Related papers: Blue Stragglers After the Main Sequence

A large fraction of massive stars evolve in interacting binary systems, which dramatically modifies the outcome of stellar evolution. We investigated the properties of blue supergiants in binary systems and whether they are suitable for…

Bifurcated patterns of blue straggler stars in their color--magnitude diagrams have atracted significant attention. This type of special (but rare) pattern of two distinct blue straggler sequences is commonly interpreted as evidence of…

Integrated spectroscopy is the method of choice for deriving the ages of unresolved stellar systems. However, hot stellar evolutionary stages, such as hot horizontal branch stars and blue straggler stars (BSSs), can affect the integrated…

We present a technique to identify the most probable dynamical formation scenario for an observed binary or triple system containing one or more merger products or, alternatively, to rule out the possibility of a dynamical origin. Our…

Physical collisions between stars occur frequently in dense star clusters, either via close encounters between two single stars, or during strong dynamical interactions involving binary stars. Here we study stellar collisions that occur…

In this paper we report on a curious feature in the V, (U-B) color-magnitude diagrams of globular clusters. In our database, we find that a considerable fraction of blue horizontal branch stars, hotter than the instability strip and cooler…

During the post-main sequence evolution massive stars pass through several short-lived phases, in which they experience enhanced mass loss in the form of clumped winds and mass ejection events of unclear origin. The discovery that stars…

We have constructed the Spectral Energy Distributions (SEDs) of a sample of Blue Straggler Stars (BSSs) in the core of the globular cluster 47 Tucanae, taking advantage of the large set of high resolution images, ranging from the…

More than half of all main-sequence (MS) stars have one or more companions, and many of those with initial masses <8 M$_\odot$ are born in hierarchical triples. These systems feature two stars in a close orbit (the inner binary) while a…

Blue straggler stars have been proposeed as powerful indicators to measure the dynamical state of Galactic globular clusters. Here we examine for the first time if this framework of blue straggler stars as dynamical clocks, which was…

Massive stars can develop into tepid supergiants at several stages of their post main-sequence evolution, prior to core He-burning, on a blue loop, or close to the final supernova explosion. We discuss observational constraints on models of…

To probe the nature of stellar evolution in dense environments, we study the dense core of the globular cluster Messier 13 using pre-refurbishment Planetary Camera-I images obtained with the Hubble Space Telescope. We find 15 blue straggler…

The dynamical evolution of globular clusters is theoretically described by a series of well known events typical of N-body systems. Still, the identification of observational signatures able to empirically describe the stage of dynamical…

Identifying bifurcated blue straggler (BS) sequences in color-magnitude diagrams (CMDs) of star clusters has long been regarded as a powerful diagnostic for distinguishing different BS formation mechanisms. While such bifurcations are…

We study the formation and evolution of stellar halos (SHs) around bright central galaxies (BCGs), focusing on their scaling relations, colors, and metallicities across cosmic time, and compare model predictions with ultra--deep imaging…

The post main-sequence evolution of massive stars is very sensitive to many parameters of the stellar models. Key parameters are the mixing processes, the metallicity, the mass-loss rate and the effect of a close companion. We study how the…

We use photometry and proper motions from Gaia DR2 to determine the blue straggler star (BSS) populations of 16 old (1-10 Gyr), nearby ($d< 3500$ pc) open clusters. We find that the fractional number of BSS compared to RGB stars increases…

In this chapter we review the various suggested channels for the formation and evolution of blue straggler stars (BSSs) in different environments and their observational predictions. These include mass transfer during binary stellar…

We used MIST isochrone fitting and a dedicated grid of stellar evolution models computed with MESA to constrain the ages of the components of the $\gamma$ Persei binary system. While individual stars can be matched to the models at specific…

Using HST/WFPC2 data, we have performed a comparative study of the Blue Straggler Star (BSS) populations in the central regions of the globular clusters AM 1, Eridanus, Palomar 3, and Palomar 4. Located at distances RGC > 50 kpc from the…