Two Doctoral students in Astronomy and Astrophysics - Hiring in process/Finished, not possible to apply

We announce two PhD positions in Astronomy and Astrophysics at the Department of Astronomy and Theoretical Physics.

(1) Validation and exploitation of Gaia data. The scientific community has recently received the second release of Gaia data in April 2018 which delivered positions, parallaxes and proper motions for more than 1.3 billion stars in our Galaxy. While the accuracy of these results is unprecedented they will still not achieve the final accuracy promised for Gaia in the early 2020's. To achieve this final accuracy much work still needs to be done in calibrating the Gaia instrument and characterizing the systematic errors that inevitably occur in such catalogues. Financed by the Swedish National Space Board (PI: David Hobbs)

(2) Formation of moon systems. The four giant planets of the Solar System - Jupiter, Saturn, Uranus and Neptune - are all hosts to extensive systems of moons. The Cassini mission to explore Saturn and its moons ended in 2018, but in 2022 ESA will launch the JUICE spacecraft and NASA will launch the Europa Clipper to study Jupiter's moon system. The formation of moon systems is nevertheless still not well understood, with competing theories stating that the moons either formed in a gaseous subdisc around the host planet or in a primordial disc of ice particles, akin to Saturn's ring but much more massive. Financed by the Knut and Alice Wallenberg Fuondation (PI: Anders Johansen)

Work duties

(1) The student will participate in the Gaia data processing for future data releases, especially improving the calibration models as well as characterizing the quality of the catalogue. Specific topics could include the accuracy of the Gaia reference frame and the parallax zero point, spatial systematic errors and proper motion patterns. Deviations in proper motions of sources between different catalogue releases can be used to indicate the presence of binary or exoplanet systems. Exploitation of the Gaia results for Galactic dynamic studies using insights into the expected correlated errors among the astrometric data is encouraged. This will be especially important when combining data for many stars (for example in clusters), where even small correlations, if not taken into account, may lead to severe underestimation of the actual uncertainties of the results.

(2) The student will run numerical simulations of the dynamics of massive particle discs orbiting around young gas giants and ice giants. Such discs may form at the planet formation stage as pebbles of ice and dust are accreted towards the planet and build up a dense circumplanetary disc due to the conservation of angular momentum. The disc material will mainly reside within the Roche limit where gravitational collapse to form moons is not possible due to the strong tidal force. The student will simulate how such a ring expands outwards due to collisions between the particles and how the outer regions collapse gravitationally to form moons. Such moons will migrate away from the planet due to tides from the remaining disc and this way entire moon systems can form.

Eligibility

The position is open to students of all nationalities who, at the time of starting the PhD studies, have obtained a Masters degree in astronomy, physics or in other ways obtained the equivalent qualifications. In case of uncertainty concerning the applicant's eligibility, it is advisable to contact the department for clarification. The discipline curriculum for postgraduate studies in Astronomy and astrophysics is found at https://www.science.lu.se/sites/science.lu.se.internal/files/syllabi_astronomy.pdf.

Good knowledge in spoken and written English is required.

Basis of assessment

Regulations concerning appointment as a doctoral Studentship can be found in the Swedish Code of Statues 1998:80. To be accepted for postgraduate studies, a student must be judged to have the competence necessary to complete a PhD during the tenure of the appointment. In addition to pursuing postgraduate studies, the doctoral student may be required to perform other duties - including research, teaching and administration - according to the specific regulations.

Application

Candidates should send a curriculum vitae (including a transcript of academic grades) and a brief statement of research interest. The application should also include the names, telephone numbers and e-mail addresses of two persons who have agreed to serve as a reference for the applicant. Note that reference letters should not be sent to us in connection with the application; we will contact the reference persons when required.

Information on the PhD programme: http://home.thep.lu.se/~bijnens/PhD/ 

Type of employment

Limit of tenure, four years according to HF 5 kap 7§.