Related papers: Long-Term Light Curve of Highly-Variable Protostel…

We discuss the optical light curves of two Be X-ray Binaries, IGR J06074+2205 and SAX J2103.5+4545 recovered from the ATLAS, ZTF and ASAS-SN databases. Both sources show long term optical variability of 620 and 420 days respectively, with…

We present the collection of all the mid- and far-IR observations (3-170 um) of the young eruptive variable PV Cep available so far in the literature. These data allow us to confirm that flux variability is a prominent feature at mid-IR…

A multiwavelength observing campaign of the T Tauri star (TTS) GM Aur was undertaken in 2019 December that obtained Swift X-ray and NUV fluxes, HST NUV spectra, LCOGT ugri and TESS photometry, CHIRON Halpha spectra, ALMA 13CO and C18O line…

We analyze high-resolution UV spectra of a small sample of Herbig Ae/Be stars (HAEBES) in order to explore the origin of the $T\sim10^5$ K gas in these stars. The C IV 1548,1550 \AA\ line luminosities are compared to non--simultaneous…

We have carried out a search for flares from the analysis of light curves for 12 active G, K, and M dwarfs. As sources of data we used ground-based observations in 2000-2020 from the photometric databases ASAS, SuperWASP, KWS. Events of…

Emission lines indicative of active accretion have been seen on a handful of low-mass companions (M < 30 MJup) to stars. Line variability is ubiquitous on stellar accretors but has never been characterized in detail on low-mass companions…

Stellar flares occasionally present a $\textit{peak-bump}$ light curve morphology, consisting of an initial impulsive phase followed by a gradual late phase. Analyzing this specific morphology can uncover the underlying physics of stellar…

The analysis of non-variable stars is generally neglected in the literature. However, such objects are needed for many calibration processes and for testing pulsational models. The photometric time series of the Kepler satellite mission…

At the center of our Galaxy lies the bright {\gamma}-ray point-like source HESS J1745-290, which is compatible in position with Sgr A star, although an association between the two remains uncertain. Using data obtained between 2004 and 2019…

gamma-Cas stars constitute a subgroup of Be stars showing unusually hard and bright X-ray emission. In search for additional peculiarities, we analyzed the TESS lightcurves of 15 gamma-Cas analogs. Their periodograms display broad frequency…

Classical T Tauri Stars (CTTSs) are highly variable stars that possess gas- and dust-rich disks from which planets form. Much of their variability is driven by mass accretion from the surrounding disk, a process that is still not entirely…

Very high-energy (VHE, E\,$>$\,100\,GeV) $\gamma$-ray data are a valuable input for multi-wavelength and multi-messenger (e.g. combination with neutrino data) studies. We aim at the conservation and homogenization of historical, current,…

We report photometry of the helium-rich cataclysmic variable ES Ceti during 2001-2004. The star is roughly stable at V ~ 17.0 and has a light curve dominated by a single period of 620 s, which remains measurably constant over the 3 year…

We present 127 new transit light curves for 39 hot Jupiter systems, obtained over the span of five years by two ground-based telescopes. A homogeneous analysis of these newly collected light curves together with archived spectroscopic,…

We report results of VI time series photometry for the bright globular cluster M5 taken between 2007-2011 using the 0.5-m telescope at Bowling Green State Univ. and the PROMPT #4 telescope at Cerro Tololo. We used DAOPHOT to obtain…

Three fields covering the central part of the globular cluster Omega Cen were surveyed in a search for variable stars. We present V-band light curves for 22 periodic variables: 9 SX~Phe stars, 7 contact binaries, 5 detached or semi-detached…

We present time series spectrophotometric observations of GQ Lupi, a typical representative of the YY Ori subgroup of T Tauri stars that show conspicuous inverse PCygni profiles. The data set consists of 32 exposures taken over 5 and 8…

We present long term monitoring of MCG-6-30-15 in X-rays, optical and near-IR wavelengths, collected over five years of monitoring. We determine the power spectrum density of all the observed bands and show that after taking into account…

We present 29 likely members of the young $\rho$ Oph or Upper Sco regions of recent star formation that exhibit "accretion burst" type light curves in $K2$ time series photometry. The bursters were identified by visual examination of their…

Young Sun-like stars at the beginning of the pre-main sequence (PMS) evolution are surrounded by accretion discs and remnant protostellar envelopes. Photometric and spectroscopic variations of these stars are driven by interactions of the…