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| Three postdoctoral positions in asteroseismology of intermediate- and high-mass stars: clusters, binaries, and yields | Closing date: 2022-02-28
Contact: Conny Aerts |
| The Institute of Astronomy of KU Leuven in Belgium is looking for three junior post-doctoral researchers to join its asteroseismology research group for a period of 3 to 5 years each. All three projects involve Kepler/TESS photometry, Gaia astrometry, and asteroseismic modelling of intermediate- and high-mass stars. The three positions concern 1) gravity-mode asteroseismology of open clusters; 2) dynamical asteroseismology of eclipsing binaries and tidal evolution; 3) yield computations calibrated by asteroseismology and the chemical enrichment of galaxies. | | ▸ more | The Institute of Astronomy (IoA) of KU Leuven is a young and vibrant research group of some 90 scientists, engineers, and administrative staff, including 6 full-time and 3 part-time professors. The institute is an expertise centre in stellar and exoplanetary astrophysics and astronomical
instrumentation, and is active in several international consortia and collaborations, involving
telescopes at observatories worldwide and in space. Members of IoA have access to parallel
computing facilities at the Flemish Supercomputer Centre. The IoA is responsible for the organisation
of the Master of Astronomy & Astrophysics and the Advanced Master of Space Studies of the Faculty
of Science, and operates the 1.2m Mercator telescope at Roque de los Muchachos, La Palma
Observatory, Canary Islands. The institute has a long tradition in instrumental, observational,
computational and theoretical studies of stellar structure and evolution, with emphasis on stellar variability.
The successful applicants will be embedded in a team of asteroseismologists led by Conny Aerts,
Joris De Ridder, and Andrew Tkachenko. They will be working jointly on mapping the internal rota(on
and mixing profiles of stars as a function of their global stellar properties such as mass, age,
metallicity, initial angular momentum, and multiplicity. The selected postdocs are expected to take
up responsibilities in the supervision of BSc, MSc, and PhD students. They will receive ample training
in the writing of personal competitive project applications as an important aspect of their future career development.
The projects rely heavily on data from the Kepler/TESS and Gaia space missions, as well as from
ground-based spectroscopic surveys characterising stellar surface properties. The assembled time
series contain a tremendous amount of information, yet to be exploited jointly. As an overarching
aim, the three postdocs will work together with a group of PhD students to extract optimal
observables from data of non-radial pulsators assembled by the surveys and exploit them to improve
the theory of stellar structure and evolution.
The three projects cover a multitude of concrete aims and tasks to be done, requiring various skills.
Candidates wishing to apply for more than one posi(on are requested to express their order of
preference.
1) Gravity-mode asteroseismology of open clusters
The applicant will develop customized methods to extract optimal lightcurves from TESS full-frame
images of open clusters, by maximally eliminating instrumental effects in the Fourier domain and by
treating crowded fields. Thorough time series analysis will be carried out for all cluster stars to
identify and extract signatures of gravity-mode oscillations, rotational modulation and possible
binarity. The applicant will perform mode identification and model the identified modes of all
pulsators and all binaries per clusters jointly with their Gaia data, featuring the strongest set of
constraints on each member?s properties. The pioneering goal is to evaluate current stellar evolution
theory and to reveal empirical relations deduced from all observed properties of the cluster stars as
new recipes for stellar evolution predictions.
2) Dynamical asteroseismology of eclipsing binaries and tidal evolution
The applicant will extract optimally defined observables from the survey data to perform joint
modelling of photometric, spectroscopic, and astrometric time series of eclipsing binaries, with the
aim to deduce accurate dynamical masses and radii. The latter quantities will be used to deduce the
ages of the binaries for two large samples of intermediate- and high-mass stars, from stellar
modelling based on the latest evolutionary models of stellar interiors and atmospheres. This will lead
to an assessment of the so-called mass discrepancy of binary stars, pulsating and non-pulsating, in
terms of their metallicities, evolutionary stages, and orbital characteristics. From the multitude of
observational constraints, the theory of binary evolution will be re-evaluated and improved
with the aim to assess the effects of tides on internal rotation and mixing of stars, and of angular
momentum of the systems.
3) Yield computations calibrated by asteroseismology and the chemical enrichment of galaxies
The applicant will calibrate internal mixing profiles due to convection, rotation, magnetism, and
possible binarity from gravity-mode pulsators in the mass range [3,25] solar masses. This will be achieved
from asteroseismic modelling based on TESS, Gaia, and spectroscopy data. The asteroseismically
calibrated mixing profiles and the resulting He and C core masses during the main sequence (MS)
and post-MS evolution will be used to calculate new stellar models up to the remnant phase. The
corresponding chemical yield predictions will be computed with tools from the ChETEC INFRA
(https://chetec-infra.eu/) EU infrastructure (2021- 2026). These chemical yields will then be used to
assess the difference between asteroseismically calibrated yields and those for current models not
calibrated by asteroseismology. The final aim is to evaluate how much these differences impact
chemical evolution models of the galaxy and Magellanic Clouds.
Requirements, offer, and online application tool via:
https://www.kuleuven.be/personeel/jobsite/jobs/60088185?hl=en&lang=en
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