Determining precise and accurate stellar parameters, and in particular ages, is of utmost importance for gaining a deeper understanding of the formation and history of the Milky Way. This is especially true for stars in the galactic halo, which belong to the oldest stars known in our Galaxy. However, due to their distance and scarcity, those

Triaxial pulsators are a recently discovered group of oscillating stars in close binary systems that pulsate around three axes at the same time. It has recently been theoretically shown that new types of pulsation modes, the tidally tilted standing (TTS) modes, can arise in these stars. We report the first detection of a quadrupole TTS oscillation

White dwarfs accreting planetary debris provide detailed insight into the bulk composition of rocky exoplanetesimals. However, only one Kuiper Belt analogue has been identified in that way so far. Here, we report the accretion of an icy extrasolar planetesimal on to white dwarf WD 1647+375 using ultraviolet spectroscopy from the Hubble Space

The Chromospheric LAyer SpectroPolarimeter missions, CLASP2 and CLASP2.1, demonstrated that the near-UV spectral region between 279.30 and 280.68 nm is suitable for studying the magnetism of the solar chromosphere. In particular, the spectropolarimetric observations in the Mg II h and k resonant doublet, Mn I 279.91 and 280.19 nm resonant lines

We present baryon acoustic oscillation (BAO) measurements from more than 14 million galaxies and quasars drawn from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2), based on three years of operation. For cosmology inference, these galaxy measurements are combined with DESI Lyman- α forest BAO results presented in a companion

We present the baryon acoustic oscillation (BAO) measurements with the Lyman- α ( Ly α) forest from the second data release (DR2) of the Dark Energy Spectroscopic Instrument (DESI) survey. Our BAO measurements include both the autocorrelation of the Ly α forest absorption observed in the spectra of high-redshift quasars and the cross-correlation of