Aims: The BL Lac 1ES 2344+514 is known for temporary extreme properties characterised by a shift of the synchrotron spectral energy distribution (SED) peak energy ν synch, p above 1 keV. While those extreme states have only been observed during high flux levels thus far, additional multi-year observing campaigns are required to achieve a coherent

Context One of the most fundamental scaling relations in galaxies is observed between metallicity and stellar mass - the mass-metallicity relation (MZR) - although recently a stronger dependence of the gas-phase metallicity with the galactic gravitational potential (ΦZR) has been reported. Further dependences of metallicity on other galaxy

We present here binary modeling for the close binary central star of the planetary nebula Hf 2-2. While binary models for 26 close binary star systems within a planetary nebula exist, this number is far too low to perform a significant statistical analysis. In order to work towards increasing this number, and thus improving the statistical results

In this study, we look specifically at binary white dwarfs where the companion is a main sequence star. In particular, we look at very hot white dwarfs, many of which demonstrate the "hydrogen problem" in which modeling of their hydrogen absorption features, and optical features in general, do not appear to give accurate temperatures. The two

The MANCHA3D code is a versatile tool for numerical simulations of magnetohydrodynamic (MHD) processes in solar/stellar atmospheres. The code includes nonideal physics derived from plasma partial ionization, a realistic equation of state and radiative transfer, which allows performing high-quality realistic simulations of magnetoconvection, as well

We present JWST images of the well-known planetary nebula NGC 6720 (the Ring Nebula), covering wavelengths from 1.6 to 25 $\, \mu$m. The bright shell is strongly fragmented with some 20 000 dense globules, bright in H 2, with a characteristic diameter of 0.2 arcsec and density n H ~ 10 5-10 6 cm -3. The shell contains a narrow ring of polycyclic