Related papers: Pulsed Accretion in a Variable Protostar
Rotation-powered millisecond radio pulsars have been spun up to their present spin period by a $10^8$ - $10^9$ yr long X-ray-bright phase of accretion of matter and angular momentum in a low-to-intermediate mass binary system. Recently, the…
Many young extra-galactic clusters have a measured velocity dispersion that is too high for the mass derived from their age and total luminosity, which has led to the suggestion that they are not in virial equilibrium. Most of these…
Surveys of young star-forming regions have discovered a growing population of planetary-mass (<13 M_Jup) companions around young stars. There is an ongoing debate as to whether these companions formed like planets (that is, from the…
We investigate under what circumstances an embedded planet in a protoplanetary disc may sculpt the dust distribution such that it observationally presents as a `transition' disc. We concern ourselves with `transition' discs that have large…
Although the Orion Nebula Cluster is one of the most studied clusters in the solar neighborhood, the evolution of the very low-mass members ($M_* < 0.25 \, M_\odot$) has not been fully addressed due to their faintness. Our goal is to verify…
We present coupled stellar evolution (SE) and 3D radiation-hydrodynamic (RHD) simulations of the evolution of primordial protostars, their immediate environment, and the dynamic accretion history under the influence of stellar ionizing and…
This article represents a short review of the variability characteristics of young stellar objects. Variability is a key property of young stars. Two major origins may be distinguished: a scaled-up version of the magnetic activity seen on…
New high-cadence observations with BRITE covering many months confirm that coupled pairs of nonradial pulsation modes are widespread among early-type Be stars. With the difference frequency between the parental variations they may form a…
We investigate the dependence of pulse amplitudes of accreting millisecond pulsars on the masses of the neutron stars. Because the pulsation amplitudes are suppressed as the neutron stars become more massive, the probability of detection of…
The high occurrence rates of spiral arms and large central clearings in protoplanetary disks, if interpreted as signposts of giant planets, indicate that gas giants form commonly as companions to young stars ($<$ few Myr) at orbital…
Accretion is one of the defining characteristics of classical T Tauri stars, fueled by the presence of a circumstellar disk comprised of dust and gas. Accretion produces a UV and optical excess, while re-radiated emission at the inner edge…
We show that for young stars which are still accreting and for which measurements of stellar age, disc mass and accretion rate are available, nominal disc age (Disc Age = Disc Mass / Accretion Rate) is approximately equal to the stellar…
Neutron stars in X-ray binary systems are fascinating objects that display a wide range of timing and spectral phenomena in the X-rays. Not only parameters of the neutron stars, like magnetic field strength and spin period evolve in their…
The earliest phases of star formation are characterised by intense mass accretion from the circumstellar disk to the central star. One group of young stellar objects, the FU Orionis-type stars exhibit accretion rate peaks accompanied by…
Early stages of stellar birth comprise of a two-step process involving the formation of two hydrostatic cores. The second step of gravitational collapse sets the radiative efficiency and accretion rate of the young protostar. These two…
From considerations of spin evolution and kinematics in the galactic potential, we argue that the pulsars B1913+16, B1534+12, and B2127+11C may be younger than previously assumed, and we find that a lower bound on the formation and merger…
The mass growth of protostars is a central element to the determination of fundamental stellar population properties such as the initial mass function. Constraining the accretion history of individual protostars is therefore an important…
Classical Be stars, regardless of spectral subtype, display multiperiodic light modulations in the frequency range 0.1-12 d$^{-1}$, when observed with high-cadence and long duration. This behaviour is attributed to non-radial pulsations…
Growing evidence suggests that protoplanetary discs may be influenced by late stage infall from the interstellar medium (ISM). It remains unclear the degree to which infall shapes disc populations at ages $\gtrsim 1$~Myr. We explore…
The luminosity of X-ray pulsars is their key parameter determining the geometry and physical conditions of the accretion flow both on the spatial scales of a binary system and on much smaller scales of emitting regions located close to the…