Related papers: Screening the Hipparcos-based astrometric orbits o…
The Stellar Planet Survey (STEPS) is an ongoing astrometric search for giant planets and brown dwarfs around a sample of ~30 M-dwarfs. We have discovered several low-mass companions by measuring the motion of our target stars relative to…
Using the absolute astrometric positions and proper motions for common stars in the Hipparcos and Gaia catalogs separated by 24.75 years in the mean epoch, we compute mass ratios for long-period, resolved binary systems without any…
Understanding demographic properties of planet populations and multiple star systems constrains theories of planet and star formation. Surveys for very low-mass companions to M-A type stars detect brown dwarfs from multiple star formation…
Context: The influence of stellar multiplicity on planet formation is not yet well determined. Most planets are found using indirect detection methods via the small radial velocity or photometric variations of the primary star. These…
With its exquisite astrometric precision, the latest Gaia data release includes $\sim$$10^5$ astrometric binaries, each of which have measured orbital periods, eccentricities, and the Thiele-Innes orbital parameters. Using these and an…
We present results on parallaxes, magnitudes and proper motions for 17 optically identified massive X-ray binaries (MXRB) which were observed during the Hipparcos astrometry mission. This sample includes the sources detected in the…
Many EHB stars have been found in short-period binaries, where the companions in these post-common envelope systems are either white dwarfs or dM stars; these systems are catalogued as hot subdwarfs because the subdwarf is the more luminous…
Abbreviated. We aim to identify new low-mass companions to young stars using the astrometric measurements provided by the Gaia space mission and complementary VLT/SPHERE data. We identify companion candidates from a sample of K-type,…
Directly-imaged planetary-mass companions offer unique opportunities in atmospheric studies of exoplanets. They share characteristics of both brown dwarfs and transiting exoplanets, therefore, are critical for connecting atmospheric…
We present an overview of our ongoing systematic search for wide (sub)stellar companions around the stars known to host rad-vel planets. By using a relatively large field of view and going very deep, our survey can find all directly…
We present the discovery of 61 wide (>5 arcsecond) separation, low-mass (stellar and substellar) companions to stars in the solar neighborhood identified from Pan-STARRS\,1 (PS1) data and the spectral classification of 27 previously known…
We have used our 1.6 m diameter off-axis well-corrected sub-aperture (WCS) on the Palomar Hale telescope in concert with a small inner-working-angle (IWA) phase-mask coronagraph to image the immediate environs of a small number of nearby…
We present the results of a deep imaging survey of stars surrounded by planets detected with the radial velocity technique. The purpose is to search for and to characterize long-period stellar and substellar companions. The sample contains…
Observations of accretion disks around young brown dwarfs have led to the speculation that they may form planetary systems similar to normal stars. While there have been several detections of planetary-mass objects around brown dwarfs…
Herbig-Haro objects (HHOs) are caused by outflows from young objects. Since the outflow relies on mass accretion from a circumstellar disk, it indicates ongoing growth. Recent results of infrared observations yielded evidence for disks…
We present the discoveries of three faint companions to young stars in the Scorpius-Centaurus region, imaged with the NICI instrument on Gemini South. We have confirmed all three companions through common proper motion tests. Follow-up…
Using the Hipparcos data, absolute magnitudes and thus the evolutionary status for the group of lambda Bootis stars were derived. The origin of this small group of non-magnetic, chemically peculiar stars, still remains a matter of debate.…
Model-independent masses of substellar companions are critical tools to validate models of planet and brown dwarf cooling, test their input physics, and determine the formation and evolution of these objects. In this work, we measure the…
AB Dor C, a low-mass companion to the young star AB Dor A has recently been imaged. Direct detection and astrometric observations have been used to solve the AB Dor C orbit and obtain a dynamical mass estimate. Near-infrared magnitudes and…
We derive and parametrize the Galactic mass function (MF) below 1 $\msol$ characteristic of both single objects and binary systems. We resolve the long standing discrepancy between the MFs derived from the HST and from the nearby luminosity…