Important notice!
The present catalogue is especially relevant for master theses in
the Research focus. Its content is not exhaustive, and students are
encouraged to contact specific teachers/researchers to ask them
about potential alternatives if they are interested in other
topics.
For the Professional focus, the master thesis must be an internship
and there is no specific offer prepared in advance. Students are
encouraged to search for opportunities out of the AGO Department.
To do so, contacting other institutes is highly recommended,
including
- Liège Space Centre (Sart-Tilman) : http://www.csl.uliege.be (or
via S. Habraken, C. Barbier) - Belgian Institute for Space Aeronomy
(Brussels) : http://www.aeronomie.be/en/ - Royal Observatory of
Belgium (Brussels) : https://www.astro.oma.be/en/ - Royal Institute
for Meteorology (Brussels) : https://www.meteo.be/en/ - The AMOS
company (Sart-Tilman) : https://www.amos.be/ - The Aerospacelab
company (Mont-Saint-Guibert): https://www.aerospacelab.be/
… or any other company involved in space activities.
About master theses out of ULiège...
Students involved in internships (abroad, in Belgium, and even at
the Centre Spatial de Liège) have to fill in an internship
agreement and a risk analysis sheet. These documents must be
completed in concertation with the person responsible for the
internship at the host institution, with the agreement of the
teacher/academic supervisor in ULiège.
Link to the required documents :
https://www.enseignement.uliege.be/cms/c_9413472/en/etape-4-fiche-d-analyse-de-risque-et-
convention
For any question or request for assistance, the contact person for
the Faculty of Sciences is Mrs Kristel Karremans:
[email protected]
In addition, for a stay abroad it is mandatory to follow an on-line
procedure to officially request the authorization to the Rector of
the University. This is necessary for the validation of the
activity abroad in the student programme and for benefiting of an
insurance coverage. The request should be introduced at least one
month (sooner is better!) before the expected date of
departure.
Contact person : J.R. Cudell
Office: 4/44 (B5a)
Availability: most afternoons in May or June. Check via e-mail if
you want to be sure,
Thematics : Cosmology and astroparticles
Description:
A number of possibilities exist (in particle physics, astroparticle
physics, dark matter, gravitational waves,…), and I encourage
interested students to come and see me.
Contact person : Prasanta Char
Office:
Availability: Online meeting can be set up with appointment by
email
Thematics : Nuclear Astrophysics
Description:
In this project, we will study the properties of rotating neutron
stars, their oscillations and the associated instabilities. In
particular, we investigate the r-mode oscillations that are known
to become unstable and emit gravitational waves. We will analyze
the growth, saturation and damping of r-modes, and their dependence
on the microphysical details of the neutron stars. We will also
examine different scenarios such as new-born young pulsars, and
accreting millisecond pulsars: their spin evolution, and the
detectability of the emitted gravitational waves.
References:
1. M. G. Alford and K. Schwenzer, 2014 Astrophys. J. 781 26 2. C.
Cuofano and A. Drago, 2010 Phys. Rev. D 82 084027 3. Ch. C.
Moustakidis, 2015 Phys. Rev. D 91 035804 4. A. Mytidis et al, 2015
Astrophys. J. 810 27
Magnetars and their structure
Contact person : Prasanta Char
Office:
Availability: Online meeting can be set up with appointment by
email
Thematics : Nuclear Astrophysics
Description:
Magnetars are neutron stars with extremely high magnetic fields. In
this project, we will study how the magnetic field affects the
spherical structure of the neutron stars. We will examine different
configurations of magnetic fields and the associated deformations.
We will compute stable models of such objects using realistic
equations of state for different magnetic field strengths. We will
also investigate gravitational wave emission from the spin
evolution of the magnetically deformed stars.
References:
1. K. Ioka and M. Sasaki, 2004 Astrophys. J. 600 296 2. A. Colaiuda
et al, Mon. Not. R. Astron. Soc. 385, 2080–2096 (2008) 3. L.
Gualtieri et al, Class. Quantum Grav. 28 (2011) 114014
Deciphering a gravitational lens with MUSE
Contact person : Dominique Sluse
Office: B5c, +1/10
Availability: The interested student(s) should contact me by email
to organise a meeting.
Thematics : Cosmology, Astrophysics; Instrumentation and
methods
Description:
Gravitationally lensed quasars are exceptional astrophysical
laboratories. They can be used e.g. to measure the expansion rate
of the Universe, quantify the dark matter content of distant
galaxies, or probe the structure of AGNs on scales inaccessible
with classical instrumentation. Wide Field Integral Field
Spectroscopy (IFS) of lensed systems is revolutionizing
gravitational lens related science. IFS data allow one to
simultaneously study, with an exceptional level of details, the
lensing galaxy, the lensed quasar, and the other galaxies along the
line-of-sight that contribute to the gravitational lensing effect.
For this project, the student will work with recently obtained IFS
data of a lensed quasar obtained with the MUSE instrument mounted
on one of the 4 very large telescopes operated by ESO at the
Paranal observatory. Those data will be used to study this system
on multiple scales. By deblending the light from the quasar images
from the light of the foreground lensing galaxy, it will be
possible to perform, for the first time, a measurement of the lens
redshift and of the lensing galaxy mass in that system. In
addition, those data will enable the study of the spectral
deformation of the quasar spectrum induced by gravitational
microlensing but also establish its main physical properties based
on the detected emission lines. In addition, it will be possible to
measure the redshifts of all the galaxies detected in the field of
view and quantify their impact on the strongly lensed system. The
details of the project may be adapted (focusing on some specific
aspects) depending of the student’ scientific interest and skills.
The students are strongly encouraged to contact me to discuss this
project. Other projects related to extragalactic astrophysics
and/or gravitational lensing are possible.
Prerequisites: Experience with python programming (e.g. via
SPAT0002-1: Programming tech- niques, numerical methods and machine
learning) is needed. Other recommended courses (not mandatory):
Extragalactic astrophysics (SPAT0011-1), Astrophysical observations
(SPAT0068- 1), Traitement de données (PHYS0931-1).
