相关论文: Improving dynamical mass constraints for intermedi…

Astrometric observations with Gaia are expected to play a valuable role in future exoplanet surveys. With current data from Gaia's third data release (DR3), we are sensitive to periods from less than 1 year to more than 4 years but, unlike…

Mass is the fundamental parameter that governs the evolution of stars, brown dwarfs, and gas-giant planets. Thus, direct mass measurements are essential to test the evolutionary and atmospheric models that underpin studies of these objects.…

We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7-M4.5), most of which have recently been identified as candidate members of nearby young moving groups…

We present the results of a high-resolution spectral differential imaging survey of 12 nearby, relatively young field L dwarfs (<1 Gyr) carried out with HST/NICMOS to search for planetary mass companions at small physical separations from…

Even though only a handful of sub-stellar companions have been found via direct imaging, each of these discoveries has had a tremendous impact on our understanding of the star formation process and the physics of cool atmospheres. Young…

We report spectroscopic observations of the nearby, 19.5 yr binary system Gls 67 AB spanning more than 35 yr. We carry out a global orbital solution combining our radial velocity measurements with others from the literature going back more…

We report the discovery of a wide co-moving substellar companion to the nearby ($D=67.5\pm1.1$ pc) A3V star $\zeta$ Delphini based on imaging and follow-up spectroscopic observations obtained during the course of our Volume-limited A-Star…

We present deep high dynamic range infrared images of young nearby stars in the Tucana/Horologium and beta Pic associations, all ~ 10 to 35 Myrs young and at ~10 to 60 pc distance. Such young nearby stars are well-suited for direct imaging…

We have been using Keck laser guide star adaptive optics to monitor the orbits of ultracool binaries, providing dynamical masses at lower luminosities and temperatures than previously available and enabling strong tests of theoretical…

We report the detections of low-mass companions to five M and L dwarfs within 10 pc of the Sun using the Hubble Space Telescope (HST) Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). Follow-up observations using the HST Advanced…

Recent studies have shown that close-in brown dwarfs in the mass range 35-55 M$_{\rm Jup}$ are almost depleted as companions to stars, suggesting that objects with masses above and below this gap might have different formation mechanisms.…

Magnetic activity and rotation are related to the age of low-mass main sequence stars. To further constrain these relations, we study a sample of 574 main sequence stars members of common proper motion pairs with white dwarfs, identified…

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…

We report the discovery of a 16-20 Jupiter mass radial velocity companion around the very young (~3 Myr) brown dwarf candidate ChaHa8 (M5.75-M6.5). Based on high-resolution echelle spectra of ChaHa8 taken between 2000 and 2007 with UVES at…

We have undertaken a series of hydrodynamic + N-body simulations in order to explore the properties of young stars. Our results suggest that the IMF may be sensitive to environment in its substellar region, with more brown dwarfs being…

Star formation theories have struggled to reproduce binary brown dwarf population demographics (frequency, separation, mass-ratio). Kernel-phase interferometry is sensitive to companions at separations inaccessible to classical imaging,…

The compact, non-thermal emission in DoAr21 has been studied with the VLBA to investigate the possibility that the residuals of the astrometry fitting are due to the reflex motion induced by a possible companion. We find that the fitting of…

We report the discovery of a candidate brown dwarf or a very low mass stellar companion (MARVELS-5b) to the star HIP 67526 from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The radial velocity curve for this…

We present a photometric $J$-band variability study of GU Psc b, a T3.5 co-moving planetary-mass companion (9-13$M_{\rm{Jup}}$) to a young ($\sim$150 Myr) M3 member of the AB Doradus Moving Group. The large separation between GU Psc b and…

We present high-resolution ALMA observations at 0.89 mm of the Class II brown dwarf 2MASS J04442713+2512164 (2M0444), achieving a spatial resolution of 0$.\!\!^{\prime\prime}$046 ($\sim$6.4 au at the distance to the source). These…