Yearslong time series of high-precision brightness measurements have been assembled for
thousands of stars with telescopes operating in space. Such data have allowed astronomers …

Rotation matters for the life of a star. It causes a multitude of dynamical phenomena in the
stellar interior during a star's evolution, and its effects accumulate until the star dies. All stars …

Context. Empirical evidence for the involvement of nonradial pulsations (NRPs) in the mass
loss from Be stars ranges from (i) a singular case (μ Cen) of repetitive mass ejections …

Context. Among intermediate-mass and massive stars, Be stars are the fastest rotators in the
main sequence (MS) and, as such, these stars are a cornerstone to validate models of …

Aims. The rapidly rotating Be star ϕ Persei was spun up by mass and angular momentum
transfer from a now stripped-down, hot subdwarf companion. Here we present the first high …

Classical B emission (Be) stars are fast rotating, near-main-sequence B-type stars. The
rotation and the presence of circumstellar discs profoundly modify the observables of active …

Context. The viscous decretion disk (VDD) model is able to explain most of the currently
observable properties of the circumstellar disks of Be stars. However, more stringent tests …

Light curves of 57 classical Be stars in TESS sectors 1–15 are examined. In most Be stars,
the periodogram shows groups at a fundamental and one or more harmonics, which we …

The extreme luminosities of massive, hot OB stars drive strong stellar winds through line-
scattering of the star's UV continuum radiation. For OB stars with an orbiting circumstellar …

This review has two parts. The first one is devoted to the Barbier–Chalonge–Divan (BCD)
spectrophotometric system, also known as the Paris spectral classification system. Although …