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Student projects

Supervisor:

Karsten Frank Brogaard

Projects fall within the broad fields of Star clusters and Binary stars with the primary aim of obtaining precise and accurate stellar ages. Below is a list of some proposed projects in each category, and some of the tasks they may involve.

In addition, a broad range of projects that makes use of our new facility “det Fjernstyrede Undervisnings Teleskop” FUT (The remote controlled teaching telescope), a 60 cm telescope for photometry, located at Mt. Kent in Australia, are offered. This facility will be used by students in the Danish upper secondary schools, and projects that can be used to teach them are encouraged. However, any other projects that can benefit from quick and easy access to a 60 cm telescope are also possible. You can choose the topic of you interest!

Star clusters

Projects can involve one or many of the following aspects:

  • Producing and analysing colour-magnitude diagrams (CMD) of cluster to infer cluster properties including the age.
  • Searching for variable stars in a star cluster – including eclipsing binary stars, see below.
  • Doing asteroseismology on giant stars in star clusters observed by Kepler, K2 or TESS, see below.
  • Improving the analysis of the cluster CMD and asteroseismology using parallax information from Gaia or/and information from cluster member eclipsing binaries, see below.

Specific projects on star clusters:

The absolute and relative ages of the open clusters NGC188 and NGC6791

You will use Gaia photometry and parallaxes to produce high quality colour-magnitude diagrams (CMDs) of the two clusters. You will derive relative and absolute ages by comparing the two CMDs and comparing to stellar model isochrones. The results will be compared to published cluster ages by Cantat-Gaudin et al. (2020) to show that their procedure is not trustworthy and why.

Improving asteroseismic masses and radii using Gaia parallaxes.

You will combine the published asteroseismic measurements of giant stars in the open cluster NGC1817 (Sandquist et al. 2020) with Gaia DR2 (or soon DR3) parallaxes and (Gaia or/and ground based) photometry to improve the mass-radius relationship of the red clump stars, and the interpretation thereof.

Variability studies of open clusters in the Kepler field

The open clusters NGC6791 and NGC6819 have been observed by the Kepler mission. Due to the crowding in the clusters light curves were not extracted for most of the stars but only the pixel data is available. This means that many variable cluster stars have still not been investigated, including some that are potentially very interesting because of their unexpected positions in the colour-magnitude diagram.
The purpose of this project is to extract photometric light curves of cluster stars and analyse them. This can be giants showing solar-like oscillations, eclipsing binary stars, non-eclipsing binary stars, stars showing spot activity, or some other kind of variability. For several of the binary stars, spectra are available from the Very Large Telescope for a full analysis.

Investigating convective-core overshooting physics with NGC2506

You will use the cluster CMD and masses and radii of cluster eclipsing binaries presented by Knudstrup et al. (2020) to calibrate the strength of convective-core overshooting in a stellar model. Then, you will derive an improved age of the cluster and investigate the consequences for the ages of other open clusters.

Eclipsing binary stars (and other variability) in the open cluster NGC2243

You will obtain time series photometry of the cluster using FUT (se above) and use it to produce light curves of eclipsing binary stars in the cluster. These can be combined with spectra from the Very Large Telescope for a full analysis of the best suited systems.

Binary stars

Projects can involve one or many of the following aspects:

  • Derivation of radial velocities of binary components from spectra using either cross correlation, broadening functions, or spectra disentangling.
  • Obtaining a photometric light curve from own photometry or from space based photometry (e.g. Kepler, K2, TESS).
  • Deriving masses and radii by modelling an eclipsing binary star using PHOEBE or JKTEBOP.
  • Comparing derived paramters to stellar model isochrones to obtain age estimates or/and to improve model physics.

Specific projects on eclipsing binary stars:

Modelling eclipsing binary stars with PHOEBE

The python program PHOEBE is excellent for deriving masses and radii of eclipsing binary stars. However, the learning curve is a bit steep. In this project you will work to improve the parameters of one or more eclipsing binary that have previously been analysed in the literature (e.g. V18 and V20 from Brogaard et al. 2012) but now have been observed also by Kepler. Apart from the scientific goal, your task will be to make a well-explained basic setup to ease the use of PHOEBE for other systems in the future.

Testing asteroseismic scaling relations using eclipsing binary stars with an oscillating giant component
You will use light curves from the K2 mission and radial velocities from spectra from the Nordic Optical Telescope to derive masses and radii of eclipsing binaries through a classical analysis and through asteroseismology in order to compare the two.

The age and distance of NGC6633

You will analyse an eclipsing binary in the open cluster NGC6633 for which we have obtained a light curve and spectra from the Nordic Optical Telescope. The model comparisons can involve also the cluster CMD and published asteroseismology from the CoRoT mission.

The true parameters of the active binary KOI-1003

The article adsabs.harvard.edu/abs/2016arXiv161000721R presents an interesting analysis of a magnetically active eclipsing binary star, KOI-1003. However, as part of a study of binary stars in the old open star cluster NGC6791 I have acquired spectra for this target, also known as V54, at the Very Large Telescope (VLT). A quick examination of the spectra has shown that the stellar parameters derived in the article must be revised.


The task of this project is to derive stellar masses, radii and effective temperatures of the components of KOI-1003 that are consistent with both photometry from Kepler (analysed in the article) and spectroscopy from the VLT. Both photometric and spectroscopic data is available.

