Related papers: RX J0942.7-7726AB: an isolated pre-main sequence w…

2MASS J11011926-7732383 AB (hereafter 2M1101AB), located in the Cha I star forming region, is a rare wide-separation brown dwarf binary. XMM-Newton and Chandra observations of 2M1101AB have allowed us to examine the influence of physical…

Serving as the progenitors of electromagnetic and gravitational wave transients, massive stars have received renewed interest in recent years. However, many aspects of their birth and evolution remain opaque, particularly in the context of…

Approximately 150 low-mass white dwarfs, with masses below 0.4Msun, have been discovered. The majority of these low-mass WDs are observed in binary systems as they cannot be formed through single-star evolution within the Hubble time. In…

In near-infrared NaCo observations of the young brown dwarf 2MASS J0041353-562112, we discovered a companion a little less than a magnitude fainter than the primary. The binary candidate has a separation of 143 mas, the spectral types are…

We present optical and X-ray observations of two tidally distorted, extremely low-mass white dwarfs (WDs) with massive companions. There is no evidence of neutron stars in our Chandra and XMM observations of these objects. SDSS…

We present an investigation into the rotation and stellar activity of four fully convective M dwarf `twin' wide binaries. Components in each pair have (1) astrometry confirming they are common-proper-motion binaries, (2) Gaia $BP$, $RP$,…

We observe 14 young low-mass substellar objects in young moving groups using the SINFONI IFS with LGS-AO to detect and characterize 3 candidate binary systems. Together with the adopted young moving group ages we employ isochrones from…

We report the discovery of 2M0056-08 as an equal-mass eclipsing binary (EB), comprising two red straggler stars (RSSs) with an orbital period of 33.9 d. Both stars have masses of 1.419 Msun, identical to within 0.2%. Both stars appear to be…

Fully convective M dwarfs typically remain rapidly rotating and magnetically active for billions of years, followed by an abrupt and mass-dependent transition to slow rotation and quiescence. A robust understanding of this process is…

We image 104 newly identified low-mass (mostly M-dwarf) pre-main sequence members of nearby young moving groups with Magellan Adaptive Optics (MagAO) and identify 27 binaries with instantaneous projected separation as small as 40 mas. 15…

We have measured the orbital parameters of seven close binaries, including six new objects, in a radial velocity survey of 38 objects comprising a hot subdwarf star with orbital periods ranging from ~0.17 to 3 d. One new system, GALEX…

Binary systems containing a magnetic white dwarf and a main-sequence star are considered extremely rare, perhaps non-existent. In the course of a search of magnetic fields in high-mass white dwarfs we have discovered a Sirius-like wide…

Low-mass X-ray binaries are binary systems composed of a compact object and a low-mass star. Recently, a new class of these systems, known as symbiotic $X$-ray binaries (with a neutron star with a M-type giant companion), has been…

We report on 22 yrs of radio timing observations of the millisecond pulsar J1024$-$0719 by the telescopes participating in the European Pulsar Timing Array (EPTA). These observations reveal a significant second derivative of the pulsar spin…

I present the discovery of the first wide M + L extreme subdwarf binary system Gaia J0452$-$36AB. The binary is located at a distance of 137.27$^{+0.68}_{-0.67}$ pc with a projected separation of 15828$\pm$78 au. I classified Gaia…

A total of 28 young nearby stars (ages $\leq 60$,Myr) have been observed in the K$_{\rm s}$-band with the adaptive optics imager Naos-Conica of the Very Large Telescope at the Paranal Observatory in Chile. Among the targets are ten visual…

The young system RX J0529.3+1210 was initially identified as a single-lined spectroscopic binary. Using high-resolution infrared spectra, acquired with NIRSPEC on Keck II, we measured radial velocities for the secondary. The method of using…

Understanding how giant planets form requires observational input from directly imaged protoplanets. We used VLT/NACO and VLT/SPHERE to search for companions in the transition disc of 2MASS J19005804-3645048 (hereafter CrA-9), an accreting…

In this paper we present the first results of a detailed spectroscopic and photometric analysis of the V = 11.7m eclipsing binary ASAS J052821+0338.5. With the FIES spectrograph at the Nordic Optical Telescope we have obtained a series of…

We present the discovery of the common proper motion M9 + L0 binary DENIS J220002.05-303832.9AB, identified serendipitously with the SpeX near infrared imager/spectrograph. Spectral types are derived from resolved near infrared spectroscopy…