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List of Bachelor Projects for 2021

In their third year bachelor students can enlist in a 15 ECTS research project between February and August. If you are interested in a project and want more details, please contact the project supervisor. For general questions please contact project coordinator Dr. Antonia Rowlinson (B.A.Rowlinson@uva.nl)

Project for Double Bachelors with Informatics:

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1.  Radiative Properties of hot accretion flows from General Relativistic Magneto-hydrodynamic Simulations

Supervisors: Doosoo Yoon, Sera Markoff
Contact:  d.yoon@uva.nl

Nowadays the primary theoretical tools for understanding the nature of hot accretion flows around black holes are general relativistic magnetohydrodynamic (GRMHD) simulations. These enable us to capture the time-dependent, turbulent evolution of the flow and sporadic (or steady) ejections of the materials from the accretion flow, which are essential to study the compact, energetic black hole system. The goal of this project is to make a connection between numerical simulations and observations of low accretion active galactic nuclei (LLAGN), including Sagittarius A* (Sgr A*), which has been observed in a wide range of wavelengths for the last couple of decades. We plan to lead our student to perform radiative transfer (GRRT) code using the number of GRMHD datasets simulating the hot accretion flows, to reproduce images and spectra that compare with observations. This will provide insight into radiative processes around supermassive black holes.

Prof. dr. S.B. (Sera) Markoff

Faculty of Science

Anton Pannekoek Institute of Astronomy

Dr D. (Doosoo) Yoon

Faculty of Science

Anton Pannekoek Institute of Astronomy

Other projects:

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2. The impact of new mass-loss rates on massive star evolution

Supervisor: Dr. Zsolt Keszthelyi, Prof. Dr. Alex de Koter 
Contact: z.keszthelyi@uva.nl

Massive stars (at least 8 times more massive than the Sun) are the building blocks of the Universe, producing chemical elements that are necessary for life. Massive stars possess powerful stellar winds, which are capable of removing typically 1 Earth-mass per year and also lead to slowing down the rotation of the star by removing angular momentum. In recent years, a variety of new mass-loss prescriptions were published, both empirical formulae and rates obtained from theoretical works. 

The goal of this project is to study state-of-the-art stellar evolution models (computed with the MESA code) and identify the impact of the various mass-loss prescriptions on the model predictions. The candidate will have to compare evolutionary tracks, primarily focusing on the main characteristics of the models, including the time evolution of stellar and rotational parameters and the surface composition. 

Dr Z. (Zsolt) Keszthelyi

Faculty of Science

Anton Pannekoek Institute of Astronomy

Prof. dr. A. (Alex) de Koter

Faculty of Science

Anton Pannekoek Institute of Astronomy

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3. Constraining planet formation scenarios using exoplanet atmosphere spectra

Supervisor: N. Khorshid, JM Desert, M. Min
Contact: n.khorshid@uva.nl

Spectral observations of exoplanets, together with atmospheric models provide us with information about the composition, structure, and dynamics of the planetary atmospheres. This information can also guide us in understanding the planet's formation history.

In this project, the student will work with existing planet formation and atmospheric models. They will study how the atmospheric spectra changes with respect to the formation history of a planet. The student will learn about theories of planet formation, analyzing atmospheric spectra, and using atmospheric models. This project involves programming and data analysis. The preferred programming language in this project is Python, but the student may need/want to use Fortran as some of the atmospheric modelling tools we will use in this project are based on Fortran.

Dr. J.M.L.B. (Jean-Michel) Desert

Faculty of Science

Anton Pannekoek Institute of Astronomy

Ms N. (Niloofar) Khorshid

Faculty of Science

Anton Pannekoek Institute of Astronomy

Dr. M. (Michiel) Min

Faculty of Science

Anton Pannekoek Institute of Astronomy

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4. Bursting atmosphere models and dense matter in neutron stars

Supervisors: Anna Watts, Tuomo Salmi
Contact: a.l.watts@uva.nl

The NICER instrument on the International Space Station is using relativistic ray-tracing of X-rays emitted from the surface of pulsars to determine the mass and the radius of neutron stars. This in turn provides information on the nature of ultra dense nuclear matter.  Future X-ray telescopes will use the same technique for accreting neutron stars where the emitted X-rays come from thermonuclear bursts on the star’s surface.  An important element of our calculations is how radiation propagates through the hot bursting atmosphere. At present we are using relatively simple formulae, but more sophisticated atmosphere models are now available.  During this project you will study these models, determine how to implement them into our ray-tracing codes, and (if time permits) apply them to real data.  