The investigation of colliding-wind binaries through high
resolution radio imaging
Contact person : Michaël De Becker
e-mail :
[email protected]
Office: B5c, +1/8
Description:
Massive stars produce strong stellar winds with typical velocities
of 2000-3000 km/s. In binary, or higher multiplicity systems where
massive stars orbit their commn centre of mass, stellar winds
collide and produce strong shocks. Such systems are valuable
laboratories to study shock physics in astrophysical plasmas. In
particular, tens of systems of that kind are known to be particle
accelerators: they accelerate charged particles up to relativistic
velocities. In the presence of the local magnetic field,
relativistic electrons produce synchrotron radiation revealed in
the radio domain. This non-thermal emission component is produced
in the colliding-wind region close to the shocks where particles
are accelerated. The investigation of the radio emission from these
systems allows us therefore to study their non-thermal
physics.
Beside that, stellar winds are also thermal radio emitters, and
what we measure through most radio observations is a composite
spectrum made up of synchrotron radiation from the colliding- wind
region and bremsstrahlung from the individual stellar winds. In
addition, the stellar winds are efficient absorbers of the
synchrotron photons produced in the colliding-wind region. This
makes the behavior of these systems quite complex to interpret.
However, if the stellar separation is long enough, high resolution
radio imaging allows us to spatially separate the synchrotron
emission region from the stellar winds. This is quite useful to
achieve a clearer view of these systems.
This master thesis work will consist in the processing, analysis
and interpretation of data obtained with the European VLBI Network
for a couple of massive binary systems. Some important steps of the
work will require to spend a few days at JIVE/ASTRON, in the north
of The Netherlands.
The main objective will be to check how such observations can help
in retrieving relevant information about these complex systems. A
significant part of the work will consist in discussing the outcome
of the observations in the appropriate scientific context.
Recommended courses: SPAT0069-1 Radio astrophysics (M. De Becker)
SPAT0008-1 Interstellar medium (M. De Becker, V. Van Grootel)
What does the study of populations of pulsars tell us about them
and about the interstellar medium?
Contact person : Michaël De Becker
e-mail :
[email protected]
Office: B5c, +1/8
Description:
Since the discovery of pulsars several decades ago, their study
constitutes a very important contribution to modern astrophysics.
In particular, pulsars are emblematic targets for radio
observatories. Among other quantities, the radio study of pulsars
allows us to determine their period, their spin-down luminosity,
their minimum magnetic field, an estimate of their age, and their
braking index.
Beside the study of pulsars specifically, radio measurement provide
us with a wealth of information on the medium that is travelled
through by their radiation. In particular, the study of pulsar time
series allows us to retrieve valuable information on the electron
number density and on the magnetic field.
This master thesis work will consist in the use of large data bases
of pulsar to extract information on pulsar populations. In
addition, a significant part of the work will aim at deriving
valuable information on the interstellar medium, specifically on
the basis of measurments of the dispersion measure and of the
rotation measure. The importance dedicated to pulsars themselves of
the interstellar medium will depend on the wish of the student and
on prelimnary results obtained in the frist steps of the master
thesis work.
A visit at ASTRON (north of The Netherlands) could be organized for
a short observation session with the Dwingeloo telescope.
A significant part of the work will consist in discussing the
outcome of the results in the appropriate scientific context.
Recommended course: SPAT0069-1 Radio astrophysics (M. De
Becker)
The impact of atmospheric eclipses on the light curves of close
massive binaries
Contact person : Gregor Rauw
Office: B5c, 2/2
Availability: Interested students should contact me by e-mail to
arrange an appointment on Lifesize or Skype.
Thematics : Stellar astrophysics
Description:
The vast majority of massive stars reside in binary or higher
multiplicity systems. Eclipsing binaries are especially important
as they allow to infer the fundamental properties (masses and
radii) of the stars. The overwhelming majority of the studies of
such systems assume that the stars are opaque and that their shapes
can be described by the Roche potential. However, massive stars
feature dense, partially optically thick stellar winds. In close
binary systems, these winds can absorb some of the light of the
companion, producing a so-called atmospheric eclipse and leading to
situations where the surface corresponding to optical depth unity
(τ=1) lies beyond the Roche lobe. Both effects (atmospheric eclipse
and R(τ=1) larger than the radius of the Roche lobe) are not
accounted for in the codes based on the Roche model. The goal of
this project is to implement a numerical code for the calculation
of light curves of close binaries which accounts for the shape of
the stars (based on the Roche potential), the mutual eclipses of
the opaque stellar surfaces and the atmospheric eclipses and to
compare the results with existing data. Attending the course on
“Variable Stars” is highly recommended.
Photometric and spectroscopic studies of an Algol binary
Contact person : Gregor Rauw
Office: B5c, 2/2
Availability: Interested students should contact me by e-mail to
arrange an appointment on Lifesize or Skype.
Thematics: Stellar astrophysics
Description:
Algol-type binaries are systems where a cool evolved star is
overflowing its Roche lobe and is transferring material to a B-type
main sequence companion. This mass-transfer process episodically
leads to the formation of an accretion disk around the mass gainer.
We propose here an in-depth study of such an Algol binary where we
combine photometric and spectroscopic observations to specify the
fundamental parameters of the stars.
The student is asked to
• get acquainted with the subject of Algol-type binaries, and with
the existing literature on the target of the study, • process and
normalize the spectroscopic observations of the system that have
been collected by our team, • perform the spectral disentangling of
the series of spectroscopic observations and classify the
components of the system, • based on the results of the previous
point, analyse the photometric lightcurve of the system and
establish the error bars on the inferred parameters, • perform a
Doppler tomography of the Hα line in order to search for signatures
of an accretion disk or other accretion structures, • summarize the
results, compare them with the literature and discuss their
implications.
Attending the course on “Variable Stars” is highly
recommended.
Line profile variability in peculiar massive stars
Contact person : Gregor Rauw
Office: B5c, 2/2
Availability: Interested students should contact me by e-mail to
arrange an appointment on Lifesize or Skype.
Thematics: Stellar astrophysics
Description:
Some massive OB stars display variations of their spectral lines
that hint either at (non-radial) pulsations at their surface or
structures inside their circumstellar environment. Studying these
phenomena opens up new avenues to learn more about the fundamental
properties of these stars. Indeed, the properties of pulsations
reflect the internal structure of the star, whilst the structures
in stellar winds bear information about the dynamics of stellar
winds and the possible impact of magnetic fields. Observationally
studying these phenomena requires long series of high-quality
spectroscopic observations. Over recent years, our team has
collected such data for several peculiar massive stars. And we
propose here an in-depth study of some of these objects.
