Context: The heating process that balances the solar chromospheric energy losses has not yet been determined. Conflicting views exist on the source of the energy and the influence of photospheric magnetic fields on chromospheric heating. Aims: We analyze a 1-h time series of cospatial Ca II H intensity spectra and photospheric polarimetric spectra

Observations of transverse coronal loop oscillations very often show the excitation and damping of oscillations in groups of coronal loops rather than in individual and isolated structures. We present results on the oscillatory properties (periods, damping rates, and spatial distribution of perturbations) for resonantly damped oscillations in a

We present new results on the nature of the Herbig-Haro-like object 73 (HHL 73, also known as [G84b] 11) based on narrow-band CCD Hα and [SII] images of the HHL 73 field, and integral field spectroscopy (IFS) and radio continuum observations at 3.6 cm covering the emission of the HHL 73 object. The CCD images allow us to resolve the HHL 73 comet

We have computed the K-correction for emission lines formed on the irradiated face of the companion stars in X-ray binaries. Our results, combined with the detection of high excitation emission lines arising from the donor star can provide the first mass determinations for either neutron stars or black holes in active Low Mass X-ray Binaries (LMXBs

We present a complete spectroscopic survey of 2414 2MASS-selected blue horizontal branch (BHB) candidates selected over 4300 deg2 of the sky. We identify 655 BHB stars in this non-kinematically selected sample. We calculate the luminosity function of field BHB stars, and find evidence for very few hot BHB stars in the field. The BHB stars located

We have conducted an extensive observational campaign of SWIFT J1753.5-0127 over the last year, since its bright our-burst episode in 2005. Using long time baseline optical photometry, we have found a new period suggestive of orbital modulation with a period of 3.2 h, we have simultaneous multi-band photometry, and high-frequency multi-band