Related papers: Close binary central stars and the abundance discr…
Binary interactions are commonplace among massive stars, giving rise observed phenomena such as X-ray binaries, stripped stars & supernovae, and gravitational-wave sources. The multiplicity properties of massive stars thus represent a…
We present the identification of 34 likely binary central stars (CSs) of planetary nebulae (PNe) from {\it Kepler/K2} data, seven of which show eclipses. Of these, 29 are new discoveries. Two additional CSs with more complicated variability…
Using proper motion data for 894 stars in the Orion Nebula Cluster (ONC) compiled by Jones & Walker in 1988, we search for binaries with apparent separations in the range 1000-5000 AU, and find an upper limit of three. Using a Monte Carlo…
A large number of direct imaging surveys for exoplanets have been performed in recent years, yielding the first directly imaged planets and providing constraints on the prevalence and distribution of wide planetary systems. However, like…
In Planetary Nebulae (PNe) and HII regions ionic abundances can be derived by using collisionally excited lines (CELs) or recombination lines (ORLs). Such abundances do not coincide for the same ion and usually abundances from ORLs are…
From high-resolution spectra, chemical abundances from collisionally excited lines (CELs) and optical recombination lines (ORLs) have been determined for planetary nebulae Cn 3-1, Vy 2-2, Hu 2-1, Vy 1-2 and IC 4997, which are young and…
We use observations from the APOGEE survey to explore the relationship between stellar parameters and multiplicity. We combine high-resolution repeat spectroscopy for 41,363 dwarf and subgiant stars with abundance measurements from the…
Planetary nebulae represent a potential late stage of stellar evolution, however the central stars (CSPNe) are relatively faint and therefore pertinent information is merely available for <20% of the Galactic sample. Consequently, the…
We study the hypothesis of high metallicity clumps being responsible for the abundance discrepancy found in planetary nebulae between the values obtained from recombination and collisionaly excited lines. We generate grids of…
We report observations of a remarkable major axes alignment nearly parallel to the Galactic plane of 5{\sigma} significance for a subset of bulge "planetary nebulae" (PNe) that host, or are inferred to host, short period binaries. Nearly…
We present high resolution spectrophotometric data for 34 galactic planetary nebulae with [WC] nuclei (WRPNe).The sample includes PNe with early and late [WC] stars and some WELS. Physical conditions and chemical abundances have been…
Evidence from the analysis of eclipsing binary systems revealed that late-type stars are larger and cooler than predicted by models, and that this is probably caused by stellar magnetic activity. In this work, we revisit this problem taking…
We have studied the time variation of the radial abundance gradients using samples of planetary nebulae, open clusters, cepheids and other young objects. Based on the analysis of O/H and S/H abundances for planetary nebulae and…
Spectra of planetary nebulae (PNe) are characterised by strong forbidden emission lines and often also by an infrared (IR) excess. A few PNe show dust obscuration events and/or harbour long-period binaries. Some post-asymptotic giant branch…
According to Aistleitner and Weimar, there exist two-dimensional (double) infinite matrices whose star-discrepancy $D_N^{*s}$ of the first $N$ rows and $s$ columns, interpreted as $N$ points in $[0,1]^s$, satisfies an inequality of the form…
In galactic centers, stars and binaries can be injected into low-angular-momentum orbits, resulting in close encounters with the central supermassive black hole (SMBH). Previous works have shown that under different conditions, such close…
We present results constraining the multiplicity of the very low mass stars and sub-stellar objects in the Orion Nebula Cluster (ONC). Our sample covers primary masses 0.012-0.1M$_{\odot}$ using archival Hubble Space Telescope data obtained…
The occurrence of planets in binary star systems has been investigated via a variety of techniques that sample a wide range of semi-major axes, but with a preponderance of such results applicable to planets with semi-major axes less than a…
The peculiar nebular emission displayed by galaxies in the early Universe presents a unique opportunity to gain insight into the regulation of star formation in extreme environments. We investigate 500 (109) galaxies with deep NIRSpec/PRISM…
Using Monte Carlo simulations and published radial velocity surveys we have constrained the frequency and separation (a) distribution of very low mass star (VLM) and brown dwarf (BD) binary systems. We find that simple Gaussian extensions…