transit times. The timing analysis reveals a significant orbital decay rate of −30.31 ms yr⁻¹, corresponding to a stellar tidal quality factor of Q′⋆ = 1.61 × 10⁵. Model selection criteria (χ²ᵣ, BIC, AIC) strongly favor orbital decay as the origin of the observed TTVs. However, a non-zero eccentricity allows apsidal precession as a viable alternative. We also derive a planetary Love number of kₚ = 0.66 ± 0.28, consistent with Jupiter’s value. While orbital decay is strongly supported, continued high-precision monitoring is required to fully constrain the system’s orbital evolution.

The orbital architectures of exoplanetary systems probe their dynamical evolution. Among various other parameters, the spin-orbit obliquity, i.e. the angle between the planet’s orbital angular momentum and star’s spin angular momentum, provides useful information about the planet migration and planet-planet interaction mechanisms. The Rossiter McLaughlin (RM) effect allows measurement of sky-projected obliquity using time resolved spectroscopy of an exoplanetary transit. We present ForwardRM, a data driven forward model for RM effect measurements. Opposed to the classical RV based methods, this approach models the line distortions in the stellar spectrum during a transit using the information from all the available out of transit spectra of the host star. Modelling the entire spectrum can allow us to introduce different kinds of velocity fields and even features like active regions in the stellar photosphere and study their impact. The line distortion models can also aid the study of transmission spectroscopy. The framework has been successfully tested on available archival spectra taken with NEID spectrograph for the transit of TOI-2076b and TOI-1268b.

Star-planet magnetic interactions (SPMI) in the sub‑Alfvénic regime, where the stellar wind speed is lower than the local Alfvén speed, can induce enhanced stellar emissions by channeling energy from the planet to the star through Alfvén wings, magnetic structures that act as tethers between the two bodies. These emissions, often observed as stellar hotspots over multiple epochs, remain poorly constrained in terms of their energy budget in the literature. We perform numerical simulations across a range of stellar and planetary parameters for typical sub Alfvénic systems to quantify the maximum power a planet can transfer under these conditions and derive a numerically supported scaling law for SPMI power. Our results show that energy transfer depends not only on the planetary obstacle but also on the extended structure of the Alfvén wings and their interaction with the stellar wind, such effects are often neglected in existing analytical models. This work provides a framework to connect model predictions of observable signals and also helps provide constraints on exoplanetary magnetic properties that are otherwise notoriously difficult to constrain.

While stellar metallicity is a known predictor of giant planet occurrence, the specific influence of individual elemental groups on planetary orbital architecture remains less understood. This work explores how $\alpha$ and iron-peak elements influence giant planet formation and migration using the Hypatia Catalog. We discover using multiple statistical tests that core accretion is accelerated by "Primary Migration Drivers" (Fe, Ca, Si, Cr, Ti) and Oxygen, which causes rapid inward migration into the Hot Jupiter regime. On the other hand, gaseous volatiles like carbon have little statistical effect, whereas "Continuous Gradient Builders" (Mn, Ni, Mg) promote gradual planet expansion without causing abrupt population divisions. We find no evidence that the nucleosynthetic origin ($\alpha$ vs. iron-peak) of a planet's building blocks influences its formation pathway; instead, the influence of these species is controlled by their solid-phase availability and condensation temperatures. By demonstrating that stellar chemistry regulates the speed of core accretion, this work provides observational evidence that elemental abundances act as a fundamental clock for the orbital evolution of giant planets.

We present our study using the VLT/ERIS NIX imager observations at 3.8 µm to directly detect protoplanet candidates responsible for the observed kinematic signatures in protoplanetary disks. By taking advantage of the long-wavelength sensitivity of the L-band, we aim to reduce the impact of circumstellar and circumplanetary dust extinction, significantly improving our ability to resolve thermal emissions from embedded protoplanets. Our targets, identified through ALMA observations of prominent spiral structures and kinematic deviations, are ideal candidates for direct imaging. This work aims to confirm the planetary nature of these features and provides initial constraints on the luminosities of the detected planets. These observations represent a crucial step in integrating kinematic and photometric techniques to calibrate the mass-luminosity relationship of young protoplanets and enhance our understanding of planet formation processes. Our findings highlight the potential of combining ALMA and NIX data to advance the study of planetary genesis in diverse disk environments.