Related papers: A Surprising Dynamical Mass for V773~Tau~B
With a combination of adaptive optics imaging and a multi-epoch common proper motion search, we have conducted a large volume-limited (D $\le$ 75 pc) multiplicity survey of A-type stars, sensitive to companions beyond 30 au. The sample for…
This paper report results from the first long-term BV(RI)c photometric CCD observations of three variable pre-main-sequence stars collected during the period from February 2007 to January 2020. The investigated stars are located in the…
Observational evidence has continued to mount that a significant fraction of rapidly rotating early-B type stars are products of binary mass transfer. However, very few mid- and late-type B stars with rapid rotation have been demonstrated…
The optical star in the T Tauri triple system is the prototype of young sun-like stars in our galaxy. This complex and dynamic system has evidence for misaligned disks and outflows, and molecular material in a circumbinary ring that…
We present the identification of WISE~J135501.90$-$825838.9 as a spectral binary system with a slight possibility of planetary-mass components in the $130-200$\,Myr AB~Doradus moving group. Peculiarities in the near-infrared spectrum of…
Very Long Baseline Interferometry (VLBI) provides high angular resolution images and has been used for stellar astrometry for decades. The DYNAMO-VLBA project utilizes the Very Long Baseline Array (VLBA) to study tight binary and multiple…
A close companion of Zeta Orionis A was found in 2000 with the Navy Precision Optical Interferometer (NPOI), and shown to be a physical companion. Because the primary is a supergiant of type O, for which dynamical mass measurements are very…
We present Halpha spectropolarimetry observations of a sample of 10 bright T Tauri stars, supplemented with new Herbig Ae/Be star data. A change in the linear polarisation across Halpha is detected in most of the T Tauri (9/10) and Herbig…
We present rotational velocities for individual components of eleven very low mass (VLM) binaries with spectral types between M7 and L7.5. These results are based on observations taken with the near-infrared spectrograph, NIRSPEC, and the…
Context. RU Lup is a Classical T Tauri star with unusually strong emission lines, which has been interpreted as manifestations of accretion. Recently, evidence has accumulated that this star might have a variable radial velocity. Aims. We…
High contrast imaging enables the determination of orbital parameters for substellar companions (planets, brown dwarfs) from the observed relative astrometry and the estimation of model and age-dependent masses from their observed…
The atmosphere of the extremely high-velocity (530-920 km/s) early B-type star HD271791 is enriched in $\alpha$-process elements, which suggests that this star is a former secondary component of a massive tight binary system and that its…
We present results from a large, high-spatial-resolution near-infrared imaging search for stellar and sub-stellar companions in the Taurus-Auriga star-forming region. The sample covers 64 stars with masses between those of the most massive…
The young, low-mass, triple system NTTS 155808-2219 (ScoPMS 20) was previously identified as a ~17-day period single-lined spectroscopic binary with a tertiary component at 0.21 arcseconds. Using high-resolution infrared spectra, acquired…
The precision of stellar models is higher than the precision at which we are able to measure the masses of most stars, with the notable exception of binaries where we can determine dynamical masses of the component stars. In addition to…
(abridged:) We study X-rays from jet-driving protostars and T Tau stars. We seek soft spectral components that may be due to shock emission, and shock-induced emission displaced from the stellar position. Two stellar samples are used, the…
Radial velocity curves for 15 bright subdwarf B binary systems have been measured using high precision radial velocity measurements from high S/N optical high-resolution spectra. In addition, two bright sdB stars are discovered to be radial…
We aim to improve the orbital elements and determine the individual masses of the components in the triple system TWA 5. Five new relative astrometric positions in the H band were recorded with the adaptive optics system at the Very Large…
We report time-resolved, high-resolution optical spectropolarimetric observations of the young double-lined spectroscopic binary V1878 Ori. Our observations were collected with the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii…
Most stars form in multiple systems whose properties can significantly impact circumstellar disk evolution. We investigate the physical and chemical properties of the equal-mass, small separation (~66 mas, ~9 au) DF Tau binary system.…