Related papers: The RCB star V854 Cen is surrounded by a hot dusty…
We present optical and infrared imaging and spectroscopy of the R Coronae Borealis-type (R Cor Bor) star IRAS 00450+7401. Optical spectra further confirm its classification as a cool R Cor Bor system, having a hydrogen-deficient carbon star…
We present a mini-survey of Galactic B[e] stars mainly undertaken with the Large Binocular Telescope (LBT). B[e] stars show morphological features with hydrogen emission lines and an infrared excess, attributed to warm circumstellar dust.…
We have measured the times of onset of recent fadings in four R CrB stars -- V854 Cen, RY Sgr, R CrB, and S Aps. These times continue to be locked to the stars' pulsation periods, though with some scatter. In RY Sgr, the onsets of fading…
We add four warmer late-type supergiants to our previous spectro-interferometric studies of red giants and supergiants. V766 Cen (=HR 5171 A) is found to be a high-luminosity log(L/L_sun)=5.8+-0.4 source of Teff 4290+-760 K and radius…
We search high-resolution and high-quality VLT/UVES optical spectra of the hot R Coronae Borealis (RCB) star DY Cen for electronic transitions of the C60 molecule and diffuse interstellar bands (DIBs). We report the non-detection of the…
We present Herschel spatially resolved images of the debris disc orbiting the subgiant Kappa CrB. Not only are these the first resolved images of a debris disc orbiting a subgiant, but Kappa CrB is a rare example of an intermediate mass…
We are undertaking the first systematic infrared (IR) census of R Coronae Borealis (RCB) stars in the Milky Way, beginning with IR light curves from the Palomar Gattini IR (PGIR) survey. PGIR is a 30 cm $J$-band telescope with a 25…
With the aim of investigating the presence of molecular and dust clumps linked to two star forming regions identified in the expanding molecular envelope of the stellar wind bubble RCW78, we analyzed the distribution of the molecular gas…
Among the distinguishing characteristics of the remarkable hot R Coronae Borealis star DY Cen, which was recently found to be a spectroscopic binary, is the presence of nebular forbidden lines in its optical spectrum. A compilation of…
Context. HD 85567 is an enigmatic object exhibiting the B[e] phenomenon, i.e. an infrared excess and forbidden emission lines in the optical. The object's evolutionary status is uncertain and there are conflicting claims that it is either a…
In this paper we present for the first time, the study of low resolution $H$- and $K$- band spectra of 7 DY\,Per type and suspects stars as well as DY\,Persei itself. We also observed $H$- and $K$- band spectra of 3 R Coronae Borealis (RCB)…
The surface abundances of extreme helium (EHe) and R Coronae Borealis (RCB) stars are discussed in terms of the merger of a carbon-oxygen white dwarf with a helium white dwarf. The model is expressed as a linear mixture of the individual…
We use Modules for Experiments in Stellar Astrophysics (MESA) to construct stellar evolution models that reach a hydrogen-deficient, carbon-rich giant phase like the R Coronae Borealis (R CrB) stars. These models use opacities from OPAL and…
We present high resolution spectra of the five known hydrogen-deficient carbon (HdC) stars in the vicinity of the 10830 Angstrom line of neutral helium. In R Coronae Borealis (RCB) stars the He I line is known to be strong and broad, often…
We have observed P-Cygni and asymmetric, blue-shifted absorption profiles in the He I 10830 lines of twelve R Coronae Borealis (RCB) stars over short (1 month) and long (3 year) timescales to look for variations linked to their…
The high resolution optical spectra of H-deficient stars, R Coronae Borealis stars and H-deficient carbon stars are analyzed by synthesizing the C2 Swan bands (0,1), (0,0), and (1,0) using our detailed line-list and Uppsala model…
EROS 2 (Experience de Recherche d'Objets Sombres) conducted a survey of the SMC between July 1996 and February 2003 in two EROS broad-band colours, V_E and R_E. The photometric data of 4.2 million stars have been searched for behaviour…
We report the discovery of two new R Coronae Borealis (RCB) stars in the Large Magellanic Cloud (LMC) using the MACHO project photometry database. The identification of both stars has been confirmed spectroscopically. One is a cool RCB star…
High-resolution optical spectra of the R Coronae Borealis (RCB) star V532 Oph at light maximum are discussed. The absolute visual magnitude M_V of the star is found to be -4.9 \pm 0.5. The elemental abundances suggest the star belongs to…
(Abridged) We present a study of the structure and dynamics of the Corona Borealis Supercluster (z ~ 0.07) based on the redshifts for 528 galaxies in the supercluster. The galaxy distribution within Corona Borealis is clumpy and appears…