Context. Determining empirical atmospheric models for the solar chromosphere is difficult since it requires the observation and analysis of spectral lines that are affected by non-local thermodynamic equilibrium (NLTE) effects. This task is especially difficult in sunspot umbrae because of lower continuum intensity values in these regions with

We study the energy flux carried by acoustic waves excited by convective motions at sub-photospheric levels. The analysis of high-resolution spectropolarimetric data taken with IMaX/SUNRISE provides a total energy flux of ~6400-7700 W m-2 at a height of ~250 km in the 5.2-10 mHz range, i.e., at least twice the largest energy flux found in previous

Detection of narrow (δλ < 0.5 Å) absorption features in C IV at λλ1548 and 1550 have been made in the spectra of 4 late B dwarfs within 200 pc of the sun; the Si IV doublet at λλ1393 and 1403 shows up in two of them. The authors argue that it is difficult to account for the strengths, widths, shapes, and C IV/Si IV ratios in terms consistent with a

IPHAS is an ongoing Hα imaging survey of the North Galactic plane. When completed, it is expected to discover several hundred new Galactic planetary nebulae, in addition to a huge number of Hα emitters. We present here the project, the methods used to search for compact and extended ionized nebulae, and some preliminary results about the ~100 new

Context. PKS 1510-089 is a flat spectrum radio quasar strongly variable in the optical and GeV range. To date, very high-energy (VHE, > 100 GeV) emission has been observed from this source either during long high states of optical and GeV activity or during short flares. Aims: We search for low-state VHE gamma-ray emission from PKS 1510-089. We

θ Cygni is an F3 spectral type magnitude V = 4.48 main-sequence star that was the brightest star observed by the original Kepler spacecraft mission. Short-cadence (58.8 s) photometric data using a custom aperture were first obtained during Quarter 6 (2010 June–September) and subsequently in Quarters 8 and 12–17. We present analyses of solar-like