The student is asked to
get acquainted with the subject of spectral line profile
variability in massive stars, and with the current knowledge of the
variability of the targets,
reduce and normalize the spectroscopic observations that have been
collected to study the variability of the targets,
apply a series of tests to the time series of spectra of each of
the stars to search for vari - ability, specify its significance
level and to establish possible periodicities,
and finally, compare the results with what is known about the stars
in the literature and discuss the implications of the
results.
Attending the classes on “Variable Stars” (SPAT0007) is certainly
helpful.
Seismic probing of subgiant stars with mixed modes
Contact person : Marc-Antoine Dupret
Office: B5c +1/12
Thematics : Astrophysics: Stellar physics, Asteroseismology
Description:
Context: Once their central hydrogen is exhausted, low-mass stars
leave the main sequence, become subgiants and next red giants. At
this evolutionary stage, stars are composed of a small-sized helium
core in contraction located below a thin hydrogen-burning shell,
all surrounded by a diluted expanding envelope. Due to their
core-envelope structure, they exhibit a peculiar kind of
stochastically-excited oscillations called mixed modes. These modes
can propagate in the central radiative region, where they behave as
gravity modes, and in the convective envelope, where they behave as
acoustic modes. Unlike pure acoustic modes in main-sequence stars,
the frequency pattern of mixed modes in the subgiant and red giant
phase gives us the unique opportunity of probing the properties not
only of their outer envelope, but also of their inner layers. Space
missions like CoRoT and Kepler revealed such very rich spectra of
oscillation including mixed modes.
Proposed work: In the team ASTA, we have very recently developed
the software EGGMiMoSA, a unique tool for the asteroseismic probing
of subgiants and red giants with mixed modes. We also have our own
stellar evolution code CLES and stellar adiabatic oscillation code
LOSC. The aim of this Master Thesis project is to use these tools
for the first seismic probing of well-chosen subgiants with very
rich oscillation spectra observed by Kepler. The work of the
student will first consist in determining the set of relevant
seismic indicators and measure their observational values for the
selected targets. Next, he/she will compute a grid of stellar
models encompassing these targets and study how the seismic
indicators depend on the global parameters of these models.
Finally, he/she will use EGGMiMoSA for an automatic search of the
stellar models best reproducing the seismic observations. As key
results of this study, the mass, age, chemical composition,
extra-mixing (the so-called overshooting) of these stars will be
accurately determined for the first time. This work could
constitute a first step before a PhD thesis dedicated to the
detailed seismic study of numerous subgiants and red giants
observed by Kepler.
Recommended courses: Stellar structure and evolution I SPAT0044-1
(& II SPAT0045-1) & Stellar stability and asteroseismology
SPAT0005-1 (M-A Dupret)
Deformation and break-up of fast rotating stars
Contact person : Marc-Antoine Dupret
Office: B5c, room 1/12
Thematics : Astrophysics: stellar physics
Description:
Context:
Many stars are rotating fast. A typical example is given by Be
stars, among which some are close to the rotation velocity
break-up. As a consequence, they are strongly deformed by the
centrifugal force. However, this deformation is neglected in nearly
all current stellar models. Taking it into account would enable
significant progress towards a more accurate modelling of fast
rotating stars and their oscillations.
Proposed work:
The main task will be to implement a code modelling accurately the
centrifugal deformation of a rigidly (or cylindrically) rotating
star. This problem has the appropriate level for a master thesis
thanks to a significant simplification: for rigid (or cylindrical)
rotation, the fluid is barotrope and the pressure and density are
constant on equi-potentials. Spherically symmetric models computed
with the Code Liégeois d’Evolution Stellaire (CLES) will be taken
as initial models. Next, solving iteratively the Poisson equation
will provide the final centrifugally deformed model. Once the code
works correctly, comparison with the approximate Roche models will
be considered (centrifugal deformation, gravity-darkening) for
models encompassing a wide range of masses and evolution stages.
Finally, a very efficient student could consider the generalization
to the non-conservative, non-barotropic case. This subject is ideal
for a student who likes solving physical problems by himself and
interpret the results. It could also constitute a first step before
a PhD thesis, which would focus on the 3D modelling of close binary
stars deformed by both rotation and tidal effects.
Recommended courses: SPAT0045-1 Stellar structure and evolution I
and II (M.A. Dupret)
Modeling TESS data of extreme horizontal branch stars by
asteroseismology
Contact person: Valérie Van Grootel
e-mail:
[email protected]
Office: B5c, room 1/13.
Description:
The TESS satellite from NASA gathers since December 2018
high-quality photometric data on various stars, for searching
transiting exoplanets but also for asteroseismology. Asteroseismol-
ogy is the study of stellar oscillations in order to tightly
constrain the physics inside stars and hence, to refine the models
of the structure and the evolution of stars.
Among these stars, TESS observes each month (one Sector of the sky
each 27 days) dozens of extreme horizontal branch stars, and
discovers/confirms pulsations in a few of them. Extreme horizontal
branch stars, also known as subdwarf B (sdB) stars, represent an
advanced stage of stellar evolution. These hot (Teff=20,000-40,000
K) and compact (log g=5.2-6.2) objects burn he- lium in their cores
into carbon and oxygen and are surrounded by an extremely thin
H-rich enve- lope. Understanding the formation of sdB stars is one
of last big mysteries of stellar evolution.
The proposed master thesis concerns the asteroseismic modeling of
sdB stars observed by TESS. First step will consist in selecting
the most promising targets for asteroseismic modeling: pres- ence
of a rich pulsation spectrum, availability of good spectroscopic
constraints. The second step is preliminary asteroseismic analyses
on the most promising targets, in order to select one that will be
studied in depth during this master thesis in the third step. The
asteroseismic modeling consists in quantitatively comparing the
computed oscillation periods for large sets of stellar models to
the observed periods. By optimizing this comparison (through
genetic algorithms that have been developed for this purpose) to
find the best-fitting model to the observations, the seis- mic
modeling will yield the global parameters (e.g. stellar mass and
radius) and internal struc- ture and composition (e.g. envelope
layering, core composition) of the star. Results will then be
exploited, by comparing them to those of other sdB stars modeled by
asteroseismology and by interpreting them in a context of sdB
formation. All the tools are available and ready for a direct
application to these TESS data.
This subject is well-suited for a student who like to work on
concrete applications of asteroseis- mology and space-based
observations.
