Related papers: The origin of R CrA variability: A complex triple …
The innermost astronomical unit in protoplanetary disks is a key region for stellar and planet formation, as exoplanet searches have shown a large occurrence of close-in planets that are located within the first au around their host star.…
T Corona Borealis (T CrB) is a symbiotic recurrent nova with an $\simeq 80$ yr recurrence interval, the eruptions of which occur on top of a $\simeq 15$ yr long high-brightness state. We show that the high-brightness state is best explained…
We present the ASCA results of intermediate-mass pre-main-sequence stars (PMSs), or Herbig Ae/Be stars (HAeBes). Among the 35 ASCA pointed-sources, we detect 11 plausible X-ray counterparts. X-ray luminosities of the detected sources in the…
Periodic increases in luminosity arising from variable accretion rates have been predicted for some close pre-main sequence binary stars as they grow from circumbinary disks. The phenomenon is known as "pulsed accretion" and can affect the…
We have identified some two-hundred new variable stars in a systematic study of a data archive obtained with the Calvin-Rehoboth observatory. Of these, we present five close binaries showing behaviors presumably due to star spots or other…
Context: The evolution of a young protocluster depends on the relative spatial distributions and dynamics of both stars and gas. Aims: We study the distribution and properties of the gas and stars surrounding the luminous (10^4 L_sun)…
Alpha Crucis is the closest very high multiplicity massive star to the Sun. At its heart is the $4" \leftrightarrow 430 \text{ au}$ binary $\alpha^1$ (A) + $\alpha^2$ (B) Cru, which combined make up the 13th visually brightest star in the…
This work presents CHARA/VEGA H$\alpha$ spectro-interferometry (R ~ 6000, and $\lambda$/2B ~ 1 mas) of HD 179218 and HD 141569, doubling the sample of Herbig Ae/Be (HAeBe) stars for which this type of observations is available so far. The…
R Coronae Borealis stars (RCBs) are rare, hydrogen-deficient, carbon-rich supergiant variable stars that are likely the evolved merger products of pairs of CO and He white dwarfs. Only 55 RCB stars are known in our galaxy and their…
The properties of the Milky Way's nuclear stellar disc give crucial information on the epoch of bar formation. Mira variables are promising bright candidates to study the nuclear stellar disc, and through their period-age relation dissect…
RW Aur is a young binary star that experienced a deep dimming in 2010-11 in component A and a second even deeper dimming from summer 2014 to summer 2016. We present new unresolved multi-band photometry during the 2014-16 eclipse, new…
$\eta$~Car is one of the most massive stars in the Galaxy. It underwent a massive eruption in the 19th century, which produced the impressive bipolar Homunculus nebula now surrounding it. The central star is an eccentric binary with a…
The nature of the accreting companion to Mira --- the prototypical pulsating asymptotic giant branch star --- has been a matter of debate for more than 25 years. Here we use a quantitative analysis of the rapid optical brightness variations…
$\kappa$CrB is a ${\sim}2.5\,$Gyr old K1 sub-giant star, with an eccentric exo-Jupiter at ${\sim}2.8\,$au and a debris disc at tens of au. We present ALMA Band 6 ($1.3\,$mm) and HST scattered light ($0.6\,\mu$m) images, demonstrating…
Eta Carinae is the nearest example of a supermassive, superluminous, unstable star. Mass loss from the system is critical in shaping its circumstellar medium and in determining its ultimate fate. Eta Car currently loses mass via a dense,…
Rapid rotation and nonradial pulsations enable Be stars to build decretion disks, where the characteristic line emission forms. A major but unconstrained fraction of Be stars owe their rapid rotation to mass and angular-momentum transfer in…
Chemically peculiar stars of the upper part of the main sequence show periodical variability in line intensities and continua, modulated by the stellar rotation, which is attributed to the existence of chemical spots on the surface of these…
We present results of variability search in the field of the young open cluster NGC 1502. Eight variable stars were discovered. Of six other stars in the observed field that were suspected for variability, we confirm variability of two,…
DI Cha A is K0-type pre-main sequence star, the brightest component of a quadruple stellar system. Here we report on a detailed study of this star based on archival VLTI/MIDI and VLTI/PIONIER infrared interferometric observations, as well…
The R Coronae Borealis (RCB) stars are rare hydrogen--deficient, carbon--rich supergiants. They undergo extreme, irregular declines in brightness of many magnitudes due to the formation of thick clouds of carbon dust. It is thought that RCB…