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Projects for Astrophysics Students 2015/16
1.
Magnetic Complexity Variations in Solar Active Region Flaring-rate
Distributions
Supervisor: Dr. D. Shaun Bloomfield
Location: TCD
One of the greatest challenges in solar physics is the reliable prediction of flaring
activity, which is a clear manifestation of the rapid release of energy stored in the
twisted magnetic fields of solar active regions (i.e., sunspot groups). It is well known
that active regions with greater magnetic complexity flare more often and are
capable of producing larger magnitude flares, but many state-of-the-art flare
prediction techniques use values of average flaring rates for different active region
complexities. The aim of this project is to investigate how the distributions of flaring
rates vary as a function of active region magnetic complexity, how well the average
flaring rates represent these distributions and how they change over a solar cycle.
2.
Determining the processes that lead to particle acceleration during solar
eruptive events
Supervisors: Dr. Eoin P. Carley and Dr. Nicole Vilmer
Location: LESIA, Paris Observatory, France
TCD Local Contact: Prof. Peter Gallagher
Eruptive activity in the solar corona can often lead to a wide variety of particle
acceleration processes, such as magnetic reconnection during a solar flare, or the
driving of a shock wave by bulk plasma motion. However, exactly which process is
more pertinent during a solar eruptive event is unknown. In this project, the student
will study radio spectral and imaging observations from the Nancay Radioheliograph
(France) to determine the details of particle acceleration in the corona. This will be
combined with extreme ultraviolet imaging observations of eruptive activity using
NASA's Atmospheric Imaging Assembly. The radio and EUV imaging will reveal in
which sites of the corona the particle acceleration originated, while the radio spectral
observations will show what kind of particle acceleration process took place (shock
or magnetic reconnection). Such a study is important in the understanding of
fundamental particle acceleration processes on the sun and can help test which
standard models of coronal eruptive activity are correct. The student will be based at
the Laboratorie d'études spatiale et d'instrumentation en astrophysiqie (LESIA),
Paris Observatory, France to work on the analysis of radio imaging and spectral
data.
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3.
Short Timescale Stellar Variability – Observations at the Monck Observatory
Supervisor: Professor Brian Espey
Location: TCD
Symbiotic binary systems generally consist of a hot white dwarf in orbit around a
large red giant. Mass is lost from the red giant, and some of this material may be
accreted directly on to the white dwarf, increasing its light output. Accretion may be a
slow, steady process in which material from the red giant’s wind is accreted, or
accretion may be much more rapid, in the form of mass transfer via. the Roche
mechanism into a semi-stable orbit around the white dwarf. The goal of this project is
to photometrically observe a number of systems to study the stability and nature of
the mass transfer process, and to characterise the timescales. Other objects may be
observed in order to quantify the accuracy obtainable with photometry at the Monck.
Note that these night-time observations will be made at the Monck Observatory as
weather permits, and may involve long hours in the cold. Competence with IDL
required.
If opportunities present, we will also attempt to acquire data for other short-timescale
phenomena (e.g., asteroid rotation curves).
4.
Automatic Detection and Characterisation of Solar Radio Bursts
Supervisor: Professor Peter T. Gallagher
Location: TCD
Solar radio bursts are produced by energetic electrons spiralling along magnetic field
lines in the solar atmosphere. They are thought to be accelerated by processes such
as magnetic reconnection or shock waves associated with flares and coronal mass
ejections. In order to understand their physical origin, basic properties such as
frequency drift rate, bandwidth, duration, and brightness must be determined with a
high degree of accuracy. In this project, the student will develop a technique to
automated identify, characterise and classify solar radio burst observed by a set of
radio
spectrometers
at
the
Rosse
Solar-Terrestrial
Observatory
(www.rosseobservatory.ie). The method will be implemented in near-realtime to
automatically detect and classify radio bursts for space weather monitoring and
forecasting purposes.
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5.
Surface Evolver simulations of foam structures
Supervisor: Professor Stefan Hutzler
Location: TCD
Foam structure is determined by the minimisation of surface area for given bubble
volumes, together with external constraints (e.g. cross-section of tube containing the
foam). This computational project will use the Surface Evolver software
(http://www.susqu.edu/brakke/evolver/evolver.html) to compute various foam
structures.
6.
Exoplanet transit timings with the Armagh Robotic Telescope.
Supervisor: Professor C S Jeffery
Location: Armagh Observatory
Evidence of planets orbiting stars other than the Sun has transformed astronomy
over the last two decades. The major discovery-technique in recent years has been
the transit method. High-precision photometry is necessary to detect the smallamplitude eclipses. Transit timings can be used to refine orbital properties, and
obtain evidence for additional planets in the exoplanet system.
This is primarily an observational project using the Armagh Robotic Telescope
(ART).
The goal will be to identify and observe exoplanet transits visible from Armagh during
October - December. The primary experimental steps will be to:
i) obtain differential photometry using the ART,
ii) reduce the data to obtain differential light curves,
iii) obtain accurate timings, reduced to a standard time system,
iv) compare with published ephemerides to look for possible deviations.