Recommended courses: SPAT0005-1 Stellar Stability and
asteroseismology, SPAT0045-1 Stel- lar structure and evolution II
(M.A. Dupret)
Contact person: Valerie Van Grootel, Francisco J. Pozuelos
e-mail:
[email protected] ;
[email protected]
Tel: Valerie: +32 4 3669730 but contact preferably by email; Fran:
+32 4 3669738
Office: B5c +1/13 & /17
Availability: Any time by email for a first contact. Due to the
COVID-19 situation, video-calls will be preferred. The preferable
time slot is from 10am to 1pm (Monday to Friday).
Thematics: Planetology and planetary systems
Description:
Theories concerning the formation and evolution of planetary
systems are, at a certain level, well understood. However, little
is known about how planetary systems end their lives. Indeed, the
evolution of a given planetary system depends upon its host star,
including when the star leaves the main sequence and starts the red
giant branch (RGB) phase, when it expands and may engulf close-in
planets. The question of what happens to these engulfed planets is
of vital importance for understanding the fate of planetary
systems. The most promising targets to address this question are
hot subdwarfs, which are hot and compact post-RGB stars with
typical sizes of 0.1-0.3R_sun and masses of 0.47M_sun.
In this research project the student will join our team and
contribute to our transit survey in the search for transiting
exoplanets orbiting hot subdwarfs. This research makes use of data
collected by space telescopes such as TESS (Transiting Exoplanet
Satellite Survey), Kepler and K2. The student will make use of
dedicated pipelines to scrutinize a pre-existing target list in the
search for signals which might hint at the presence of planets. For
each event that overcomes the vetting process, a ground-based
follow-up campaign with the TRAPPIST telescopes will be proposed
and executed to rule out potential sources of false positives and
strengthen the evidence of their planetary nature. More information
on the project can be found in this paper :
http://arxiv.org/abs/2104.10462 Recommended course: SPAT0063-1
Introduction to exoplanetology (M. Gillon)
Contact person: Valerie Van Grootel, Francisco J. Pozuelos
e-mail:
[email protected] ;
[email protected] Tel:
Valerie: +32 4 3669730 but contact preferably by email; Fran: +32 4
3669738
Office: B5c +1/13 & /17
Availability: Any time by email for a first contact. Due to the
COVID-19 situation, video-calls will be preferred. The preferable
time slot is from 10am to 1pm (Monday to Friday).
Thematics: Planetology and planetary systems
Description:
Theories concerning the formation and evolution of planetary
systems are, at a certain level, well understood. However, little
is known about how planetary systems end their lives. Indeed, the
evolution of a given planetary system depends upon its host star,
including when the star leaves the main sequence and starts the red
giant branch (RGB) phase, when it expands and may engulf close-in
planets. The question of what happens to these engulfed planets is
of vital importance for understanding the fate of planetary
systems. The most promising targets to address this question are
hot subdwarfs, which are hot and compact post-RGB stars with
typical sizes of 0.1-0.3R_sun and masses of 0.47M_sun.
In this research project the student will join our team and
contribute to our transit survey in the search for transiting
disintegrating exoplanets. After the RGB phase of its host star, an
underlying hot rocky exoplanet may suffer a body-disruption event,
which could produce an elongated tail of dusty material. This
research makes use of data collected by space telescopes such as
TESS (Transiting Exoplanet Satellite Survey), Kepler and K2. We now
have a performing tool to detect the transits of evaporating
bodies, which will be used by the student to scrutinize a
pre-existing target list in the search for signals which might hint
at the presence of disintegrating exoplanets. For each event that
overcomes the vetting process, a ground-based follow-up campaign
with the TRAPPIST telescopes will be proposed and executed to rule
out potential sources of false positives and strengthen the
evidence of their nature. More information on the project can be
found in this paper : http://arxiv.org/abs/2104.10462
Recommended course: SPAT0063-1 Introduction to exoplanetology (M.
Gillon)
Contact person : Laetitia Delrez, Francisco J. Pozuelos
e-mail:
[email protected],
[email protected]
Tel: Laetitia Delrez: +32 4 366 97 63 / Francisco Pozuelos: +32 4
366 97 38
Office: Laetitia Delrez: B5c -1/2 / Francisco Pozuelos: B5c
+1/15
Availability: Interested students should contact us by email to
arrange a meeting
Thematics: Planetology and planetary systems
Description:
Exoplanets transiting bright and nearby stars are key objects for
advancing our knowledge of planetary formation and evolution.
Thanks to their special geometry and the brightness of their host
star, we can indeed measure their radius, mass (in combination with
radial velocity measurements or via transit timing variations), and
orbital parameters, and we can also study their atmosphere. In
particular, multi-planetary systems with several planets transiting
the same bright star are targets of paramount importance, as they
make it possible to compare several planets in the same system and
better constain their properties and histories.
Launched in April 2018, NASA’s Transiting Exoplanet Survey
Satellite (TESS) is searching the whole sky for small planets
transiting bright nearby stars. As of April 2021, TESS has
identified 2650 planet candidates, also known as TESS Objects of
Interest (TOIs), of which 122 have been confirmed so far. The
detection of a transiting planet around a given target enhances the
probability that other planets in the system - if any - are also
transiting (assuming small mutual inclinations between the orbital
planes of the planets). However, these extra planets may have been
missed by the TESS automatic detection pipeline if they produce
transit signals that are below the set detection threshold. This
can happen for planets with long orbital periods (with only a few
transits covered by the TESS data) and/or small radii (shallow
transits). The goal of this project is to scrutinize the TESS light
curves of a selected number of targets for which the TESS pipeline
detected at least one TOI, to search for possible signals that may
hint at the presence of other planets. We will focus here on bright
Sun-like stars that could be followed up with ESA’s new
Characterizing ExOPlanets Satellite (CHEOPS, launched in December
2019). Unlike previous exoplanet detection missions, like TESS,
CHEOPS is an exoplanet follow-up mission, designed to collect
ultra-high precision photometry of known transiting planets (or
candidates) around bright stars (a single star observed at a time).
Thanks to its high precision and versatility, CHEOPS is perfectly
suited to follow up and confirm the promising low signal- to-noise
TESS candidates that may be found in the framework of this
project.
Facilities, tools, and supervision: The student will be provided
with a work station in the existing students’ office and all the
tools needed to analyse the TESS data. The student will meet with
the supervisors ideally every week to perform a weekly progress
review of the project, where he/she will be able to discuss
difficulties, new ideas, etc. The student will be invited to join
meetings of the ExoTIC group (Exoplanets in Transit :
Identification and Characterization), where other exoplanet-related
topics are discussed.
