Context. We present the first high-cadence multiwavelength radial-velocity observations of the Sun-as-a-star, carried out during 57 consecutive days using the stellar échelle spectrograph at the Hertzsprung SONG Telescope operating at the Teide Observatory. Aims: Our aim was to produce a high-quality data set and reference values for the global

The Legacy PLANCK all-sky Sunyaev-Zeldovich (SZ) galaxy cluster catalogues PSZ1 and PSZ2 (Planck Collaboration XXIX 2013; Planck Collaboration XXVII 2015) provide for the first time the possibility to detect galaxy clusters using the SZ effect signature in a full sky survey. However, in order to constrain cosmological parameters from these

With both nebular- and stellar-derived abundances of ≲1/10 Z_{⊙ } and low foreground extinction, Sextans A is a prime candidate to replace the Small Magellanic Cloud as reservoir of metal-poor massive stars and reference to study the metal-poor Universe. We report the discovery of two early O-type stars in Sextans A, the earliest O-type stars with

One of the most challenging open questions in Astrophysics is how Active Galactic Nuclei (AGNs) are fueled. For this to happen, gas has to be driven from the outskirts of the galaxy to the nuclear regions. Different mechanisms such as bars (large-scale and nuclear), lopsided disks, m=1, 2 instabilities or warps have been suggested to remove the gas

The parallax expansion and kinematics of a nova shell can be used to assess its age and distance, and to investigate the interaction of the ejecta with the circumstellar medium. These are key to understand the expansion and dispersal of the nova ejecta in the Galaxy. Multi-epoch images and high-dispersion spectroscopic observations of the recently

In this work, we have applied a semi-empirical spectral classification method for OB-stars using the APOGEE spectrograph to a sample of candidates in the W3–W4–W5 (W345) complexes. These massive star-forming regions span over 200 pc across the Perseus arm and have a notorious population of massive stars, from which a large fraction are members of