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Massive stars commonly form binaries that can evolve into compact systems via common envelope evolution (CEE), a critical but poorly understood phase -- especially when the companion is a neutron star. Understanding the drag force exerted…
The Optical Gravitational Lensing Experiment (OGLE), originally designed to search for microlensing events, provides a rich and uniform data set suitable for studying the variability of certain types of objects. We used the OGLE data to…
We examine recent studies on the formation rate of planetary nebulae and find this rate to be about one-third of the formation rate of white dwarfs. This implies than only about one-third of all planetary nebulae that evolve to form white…
The extremely accurate estimates of stellar variability and radial velocity in the Gaia Data Release 3 (Gaia DR3) have enabled us to examine the close binarity and radial velocity (RV) of central stars (CSs) of planetary nebulae (PNe). This…
We report the results of an [O III] 5007 spectroscopic survey for planetary nebulae (PNe) located within the star clusters of M31. By examining R ~ 5000 spectra taken with the WIYN+Hydra spectrograph, we identify 3 PN candidates in a sample…
Core-collapse supernovae (SNe), marking the deaths of massive stars, are among the most powerful explosions in the Universe, responsible, e.g., for a predominant synthesis of chemical elements in their host galaxies. The majority of massive…
We present a detailed study of the stellar and orbital parameters of the post-common envelope binary central star of the planetary nebula Ou~5. Low-resolution spectra obtained during the primary eclipse -- to our knowledge the first…
We calculate the orbital evolution of binary systems where the primary star is an evolved red giant branch (RGB) star, while the secondary star is a low-mass main sequence (MS) star or a brown dwarf. The evolution starts with a tidal…
It is widely believed that central star binarity plays an important role in the formation and evolution of aspherical planetary nebulae, however observational support for this hypothesis is lacking. Here, we present the most recent results…
The massive semi-detached binary with a long-term decreasing orbital period may involve a rapid mass-transfer phase in Case A, and thus they are good astrophysical laboratories for investigating the evolution of massive binary stars. In…
Planetary nebulae (PNe) can be used to trace intermediate and old stellar populations in galaxies and the intracluster medium out to approximately 20 Mpc. PNe can be easily identified with narrow-band surveys, and their chemical abundances…
We have, for the first time, compiled a nearly complete census of planetary nebulae (PNe) centred on the Sun. Our goal is the generation of an unbiased volume-limited sample, in order to answer some long-standing statistical questions…
Even after decades of usage as an extragalactic standard candle, the universal bright end of the planetary nebula luminosity function (PNLF) still lacks a solid theoretical explanation. Until now, models have modeled planetary nebulae (PNe)…
We present in this contribution our set of multiwavelength synthesis models including the evolution of single and binary stars. The main results we have obtained can be summarized as follows: (a) massive close-binary systems will start to…
Context. The majority of massive stars are born with a close binary companion. How this affects their evolution and fate is still largely uncertain, especially at low metallicity. Aims. We derive synthetic populations of massive…
Following the discovery of blue large-amplitude pulsators (BLAPs), single star evolu- tion models of post red giant branch stars that have undergone a common envelope (CE) ejection in the form of a high mass loss rate have been constructed…
We present low resolution spectroscopic observations for a sample of 53 planetary nebulae (PNe) located in the southern sky between Vela and Norma constellations and pertaining to the Galactic disk with expected Galactocentric distance…
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…
We present a period-luminosity-amplitude analysis of 5899 red giant and binary stars in the Large Magellanic Cloud, using publicly available observations of the MACHO project. For each star, we determined new periods, which were…
As part of our continuing study of light variability in proto-planetary nebulae (PPNe), we present the results from a long-term study of nine southern hemisphere objects. We have monitored their light variations over a nine-year interval…