Related papers: The Case for an Early Solar Binary Companion
Stars in globular clusters formed and evolved in the most extreme environment: high density and low metallicity. If the formation of stars and planets are at all sensitive to environmental conditions, this should therefore be evident in…
To date, several exoplanets have been discovered orbiting stars with close binary companions (a~<30 AU). The fact that planets can form in these dynamically challenging environments implies that planet formation must be a robust process.…
Directly imaged exoplanets in wide orbits challenge current gas giant formation theories. They need to form quickly and acquire enough material before the disk dissipates, which cannot be accommodated by in-situ formation by core accretion.…
Binary systems are very common among field stars. While this relatively small number of planets in binaries is probably partly due to strong observational biases, there is, however, statistical evidence that planets are indeed less frequent…
The aim of this work is to study the impact of a binary companion on the evolution of two-planet systems during both the type-II migration phase and their long-term evolution after the dissipation of the protoplanetary disk. We use the…
Recent observations show that planet can reside in close binary systems with stellar separation of only about 20 AU. However, planet formation in such close binary systems is a challenge to current theory. One of the major theoretical…
Binary populations in young star clusters show multiplicity fractions both lower and up to twice as high as those observed in the Galactic field. We follow the evolution of a population of binary stars in dense and loose star clusters…
There is a striking and unexplained dearth of brown dwarf companions in close orbits (< 3AU) around stars more massive than the Sun, in stark contrast to the frequency of stellar and planetary companions. Although rare and relatively…
In studying encounters between binaries and single stars, one is interested in three classes of events: exchanges of stars, hardening of the original binary by a third star, and the production of merged objects. We present a means for…
A survey of currently known planet-hosting stars indicates that approximately 25% of extrasolar planetary systems are within dual-star environments. Several of these systems contain stellar companions on moderately close orbits, implying…
The stars that populate the solar neighbourhood were formed in stellar clusters. Through N-body simulations of these clusters, we measure the rate of close encounters between stars. By monitoring the interaction histories of each star, we…
We performed populations synthesis calculations of single stars and binaries and show that binary evolution is extremely important for Galactic astronomy. We review several binary evolution models and conclude that they give quite different…
Although the sample of exoplanets in binaries has been greatly expanded, the sample heterogeneity and observational bias are obstacles toward a clear figure of exoplanet demographics in the binary environment. To overcome the obstacles, we…
The frequency of low-mass pre-main sequence binary systems is significantly lower in the Trapezium Cluster than in Taurus-Auriga. We investigate if this difference can be explained through stellar encounters in dense clusters. To this…
We report here on two complementary population synthesis studies which relate directly to the formation and evolution of neutron star binaries in globular clusters. In the first, we compute the probability of retaining neutron stars in…
The masses of compact objects like white dwarfs, neutron stars and black holes are fundamental to astrophysics, but very difficult to measure. We present the results of an analysis of subluminous B (sdB) stars in close binary systems with…
Context: Field stars are not always single stars, but can often be found in bound double systems. Since binary frequencies in the birth places of stars, young embedded clusters, are sometimes even higher than on average the question arises…
Models of binary star interactions have been successful in explaining the origin of field hot subdwarf (sdB) stars in short period systems, but longer-period systems that formed via Roche-lobe overflow (RLOF) mass transfer from the present…
We present high-resolution speckle interferometric imaging observations of TESS exoplanet host stars using the NN-EXPLORE NESSI instrument the at the 3.5-m WIYN telescope. Eight TOIs, that were originally discovered by Kepler, were…
Binaries are very common in galaxies, and more than half of Galactic hot subdwarf stars, which are thought as a possible origin of UV-upturn of old stellar populations, are found in binaries. Previous works showed that binary evolution can…