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The spectral features of HD 94509 are highly unusual, adding an extreme to the zoo of Be and shell stars. The shell dominates the spectrum, showing lines typical for spectral types mid-A to early-F, while the presence of a late/mid B-type…
Space-based photometric measurements first revealed low-amplitude irregularities in the pulsations of Cepheid stars, but their origins and how commonly they occur remain uncertain. To investigate this phenomenon, we present MOST space…
We present Cousins $R$ and $I$ band photometry of variable stars in a $\sim13'\times 13'$ region in the disk of M31 galaxy, obtained during 141 nights. Of the 26 Cepheid variables present in the region, two are newly discovered, 11 are…
This first VELOCE data release comprises 18,225 high-precision RV measurements of 258 bona fide classical Cepheids on both hemispheres collected mainly between 2010 and 2022, alongside 1161 additional observations of 164 other stars. The…
We report on the discovery with Chandra of a strong modulation (~90% pulsed fraction) at ~6.4 h from the source CXOU J123030.3+413853 in the star-forming, low-metallicity spiral galaxy NGC 4490, which is interacting with the irregular…
We made photometric and spectroscopic observations of the rapidly pulsating subdwarf B star EC 09582-1137 with the aim of determining the target's fundamental structural parameters from asteroseismology. The new data comprise ~ 30 hours of…
Tidally tilted pulsators (TTPs), whose pulsation axis aligns with the binary's semi-major axis, represent a newly established class of oscillators in binary systems. While all previously known TTPs are either $\delta$ Scuti or subdwarf…
Classical Cepheid variable stars have been important indicators of extragalactic distance and Galactic evolution for over a century. The Spitzer Space Telescope has opened the possibility of extending the study of Cepheids into the mid- and…
We present the results of an analysis of 21 spectra of alpha UMi (Polaris) obtained in September - December 2015. Frequency analysis shows an increase of the pulsation period up to 8.6 min in comparison to the 2007 observational set. The…
B and V photometry has been obtained for variable stars in the northeast arm of the Small Magellanic Cloud (SMC). Periods and lightcurves have been determined for 237 periodic variables, including 201 Cepheids, 68 of which are newly…
MACHO Project photometry of 45 LMC FO/SO beat Cepheids which pulsate in the first and second overtone (FO and SOo, respectively) has been analysed to determine the lightcurve characteristics for the SO mode of Cepheid pulsation. We predict…
This is the first of two papers reporting measurements from a program to determine the Hubble constant to 5% precision from a refurbished distance ladder. We present new observations of 110 Cepheid variables in the host galaxies of two…
There is a small group of peculiar early-type stars on the main sequence that show different rotation velocities from different spectral lines. This inconsistency might be due to the binary nature of these objects. We aim to verify this…
Context. The existence of a significant population of Ap stars with very long rotation periods (up to several hundred years) has progressively emerged over the past two decades. However, only lower limits of the periods are known for most…
The circumstellar envelopes (CSE) of Cepheids are still not well characterized despite their potential impact on distance determination via both the period-luminosity relation and the parallax-of-pulsation method. This paper aims to…
Aims. HD166734 is an eccentric eclipsing binary system composed of two supergiant O-type stars, orbiting with a 34.5-day period. In this rare configuration for such stars, the two objects mainly evolve independently, following single-star…
DH Cephei is a prominent O+O-type binary system in the NGC 7380 open cluster. Our high-precision multi-band polarimetry demonstrates synchronous linear polarization variations with the orbital period. Using Stokes parameters, we derived the…
Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young…
We report the discovery of EPIC 201498078b, which was first identified as a planetary candidate from Kepler K2 photometry of Campaign 14, and whose planetary nature and orbital parameters were then confirmed with precision radial…
High-resolution atmospheric flow simulations of the tidally-locked extrasolar giant planet, HD 209458b, show large-scale spatio-temporal variability. This is in contrast to the simple, permanent day/night (i.e., hot/cold) picture. The…