Related papers: The magnetically-active, low-mass, triple system W…

We present the discovery of the totally eclipsing long-period (P = 771.8 d) binary system WOCS 23009 in the old open cluster NGC 6819 that contains both an evolved star near central hydrogen exhaustion and a low-mass (0.45 Msun) star. This…

The ultra-diffuse galaxy (UDG) NGC1052-DF2 has captured the interest of astronomers ever since the low velocity dispersion measured from ten globular clusters (GCs) suggested a low dark matter fraction. Also, its GC system was found to be…

We report on the properties of the low-mass stars that recently formed in the central ~ 2.7'x2.7' of 30 Dor including the R136 cluster. Using the photometric catalogue of De Marchi et al. (2011c), based on observations with the Hubble Space…

We present simultaneous high-resolution optical spectroscopy and X-ray data of the X-ray binary system GR Mus (XB1254-690), obtained over a full range of orbital phases. The X-ray observations are used to re-establish the orbital ephemeris…

The Procyon AB binary system (orbital period 40.838 years, a newly-refined determination), is near and bright enough that the component radii, effective temperatures, and luminosities are very well determined, although more than one…

Aims: We investigate the photometric properties of the M7.5 equal-mass binary VHS J1256-1257AB, which, combined with the late-L dwarf VHS J1256-1257 b, forms one of the few young triple systems of ultra-cool dwarfs currently known. Methods:…

Four magnetic white dwarfs have been found in the course of the Hamburg/ESO Survey for bright QSOs. The objects have been selected as QSO candidate on the basis of its blue continuum and the apparent absence of strong hydrogen or helium…

We have used the HIRES echelle spectrograph in the Keck I telescope to obtain high-resolution spectroscopy of 51 late-type M dwarfs in the Hyades cluster. Cross-correlating the calibrated data against spectra of white dwarfs allows us to…

We measure precise orbits and dynamical masses and derive age constraints for six confirmed and one candidate Sirius-like systems, including the Hyades member HD 27483. Our orbital analysis incorporates radial velocities, relative…

The fundamental properties of low-mass stars are not as well understood as those of their more massive counterparts. The best method for constraining these properties, especially masses and radii, is to study eclipsing binary systems, but…

We investigated the possibility of using two recently characterised triply eclipsing triple systems to constrain stellar model parameters. We specifically focused on evaluating the influence of the underlying astrophysical assumptions…

We report high-resolution spectroscopic observations of the young star HD 34700, which confirm it to be a double-lined spectroscopic binary. We derive an accurate orbital solution with a period of 23.4877 +/- 0.0013 days and an eccentricity…

Measured from high-resolution spectra, we present Ca II K line chromospheric fluxes in 35 G dwarf stars of 5 open clusters to determine the age-activity-rotation relationship from the young Hyades and Praesepe (0.6 Gyr) to the old M 67 (~…

We present the discovery of NGTS-3Ab, a hot Jupiter found transiting the primary star of an unresolved binary system. We develop a joint analysis of multi-colour photometry, centroids, radial velocity (RV) cross-correlation function (CCF)…

We present the identification of two previously known young objects in the solar neighbourhood as a likely very wide binary. TYC 9486-927-1, an active, rapidly rotating early-M dwarf, and 2MASS J21265040-8140293, a low-gravity L3 dwarf…

We present Hubble Space Telescope Planetary Camera UVI data for the little-studied cluster Hodge 301 3' northwest of 30 Doradus' central ionizing cluster R136. The average reddening of Hodge 301 is found to be <E(B-V)> = (0.28+-0.05) mag…

Using the Hubble Space Telescope, we detail the first abundance analysis enabled by far-ultraviolet spectroscopy of a low-mass (~0.19 Msun) white dwarf (WD), GALEX J1717+6757, which is in a 5.9-hr binary with a fainter, more-massive…

We present a method to calculate masses for components of both eclipsing and non-eclipsing binary systems as long as their apsidal motion rates are available. The method is based on the fact that the equation that gives the rate of apsidal…

Despite being the most common types of stars in the Galaxy, the physical properties of late M dwarfs are often poorly constrained. A trend of radius inflation compared to evolutionary models has been observed for earlier type M dwarfs in…

Until recently almost nothing was known about the evolution of magnetic fields found in upper main sequence Ap/Bp stars during their long main sequence lifetime. We are thus studying magnetic Ap/Bp stars in open clusters in order to obtain…