Recommended course: SPAT0063-1 Introduction to exoplanetology
e-mail :
[email protected]
Tel : +61 3990 20 767
Office: Currently at Monash University (Australia). Back at ULiège
in September 2021.
Availability: Availability by email or through zoom.
Thematics : Planetology and planetary systems
Description:
The indirect discovery of thousands of exoplanets with different
masses, radii and orbital separations suggests a variety of
pathways for the evolution of planetary systems. But do giant
planets share common formation mechanisms? The advent of a new
generation of sub-mm and high-contrast infrared instruments have
recently provided direct images of protoplanetary discs, the birth
environment of planets, revealing a wealth of structures
potentially related to embedded planets (gaps, spiral arms,
asymmetries). In only one system have protoplanets been
unambiguously confirmed so far though, limiting our understanding
of planet formation.
In this project, the student will use archival data obtained with
the SPHERE high-contrast imaging instrument of the Very Large
Telescope on a sample of discs showing hints of planet presence.
The student will learn how to reduce data using the supervisor's
pipeline, and test novel image processing techniques to model and
subtract the bright emission from the star in order to produce new
high-fidelity images of protoplanetary discs to identify new direct
(point source) or indirect evidence (e.g.: spiral arms) of embedded
protoplanets. The project will heavily rely on routines implemented
in an open-source python package of high-contrast imaging routines
developed in Liège, called VIP. The project will also involve
adapting existing routines in order to further push the performance
of high-contrast imaging processing algorithms.
Recommended background (albeit non-exclusive):
Contact person : Olivier Absil, Carl-Henrik Dahlqvist, Valentin
Christiaens
e-mail :
[email protected]
Tel : 04/366.97.24
Office: B5c +2/19
Availability: I’m working mostly from home. Please contact me by
email if you wish to meet (either face-to-face at B5c, or by
videoconference).
Thematics : Planetology and planetary systems
Description: Despite the advent of new-generation, extreme adaptive
optics systems like VLT/SPHERE and Gemini/GPI, the number of
directly imaged exoplanets is still less than about 20. Any new
detection is still therefore a very important step in our knowledge
of planetary system architectures and planetary evolution. Among
the reasons for this low detection rate are the poor sensitivity of
direct imaging instruments at small orbital separations where most
of the planets are supposed to be found (1-10 au), and poor
sensitivity to cold, mature planetary systems (> 100 Myr). Part
of these limitations can be overcome by observing nearby, young
stars in the thermal infrared, where exoplanets are supposed to
produce most of their thermal emission. This was the aim of the
ISPY survey, carried out over about 130 nights in 2015-2019 with
the ULiège vortex coronagraph installed on the NACO camera at the
Very Large Telescope (VLT). While the ISPY survey is already
largely analysed, and partly published by the coordinating team
(Launhardt et al. 2020), the results so far were obtained with
standard post- processing techniques, such as Principal Component
Analysis. Within the PSILab group at the STAR Institute, we have
recently proposed a new technique (the RSM map, Dahlqvist et al.
2020, 2021) to process high-contrast imaging data, which was shown
to perform better than state-of-the-art algorithms, based on the
“Exoplanet Imaging Data Challenge” (Cantalloube et al. 2020). The
RSM map has recently been improved to run in a fully automatic way
(Dahlqvist et al., in prep). The goal of this project is to revisit
the ISPY archive and search for faint companions that would have
been missed by standard post-processing techniques to date. The
main tasks of the master student will be: (i) to identify all the
suitable stars in the ISPY survey archive maintained by ESO, (ii)
to calibrate the NACO data using the calibration pipeline developed
by Valentin Christiaens, and (iii) to process all the calibrated
data with the new auto-RSM package developed by Carl-Henrik
Dahlqvist. The main outcome of the project will consist of a list
of candidate companions, and of improved sensitivity limits for all
the selected stars. Depending on the pace of the progress, some of
these candidate companions could be confirmed by using other data
sets, or by requesting new observing time at major observatories
(e.g., VLT, Keck, LBT). Another follow-up would be to use the new
sensitivity limits to revisit the constraints on exoplanet
populations.
Recommended background: (SPAT0063) Introduction to exoplanetology
(M. Gillon), (SPAT0067) Atmospheric and adaptive optics (O. Absil),
Programming experience with python is also recommended.
Contact Person: Jehin Emmanuël
Description:
The TRAPPIST telescopes installed at the la Silla observatory in
Chile in 2010 and in Morocco in 2016 by our team are dedicated to
the research and the study of exoplanets in transit and the study
of the small bodies of the Solar System (comets and asteroids).
Each night, since 10 years in Chile and 4 years in Morocco we
collect hundreds of images of one or two fields during several
hours to search for exoplanets in transit. This constitutes a
unique dataset of about 2.5 million images to be explored to
discover new asteroids and comets. In this work we propose the fine
tuning and the use of a recently developed pipeline to detect as
many moving objects of the Solar System as possible in those
archive images. Among these objects most will be already known
asteroids but sometimes also a new object still unknown will be
found. As some fields are observed several nights in a row and for
many hours it will be possible to build rotation light curves for
many of these objects. By adapting the pipeline it is also possible
to find objects that move more slowly like distant comets and
Trans-Neptunian objects or faster like Near Earth asteroids.
Objectives: adapt the detection strategies according to the type of
objects to detect (close Near Earth Asteroids (NEA), or very
distant Trans-Neptunian Objects (TNO)) and run the pipeline for
automatic detection on the archive database. Collect from the
results of the pipeline for each night the astrometric data and
check the identification of the objects found. Submit the
measurements of the unknown objects to the Minor Planet Center
(MPC). Collect also the photometric measurements for each target
found and build their light curves to try to find the asteroid
rotation period. Most of these rotation light curves will be new
and might be published in a paper.
https://www.trappist.uliege.be/
Study of the chemical composition of comets atmospheres using the
TRAPPIST telescopes
Contact person: Jehin Emmanuël
Description:
Comets are among the best preserved specimens of the primitive
solar nebula. This status of “fossils” gives them a unique role in
understanding the origins of the solar system. The success of the
Rosetta space mission was very important and is changing our
knowledge about comets. But it showed also that observations from
the ground continue to be important: they make it possible to
supplement the data in situ by obtaining information on larger
scales of the coma and tails, and for a much larger number of
comets, which is necessary to extrapolate the results to the entire
cometary population. The link between the composition of comets and
their dynamic history must still be clarified and a complete comet
classification is still missing.