Given the unpredictability of Irish weather, this project will include options to study
the theoretical interpretation of exoplanet transit lightcurves in terms of stellar and
exoplanet properties, and to make observations of stellar oscillations in, for
example, subluminous B stars. The close link between PLAnetary Transits and
stellar Oscillations is recognized by the name of the next ESA medium-sized mission
- PLATO.
Although the ART can be operated remotely, it should be assumed that the student
will be present in Armagh and available at night to monitor the observations.
Demonstrable competence in experimental procedures is required. On-site
accommodation is available; terms are negotiable.
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7.
Chemical Abundance Analyses of Exotic Stars
Supervisor: Professor C S Jeffery
Location: Armagh Observatory
As stars approach the end of their lives, their surface chemistry may be heavily
modified by a combination of different processes. The sky is littered with stellar
remnants which show a range of exotic chemical signatures. Measuring the
chemistries is just one of many tools necessary to understand how some of these
stars have evolved, and one that often leads to great surprises.
Mixing mechanisms include convection, where exotic nuclear products are dredged
up from the deep interior, radiative levitation, where individual high-opacity ions form
thin layers in the stellar atmosphere, and accretion, where material from another star
replaces the original surface. Decoding which elements are present requires highresolution spectroscopy, the construction of a model atmosphere and a procedure to
match the observed and theoretical spectrum.
This project will aim to measure the abundances of several exotic species in the
spectrum of at least one highly-evolved star, using data obtained with the Hubble
Space Telescope.
It will involve:
i) identifying absorption lines in the observed spectrum,
ii) using theoretical atomic data to create a linelist for the model spectrum,
iii) using existing codes to construct model atmospheres and theoretical spectra,
iv) matching the model to the observation and hence deriving the abundances of
exotic species.
v) interpreting the surface chemistry in terms of an evolution model.
In order to provide training in use of the stellar atmosphere codes, the student should
expect to spend most of his/her time in Armagh. Competence in using linux
computers and some programming experience are essential. On-site
accommodation may be available; terms are negotiable.
8.
Understanding the connection between Coronal Mass Ejections and Global
Waves
Supervisor(s): Dr. David Long / Dr. David Pérez-Suárez (Group Head: Professor
Louise Harra)
Location: Mullard Space Science Laboratory, University College London,
Surrey, UK
TCD Local Contact: Prof. Peter Gallagher
Coronal mass ejections (CMEs) are the most spectacular events occurring in our
heliosphere. Propagating at speeds of up to 2000 km/s, they can travel from the Sun
to the Earth in just a few days and with their high speeds, magnetic field and mass of
up to 10^12 kg, they can cause major problems in the near-Earth environment. On
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the Sun, the eruption of a CME can produce a wave which propagates across the
surface of the Sun at speeds of up to 1000 km/s, although the exact nature of the
relationship between the wave and CME is not well understood. This project will
investigate the wave-CME connection using CorPITA and CORIMP, a suite of
automated detection codes originally developed at Trinity College Dublin and now
used worldwide. This project will require original coding in IDL/Python, basic shell
scripting and a keen interest in big data analysis!
The student should expect to spent most of the time working in the Solar Physics
Research Group at Mullard Space Science Laboratory, University College London.
The Solar Group has strong research links with research groups in Japan, France,
Belgium, Ireland and the USA and has a deep involvement with both current and
future space missions (including Hinode, Solar Orbiter and Solar-C). Accommodation
will be provided in a nearby village.
9.
Long term Evolution pattern of Active Regions on the Sun.
Supervisor: Dr. Sreejith Padinhatteeri (Group leader: Prof. Peter Gallagher)
Location: TCD
Sunspots are the most dominant features on the Sun surface. They harbour complex
concentrations of magnetic field that become entangled in the plasma ocean that is
solar surface, otherwise known as the photosphere. They migrate across the solar
disk, close to the solar equator, and they can rapidly evolve and release enormous
amount of energy over times scales of minute to days. Understanding their long--‐
term evolution behaviour is an important problem in Solar physics. During this project
the student will look at last 15 year’s data from satellite based instruments and nearly
100 years data from ground based observatories like Kodaikkanal observatory India,
and Mount Wilson Observatory, USA to study long term evolution pattern of the
active regions over many solar cycles.
10.
New insights into the 3D nature of solar sunspots at the highest resolution
Supervisors: Dr. Eamon Scullion (Group leader: Prof. Peter Gallagher)
Location:
TCD
Sunspots are one of the most dominant features to appear on the Sun surface. They
harbor dense concentrations of magnetic field that become entangled in the plasma
ocean that is the solar atmosphere. Their magnetic influence spreads far out from
the surface and they appear to migrate across the solar disk, close to the solar
equator. During this project the student will analyze the 3D properties of sunspots,
which are tracked across the solar disk at the highest resolution available, from
observations taken by Trinity Astrophysics Group at the Swedish 1-m Solar
Telescope, located on La Palma, Canary Islands.
(http://dubshen.astro.su.se/wiki/index.php/Swedish_1meter_Solar_Telescope).
As
leading edge sunspots migrate across the disk, their projection with respect to the
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Earth changes and in turn we can learn about their 3D nature. Stereoscopic image
processing techniques within IDL will be developed to reconstruct important changes
in the ultra fine-scale structures of the outer portions (penumbra) of sunspots
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