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.

It is our pleasure to welcome Dr Raphaëlle Haywood from the University of Exeter to the Centre for Exoplanets and Habitability seminar series. Dr Haywood will be giving a talk titled 'There’s No Place Like Home: Placing Earth in its Astronomical and Geological Contexts'.

Abstract:
Recent revolutionary discoveries in astronomy are showing that Earth is one of billions of planets, and that terrestrial, temperate planets are commonplace in our galaxy. Geological records indicate that Earth has been many different worlds over time, and life has shown extraordinary resilience through these planetary changes. If we could go to the stars and point our telescopes back at Earth, what would we see? How does life alter Earth's astronomical character? We will look at one of Earth's defining ecosystems: the Amazon rainforest, which is observable from cosmic distances. We will reflect on the impact of various human civilisations. Ultimately, we will draw on these astronomical and geological perspectives to demonstrate that humanity's flourishing is profoundly tied to maintaining this world, here, that we co-evolved with.

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.

CEH member Richard West leads the fascinating discovery of an exoplanet that falls in the middle of what has been termed the 'Neptunian desert'. This refers to a region close-in to the parent star where previously no Neptune-sized exoplanets had been found. NGTS-4b has a mass 20 times that of the Earth and orbits its star (a 13th mag K dwarf) once every 1.34 days! What's more, it's the smallest planet discovered by a wide-field ground-based photometric survey to date - excellent work!

This study was published in Monthly Notices of the Royal Astronomical Society, Volume 486, Issue 4, July 2019, Pages 5094–5103

Open access link: arXiv

CEH members involved: Richard West (lead), Daniel Bayliss, James Jackman, George King, James McCormac, Peter Wheatley, David Armstrong, Paul Chote, Ben Cooke, Emma Foxell, Boris Gänsicke, Tom Louden & Don Pollacco

Dimitri Veras leads an interdisciplinary team of astronomers and biologists in a study exploring the dynamical and biological constraints of interplanetary panspermia. This is the theory that life can hop from planet to planet via some mechanism, most likely aboard asteroids or comets.

This work was published in Astrobiology, Volume 18, Number 9

Open access link: arXiv

CEH members involved: Dimitri Veras (lead), David Armstrong, James Blake, Jose Gutiérrez-Marcos & Hendrik Schäefer