The early Universe, together with many nearby dwarf galaxies, is deficient in heavy elements. The evolution of massive stars in such environments is thought to be affected by rotation. Extreme rotators among them tend to form decretion disks and manifest themselves as OBe stars. We use a combination of UB, Gaia, Spitzer, and Hubble Space Telescope

Galaxy clusters are useful laboratories to investigate the evolution of the Universe, and accurate measurement of their total masses allows us to constrain important cosmological parameters. However, estimating mass from observations that use different methods and spectral bands introduces various systematic errors. Here we evaluate the use of a

Aims: With the aim of finding microlensing binaries containing brown dwarf (BD) companions, we investigate the microlensing survey data collected during the 2016-2018 seasons. Methods: For this purpose, we first modeled lensing events with light curves exhibiting anomaly features that are likely to be produced by binary lenses. We then sorted out

We report the confirmation and characterisation of TOI-1820 b, TOI-2025 b, and TOI-2158 b, three Jupiter-sized planets on short-period orbits around G-type stars detected by TESS. Through our ground-based efforts using the FIES and Tull spectrographs, we have confirmed these planets and characterised their orbits, and find periods of around 4.9 d

The cosmological information extracted from photometric surveys is most robust when multiple probes of the large scale structure of the Universe are used. Two of the most sensitive probes are the clustering of galaxies and the tangential shear of background galaxy shapes produced by those foreground galaxies, so-called galaxy-galaxy lensing

A direct detection experiment with gallium arsenide (GaAs) as a cryogenic scintillator is proposed to search for dark matter in the mass range below 1 GeV . To detect scintillation photons with high sensitivity, we are developing Lumped Element Kinetic Inductance Detectors (LE-KIDs). We report the first fabrication of the aluminum-niobium LE-KIDs