Related papers: High-resolution imaging of Galactic massive stars …
We present results of the largest, most comprehensive study ever done of the stellar multiplicity of the most common stars in the Galaxy, the red dwarfs. We have conducted an all-sky, volume-limited survey for stellar companions to 1120 M…
Observations at various wavelengths of late B-type stars exhibiting strong overabundances of the chemical elements Hg and Mn in their atmospheres indicate that these stars are frequently found in binary and multiple systems. We intend to…
The study of stellar multiplicity offers important constraints on the structure of the Galaxy as well as stellar and planet formation and evolution. Focusing on the most immediate solar neighbourhood benefits from obtaining both complete…
The vast majority of extrasolar planets are detected by indirect detection methods such as transit monitoring and radial velocity measurements. While these methods are very successful in detecting short-periodic planets, they are mostly…
We present the earliest results of our NACO/VLT sparse aperture masking (SAM) campaign to search for binarity in a sample of 60 O-type stars. We detect Delta Ks < 5 mag companions for 20-25% of our targets with separations in the range…
We discuss the observed multiplicity of massive stars and implications on theories of massive star formation. After a short summary of the literature on massive star multiplicity, we focus on the O- and B-type stars in the Orion Nebula…
We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the Fine Guidance Sensor 1R (FGS1r) on the Hubble Space Telescope. FGS1r is able to resolve binary systems with…
Given the high incidence of binaries among mature field massive stars, it is clear that multiplicity is an inevitable outcome of high-mass star formation. Understanding how massive multiples form requires the study of the birth environments…
The study of the multiplicity of massive stars gives hints on their formation processes and their evolutionary paths, which are still not fully understood. Large separation binaries (>50 milliseconds of arc, mas) can be probed by…
AstraLux is the Lucky Imaging camera for the Calar Alto 2.2-m telescope and the 3.5-m NTT at La Silla. It allows nearly diffraction limited imaging in the SDSS i' and z' bands of objects as faint as i'=15.5mag with minimum technical effort.…
Stellar systems consisting of three or more stars are not an uncommon occurrence in the Galaxy. Nearly 50% of solar-type wide binaries with separations >1000 au are actually higher-order multiples with one component being a close binary.…
We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the NIRI camera and ALTAIR adaptive optics system of the Gemini North telescope. We observed 74 O- and early…
One of the most remarkable properties of massive stars is that almost all of them are found in binaries or higher-order multiple systems. Observations that cover the full companion mass ratio and separation regime are essential to constrain…
We have conducted an angular differential imaging survey with NIRC2 at Keck in search of close-in substellar companions to a sample of seven systems with confirmed planetary-mass companions (PMCs) on wide orbits (>50 AU). These…
We present a description of the observations and data reduction procedures for an extensive spectroscopic and multi-band photometric study of nine high redshift, optically-selected cluster candidates. The primary goal of the survey is to…
The fraction of binary stars is an important ingredient to interpret globular cluster dynamical evolution and their stellar population. We investigate the properties of main-sequence binaries measured in a uniform photometric sample of 59…
The recent discovery of a transiting planet around WASP-33, the misalignment of the stellar rotation axis and the planet orbit, the possible existence of an additional planet in the system, and the presence of $\delta$ Scuti pulsations in…
Stellar halos are the only major stellar component of disk galaxies that lack systematic observational characterization, yet they encode critical information about galaxy merger histories. We present the first systematic census of stellar…
Super-resolution (SR) advances astronomical imaging by enabling cost-effective high-resolution capture, crucial for detecting faraway celestial objects and precise structural analysis. However, existing datasets for astronomical SR (ASR)…
This thesis focuses on the statistical properties of wide binary (WB) star systems in the Galactic field. For the present study we select a homogeneous sample covering about 675 square degrees in the direction of the NGP. It contains nearly…