Mr T.H.J. (Tuomo) Salmi

Faculty of Science

Anton Pannekoek Institute of Astronomy

Prof. A.L. (Anna) Watts

Faculty of Science

Anton Pannekoek Institute of Astronomy

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5. Modeling high-resolution transmission spectra of exoplanet atmospheres

Supervisor: Antonija Oklopčić
Contact: a.oklopcic@uva.nl

Spectroscopic observations of exoplanet transits offer us insight into the properties of exoplanet atmospheres, such as their chemical composition and temperature. By analyzing the spectra at high resolution, we can also measure the speed of atmospheric winds and outflows . Such observations are often made at wavelengths of prominent spectral lines, such as the sodium D doublet, the hydrogen H-alpha line, or the helium 1083 nm triplet, that are present the spectra of both the planet and its host star. The fact that these lines are shared between the planet and the star can lead to uncertainties and biases in the inferred properties of the planet's atmosphere, if the effects are not properly modeled. In this project, the student will develop tools to model the changes in the spectral line shape during planetary transits, by taking into account stellar disk inhomogeneity (caused by phenomena related to stellar activity), center-to-limb variations, and the Rossiter-Mclaughlin effect.

Dr. A. (Antonija) Oklopčić

Faculty of Science

Anton Pannekoek Institute of Astronomy

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6. Signatures of magnetic fields in exoplanet atmospheres

Supervisor: Antonija Oklopčić
Contact: a.oklopcic@uva.nl

Most planets in the solar system have or previously had a global magnetic field, yet not much is known about magnetic fields in exoplanets. The presence of a magnetic field in an exoplanet could have important consequences for the extent, composition, and evolution of its atmosphere, by controlling atmospheric escape and its interaction with the stellar wind. Recently, a new method for detecting magnetic fields in the atmospheres of close-in exoplanets has been proposed. It is  based on measuring the polarization of radiation during exoplanet transit observations at the wavelength of the helium line at 1083 nm. Assuming exoplanet magnetic fields with strengths comparable to the magnetic fields observed in solar system planets, polarization signals in the helium 1083 nm line should be detectable with high-resolution spectropolarimeters operating at these wavelengths. So far, the expected linear and circular polarization signals have been calculated using a highly simplified model of exoplanet atmospheres. In this project, the student will investigate realistic 3D geometries of global magnetic fields in exoplanet atmospheres and calculate the expected polarization signal and the feasibility of its detection with the existing and future telescopes. 

Dr. A. (Antonija) Oklopčić

Faculty of Science

Anton Pannekoek Institute of Astronomy

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7. Modelling the X-ray spectral-timing properties of accreting black holes

Supervisor: Phil Uttley
Contact: p.uttley@uva.nl

The accreting black holes in X-ray binary systems often show strong X-ray variability on time-scales from minutes down to a few hundredths of a second. The variability is generated in the innermost regions of the turbulent flow of gas on to the black hole. By measuring the relative variations in different energy bands using ’spectral-timing’ techniques, we can work out (qualitatively) what the structure of these regions is, because the different bands are dominated by different emitting components, such as the accretion disk and ‘corona’. 

Recently we’ve developed new physical models to fit directly to the spectral-timing data, which allows us to put more quantative constraints on the structure of the inner regions. However, the models we have investigated so far are fairly simple and don’t include all of the behaviour that we see in the variability. The aim of this project is to develop some Python-coded simulations of the variable accretion flow, including the different spectral components and effects. You can then use these simulations to test how well the model-fitting works to reproduce the parameters you used in your simulation, and suggest improvements which could lead to better models for the spectral-timing behaviour.

Dr. P. (Phil) Uttley

Faculty of Science

Anton Pannekoek Institute of Astronomy

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8. The evolution of planet forming disks as seen in high resolution near infrared observations

Supervisors: Christian Ginski, Carsten Dominik
Contact: c.ginski@uva.nl

The student will work with high spatial resolution imaging data of planet forming circumstellar dust and gas disks. These observations have been obtained with the worlds leading optical and near infrared telescope the ESO/VLT and the extreme adaptive optics imager SPHERE. In the past 5 years we have learned that circumstellar disks show a surprising complexity and diversity when observed with high angular resolution.

The student will try to use existing (archival) data to search for similarities in disks in different star forming regions or around similar central stars. The student will use an existing pipeline to reduce the data and will then write their own basic analysis tools, ideally using Python. Depending on the results of the project and the interest of the student a long term involvement in the large observing program DESTINYS, of which I am the PI, is possible.

