We offer two STFC studentships per year to work within one of the group's research areas as detailed under "research". These studentships are also open to non-UK EU citizens (although only the fees part is paid in this case unless you have been resident in the UK for the past three years). This year we are also offering four European Research Council funded positions, which are open to any nationality. In addition, there are University Research Scholarships and Overseas Research Scholarships (each year the deadline for the latter is January so early applications are encouraged). i
The application form and further details of the application process can be found on the department's postgraduate admissions pages, where information on financial support can also be found. Please note the application form is generic for the University of Leeds. In particular, you do not need to add your own research proposal in Section L, but rather should indicate which of the listed projects you are interested in. If you wish to suggest a project of your own you must first seek approval of a supervisor within the Astrophysics Group at Leeds. Any PhD applicant to the University of Leeds must have a first degree with a 2(i) qualification or equivalent (approximately 60%).
We also offer a one year Master Research course. There is no funding available for this from within the University, so applicants must be able to support themselves. Interested parties are welcome to contact any of the staff members in the Astrophysics Group. Normally a first degree with a 2(i) qualification or equivalent is required for this, though mitigating circumstances may be taken into account.
Star Formation and Feedback
Our group's research interests are outlined here in greater detail. Briefly, our group carries out observational and theoretical studies of massive star formation, and the effects of these stars on their surroundings. On the observational side we have recently completed surveys of the Galactic Plane at mid-IR and radio wavelengths that have yielded the largest, well-selected samples of massive young stellar objects and ultra-compact H II regions to date. The Leeds group has led these two major international survey projects and is heavily involved in other ongoing Galactic Plane surveys at near-IR, far-IR, sub-millimetre and radio wavelengths. On the theoretical side we have expertise in the hydrodynamical and magnetohydrodynamical (MHD) interaction of high Mach number flows, and the effect of adding ablated/evaporated material from cold clumps into these flows. We use state-of-the-art dynamical codes to study these interactions, and radiative transfer codes to simulate observations, aid the interpretation of the data, and drive future observations.
This year the following projects are recruiting.
How do Massive Stars Form?
Massive stars control much of the evolution of galaxies. Their intense output of ultraviolet radiation, stellar winds and ultimate demise as supernovae shapes the interstellar medium. The formation of such massive stars throws up interesting puzzles since that same high luminosity repels infalling material preventing growth during the early stages. The aim of our research in observational massive star formation at Leeds is to study how the emerging protostar interacts with its surroundings. We have been active in several major international collaborations over the past decade that have addressed this problem. Both the Red MSX Source Survey and the Cornish VLA Survey were led by us, and the next two projects make extensive use of the objects found by the RMS survey in particular.
This image shows an artist's sketch of the high mass protostar W33A. The typical components of such a system are the central star, its surrounding accretion disk, an outflow/jet. In reality the disk will connect onto the material in the surrounding molecular cloud, obscuring the central source even further.
Jets and Winds from Massive Protostars:
This project will give a much clearer view of how these stars form through studying the properties of the "radio quiet" massive protostars in the radio. Massive protostars profoundly influence their surroundings as they are forming, whilst still deeply embedded in the dense molecular cloud. In addition to well studied molecular outflows, this feedback takes the form of fast ionized jets and winds. In this project you will use data from the Australia Telescope Compact Array, the Jansky Very Large Array and e-MERLIN to study a sample of massive protostars that are currently in the process of forming. These data will give a map of the radio continuum emission with unprecedented sensitivity, allowing the origin of of the emission to be determined, and hence the physical mechanism responsible, for the first time for such a large sample. This will help constrain whether a radiatively driven wind or jet is present, which can be compared to other data to allow a picture of the object's evolutionary state to be determined. You will take charge of reducing and analysing the ATCA and JVLA data, and extracting fluxes from the eMERLIN Legacy Survey "Feedback Processes in Massive Star Formation" for the massive protostars. You will also have the opportunity to compare the results to appropriate models for jets and winds.
