Aims: The aim of the project is to search for lithium in absorption at 6707.8 Å to constrain the nature and mass of the brightest low-metallicity L-type dwarfs (referred to as L subdwarfs) identified in large-scale surveys. Methods: We obtained low- to intermediate-resolution (R ~ 2500-9000) optical (~560-770 nm) spectra of two mid-L subdwarfs

We compare {{{H}}}α emission profiles of 12 dynamically confirmed black holes (BHs) and 2 neutron star X-ray transients (SXTs) in quiescence with those of a sample of 43 Cataclysmic Variables (CVs), also quiescent. The FWHM of the {{{H}}}α line in SXTs is tightly correlated with the velocity semi-amplitude of the donor star {K}2=0.233(13){FWHM}

We present the discovery of 49 new photometrically classified T dwarfs from the combination of large infrared and optical surveys combined with follow-up Telescopio Nazionale Galileo photometry. We used multiband infrared and optical photometry from the United Kingdom Infrared Telescope and Sloan Digital Sky Surveys to identify possible brown dwarf

Aims: We study the variation in the magnetic field strength, area, and continuum intensity of umbrae in solar cycles 23 and 24. Methods: We analyzed a sample of 374 sunspots observed from 1999 until 2014 with the Tenerife Infrared Polarimeter at the German Vacuum Tower Telescope and the Facility InfRared Spectropolarimeter at the Dunn Solar

Due to stellar rotation, the observed radial velocity of a star varies during the transit of a planet across its surface, a phenomenon known as the Rossiter–McLaughlin (RM) effect. The amplitude of the RM effect is related to the radius of the planet which, because of differential absorption in the planetary atmosphere, depends on wavelength

Context. Because of its proximity, Mrk 421 is one of the best sources on which to study the nature of BL Lac objects. Its proximity allows us to characterize its broadband spectral energy distribution (SED). Aims: The goal is to better understand the mechanisms responsible for the broadband emission and the temporal evolution of Mrk 421. These