In this context, we propose the observation and analysis of the
coma of two or three bright comets with the TRAPPIST telescopes
network. These robotic telescopes installed by our team in Chile
(in 2010) and in Morocco (in 2016) are equipped with narrow band
filters to isolate the emissions of different gases and dust
contained in the atmosphere of comets. The student will have to
prepare the observations, calibrate the data and calculate the
production rates of the different gases using the so-called Haser
model (1957). The necessary tools for this kind of measures have
already been developed in our team. The student will have to become
familiar with the various techniques, adapt and improve if
necessary the reduction procedures and scripts and run the models.
The results might lead to the publication of a short article.
The work will be done in the comet group of the OrCa Service (+1)
and the TRAPPIST team https://www.trappist.uliege.be/
Building an atlas of cometary emission lines and identifying
unknown emissions in comet spectra
Contact person: Jehin Emmanuël
Description:
Comets are among the best preserved specimens of the primitive
solar nebula. This status of “fossils” gives them a unique role in
understanding the origins of the solar system. The success of the
Rosetta space mission was very important and is changing our
knowledge about comets. But it showed also that observations from
the ground continue to be important: they make it possible to
supplement the data in situ by obtaining information on larger
scales of the coma and tails, and for a much larger number of
comets, which is necessary to extrapolate the results to the entire
cometary population. The link between the composition of comets and
their dynamic history must still be clarified and a complete comet
classification and surface composition of nuclear ices is still
missing.
To pursue this goal a complete inventory of the emission lines
present in cometary spectra is for instance needed and as strange
as it might seems, in the high resolution spectra of comets,
hundreds emission lines are still to be identified. In this
context, we propose to the student to build an atlas and a
catalogue of the thousands of emission lines known and belonging to
molecular species like OH, NH, CH, CN, C2, etc. using one of the
best spectrum of a comet obtained in the visible with the UVES high
resolution spectrometer of the Very large Telescope (VLT) by our
team. This spectrum of comet C/2003 T7 (LINEAR) covers all the
optical range from 300 nm to 1000 nm at high resolution and high
signal-to-noise. The work will consist to understand the processes
of line emissions in comets, the components of a comet spectrum
(dust and gas), to find the list of lines for all the known species
and identify them in the spectrum of the comet, and list them. The
lines not identified will be indicated and searched for in atomic
and molecular line databases for possible matches. The final goal
is to make an atlas similar to the comet deVico atlas from Cochran
2012 displaying the spectrum with the lines identified and build a
catalogue with those lines detected (identified or not identified).
If time allows this atlas and catalogue will be made available
through a webpage that could be queried to display given spectral
regions selected by the user (with the help of our IT support). No
new data reduction will be requested but the student needs to work
with several software of his choice to display the spectra, be able
to make detailed graphics, do bibliographic search, and work on
long line list tables among other things.
The work will be done in the comet group of the OrCa Service
(+1)
Characterising the different components of the Jovian aurorae with
Juno-UVS observations
Contact person : Bertrand Bonfond
Office: B5c 0/2
Availability: From Monday to Thursday afternoon. Please send an
email in advance. Skype is also a possibility.
Thematics : Planetology and planetary systems
Description:
Juno is a NASA mission dedicated to the exploration of the planet
Jupiter. It orbits around the giant planet since July 2016,
bringing a wealth of discoveries and unprecedented observations.
Among its instruments sits an imaging spectrograph (Juno-UVS)
dedicated to the observations of the Jovian aurorae. The most
prominent feature of the Jovian aurorae is an incomplete curtain
centred around the magnetic pole and called the main emissions. The
main emissions also mark the boundary of the two other regions of
the aurorae: the polar emissions and the outer emission,
equatorward of the main emissions. The student will use the image
processing tools developed at the Laboratory for Planetary and
Atmospheric Physics (www.lpap.uliege.be) to monitor the evolution
of the emitted power, the brightness and the UV color in these
three regions on the Juno-UVS dataset. The student will then
characterize the global morphology of the aurora and interpret
their meaning in terms of magnetospheric physics.
The courses SPAT0028-2 and/or SPAT0023-1, as well as SPAT0032-2 are
highly recommended.
Contact person : Denis Grodent
Office: B5c – 0/5
Thematics : Planetology and planetary systems; Instrumentation and
methods.
Description: The auroras and magnetospheres of Jupiter and
Saturn
The Laboratory for Planetary and Atmospheric Physics has gained a
great deal of experience in the atmospheres, auroras and
magnetospheres of Jupiter and Saturn, among other planets. The
international reputation of the laboratory has allowed it to be
involved in major planetary missions such as Cassini, Juno ou
JUICE, and to be regularly selected for observations with space
telescopes such as HST, Chandra or XMM-Newton. The quantity and
variety of data acquired or being acquired allows us to propose
tailored subjects for master thesis (or doctoral thesis) according
to the students’aspirations. For example, the topics can be based
on:
- the analysis of dynamic auroral images using existing procedures
or those to be improved
- the development of new analysis techniques, including Machine
Learning - analysis of in-situ data (other than images) - modelling
of magnetospheric and/or auroral (atmospheric) phenomena involving
a non-
negligible amount of programming.
This work may be carried out at LPAP under the guidance of LLPAP
specialists: - Denis GRODENT - Bertrand BONFOND - Benjamin
PALMAERTS - Ruilong GUO
Such research projects may be illustrated with the following
original study papers involving LPAP members: D. Grodent et al.
(2018) “Jupiter’s aurora observed with HST during Juno orbits 3 to
7”, http://hdl.handle.net/2268/221312
B. Bonfond et al. (2019) “Bar Code Events in the Juno-UVS Data: A
Signature of ~10 MeV Electron Microbursts at Jupiter”,
http://hdl.handle.net/2268/229352
B. Palmaerts et al. (2018) “Auroral storm and polar arcs at Saturn
– Final Cassini/UVIS auroral observations”,
http://hdl.handle.net/2268/225773
R. Guo et al. (2018) “Rotationally driven magnetic reconnection in
Saturn’s dayside”, https://doi.org/10.1038/s41550-018-0461-9
Contact person : Murielle Kirkove
Description:
Critical for marine security, logistic management, and
eco-sociological issues, the near-real time monitoring of ships in
coastal areas is an important subject. Ship monitoring is usually
performed based on the use of the Automatic Identification System
(AIS) normally embarked on board of most ships. Nevertheless, some
ships are not equipped with such systems, and may have the
intention to harm citizens or materials. This is particularly the
case in conflict zones or areas with high a significant economic
potential (piracy, human trafficking, or armed conflict). These
reasons pushed governments, researchers, and NGOs in developing
techniques to identify these ships and compare them with AIS
data.
