Possible PhD projects
for students planning to start in 2011/2012
For further details, please contact the staff member concerned, by completing their email address [in brackets] with @st-andrews.ac.uk
Areas of research:
Spindown of solar-type stars in nearby open clusters
Prof Andrew Cameron [acc4],
Dr Jane Greaves [jsg5]
Solar-type stars are born with a variety of spin rates. Magnetic braking
theory predicts that the spread should narrow after a few times 10^8 y but
observational surveys remain scanty. We will compile a complete survey of
rotation periods in open clusters spanning the critical age range using
SuperWASP photometry.
Coronal structure of low mass stars
Prof Moira Jardine [mmj],
Prof Andrew Cameron [acc4]
Low mass (fully convective) stars appear to generate magnetic fields
whose surface distributions are fundamentally different to those of higher
mass stars. We will use existing Zeeman-Doppler maps of these surface
magnetic fields to model the coronal structure and X-ray emission of these
stars.
Magnetic cycles in young stars
Prof Moira Jardine [mmj],
Dr Kenneth Wood [kw25]
In very young stars, material accreting from a surrounding disk is
channelled by the star's magnetic field onto the stellar surface. We will
use recently-acquired magnetic maps of these stars to model the impact of
magnetic cycles on this accretion process.
Star-Planet Interaction
Prof Moira Jardine [mmj]
Tau Boo is the only star for which we have been able
to track the full cyclic reversal of the stellar magnetic
field. This system is also well-known, however, because
it hosts a Hot Jupiter that is so close to the star that it may lie
within the stellar corona. What is the nature of the interaction
between the star and planet in this case and is it related to
the puzzling nature of the very short magnetic cycle? This
project will investigate tau Boo and other similar star-planet systems.
Structure and evolution of protoplanetary disks.
Dr Kenneth Wood [kw25],
Dr Jane Greaves [jsg5]
Understanding the structure, composition, and dynamics of protoplanetary
disks are crucial for planet formation theories. This project will combine
dynamical models of disks with 3D radiation transfer and new
multiwavelength imaging and spectroscopy to study dust growth and
settling, disk-planet interactions, and signatures of massive,
self-gravitating disks.
Diffuse ionized gas in galaxies
Dr Kenneth Wood [kw25]
Extensive layers of diffuse ionized gas are observed in the Milky Way and
other galaxies. This project will study the structure, ionization,
heating, and dynamics of diffuse ionized gas using a combination of 3D
Monte Carlo radiation transfer codes and recent 3D dynamical models of a
supernova driven ISM.
Triggering of star formation
Prof Ian Bonnell [iab1]
There are several outstanding issues in current models of star
formation. One of these is the role of feedback from young stars
in producing subsequent generations of young stars.
Triggering of star formation through supernova events is likely to be
the dominant mechanism. Numerical simulations of SNII impacting on
molecular clouds and the triggering of star formation will be used to develop
physical models, and ultimately observational predictions and tests of the
process.
Star formation in dwarf galaxies
Prof Ian Bonnell [iab1]
This project is to develop the first models of resolved
star formation on galactic scales. This will involve
modelling a full galactic potential and how it drives
the formation of molecular clouds and the onset
of gravitational collapse and star formation.
feedback from ionisation and supernova will be
included to assess molecular cloud lifetimes and
star formation efficiencies.
Forming comet belts around nearby stars
Dr Jane Greaves [jsg5],
Prof Andrew Cameron [acc4]
Collisions of comets create dust belts that can be imaged at
submillimetre wavelengths. The SCUBA-2 Legacy Survey starting early-2010
will explore what kinds of star have comets and if this is a signpost of
extrasolar planets. We will help analyse the database of 500 stars to
identify underlying stellar influences.
Atmospheric fingerprints of planets and Brown Dwarfs
Dr. Christiane Helling [ch80]
These projects will investigate the atmospheres of planets and Brown
Dwarfs which contain the fingerprints of their physics and
chemistry. Atmospheres of Brown Dwarfs and giant gas planets are
forming clouds that can be made of silicate and iron dust rather than
of water. Any clouds leave a trace of an individually depleted gas
which determines the spectral appearance of the planet/Brown Dwarf as
well as it does influence the dynamic behaviour of the atmosphere.
Using a detailed model of dust formation, possible topics include:
- Atmosphere's response on planetary evolutionary events like
volcanism, dust/gas accretion, mass loss during star-planet
interaction applying and extending a dust cloud formation code
- Modeling atmospheres of planets/Brown Dwarfs in nearby galaxies,
like the Large and the Small Magellanic Cloud applying the
Drift-Phoenix atmosphere code
- Modeling planetary atmospheres under the influence of disk
evolution combining results from protoplanetary disk evolution
model with atmosphere modeling
Dark Matter in Galaxies
Mass Distribution of the Galaxy
Dr HongSheng Zhao [hz4]
The mass distribution of the Galaxy is being / will be mapped out in
great detail in the next decade with the numerous surveys of the Galaxy,
including Segue, RAVE, GAIA, and completed ones like 2MASS, DENIS. A model
for the potential and phase space of the galaxy is essential to bring
various pieces of information together. The student will develop such
models building on experience from existing models.
Annihilation of Dark Matter
Dr HongSheng Zhao [hz4]
A main diagnostic of the particle dark matter is its annihilation rate,
which depends sensitively on the dark matter density profile. The student
will explore various density models of the dark matter, taking into
account the effects of black holes and baryonic dynamics.
