Related papers: The Rotationally Modulated Polarization of $\xi$ B…
Aims. We aim to investigate the long-term temporal evolution of the magnetic field of the solar-type star \xi Bootis A, both from direct magnetic field measurements and from the simultaneous estimate of indirect activity indicators.…
We report the results of intensive monitoring of the variability in the H$\alpha$ line for two F-type stars, $\tau$ Boo and $\upsilon$ And, during the last four years 2019-2022, in order to investigate their stellar magnetic activity. The…
An extensive spectroscopic study on \xi Boo A (chromospherically active solar-type star) was conducted based on the spectra obtained in 2008 December though 2010 May, with an aim to detect any spectrum variability and to understand its…
We present simultaneous UBV polarimetric and photometric observations of the pre-main-sequence binary AK Sco, obtained over 12 nights, slightly less than the orbital period of 13.6 days. The polarization is a sum of interstellar and…
Using the Submillimeter Array, we have made the first high angular resolution measurements of the linear polarization of Sagittarius A* at submillimeter wavelengths, and the first detection of intra-day variability in its linear…
The fact that the O-type close binary star system AO~Cassiopeiae exhibits variable phase-locked linear polarization has been known since the mid-1970s. In this work, we re-observe the polarization arising from this system more than 50 years…
We present recent polarimetric results of magnetically active late-type dwarfs. The polarization in these stars is found to be wavelength dependent, decreasing towards the longer wavelength. The average values of degree of polarization in…
We present the first optical polarimetric measurements of RX J1141.3-6410 which confirm that star as a polar. The circular polarization varies between 0 and 13% with the orbital period. Halpha spectroscopy shows that this line is formed by,…
(abridged) There is considerable interest in the possible interaction between parent stars and giant planetary companions in 51 Peg-type systems. We demonstrate from MOST satellite photometry and Ca II K line emission that there has been a…
Despite of the importance of magnetic fields for the full understanding of the properties of accreting Herbig Ae/Be stars, these fields have scarcely been studied over the rotation cycle until now. One reason for the paucity of such…
The paper presents the results of long-term homogeneous spectroscopic studies of the Herbig Ae/Be star HD 141569A obtained in the optical range. We detect spectral variability on timescales of months to years, including changes in the…
We present a magnetic-field surface map for both stellar components of the young visual binary ksi Boo AB (A: G8V, B: K5V). Employed are high resolution Stokes-V spectra obtained with the Potsdam Echelle Polarimetric and Spectroscopic…
We investigate the structure of the O-type binary system HD 48099 by measuring linear polarization that arises due to light scattering process. Linear polarization measurements of HD 48099 in the B, V and R passbands with the high-precision…
We measured the linear polarization of Sagittarius A* to be 7.2 +/- 0.6 % at 230 GHzusing the BIMA array with a resolution of 3.6 x 0.9 arcsec. This confirms the previously reported detection with the JCMT 14-m antenna. Our high resolution…
One of the aims of the BCool programme is to search for cycles in other stars and to understand how similar they are to the Sun. In this paper we aim to monitor the evolution of $\tau$ Boo's large-scale magnetic field using high-cadence…
We report on UBVRI polarimetry of the recently identified Intermediate Polar 1WGA J1958.2+3232, carried out on 2000 August, 4-6 at the Nordic Optical Telescope. Circular polarization was detected in R and I bands with an increasing absolute…
The polarization of light across individual spectral lines contains information about the circumstellar environment on very small spatial scales. We have obtained a large number of high precision, high resolution spectropolarimetric…
We obtained thirteen spectropolarimetric observations of the strongly magnetic rapidly oscillating Ap star HD154708 over three months with the multi-mode instrument FORS1, installed at the 8-m Kueyen telescope of the VLT. These observations…
We report on the submillimeter properties of Sagittarius A* derived from observations with the Submillimeter Array and its polarimeter. We find that the spectrum of Sgr A* between 230 and 690 GHz is slightly decreasing when measured…
We report the detection of modulated circular polarization in V795 Her. The degree of polarization increases with wavelength and is modulated with a period of 19.54 min, which is very close to the reported optical QPO period. The modulation…