Many of these techniques are based on RAdio Detection And Ranging
(RADAR). In particular, the important increase of Synthetic
Aperture Radar (SAR) satellites such as Sentinel allows a near-
real time operational ship monitoring systems. Potential targets
are localized either automatically or through a simple visual
inspection of SAR images. A few years ago, at the Centre Spatial de
Liège (CSL), we implemented a processing technique for
automatically detecting potential ships within open seas areas
using SAR data. This technique is based on simple detection
algorithm (CFAR) and includes selector to limit detection to open
sea surfaces. Since then, machine learning, and deep learning in
particular, drastically push the accuracy limit obtainable by the
current state-of-the-art approaches. In this context, we are
looking for a motivated master student to explore different ways to
detect ships from SAR Remote Sensing and Machine Learning
Techniques. The student will benefit from the expertise of the
signal processing group of CSL, under the supervision of Murielle
Kirkove and Quentin Glaude.
The master student will be responsible for developing an automatic
tool to download and preprocess SAR images including ships from the
Sentinel database, labeling these images according to their ship
content identified by AIS data, constructing a database from this
labelization and choosing the best Machine Learning technique for
the automatic detection of ships. This work can also include a
comparison with the results obtained by our current method. The
outcomes of the master thesis are expected to contribute to the
field of automatized object detection and classification in SAR
imaging. Recommended skills/courses: SPAT0032-1: Remote sensing,
ELEN0062: Introduction to Machine learning, INFO8004-1: Advanced
machine learning
Remark : topic highly appropriate for the professional focus
Whitening of Doppler data in Radioscience
Contact person: Promotor: Véronique Dehant; Co-Promotor: S. Le
Maistre
e-mail:
[email protected] and
[email protected]
Office: Royal Observatory of Belgium
Availability: any time by skype; please email to decide when
Thematics: Planetology
Description:
The ground stations tracking satellites on Earth, the DSN (Deep
Space Network - NASA) and ESTRACK (European Space Tracking – ESA)
communicate directly with the spacecraft (S/C) using uplink (Earth
→ S/C) and downlink (S/C → Earth) radiosignal in X-band, S-band or
Ka-band.
When the Earth is in the field of view of the S/C antennas, when
the S/C is in the field of view of the Ground station (GS)
antennas, and when programmatic allows it, the S/C transmit their
data in a limited time (telemetry) and the GS transmit the commands
for operating the S/C and its instruments. The scientific data that
we are interested in in this case are the tracking Doppler data
provided by the downlink at the DSN and ESTRACK either in One-Way
(S/C → Earth or Two-Way (Earth → S/C → Earth). Data are often
temporally correlated and therefore require pre-processing. The
objective of this master thesis is to apply an algorithm of data
whitening in order to decorrelate them and better dig out the
Doppler signal out of the noise.
The method will be tested on and applied to the NASA InSight
radioscience data (on the surface of Mars since November
2018).
This work can lead to a publication and be continued into a PhD
thesis (application to real data of other radioscience data such as
the future ExoMars 2020 data of the Belgian instrument LaRa).
Task description:
Examine the different whitening algorithms that allow to process
highly noisy data and compare their respective performance.
Implement in MATLAB the whitening algorithm that will minimize the
noise present in the Doppler data (DSN and ESTRACK files).
Application to the Radioscience InSight data.
Contact person: Promotor: Véronique Dehant; Co-Promotor: S. Le
Maistre and N. Bergeot
e-mail:
[email protected],
[email protected], and
[email protected]
Tel: 02 373 0266 (V. Dehant)
Office: Royal Observatory of Belgium
Availability: any time by skype; please email to decide when
Thematics: Planetology
Description: The aim of this study is to analysis the effects of
plasma turbulence in the solar wind on Doppler radio measurements
from interplanetary spacecraft. A spacecraft receives an uplink
signal at X-band (7.3 GHz), and transmits data (telemetry or
science data) to Earth at X-band (8.4 GHz). In addition, a small
amount of downlink power is transmitted at S-band (2.3 GHz) for
evaluating the link performance. The two-way communication involves
a 34-m ground station on the Earth that is equipped to emit an
X-band signal and to receive both X- and S-band signals. At the
ground station a loop tracker records carrier phase at both
downlink carriers and this data is analyzed to examine the effect
of charged particles, from solar plasma and the Earth’s ionosphere,
on Doppler passes typically used for tracking and navigation of
interplanetary spacecraft. The Doppler tracking data allows, for
example, calculating the gravitation field of the planet around
which the spacecraft is orbiting. The experimental data set that
will be used in this study are dual-frequency tracking of the
European Space Agency’s (ESA) Mars Express (MEX) spacecraft.
Task Description :
Based on the power spectral analysis of the dual-band data, the
objective of this work is to determine an appropriate model for
treating charged particles in single-band Doppler tracking. The
statistic of phase variations will be described in terms of Allan
variances (root-mean-square differenced-phase variations) and
classical frequency variance. A realistic modelling of the charged
particle variations should be adopted in good agreement with
current models developed to estimate the solar plasma variations as
a function of SEP angle.
This work can lead to a publication and can be continued in a PhD
thesis.
Contact person: Promotor: Véronique Dehant; Co-Promotors: S. Le
Maistre, M. Yseboodt
e-mail:
[email protected] [email protected] et
[email protected]
Tel: 02 373 0266 (V. Dehant)
Office: Royal Observatory of Belgium
Availability: any time by skype; please email to decide when
Thematics: Planetology
Description:
The SBI (Same Beam Interferometry) technique can provide very
precise measurements of the distance difference between two
spacecraft or landers. This involves simultaneously tracking two or
more landers with identical transponders from a single antenna on
Earth. The radio signals emitted are relayed by the landers to the
Earth station, where they are recorded and then combined in an
interferometric mode to form a differential phase measurement.