GAMA: Galaxy and Mass Assembly
Prof Simon Driver [spd3]
The Galaxy And Mass Assembly survey (GAMA) is a major global collaboration led from St Andrews which brings together data streams from the latest cutting edge facilities from the ground and space including: AAT, UKIRT, VISTA, VST, HERSCHEL, WISE, GALEX, ASKAP and GMRT. The data are being used to study the clustering properties, structural properties, baryon content, and energy output of the nearby galaxy population and their recent evolution over the past 5 billion years. The main objective is to establish a direct empirical blueprint for the formation and evolution of galaxies. Students are sought to work on all aspects of this project and in particular fresh data arriving from the newly commissioned VISTA telescope and the newly launched HERSCHEL and WISE space missions as well as to participate in the routine annual spectroscopic observations at the Anglo-Australian Telescope at Siding Springs Observatory. Students should expect to work within a small group at St Andrews embedded in a large international collaboration and will obtain insight into multi-wavelength data analysis, processing of large information rich data sets, and the physics underpinning galaxy formation and evolution. One or two students are sought to join the project from September 2011.
Echo Mapping of AGN
Prof Keith Horne [kdh1]
Light travel time delays enable micro-arcsecond mapping of accretion
disks and broad emission-line regions around the super-massive black holes
in the nuclei of active galaxies. RoboNet provides the UK with unique
datasets for measurement of black hole masses, accretion rates, and
luminosity distances. The student will acquire and analyse such datasets,
using parameterized models and Hornes maximum entropy fitting code
MEMECHO.
Microlens Survey for Cool Planets
Prof Keith Horne [kdh1]
Intensive monitoring of Galactic Bulge microlensing events is being used
to discover cool planets in 1-5 AU orbits around the lens stars. Our
PLANET/RoboNet team has just discovered a 5 earth-mass planet. In the next
4 years we aim to measure the abundance and mass function of cool planets
to test theories of planet formation and migration. The student will work
with our team to acquire and analyse observations, fit microlens models to
characterize the planetary and other anomalies.
Wide-angle search for transiting planets
Prof Andrew Cameron [acc4]
The WASP project (http://www.superwasp.org) is a consortium comprising 6 UK universities and 3 overseas observatories. We use two arrays of wide-field camera lenses backed by large-format CCDs to perform high-precision photometry of millions of stars each night, looking for the 1% dips in light that betray gas-giant planets whose orbital planes are close enough to the line of sight that they transit their host stars. Our current catch stands at 34 planets confirmed by radial-velocity follow-up. There is an opening at St Andrews for a PhD student to work on a combination of project infrastructure and science exploitation. Possible components of a PhD project include:
- Improving the quality of the SuperWASP photometry using image-subtraction and profile-fitting methods;
- Improving the transit detection and pre-selection criteria to eliminate astrophysical and other false positives;
- Measuring stellar spin rates and spin-orbit misalignments using time-resolved spectroscopy during transits;
- Determining the ages of transiting planet systems from the spin rates of the host stars;
- Modelling the tidal spin-orbit interaction between the closest-orbiting hot Jupiters and their host stars;
- Using high-resolution time-series transit spectroscopy to confirm the presence of planets around early-type stars;
- Reconciling the planet catch with models of the galactic planet population and observational detection thresholds;
- Modelling the infrared spectra of hot-Jupiter atmospheres for comparison with Spitzer/IRAC secondary-eclipse photometry;
- Building or using simple planetary structural models as a tool to aid understanding of the mass-radius relation for transiting hot Jupiters as a function of age, core mass, envelope metallicity, stellar irradiation etc.
Studying planet populations by means of gravitational microlensing
Dr Martin Dominik [md35]
With more than 400 planets orbiting stars other than the Sun known (as of
March 2010), observing campaigns now need to evolve from the pure
detection of planets to studies that allow to infer the statistical
properties of the underlying populations that are being probed. Only by
comparing a wide planet census with model predictions of planet formation
and evolution, will we be able to understand the origin (and future!) of
habitable planets, and Earth in particular. Due to their probabilistic
nature, gravitational microlensing experiments are particularly
challenging, but they are suited to provide insight that remains hidden to
any other known technique, with a sensitivity reaching even below Earth
mass, and the possibility to spot signatures of planets orbiting stars in
other galaxies. The realisation of a fully-deterministic observing
strategy is a necessary prerequisite for measuring planet abundances. Over
the recent years, we have been working on the development of the
world-leading technology for implementing an automated microlensing
campaign that is carried out by means of our
RoboNet-II and
MiNDSTEp
telescope networks, and informed about the targets to be observed by the
publically-accessible
ARTEMiS
system. Two specific topics currently call
for special attention:
1) Further development of ARTEMiS is required to provide a target
recommendation for a non-proprietary heterogeneous network of telescopes
according to a user-defined strategy, the currently available data, the
individual telescope capabilities, and the observability. Gravitational
microlensing is a showcase application for modern telescope scheduling,
and by its strong demands on flexibility and reaction time leads to
pioneering concepts that can be of far more general use. Moreover, ARTEMiS
not only provides tools to astronomers, but also brings forefront science
to the general public.
2) Imperfections in the data reduction lead to various types of spurious
signals, which either need to be properly identified and separated from
real variations, or to be treated statistically as a form of background
noise. The low-mass sensitivity limit of our campaigns crucially depends
on how well we understand this. Moreover, a proper understanding of false
positives will make a difference on the efficiency of our monitoring
programme by allowing more appropriate decisions based on real-time data.