Related papers: What's Their Age Again? A Blue-Straggler Merger Sc…
Massive stars are often born in triples, where gravitational dynamics and stellar interactions play a crucial role in shaping their evolution. One such pathway includes the merger of the inner binary, transforming the system to a binary…
Stripped-envelope stars (SESs) form in binary systems after losing mass through Roche-lobe overflow. They bear astrophysical significance as sources of UV and ionizing radiation in older stellar populations and, if sufficiently massive, as…
Stellar mergers are responsible for a large variety of astrophysical phenomena. They form blue straggler stars, give rise to spectacular transients, and produce some of the most massive stars in the Universe. Here, we focus on mergers from…
Because the majority of massive stars are born as members of close binary systems, populations of massive main-sequence stars contain stellar mergers and products of binary mass transfer. We simulate populations of massive stars accounting…
We study the production of main sequence mergers of tidally-synchronized primordial short-period binaries. The principal ingredients of our calculation are the angular momentum loss rates inferred from the spindown of open cluster stars and…
This chapter describes the current state of models of individual blue stragglers. Stellar collisions, binary mergers (or coalescence), and partial or ongoing mass transfer have all been studied in some detail. The products of stellar…
Imaging spectroscopy using the new Palomar Integral Field Spectrograph is presented for the Pa-alpha line in four ultraluminous infrared galaxies. In most cases, we are able to establish the geometry of the merger, and thus estimate the…
On the pre-main-sequence, the rotation rates of Sun-like stars are dictated by the interplay between the protostellar disk and the star's contraction. At ages exceeding 100 million years (Myr), magnetic spin-down erases the initial stellar…
We derive a new age for the Gamma^2 Velorum binary by comparing recent observations to our set of binary models. We find that it is very unlikely the stars have not interacted, which implies that previous estimates of the age from…
Approximately 10% of massive OBA main-sequence (MS) and pre-MS stars harbour strong, large-scale magnetic fields. At the same time there is a dearth of magnetic stars in close binaries. A process generating strong magnetic fields only in…
We have derived ages for 13 young (<30 Myr) star-forming regions and find they are up to a factor two older than the ages typically adopted in the literature. This result has wide-ranging implications, including that circumstellar discs…
Stellar mergers are important processes in stellar evolution, dynamics, and transient science. However, it is difficult to identify merger remnant stars because they cannot easily be distinguished from single stars based on their surface…
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…
We explore the possibility that the star alpha Orionis (Betelgeuse) is the outcome of a merger that occurred in a low mass ratio (q = M2/M1 = 0.07 - 0.25) binary system some time in the past hundreds of thousands of years. To that goal, we…
The ages of stars have historically relied on isochrone fitting of standardised grids of models. While these stellar models have provided key constraints on observational samples of massive stars, they inherit many systematic uncertainties,…
The Milky Way was shaped by the mergers with several galaxies in the past. We search for remnant stars that were born in these foreign galaxies and assess their ages in an effort to put upper limits on the merger times and thereby better…
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…
[Abbreviated] We have investigated the color-magnitude diagram of Omega Centauri and find that the blue main sequence (bMS) can be reproduced only by models that have a of helium abundance in the range Y=0.35-$0.40. To explain the faint…
Establishing ages for young clusters is key for properly tracking the star formation history of a region. In this paper we investigate a new approach to estimating ages for young populations, based on the well-founded assumption that the…
Stellar mergers lead to diverse phenomena: rejuvenated blue stragglers, magnetised and peculiar stars, transients and nebulae. Using a grid of about 6000 detailed 1D binary evolution models (initial component masses of…