Since the media crossed by the two signals (for example the
interplanetary plasma or the Earth's atmosphere) are the same,
these sources of error are largely canceled out in the case of an
SBI measurement.
These measurements will make it possible to observe precisely the
deformations of the surface of Mars due to the tides as well as its
rotation, which will add precise constraints on the interior of
Mars (such as the state and the size of the nucleus for example) as
well as on mass exchanges between the polar ice caps and the
atmosphere.
For the proposed work, simulations will be carried out to quantify
the contribution of this type of measurement on our knowledge of
the parameters of rotation and tide. Measurements are generated and
then used to extract interesting information and to see what level
of precision is possible. This allows to test different mission
configurations and see which one is most conducive to the
experience.
It will also be asked to test new configurations such as for
example a lander on Mars, the second being on Phobos, one of the
moons of Mars.
The software used was developed at the Royal Observatory of Belgium
in the case of Doppler and SBI measurements between a Martian
lander and the Earth. The orbital movement of Phobos around Mars
will have to be added to the software then simulations will have to
be performed and analyzed for many configurations, in order to see
which is the best mission strategy.
This work can lead to a scientific publication.
Task description:
Get familiar with existing codes for computing SBI measurements
Compute the associate Mars interior parameters Determine the best
strategy to obtain the best information.
This work can lead to a publication and can be continued in a PhD
thesis.
Contact person: Promotor: Véronique Dehant; Co-Promotors: Ozgur
Karatekin, Nicolas Bergeot, Florian Bodranghien
e-mail:
[email protected] [email protected] [email protected] and
[email protected]
Tel: 02 373 0266 (V. Dehant)
Office: Royal Observatory of Belgium
Availability: any time by skype; please email to decide when
Thematics: Planetology
Description:
The satellites of the American GPS system are at an altitude of
about 20,000 km, those of the Russian GLONASS system at an altitude
of about 19,000 km, and those of the European GALILEO system at an
altitude of about 23,000 km. All these GNSS satellites (Global
Navigation Satellite System) actually overlook a large number of
low satellites equipped with GNSS receivers, including
nanosatellites which will be launched in the future (> 2019) by
the firm Aerospacelab. The radiofrequencies used are each time at
least greater than 2; this makes it possible to combine the
frequencies to obtain the TEC (Total Electron Content), that is to
say the electron content of the ionosphere. The Earth's ionosphere
is a region outside the atmosphere that contains a high
concentration of free electrons. We now know that electrical events
occur when clouds of charged particles are projected by the solar
wind or by a solar flare or Coronal Mass Ejection (CME). When the
eruption is intense, if the Earth is in the path of charged
particles, the result can be catastrophic for all communication
systems. It is therefore necessary in the future to monitor the
activity of the Sun and its effects on our atmosphere (we speak of
space weather), and in particular to measure the TEC. In this
context, Aerospacelab has equipped and will equip its
nanosatellites with GNSS receivers. The master thesis consists in
studying the geometry of the orbits of the different satellites in
play to see what can bring future nanosatellites to our knowledge
of the ionosphere and in particular in the layers close to the
height of cube-satellites. If data is already available, we can
also apply what will be developed.
This work can lead to a scientific publication and extend into a
doctoral thesis.
Task description:
Get familiar with GNSS data analysis and TEC Use the geometry of
the GNSS to determine TEC
Determine what this can bring to TEC maps
Contact person: Promotor: Véronique Dehant; Co-Promotors: Ozgur
Karatekin, Sébastien Le Maistre, Orkun Temal
e-mail:
[email protected] [email protected] [email protected] and
[email protected]
Tel: 02 373 0266 (V. Dehant)
Office: Royal Observatory of Belgium
Availability: any time by skype; please email to decide when
Thematics: Planetology
Description:
The Martian atmosphere is very thin but participates in the process
of sublimation and condensation of the polar caps. A quarter of
this atmosphere condenses in the poles according to the seasons.
These mass movements induce variations in the rotation of Mars and
a polar motion. This movement has seasonal components. There is
also a free oscillation mode, the Chandler wobble, which would be
excited by the atmosphere. The master thesis consists in
calculating the amplitudes of the polar motion linked with the
Chandler wobble using the outputs of a general circulation model of
the Martian atmosphere. This work can lead to a scientific
publication and extend into a doctoral thesis.
Task description:
Get familiar with GCM of the Martian atmosphere Compute polar
motion excitation Compute CW excitation
e-mail:
[email protected] [email protected] and
[email protected]
Tel: 02 373 0266 (V. Dehant)
Office: Royal Observatory of Belgium
Availability: any time by skype; please email to decide when
Thematics: Planetology
Description:
The Planetary Radio Interferometry and Doppler Experiment (PRIDE)
technique exploits the radio transmitting capabilities of
spacecraft from the most modern space science missions. A very high
sensitivity of Earth-based radio telescopes (see Figure) involved
in astronomical and geodetic Very Long Baseline Interferometry
(VLBI) observations and an outstanding signal stability of the
radio systems allow PRIDE to conduct precise tracking of planetary
spacecraft. The data from individual telescopes are processed both
separately and jointly (involving correlators) to provide Doppler
and VLBI observables, respectively. The accurate examination of the
changes in phase of the radio signal propagating from the
spacecraft to each of the ground radio telescopes on Earth make the
“open-loop” Doppler observables derived from each telescope very
useful for different fields of planetary research. The Doppler data
are called “open-loop” as the receiving ground station does not
lock on the signal but receives the signal as it is in a frequency
band around the expected received signal. “Closed-loop” Doppler
data obtained by deep space tracking networks, such as the NASA
Deep Space Network (DSN) and the ESA tracking station network
(ESTRACK), are routinely used for navigation and science
applications. The Doppler data are called “closed-loop” as the
receiving ground station has the technical capability to lock on
the signal.
For the future LaRa (Lander Radioscience) experiment that will be
launched to Mars in 2022, we envisage to use this “open-loop
Doppler” technique in order to increase the precision on the data.
By tracking the LaRa signal, Earth-based radio telescopes involved
in the PRIDE experiment can provide open-loop Doppler tracking
data. The technique of processing the data is very different for
“open-loop Doppler” compared to “closed-loop” Doppler, and will
have to be fully developed. The partnership with JIVE (Joint
Institute for VLBI ERIC) and the Technical University Delft will
help us to use existing codes and not to start from scratch.
Task description:
Get familiar with open-loop data processing Application to LaRa
Computing of the improvement