Research :: PhD Topics for 2017 :: Stars

Topics under the thematic line Towards a comprehensive study of starsavailable for the 2017 Call (3 PhD Topics):

  • 2017/221 - Ensemble asteroseismology of solar-type stars with the NASA TESS mission
  • 2017/222 - A new tool for the asteroseismic characterization of large samples of pulsating stars
  • 2017/223 - Magnetic activity and its impact on stellar physics and exoplanets research

For details, please see below the abstract and advisors for each topic. Prospective candidates are welcome to contact directly the proposers of the topics for inquiries and further details.

2017/221 - Ensemble asteroseismology of solar-type stars with the NASA TESS mission

Advisors: Tiago Campante (Univ. of Göttingen), Mikkel N. Lund (Aarhus University), Margarida Cunha (IA U.Porto)

The Transiting Exoplanet Survey Satellite (TESS) is a NASA space mission, with launch scheduled for March 2018, that will perform an all-sky survey for planets transiting bright nearby stars. Furthermore, TESS’s excellent photometric precision will enable asteroseismology, the detailed study of stars by the observation of their natural, resonant oscillations. Asteroseismology is proving to be particularly relevant for the study of solar-type stars (i.e., low-mass, main-sequence stars and cool subgiants), in great part due to the exquisite photometric data made available by NASA’s Kepler space telescope and, more recently, by the repurposed K2 mission. In extending the legacy of Kepler/K2, the main goal of this project will be to perform an ensemble asteroseismic study of bright solar-type stars that reside in the solar neighborhood, making use of data collected by TESS during its 2-year primary mission. To that end, we propose an end-to-end PhD project that will provide the student with skills in photometric time-series preparation from pixel data, asteroseismic data analysis and stellar modeling techniques. The implications of this project are far- reaching. The proposed research will provide a well characterized sample of benchmark solar-type stars to be used in studies of exoplanetary systems and of the chemical evolution of the solar neighborhood, the latter of which will impact on Galactic archaeology studies.

University: Porto

Type: This topic may correspond to a mixed fellowship with up to 1 year abroad.

2017/222 - A new tool for the asteroseismic characterization of large samples of pulsating stars

Advisors: Margarida Cunha (IA U.Porto), Pedro Avelino (IA U.Porto & DFA/FCUP), Dennis Stello (Univ. of New South Wales)

As a result of the launch of the CoRoT and Kepler satellites, the astronomical community has, today, exquisite asteroseismic data on thousands of red giant stars. The analysis of just a fraction of these data has already led to a number of very exciting new results, published in high-impact journals, such as Nature and Science. Moreover, given the approval by ESA of the mission PLATO2.0 (launch around 2024), it is expected that in a decade the number of red giants with detected oscillations will increase by orders of magnitude. To exploit this large observational sample of stars, further development of asteroseismic tools is required. In particular, it is imperative that we have tools capable of modelling the pulsations in large grids of red giant models, covering a wide parameter space (in mass, age, metallicity), in a reasonable amount of time. In this context, a primary goal of this project is to develop a new linear adiabatic pulsation code, significantly more efficient than those currently available, that may be applied to large grids of red giant models, necessary to fully exploit the available data. The code will then be applied in the characterization of the red giant populations for which space-based data are already available, and in the study of particular aspects of the physics of these stars. The proposed tool will constitute a magnificent step forward towards the preparation for the exploitation of the data that will be acquired by the PLATO2.0 mission.

University: Porto

Type: This topic may correspond to a mixed fellowship with up to 1 year abroad.

2017/223 - Magnetic activity and its impact on stellar physics and exoplanets research

Advisors: Margarida Cuna (IA U.Porto), Nuno C. Santos (IA U.Porto & DFA/FCUP)

The study of magnetic activity in stars is now at the center of the attention of the astrophysical community. Its relevance is clear in the context of stellar physics, where there is an effort to understand the necessary conditions for the development of dynamos capable of explaining the observations of the sun and other stars. But its relevance is also evident in the context of the study of sun-earth interactions and in the search for and characterization of earth-like exoplanets. In this project it is proposed that the student develops a new tool capable of simulating more realistically than what is currently done, observables of the greatest importance in the context of the study of stellar activity and of its impact on exoplanets’ research. Based on this tool, the student must first determine the conditions necessary for a robust inference of information about the rotation and activity of stars, as well as about the presence and characteristics of exoplanets. In a second phase, the student should make such inferences from actual data. This tool will be instrumental for a more robust extraction of the information contained in the Kepler (NASA) light curves and in preparing for the exploration of data from future NASA, ESA, and ESO instruments.

University: Porto