For further details contact: Dr Stuart Lumsden
Massive Protostars in the InfraredMassive protostars emit significantly in the near, mid-infrared and far-infrared. Continuum emission comes from dust heated by the central star, and line emission comes from ionised gas in jets and winds and molecular gas in outflows and accretion disks. These disks and outflows provide the key to our understanding of the formation of these stars, as material accretes onto the stars through the disk, while in parallel, some material is ejected in powerful winds. In our research in Leeds, we observe this circumstellar material at the highest resolutions possible as most of the action takes place in the inner regions, very close to the central star. In this project, you will use recent observations to address the issue of mass accretion onto the stars. You will not only manipulate the raw data, but also apply fundamental and state-of-the-art techniques in order to interpret and analyze the results.
For further details contact: Prof Rene Oudmaijer
The Calm Before the Storm: Prestellar Cores as Astrophysical Laboratories
Stars like our Sun and planets like our Earth form in dense regions within interstellar molecular clouds, called pre-stellar cores (PSCs). PSC provide the initial conditions in the process of star and planet formation, but the gap between a PSC and a protostar/protoplanetary disk system is still vast. The main reason for this is that PSC nuclei remain unexplored and large uncertainties concerning basic astrophysical processes exist, including: the formation and evolution of ice mantles around dust grains (i.e. surface chemistry); the variation of the size distribution of dust grains during gravitational collapse; the cosmic-ray ionization rate; the "metal" abundance; the H2 ortho-to-para ratio; the abundance of atomic oxygen in molecular clouds. In current models, these parameters/processes are typically fixed to some "canonical" values and variations across PSCs are neglected. With the new generation of telescopes and advances in radiative transfer and dynamical/chemical modelling, the time has come to fill this gap.
PSCs are dark, cold and quiescent. They are the simplest units in the process of star formation. Thus, they provide a unique opportunity for the study of fundamental astrophysical processes in a "calm" environment, just before the battering of the protostellar "storm". For this reason, PSCs can be used as ideal laboratories to refine our understanding of how stars and planets form. As part of a project funded by the European Research Council, Prof. Paola Caselli and an international team of scientists will study star and planet formation, from the earliest phases of pre-stellar cores to the formation of protoplanetary disks. The overall aim of the project is to merge theoretical astrochemical, magneto-hydrodynamical and radiative transfer models, and constrain them by detailed observations.
Project 1: Observations. The student will work on millimeter and sub-millimeter (single dish and interferometric) observations and data reduction/analysis of pre-stellar cores embedded in different Galactic environments, as well as on observations of simulated pre-stellar cores, using radiative transfer codes. This will provide a detailed comparison between observations and simulations, which will put stringent constraints on models of the formation and dynamical evolution of pre-stellar cores. Environmental effects on the structure of cores will also be studied.
Project 2: Ionization structure and dynamical evolution. The student will work on astrochemical models of pre-stellar cores, focussing on the degree of ionization during dynamical evolution. The degree of ionization in dense cores of molecular clouds is thought to be the fundamental parameter regulating the rate of star formation. This is due to the process of ambipolar diffusion, whereby the neutral particles in dense cores of low ionization contract relative to the magnetic field and the ionized component. The student will also compare model results with observational data on pre-stellar cores in different environments and quantify how the structure and dynamical evolution of pre-stellar cores are affected by different external conditions.
Project 3: Deuterium fraction and spin states. The student will focus on the formation and destruction pathways of deuterated species, which best trace the high density regions of pre-stellar cores. This is fundamental to compare with observations and constrain chemical/dynamical models. As deuterium fractionation is sensitive to the ortho-to-para ratio of molecular hydrogen, the student will include the spin states of H2 in the astrochemical model and follow the chemistry of ortho and para H2 during the pre-stellar core evolution. The student will also work on a reduced chemical network to be included in the dynamical code.
Project4: Surface chemistry and dust coagulation. The student will focus on the evolution of dust grains during pre-stellar core contraction. In the cold and dense pre-stellar cores, atoms and molecules tend to freeze-out onto dust grains, producing thick icy mantles which boost dust coagulation. The formation of icy mantles will be followed with the use of astrochemical models, where gas and surface chemistry will be coupled together. Dust coagulation will also be taken into account. The student will then compare model results with observations of ice mantle composition toward embedded young stellar objects and gas phase abundances in the hot regions surrounding protostellar objects, where icy mantles evaporate.
Applications are welcome from any nationality for these ERC funded positions.
For further details contact: Prof Paola Caselli
Further InformationInterested parties may also contact the postgraduate admissions secretary for further information:
Ms. Faith Bonner
Phone: +44 (0)113 34 33839