Prof. dr. C. (Carsten) Dominik

Faculty of Science

Anton Pannekoek Institute of Astronomy

Dr. rer. nat. C. (Christian) Ginski

Faculty of Science

Anton Pannekoek Institute of Astronomy

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9. Geometric and dust properties of the planet forming disk around the Herbig star HD97048

Supervisors: Christian Ginski, Ryo Tazaki, Carsten Dominik
Contact: c.ginski@uva.nl

In the past 5 years new instrumentation has allowed us to capture detailed images of planet forming dust disks around nearby young stars.

The student will work with a newly recorded image of the disk around the Herbig star HD97048. The data was taken with the SPHERE extreme adaptive optics imager at the ESO Very Large Telescope and shows the disk in polarized scattered light in the near infrared. The specific system is well known from previous similar observations to possess a multi-ringed sub-structure that may be caused by forming proto-planets.

The newly available data for this project is of much higher quality than previous data sets. The student will fit geometric disk parameters using the data, to determine the disk vertical structure.

Once the disk geometry is found, the student can extract the scattering phase function of the dust particles from the data set. Using this information and literature data the student can constrain the dust properties in the disk like size and complexity of the dust particles and possibly some mineralogy. These dust particles constitute the basic building blocks of developing planets.

Prof. dr. C. (Carsten) Dominik

Faculty of Science

Anton Pannekoek Institute of Astronomy

Dr. rer. nat. C. (Christian) Ginski

Faculty of Science

Anton Pannekoek Institute of Astronomy

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10. Millimeter-wave scattering polarization from vertically stratified protoplanetary disks

Supervisors: Ryo Tazaki, Carsten Dominik     
Contact: r.tazaki@uva.nl

The first step of planet formation is the growth of small sub-micrometer-sized particles to much larger aggregates in protoplanetary disks. Theoretical predictions say that these aggregates should grow to millimeters or larger sizes quickly.  A new observational tool currently being used to actually measure the sizes of the aggregates in the disks is polarimetry at mm wavelengths. Surprisingly, these observations suggest the maximum grain radius much smaller than previous estimates. In this project, we try to reconcile this mismatch by performing 3D Monte Carlo radiative transfer simulations of protoplanetary disks. To this end, we focus on the variation of grain size perpendicular to the disk and see how that impacts the scattering polarization.

Prof. dr. C. (Carsten) Dominik

Faculty of Science

Anton Pannekoek Institute of Astronomy

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11. Growing the planets by pebble accretion

Supervisors: Rico Visser, Carsten Dominik
Contact: r.g.visser@uva.nl

The stages of planet formation encompass a factor 10^40 mass increase from the smallest dust grains to the gas giants such as Jupiter and Saturn. Throughout these stages many physical processes play a role. Even today, coming up with a consistent theory that matches observational data from young protoplanetary disks remains challenging. For example, we encounter growth barriers already in the early stages of planetary growth. Classical planet formation scenarios such as core accretion have difficulty growing a planet within the lifetime of the gaseous protoplanetary disk.

One promising new theory to overcome planetary growth barriers is Pebble Accretion. In Pebble Accretion a small planetoide/asteroide (read body) is sweeping up small ‘pebbles’ in the young gaseous protoplanetary disk. It turns out that the gas damping produces large collision cross-sections for these small bodies since the gas slows down the pebbles in an encounter. The conspiracy between the small body’s gravity and the disk gas can lead to fast growth of the small body well within the disk lifetime.

The efficiency of pebble accretion for bodies with an atmosphere

In this project you will investigate what the growth efficiency is of a body undergoing pebble accretion in the presence of an atmosphere bound to the body. You will set up a three body problem with a star, gas drag, small pebbles and a planetesimal in orbit around the star. As the pebbles move towards the body to be swept up they will encounter the atmosphere of the body which might alter the dynamics before they hit the solid surface.

Project goal

The goal is to quantify what this effect is and how this will affect the efficiency of growth by pebble accretion.
Skills needed/recommended: ​Programming, Latex

Prof. dr. C. (Carsten) Dominik

Faculty of Science

Anton Pannekoek Institute of Astronomy

Mr R.G. (Rico) Visser MSc

Faculty of Science

Anton Pannekoek Institute of Astronomy

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12. Characterizing the outbursts of very faint X-ray binaries: X-ray spectra

Supervisor: Dr. Nathalie Degenaar
Contact: n.d.degenaar@uva.nl

X-ray binaries are binary star systems that contain a black hole or a neutron star that gravitationally attracts, or 'accretes', the outer layers of its companion star. Typically, the black hole or neutron star is feeding off its companion for a few weeks or months at a time, after which it goes into hibernation for several years until a new outburst of accretion occurs. These ‘transient’ X-ray binaries have been known and studied for many decades. However, there is a subclass that is unusually dim and hence much harder to study, the very-faint X-ray binaries. Due to limited studies, it is not yet understood why these very-faint X-ray binaries are so dim compared to the general population.