Supervisor:

Günter Houdek

Stellar-convection properties across the Hertzsprung-Russell diagram
Convective transport of heat and momentum plays an important role in any phase of stellar evolution. Currently adopted one-dimensional (1D) convection models in stellar evolution calculations are still very simplified and subject to various parameters that need calibration. Results from sophisticated three-dimensional (3D) hydrodynamical simulations of the outer stellar convection zones can be used to calibrate the simpler 1D  convection models. It is the aim of this project to investigate convection properties in stars located at different points in the Hertzsprung-Russell diagram by calibrating 1D convection models with results from 3D simulations.

Measuring the depths of surface convection zones in Kepler stars
High-quality frequency measurements in many solar-like stars were obtained from the NASA Kepler mission. With the help of asteroseismic diagnostic techniques, which make use of certain combinations of the measured stellar
frequencies, it is possible to determine the extent of the surface convection zones. The knowledge of the depth of the surface convection zone is of great importance for stellar evolutionary calculations. The aim of this project is
to measure the acoustic glitch properties of the base of convection zones in various Kepler stars with the help of a seismic diagnostic procedure.

Calibrating the location of the theoretical instability strip in the HR-diagram
Accurate measurements of stellar pulsations in classical variables (stars with overstable, heat-driven, oscillations) are now available thanks to the NASA mission Kepler and ground-based observation campaigns. A long-standing problem has been the modelling of the location of the cool edge of the classical instability strip in the Hertzsprung-Russell (HR) diagram. The aim of this project is to use an existing, advanced, pulsation programme for computing the location of the instability strip and to calibrate the convection parameters with the help of observational data.


Supervisor:

Simon Albrecht

Kepler-18: measuring planetary densities from high precision photometry alone
Measuring radii and masses of the smallest extra solar planet is challenging. However observations of planetary transits in front of their stars let us measure their radii. If additional planets are present in the system then their masses perturb the orbit of the transiting planets. In this project you will use photometry from the Kepler space mission to measure the masses and densities of planets in the Kepler-18 system

What can we learn about the interiors of small terrestrial extra solar planets
In this work you will review what we know about the structure of terrestrial planets inside and outside the solar system. Next you will try to constrain the type of material rocky extra solar planets made of.

Phase curve simulator
In this work you will write the code for a simulator which allows you to estimate how exoplanets will look in reflected star light at different orbital phases. You will use some simple assumptions about the surface properties. If time permits then you will also include the thermal emission form the planet in the simulator, and compare the results to phase curves from the Kepler space mission.

How to form Hot-Jupiter
A review of what we know (and not know) about the formation of gas giant planets like Jupiter and Saturn.  However these planets orbit their stars at a distance of 1/20 the Sun-Earth distance. The existence of Hot Jupiters is one of the most persistent problems in extra solar planet science.


Supervisor:

Victor Silva Aguirre

Please check isimba.dk/student-projects/


Supervisor:

Mads Fredslund Andersen

Software development and color imaging using the new SONG SkyCam – 2

A new small 6'' telescope + a CCD camera and a filter wheel will be mounted on the side of the SONG telescope on Tenerife in March 2016.  If you have a flair for programming or a high interest in learning how to, this project might be of interest. You will develop the control software for the CCD camera and filter wheel in the programming language of Python. Part of the project will be focused on characterizing the CCD and determine the daily automatic operation of the instrument. Another part of the time will be spent using the instrument to create color images of astronomical phenomenons like dust clouds, galaxies, nebulas etc.

Photometry of images collected using the SONG SkyCam – 1

A small CCD camera with a 180mm lens is attached on the side of the SONG telescope on Tenerife and has collected huge amount of data in the last few years. In this project you will deal with the basics of astronomical photometry. You will adapt existing packages in Python to produce an automated pipeline for the steady data flow coming from SkyCam – 1. The pipeline will be developed to handle the data which will start to come from the new SkyCam – 2 as well. Characterizing the photometry precision will be an essential part of the project.

Pointing system and astrometry precision of the SONG SkyCam – 1

The piggybag SkyCam – 1 and the coming SkyCam – 2 are mounted on the side of the 1m SONG telescope located at Tenerife and therefore points at the same field as the mother telescope. These two instruments can potentially  be used to correct the telescope pointing and be used when normal pointing procedures fail. This project will focus on determining the precision at which the pointing can be done using both SkyCam – 1 and SkyCam – 2. Implementing the new pointing system into the SONG robotic software will be an important part of the project.


Supervisor:

Frank Grundahl

SONG relateret

Generelt: høj-præcisions radial-hastigheder med ThAr metoden, som regel af binær-stjerner, bestemmelse af masser. Test af analyse-metoder og procedurer kan også være en mulighed.

Bi-sector analyse - '3rd signature of convection'

Her studeres hvordan konvektionen opfører sig i de ydre lag af klare stjerner. Data fra SONG teleskopet.

Fotometri fra K2 af stjernehobe ( med Rasmus Handberg og Karsten Brogaard):

M67 - eftersøgning af variable, svingninger i røde kæmpestjerner

Bestemmelse af absorptionen i retning af Mælkevejens ældste stjernehobe

Analyse af linie-styrken for interstellare Na linier for at bestemme absorptionen i retning til udvalgte stjernehobe. Dette vil føre til forbedrede temperaturer for stjernerne i hobene og ultimativt bedre aldre.

Kom og snak om mulighederne!


Supervisor:

Christoffer Karoff

Sammenligning af asteroseismiske og gyrokronologiske aldre

En stjernes alder kan bl.a. bestemmes vha. af asteroseismology og rotation. Dette projekt går ud på at undersøge om de aldre der er blevet bestemt med disse to teknikker, på baggrund af data fra Kepler og TESS satellitterne, er konsistente.