Teaching: Lab courses in astrophysics

taught at the Institute for Astrophysics, University Göttingen

In collaboration with a member of staff (Polis Papaderos) and a fellow student (Hagen Meyer) I was in charge of designing the experiment from base up, starting with possible science questions We then had to make sure the student can complete all necessary work (incl. observations, data reduction, and data interpretation, but not including the time for familiarizing with the subject or writing up the final report) can be completed within the alloted time range of 8 hours.

We then continued to write the instructions, research supplementary background information that would be helpful for the student to know, and run the experiment ourselves several times to ensure we did not overlook or miss anything as well as to gain the necessary experience to handle potentially arising problems

All experiments had a small collection of recommended background material (book excerpts, seminal papers, etc) that students could borrow from the instructor. This material is available upon request, but due to copyright restrictions cannot be published online.

Crowded Field Photometry of star clusters

Aim and Objective

The aim of this experiment is to obtain your own observations of two star clusters with our 50cm telescope, to reduce the collected data and then interpret the obtained information. Besides the distance we will also derive physical parameters such as age and metallicity using different methods.

Observations and methods

For this experiment you will observe 2 different clusters in 3 different photometric bands (BVR - blue, green and red). To allow later analysis of the obtained data we will also obtain photometry of several calibration stars. With this data we can use the DAOPHOT package to extract magnitudes and colors for all stars in the field and plot them as a color-magnitude diagram (see above). By overplotting and matching a range of theoretical isochrones that describe the shape and position of the diagram as function of time and metallicity we can derive the distance to the cluster, the foreground reddening, as well as its age and metallicity.

Instructions and materials

• Project instructions: German - English (Google translated)
• How-to Guide to controling the telescope and CCD camera: German - English (Google translated)
• Short reference manual for the Mr. Miller data reduction pipeline: German - English (Google translated)
• Data Reduction with Mr. Miller - Step by Step: German - English (Google translated)
• Stellar photometry using DAOPHOT: German - English (Google translated)

Surface photometry of galaxies

Aim and Objective

The aim of this practical experiment is to independently plan the observation of two galaxies of different Hubble types, execute the observations and interpret the obtained data.

As part of the experiment we derive the radial decrease in surface brightness and the mean age of the stellar population as function of radius. By analyzing the color gradients within the galaxy we can also get some insight into the formation history of the galaxy.

Observations

Since the observation of diffuse extended objects is complicated by the scattered light from the surrounding city,some important things to be considered during the subsequent reduction of the raw data. For this reason we developed Mr. Miller, a special data reduction software that partially automates and hence simplifies the data reduction process as much as possible.

Because of the weather-dependence of the observations you have to be flexible. The important steps (selection of objects, etc. ..) should be done in advance, so you can get started right away once the weather conditions are sufficiently good.

Instructions and materials

• Project instructions: German - English (Google translated)
• How-to Guide to controling the telescope and CCD camera: German - English (Google translated)
• Short reference manual for the Mr. Miller data reduction pipeline: German - English (Google translated)
• Data Reduction with Mr. Miller - Step by Step: German - English (Google translated)

Larger project practicals (duration 2 weeks full-time)

taught at the Institute for Astrophysics, University Göttingen

The idea behin these projects is for a small group of students (3-5) to gain first research experience. The group first decides on a general topic and then picks a tutor from the respective department. Together they then elaborate the details, formulate the science goal and come up with the methods and techniques that are best suited to pursue their goal. I was mentoring two groups that both used the institute's telescope to gather astronomical observations of stars and galaxies, respectively, to investigate the following topics:

• Determination of the speed of light using the variable star VZ Cnc

Although the basic idea behind this experiment sounds simple it requires careful working to gain a reasonably acurate answer: We observe a variable star that we use as accurate metronome at different positions on earths orbit around the sun. From the different path lenghts to the star and the observed shift in the stars light-curve we can then derive the speed of light.

• Spectroscopy of Active Galactic Nuclei

This experiment is in its nature an extension of the beginners lab experiment on the classification of Active Galactic Nuclei. The students used the then newly commissioned spectrograph mounted on the institutes telescope to obtain long-slit spectra of several bright nearby AGNs. Wavelength calibration was achieved via obsverations of spectral lamps with a known spectra. After data reduction and wavelength calibration the students can then derive a distance towards the galaxies via their redshifts. The shape of their emission lines furthermore allows to classify the type of the AGN into Seyfert 1s and Seyfert 2s.

Since many of the spectra were rather noisy, we decided to also obtain spectra of several bright stars to classify their spectral type by studying their effective temperature as well as the strength of several strong absorption lines.

Lab courses for minor subject students

taught at the Institute for Atomic and Nuclear Physics, University Göttingen

In total students had to do 20 experiments, covering topics across the full physics spectrum. Each session lasted 4 hours, covering 2 experiments. My job was to review the neccessary basics, introduce each of the experiments and give instructions on what the goal and methods are. During the experiments I was making sure the students handled the experiments safely, answer questions and help out where with problems.

Each of the experiments came with a set of questions, some of which had to be prepared beforehand, while most questions were meant to use the recorded measurements to compute certain quantities

Topics for the experiments were:

1. Elastic Collisions
2. Torsional/Rotary ascillations
3. Capillarity and Buoyancy
4. Internal friction of fluids
5. Specific heat capacity
6. Molar heat capacity of air
7. Lens equations
8. Microscope
9. Refrective index of glass
10. Measuring the wavelength of light via diffraction on a grating
11. Thermal element
12. Characteristic curves of various conductors
13. Electrical networks
14. Nonstationary diffusion
15. Cathode ray oscillograph
16. Electrical coils and transformer
17. Solar cell and semi-conductor diode
18. Transistor
19. Artificial redioactivity
20. Specific electron charge e/m

Preparation of teaching material

Revision of three astronomy beginner's-lab instructions:

• Spectra of active galactic nuclei: German - English (Google translated)
• Morphology of galaxies: German - English (Google translated)
• Photometrie of star clusters: German - English (Google translated)