Astrophysics at Keele: planets, stars and galaxies.

Lead Research Organisation: Keele University
Department Name: Faculty of Natural Sciences

Abstract

In understanding our place in the universe we need to know how many planets there are and how planetary systems form and evolve. The best way of studying planets is to find the ones that pass in front of ("transit") their star. By looking for the tiny dips in a star's light caused by a transiting planet, Keele's WASP-South survey has found more transiting planets than anyone else in the Southern hemisphere, and is using them to answer questions about how planetary systems form.

Planets form around young stars, and star and planet formation are intimately connected. Keele will process the data from a very large survey of young stars and clusters of stars, using spectra obtained by ESO's Very Large Telescope, to combine with the unprecedented astrometry soon to be obtained by ESA's Gaia mission. The combination will provide the biggest survey yet of how stars and stellar clusters form and evolve.

The two Magellanic Clouds are the two galaxies closest to our own, so close that they interact with our galaxy, providing an excellent opportunity to study how galaxies affect each other, with collisions and mergers thought to be important factors in explaining galaxies today. Keele will exploit the Vista Magellanic Cloud near-infrared survey to map out star formation across entire interacting galaxy systems and study how star formation differs between the Magellanic Clouds and our galaxy.

At the cores of galaxies, supermassive black holes can grow by sucking in material from their surroundings. It is now realised that powerful winds generated by the swirling around a black hole can both regulate the growth of the black hole and affect the future evolution of the whole galaxy. A Keele-led program using the latest X-ray satellites studies the X-ray emission generated by the extreme gravity of the black hole to map out the distribution of the spin periods of the black holes, to study how they interact with their host galaxies.

In order to understand both stars and planets transiting stars we need to know the relation between the masses and the radii of stars. This is not known accurately enough currently, but we can improve this by using newly discovered eclipsing binary stars to measure both masses and radii and thus map out the mass-radius relation.

Planned Impact

Keele has a strong and active programme of outreach and the promotion of the public understanding of science. Keele Astrophysics is particularly strong in this regard, and roughly half of the whole university's science outreach interactions can be attributed to the astrophysics group. In particular we:

(1) Use all opportunities to promote our work in local and national media, through press releases and involvement in television programmes.

(2) We have made the Keele Earth and Space Observatory the main science attraction for the local Stoke-on-Trent area. This brings over 3500 visitors a year onto campus, including school and scout groups.

(3) We have developed an Exoplanetarium featuring Keele exoplanet research which is taken out into schools. It has now been seen by over 4100 primary-school children, over 3700 secondary-school children and 1400 members of the general public, and produces excellent feedback from school kids and their teachers.

Keele's programme of science outreach is targeted at pupil inspiration and aspiration in the Stoke-on-Trent region, an area of relative deprivation with relatively low rates of university participation, which thus benefits from astrophysics research in its midst.

Publications

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Borkovits T (2021) BG Ind: the nearest doubly eclipsing, compact hierarchical quadruple system in Monthly Notices of the Royal Astronomical Society

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Choplin A (2016) Clues on the first stars from CEMP-no stars in Proceedings of the International Astronomical Union

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Choplin Arthur (2016) Nucleosynthesis in the first massive stars in arXiv e-prints

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Clark B (2018) An Analysis of Transiting Hot Jupiters Observed with K2: WASP-55b and WASP-75b in Publications of the Astronomical Society of the Pacific