相关论文: Testing Theory with Dynamical Masses and Orbits of…
Ultra-cool dwarfs as wide companions to subgiants, giants, white dwarfs and main sequence stars can be very good benchmark objects, for which we can infer physical properties with minimal reference to theoretical models, through association…
Given that mergers are often invoked to explain many exotic phenomena in massive star evolution, understanding the evolutionary phase directly preceding a merger, the overcontact phase, is of crucial importance. Despite its importance,…
M-dwarfs are the most abundant stars in the galaxy and popular targets for exoplanet searches. However, their intrinsic faintness and complex spectra inhibit precise characterisation. We only know of dozens of M-dwarfs with fundamental…
The aim of the Degenerate Objects around Degenerate Objects (DODO) survey is to search for very low mass brown dwarfs and extrasolar planets in wide orbits around white dwarfs via direct imaging. The direct detection of such companions…
We present preliminary astrometric results for the closest known brown dwarf binary to the Sun: Epsilon Indi Ba, Bb at a distance of 3.626 pc. Via ongoing monitoring of the relative separation of the two brown dwarfs (spectral types T1 and…
The physical properties of faint stellar and substellar objects often rely on indirect, model-dependent estimates. For example, the masses of brown dwarfs are usually inferred using evolutionary models, which are age dependent and have yet…
We perform hydrodynamic simulations of mass transfer in binaries that contain a white dwarf and a neutron star (WD-NS binaries), and measure the specific angular momentum of material lost from the binary in disc winds. By incorporating our…
A long standing and unverified prediction of binary star evolution theory is the existence of a population of white dwarfs accreting from sub-stellar donor stars. Such systems ought to be common, but the difficulty of finding them, combined…
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…
The evolution of a binary star system by various analytic approximations of mass transfer is discussed, with particular attention payed to the stability of these processes against runaway on the thermal and dynamical timescales of the mass…
The aim of the Degenerate Objects around Degenerate Objects (DODO) survey is to search for very low mass brown dwarfs and extrasolar planets in wide orbits around white dwarfs via direct imaging. The direct detection of such companions…
The evolution of binaries consisting of evolved main sequence stars (1 < M_d/Msun < 3.5) with white dwarf companions (0.7 < M_wd/Msun < 1.2) is investigated through the thermal mass transfer phase. Taking into account the stabilizing effect…
We construct a set of binary evolutionary sequences for systems composed by a normal, solar composition, donor star together with a neutron star. We consider a variety of masses for each star as well as for the initial orbital period…
Binary stars are responsible for many unusual astrophysical phenomena, including some important explosive cosmic events. The stability criteria for rapid mass transfer and common-envelope evolution are fundamental to binary star evolution.…
We present the current status of the analytic theory of brown dwarf evolution and the lower mass limit of the hydrogen burning main sequence stars. In the spirit of a simplified analytic theory we also introduce some modifications to the…
We present a method for measuring the physical parameters of the coldest T-type brown dwarfs using low resolution near infrared spectra. By comparing H_2O- and H_2-sensitive spectral ratios between empirical data and theoretical atmosphere…
We present here the results of astrometric, photometric and spectroscopic observations leading to the determination of the orbit and dynamical masses of the binary L dwarf 2MASSW J0746425+2000321. High angular resolution observations spread…
We present the results of an analysis aimed at testing the accuracy and precision of the PARSEC v1.2S library of stellar evolution models, in a Bayesian framework, to infer stellar parameters. We mainly employ the online DEBCat catalogue by…
The newly discovered brown-dwarf eclipsing binary 2MASS J05352184-0546085 provides a unique laboratory for testing the predictions of theoretical models of brown-dwarf formation and evolution. The finding that the lower-mass brown dwarf in…
We study binary stars moving through a uniform dark matter background and experiencing dynamical friction. The centre-of-mass motion of the pairs is taken into account. We derive formulas and timescales for the secular evolution of the…