相关论文: ACRONYM IV: Three New, Young, Low-mass Spectroscop…

Mass, radius, and age are three of the most fundamental parameters for celestial objects, enabling studies of the evolution and internal physics of stars, brown dwarfs, and planets. Brown dwarfs are hydrogen-rich objects that are unable to…

We report on nine wide common proper motion systems containing late-type M, L, or T companions. We confirm six previously reported companions, and identify three new systems. The ages of these systems are determined using diagnostics for…

Double-lined spectroscopic binaries (SB2) allow us to determine a lower limit of the masses of their components directly to test stellar models. In this work, our aim is to derive the orbital and physical parameters of GJ1284, a young SB2.…

Young M-type binaries are particularly useful for precise isochronal dating by taking advantage of their extended pre-main sequence evolution. Orbital monitoring of these low-mass objects becomes essential in constraining their fundamental…

We surveyed thirteen very low mass (VLM; M < 0.2 M_sun) objects in the Taurus star-forming region using near-infrared diffraction-limited imaging techniques on the W.M. Keck I 10 m telescope. Of these thirteen, five were found to be binary,…

Low-mass stars exhibit substantial pre-main sequence evolution during the first ~100 Myrs of their lives. Thus, young M-type stars are prime targets for isochronal dating, especially in young moving groups (YMGs), which contain large…

We present the results of a long term orbit monitoring program, using sparse aperture masking observations taken with NIRC2 on the Keck-II telescope, of seven G to M-type members of the Upper Scorpius subgroup of the Sco-Cen OB association.…

We report the selection and spectroscopic confirmation of 129 new late-type (K3-M6) members of the Tuc-Hor moving group, a nearby (~40 pc), young (~40 Myr) population of comoving stars. We also report observations for 13/17 known Tuc-Hor…

The K-type binary star HD 102077 was proposed as a candidate member of the TW Hydrae Association (TWA) which is a young (5-15 Myr) moving group in close proximity (~50 pc) to the solar system. The aim of this work is to verify this…

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…

Context. Intrinsic H$\alpha$ emission can be advantageously used to detect substellar companions because it improves contrasts in direct imaging. Characterising this emission from accreting exoplanets allows for the testing of planet…

The Her-Lyr assoc., a nearby young MG, contains a few tens of ZAMS stars of SpT F to M. The existence and the properties of the Her-Lyr assoc. are controversial and discussed in the literature. The present work reassesses properties and the…

We report the discovery of 14 low-mass binary systems containing mid-M to mid-L dwarf companions with separations larger than 250 AU. We also report the independent discovery of 9 other systems with similar characteristics that were…

We present high resolution Laser Guide Star Adaptive Optics imaging of 43 late-M, L and T dwarf systems with Keck/NIRC2. These include 17 spectral binary candidates, systems whose spectra suggest the presence of a T dwarf secondary. We…

We have completed a high-resolution (R=60,000) optical spectroscopic survey of 185 nearby M dwarfs identified using ROSAT data to select active, young objects with fractional X-ray luminosities comparable to or greater than Pleiades…

We present a spectroscopic and kinematic analysis of 79 nearby M dwarfs in 77 systems. All are low-proper-motion southern hemisphere objects and were identified in a nearby star survey with a demonstrated sensitivity to young stars. Using…

Gaia EDR3 offers greatly improved kinematics for nearby objects, including members of nearby young stellar moving groups (NYMGs). In this study, we aim to identify low-mass NYMG members (spectral types of M0 to mid-L) in Gaia EDR3. We…

Optical spectroscopy is used to confirm membership for 8 low-mass candidates in the young Beta Pic moving group (BPMG) via their radial velocities, chromospheric activity and kinematic parallaxes. We searched for the presence of the Li I…

We present a detailed characterization of 2MASS J04435750+3723031, a low-mass companion orbiting the young M2 star, 2MASS J04435686+3723033, at 7.6 arcseconds (550 AU) with potential membership in the 23 Myr $\beta$ Pictoris moving group…

We present new radial velocity (RV) measurements for 11 candidate young very-low-mass stars and brown dwarfs, with spectral types from M7 to L7. Candidate young objects were identified by features indicative of low surface gravity in their…