Related papers: Massive Star Multiplicity: The Cepheid W Sgr
The magnetic, chemically peculiar A-star HR 710 (HD 15144, ADS 1849A, AB Cet) has a close companion in a nearly circular orbit. Its 3-day period is unusually short for such stars. The system emits moderately hard x-rays, which likely come…
We report spectroscopic observations of the star HIP 50796, previously considered (but later rejected) as a candidate member of the TW Hya association. Our measurements reveal it to be a single-lined binary with an orbital period of 570…
Young intermediate-mass stars have become high-priority targets for direct-imaging planet searches following the recent discoveries of planets orbiting e.g. HR 8799 and Beta Pictoris. Close stellar companions to these stars can affect the…
We conducted a detailed spectroscopic and photometric characterization of the planet-hosting wide binary HD 202772A/B. No planet has been detected around HD 202772B, whereas HD 202772A, more evolved than its companion and near the end of…
About a third of the hot subdwarfs of spectral type B, which are mostly core-helium burning objects on the extreme horizontal branch, are found in close binaries with cool, low-mass stellar, substellar, or white dwarf companions. They can…
The extrasolar planetary system around HR 8799 is the first multiplanet system ever imaged. It is also, by a wide margin, the highest mass system with >27 Jupiters of planetary mass past 25 AU. This is a remarkable system with no analogue…
$\mu$ Her is a nearby quadruple system with a G-subgiant primary and several low mass companions arranged in a 2+2 architecture. While the BC components have been well characterized, the Ab component has been detected astrometrically and…
We aim at determining the masses of Cepheids in binary systems, as well as their geometric distances and the flux contribution of the companions. The combination of interferometry with spectroscopy will offer a unique and independent…
The star NGC 3603-A1 has long been known to be a very massive binary, consisting of a pair of O2-3If*/WN5-6 stars, which show Wolf-Rayet-like emission due to their luminosities being near the Eddington limit. The system has been poorly…
We describe the discovery of a solar neighborhood (d=468 pc) binary system with a main-sequence sunlike star and a massive non-interacting black hole candidate. The spectral energy distribution (SED) of the visible star is described by a…
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…
We report on our analysis of HST/NICMOS snapshot high resolution images of 255 stars in 201 systems within ~10 parsecs of the Sun. Photometry was obtained through filters F110W, F180M, F207M, and F222M using NICMOS Camera 2. These filters…
We report the discovery of a transiting planet with an orbital period of 1.36d orbiting the brighter component of the visual binary star BD -07 436. The host star, WASP-77A, is a moderately bright G8V star (V=10.3) with a metallicity close…
Aims. We aim to characterize the properties of the inner companion of the S-type AGB star pi1 Gru and to identify plausible future evolutionary scenarios for this triple system. Methods. We observed pi1 Gru with ALMA and VLT/SPHERE. In…
The visual A component of the Gliese 586AB system is a double-lined spectroscopic binary consisting of two cool stars with the exceptional orbital eccentricity of 0.976. Such an extremely eccentric system may be important for our…
The emission-line binary ALS 8814 was recently proposed as a Be star + black hole (BH) binary based on large-amplitude radial velocity (RV) variations of a Be star and non-detection of spectroscopic features from a luminous companion. We…
We present the result of IR observations in the K band of 39 bright AeBe stars in the northern hemisphere. Using the shift-and-add technique, we were able to detect nearby objects as close as 0.4'' from the primary star. We found 9 stars…
We report the discovery and characterisation of WASP-180Ab, a hot Jupiter confirmed by the detection of its Doppler shadow and by measuring its mass using radial velocities. We find the 0.9 $\pm$ 0.1 $M_{\rm Jup}$, 1.24 $\pm$ 0.04 $R_{\rm…
AIMS: The object W Aql is an asymptotic giant branch (AGB) star with a faint companion. By determining more carefully the properties of the companion, we hope to better constrain the properties of the AGB star. METHODS: We present new…
Most (or possibly all) massive stars reside in multiple systems. From stellar evolution models, numerous systems with an OB star coupled to a black hole would be expected to exist. There have been several claimed detections of such pairs in…