A growing number of close binary stars are being discovered among central stars of planetary nebulae. Recent and ongoing surveys are finding new systems and contributing to our knowledge of the evolution of close binary systems. The push to find more systems was largely based on early discoveries which suggested that 10%–15% of all central stars

Context. Non-radial oscillations, observed in thousands of red giants by the space missions CoRoT and Kepler, allow us to greatly improve our understanding of stellar structure and evolution in cool low-mass stars. The currently available Kepler light curves contain an outstanding amount of information, but a detailed analysis of the individual

Recent high-resolution and high-cadence observations have surprisingly suggested that prominence barbs exhibit apparent rotating motions suggestive of a tornado-like structure. Additional evidence has been provided by Doppler measurements. The observations reveal opposite velocities for both hot and cool plasma on the two sides of a prominence barb

We undertake a study of M51 ULX-7, using archival data from XMM-Newton, Chandra and NuSTAR, and optical and radio data from HST and VLA. The source has a consistently hard powerlaw X-ray spectrum with Γ˜1.5 and has high short-term variability, with all XMM-Newton observations having 30-40 percent rms. This is unusual variability behaviour for a ULX

We report the discovery of SDSS J131326.89-001941.4, an ultra iron-poor red giant star ([Fe/H] ≃ -4.3) with a very high carbon abundance ([C/Fe] ≃ +2.5). This object is the fifth star in this rare class, and the combination of a fairly low effective temperature (Teff ≃ 5300 K), which enhances line absorption, with its brightness (g = 16.9), makes

We present a high-resolution elemental-abundance analysis for a sample of 23 very metal-poor ([Fe/H]