][ Florian Formanek - research@OULU ][

Summer 2000: Astronomy Division - University of Oulu (Oulu, Finland)
Study of a eclipsing binary star system
(A training period during my master's degree brought me to...Astronomy:)
- R. Duemmler, C. Doucet, F. Formanek, I. Ilyin and I. Tuominen "The radial velocities and physical parameters of ER Vul"
A&A 402, 745 (2003). PDF

During summer 2000 I was able to spent time in the north of Finland (latitude 65°), through an Erasmus student exchange program. I made a training period in the Astronomy Division (Department of Physical Sciences) of the University of Oulu under the direction of Dr. Rudolf Duemmler and Prof. Ilkka Tuominen.

At that time they were studying an eclipsing binary called ER Vul (HD 200391) which consists of two nearly identical solar-type stars. My contribution has been to process high quality spectra obtained with the SOFIN échelle spectrograph at the Nordic Optical Telescope on La Palma island (Spain) and the coudé spectrograph at the 2m RCC telescope of the National Astronomical Observatory at Rozhen (Bulgaria), in order to determined improved values for the orbital and some physical parameters of the binary system.
Due to their very close orbit, the period being about 0.7 day, the two stars rotate very fast which leads to a blending of many spectral lines at all phase since both components of ER Vul are of similar spectral type. This effect can lead to systematic error when measuring the radial velocity curves.

The above picture shows the average spectrum of ER Vul near one of the conjunction (alignment with Earth) phases compared to the spectrum of the Sun (orange lines), artificially spun-up with two different projected rotational velocities.

More information to come...

For more information about binary stars, I recommend you to read the Wikipedia page on the subject which is well detailed.

album page