Related papers: Multiwavelength optical observations of the chromo…
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…
Future solar missions and ground-based telescopes aim to understand the magnetism of the solar chromosphere. We performed a supporting study in Quintero Noda et al. (2016) focused on the infrared Ca II 8542 A line and we concluded that is…
The chromospheric H-alpha spectral line is a strong line in the spectrum of the Sun and other stars. In the stellar regime, this spectral line is already used as a powerful tracer of stellar activity. For the Sun, other tracers (i.e, CaII…
We present the first orbital elements for the massive close binary, HD 115071, a double-lined spectroscopic binary in a circular orbit with a period of 2.73135 +/- 0.00003 days. The orbital semiamplitudes indicate a mass ratio of M_2/M_1 =…
Recent CCD observations were performed in the period 1998-2004 for a large sample of visual double and multiple stars selected from the Hipparcos Catalogue and/or from the Gliese Catalogue of Nearby Stars. Accurate astrometric and…
We report on optical high-dispersion spectroscopic monitoring observations of the Be/X-ray binary A0535+26/V725 Tau, carried out from November 2005 to March 2009. The main aim of these monitoring observations is to study spectral…
The detection of Earth-like planets with the radial-velocity method is currently limited by the presence of stellar activity signatures. On rotational timescales, spots and plages (or faculae) are known to introduce different RV signals,…
We present a program of routine lunar occultations, at optical and near-IR wavelengths, recently started at the 1.5m Spanish telescope at the Calar Alto Observatory. Both a CCD and an infrared array detector are used. The program is aimed…
We report on the results of a new spectroscopic monitoring campaign of the quasar PG 0026+129 at the Calar Alto Observatory 2.2m telescope from July 2017 to February 2020. Significant variations in the fluxes of the continuum and…
We present the latest results of our spectroscopic observations and refined modelling of a sample of detached eclipsing binaries (DEBs), selected from the $Kepler$} Eclipsing Binary Catalog, that are also double-lined spectroscopic binaries…
Statistical characterization of secondary subsystems in binaries helps to distinguish between various scenarios of multiple-star formation. The DSSI speckle instrument was used at the Gemini-N telescope for several hours in 2015 July to…
Optical and near-infrared observations are compiled for the three gamma-ray binaries hosting Be stars: PSR B1259-63, LSI+61 303, and HESS J0632+057. The emissions from the Be disk are considered to vary according to the changes in its…
The solar chromosphere has historically been studied from spectral lines in the visible and UV, notably H{\alpha}, Ca ii, Mg ii and Ly{\alpha}. Observations at long UV wavelengths (304, 1600 and 1700 {\AA}) from space have been recently…
Aims. With the Solar Optical Telescope on Hinode, we investigate the basic properties of high-degree solar oscillations observed at two levels in the solar atmosphere, in the G-band (formed in the photosphere) and in the Ca II H line…
Several strong resonance lines, such as H I Ly-$\alpha$, Mg II k, Ca II K, Ca I 4227 \AA\, which are characterized by deep and broad absorption profiles in the solar intensity spectrum, show conspicuous linear scattering polarization…
We investigate the spectral characteristics of the Be/X-ray binary system, EXO 051910+3737.7, in which Be/X-ray systems are the largest sub-class of high-mass X-ray binaries. Spectroscopic observations are taken by the Thai National…
We are conducting a comprehensive investigation of V815 Her using photometric and spectroscopic data to understand the origin of the activity and what influences it in the short and long term. Using TESS photometry we performed light curve…
Context: OB stars are important in the chemistry and evolution of the Universe, but the sample of targets well understood from an asteroseismological point of view is still too limited to provide feedback on the current evolutionary models.…
We obtained new high-resolution spectra using the Lijiang 1.8-m and 2.4-m telescopes to investigate the chromospheric activities of V1355 Ori as indicated in the behaviors of Ca ii H&K, Hdelta, Hgamma, Hbeta, Na i D1, D2, Halpha and Ca ii…
We present Doppler and modulation tomography of the low-mass X-ray binary V691 CrA with data obtained using the 6.5-m Magellan Baade telescope at the Las Campanas Observatory in 2010 and 2011. The disc and hotspot are observed in H\alpha…