In this project, the student will perform the first systematic analysis of the X-ray spectra of very-faint X-ray binaries in order to understand their emission properties. By comparing this with that of well-studied bright X-ray binaries, we aim to find clues to why these systems are so dim. The student will work with X-ray data obtained with two NASA satellites, NuSTAR and Swift.

Dr N.D. (Nathalie) Degenaar

Faculty of Science

Anton Pannekoek Institute of Astronomy

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13. Characterising the outbursts of very faint X-ray binaries: X-ray light curves

Supervisor: Dr. Nathalie Degenaar
Contact: n.d.degenaar@uva.nl

X-ray binaries are binary star systems that contain a black hole or a neutron star that gravitationally attracts, or 'accretes', the outer layers of its companion star. Typically, the black hole or neutron star is feeding off its companion for a few weeks or months at a time, after which it goes into hibernation for several years until a new outburst of accretion occurs. These ‘transient’ X-ray binaries have been known and studied for many decades. However, there is a subclass that is unusually dim and hence much harder to study, the very-faint X-ray binaries. Due to limited studies, it is not yet understood why these very-faint X-ray binaries are so dim compared to the general population.

In this project, the student will perform the first systematic analysis of the X-ray light curves of very-faint X-ray binaries in order to characterise the duration, decay time, recurrence rate and energy output. By comparing this with that of well-studied bright X-ray binaries, we aim to find clues to why these systems are so dim. The student will mainly work with X-ray data obtained with two NASA satellites, RXTE and Swift.

Dr N.D. (Nathalie) Degenaar

Faculty of Science

Anton Pannekoek Institute of Astronomy

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14. Observational Astronomy with the Anton Pannekoek Observatory

Supervisor: Rasjied Sloot
Contact: M.R.Sloot@uva.nl  

The student will gather (most of) his or her own data using telescopes and instruments available in our Observatory.
Students can come up with their own research topic. A few suggestions are:

Exoplanet transits: determining orbital parameters of planetary systems
-Determine stellar properties of pulsating stars
-Eclipsing binaries: modeling stellar properties
-Determining the age and distance of open clusters of globular clusters
-Measure the redshift objects at large distances

Solar topics:
-Spectroheliography
-High-resolution spectroscopy of the sun using the APO Heliostat

Mr M.R. (Rasjied) Sloot MSc

Faculty of Science

Anton Pannekoek Institute of Astronomy

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15. Searching for ultra-fast radio bursts

Supervisors: Jason Hessels, Kenzie Nimmo & Mark Snelders
Contact: j.w.t.hessels@uva.nl

Fast radio bursts (FRBs) are mysterious flashes of radio waves that originate from distant galaxies. Typically lasting for roughly a millisecond, they can carry roughly as much energy as the Sun emits in an entire day.  We still don't understand what produces FRBs, but many theories invoke neutron stars with high magnetic fields in order to explain the short duration of the emission and its high luminosity. Some FRBs appear to be one-off events, whereas sources of repeats FRBs are also known.  In this BSc project, you will analyse observations of the first-known repeating FRB source.  These unique data were taken with the Green Bank Telescope and the Breakthrough Listen recording system.  The relatively high radio frequency and availability of `voltage data', in which both the amplitude and phase of the signal is preserved, allows us to search for radio bursts on microsecond timescales.  Have we missed signals in these data because they sometimes last for only a small fraction of a millisecond?  We aim to find out!

Dr. J.W.T. (Jason) Hessels

Faculty of Science

Anton Pannekoek Institute of Astronomy

Ms K. (Kenzie) Nimmo

Faculty of Science

Anton Pannekoek Institute of Astronomy

Mr M.P. (Mark) Snelders MSc

Faculty of Science

Anton Pannekoek Institute of Astronomy

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16. Identifying OB associations and runaway stars associated with supernova remnants using GAIA

Supervisor : Jacco Vink
Contact : J.Vink@uva.nl

A large fraction of supernovae should be in or near te OB associations, as the supernova explosion concerned a massive star that was part of the association. Only a handful of associations between supernova remnants and OB associations are known. However, with GAIA we can routinely check on this now. A problem is that not always the distance to the supernova remnant is know. For this project we concentrate on remnants with reasonably well known distances. Apart from looking at the OB association, we will also check for high velocity stars that may have been part of a binary system: one star exploded, the other was slingshot away.

Dr. J. (Jacco) Vink

Faculty of Science

Anton Pannekoek Institute of Astronomy