Enno von Nussbaum
Otto-von-Taube Gymnasium
Titel der Forschungsarbeit: Bestimmung der Entfernung des Röntgendoppelsterns 4U 1630-47 mithilfe des Röntgenteleskops Chandra und des Radioteleskops APEX
Institut: Max-Planck-Institut für extraterrestrische Physik
Arbeitsgruppe: Arbeitsgruppe Hochenergie-Astrophysik
Betreuung: Dr. Thomas Stanke
Abstract der Forschungsarbeit
The aim of this research work is to determine the distance to the X-ray binary 4U 1630-47. Astronomical distance determination is generally difficult, as there are only a few reference points for the distance of such objects. This X-ray source had an X-ray outburst that was observed both directly and via a scattering molecular cloud. The scattered X-rays form a halo around the source. Using observations from Chandra and APEX, I have compared the structure of the halo and the molecular clouds in the line of sight to 4U 1630-47, which indicates that a molecular cloud with a radial velocity of -79 km/s is mainly responsible for the scattering of the X-rays forming the halo. The determination of the distance using the Galactic Rotation Curve of this molecular cloud resulted in two different values due to the near-fardistance ambiguity: 4.7 kpc and 10.3 kpc. I found another cloud with a radial velocity of -105 km/s, which seems to have absorbed part of the X-rays from the halo, meaning it has to be between Earth and the scattering cloud. This cloud’s distance from Earth is found to be at least 6.2 kpc. Thus, the cloud with a radial velocity of -79 km/s is most likely at the far distance, because the near distance is lower than the distance of the absorbing cloud. The distance to 4U 1630-47 can be determined from the time difference between the observation of the X-ray burst and the observation of the halo and the extent of the halo using geometry. The resulting distance is 11.0 kpc ± 0.8 kpc.