Martin Paetzold

The SARS algorithm: detrending CoRoT light curves with Sysrem using simultaneous external parameters

Surveys for exoplanetary transits are usually limited not by photon noise but rather by the amount of red noise in their data. In particular, although the CoRoT space-based survey data are being carefully scrutinized, significant new sources of systematic noises are still being discovered. Recently, a magnitude-dependant systematic effect was discovered in the CoRoT data by Mazeh et al. and a phenomenological correction was proposed. Here we tie the observed effect to a particular type of effect, and in the process generalize the popular Sysrem algorithm to include external parameters in a simultaneous solution with the unknown effects. We show that a post-processing scheme based on this algorithm performs well and indeed allows for the detection of new transit-like signals that were not previously detected.

Faraday-rotation fluctuations from radio-sounding measurements of the circumsolar plasma using polarized signals from the HELIOS-1 and HELIOS-2 space probes

Fluctuations in the Faraday rotation of the plane of polarization of S-band (2.3 GHz) radio signals transmitted through the solar corona by the HELIOS-1 AND HELIOS-2 space probes are analyzed. Simultaneous measurements of the Faraday-rotation fluctuations at the Goldstone and Canberra stations have yielded estimates of the velocity of perturbations of the magnetic field in the circumsolar plasma at heliocentric distances of three to six solar radii. The velocity of these perturbations is a combination of the Alfvén and solar-wind speeds. Temporal spectra of the Faraday-rotation fluctuations are obtained based on a large volume of observational data obtained in various years in four cycles of radio-sounding experiments. Filtration of the input data using spectral, correlation, and wavelet analyses shows that trains of quasi-periodic oscillations of the magnetic field with various amplitudes and periods from 2 to 160 min are regularly present in the Faraday-rotation fluctuations. This quasi-periodic character of these perturbations supports their connection with Alfvén waves propagating in the circumsolar plasma.