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A Pathway to the Confirmation and Characterisation of Habitable Alien Worlds

Since the confirmation of the first planets outside our solar system in the 1990s, we have made tremendous progress towards answering this question. Yet, the confirmation of a true Earth-analogue still evades us. On top of this, if we are truly to understand the origins of life in the cosmos, we must also create a complete picture of planetary formation, evolution, and habitability.

However, each of these aspects necessitates a detailed knowledge of solar-type stars. This is because we study exoplanets indirectly by analysing their much more luminous host stars. For example, most planet confirmation relies on the Doppler wobble of the host star, induced by the planet. Moreover, we can learn about a planet's dynamical history from mapping its projected orbit as it transits its host star. Hence, stellar surface inhomogeneities can impact planetary interpretations, and can completely swamp the signals from rocky worlds.

My research, as a UKRI Future Leaders Fellow, aims to overcome these hurdles. For this, I study stellar surfaces from a two-pronged approach: with state-of-the-art 3D simulations and using transiting planets to empirically probe stellar surfaces.

Abstract:
Are we alone in the Universe? Since the confirmation of the first planets outside our solar system in the 1990s, we have made tremendous progress towards answering this question. Yet, the confirmation of a true Earth-analogue still evades us. On top of this, if we are truly to understand the origins of life in the cosmos, we must also create a complete picture of planetary formation, evolution, and habitability. However, each of these aspects necessitates a detailed knowledge of Sun-like stars. This is because we study exoplanets indirectly by analysing their much more luminous host stars. For example, most planet confirmation relies on the Doppler wobble of the host star, induced by the presence of the planet. Moreover, we can learn about a planet's dynamical history from mapping its projected orbit as it transits its host star. Hence, if there are inhomogeneities on the stellar surface, they can impact planetary interpretations and even completely swamp the signals from rocky worlds. In this talk, I will discuss how we confirm and characterise planets outside our solar system and how our knowledge of their host stars poses a fundamental hurdle we must overcome on the pathway to rocky, temperate worlds.


Habitability Seminar - Anders Sandberg

Seminar title: Inhabiting the universe: what are the limits for habitats across the future of the universe?

It was our pleasure to welcome Anders Sandberg from the Future of Humanity Institute, University of Oxford. Anders gave an exhilarating overview of a number of potential futures for life, both as we know it and otherwise. After considering the likeliness of finding alien life given our current observational and theoretical understanding, Anders moved on to consider a variety of avenues for life to flourish in the upcoming eras of the universe.


Ground-based detection of G star superflares with NGTS

CEH member James Jackman leads a recent study of flares in G-type stars, as observed using NGTS. The study shows that G-stars can have flares many times the energy of the Carrington event, and the primary detection is one of the largest amplitude superflares detected from a bright G star.

This work was published in Monthly Notices of the Royal Astronomical Society, Volume 477, Issue 4, p.4655-4664

Open access link: arXiv

CEH members involved: James Jackman (lead), Peter Wheatley, Chloe Pugh, Boris Gänsicke, Anne-Marie Broomhall, David Armstrong & James McCormac


Cool DZ white dwarfs II: compositions and evolution of old remnant planetary systems

CEH member Mark Hollands leads a new study which examines pollution of cool DZ white dwarfs.

This work was published in Monthly Notices of the Royal Astronomical Society, Volume 477, Issue 1, p.93-111

Open access link: arXiv

CEH members involved: Mark Hollands (lead), Boris Gänsicke


Automatic vetting of planet candidates from ground based surveys: Machine learning with NGTS

CEH member David Armstrong has published a new study on automatic vetting of exoplanet candidates using machine learning techniques. In this work he applies it to candidates from NGTS, but the technique is extendable to other transiting exoplanet surveys.

This work was published in Monthly Notices of the Royal Astronomical Society, Volume 478, Issue 3, August 2018, Pages 4225–4237

Open access link: arXiv

CEH members involved: David Armstrong (lead), James McCormac, Daniel Bayliss, Tom Louden, Don Pollacco, Richard West & Peter Wheatley


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