Related papers: Variability of young stellar objects: accretion, d…
Here, I review some recent works on magnetism of cool, main-sequence stars, their winds and potential impact on surrounding exoplanets. The winds of these stars are very tenuous and persist during their lifetime. Although carrying just a…
A radiation-driven disk wind model is proposed that offers great promise of explaining the extreme mass loss signatures of massive young stellar objects (the BN-type objects and more luminous Herbig Be stars). It is argued that the dense…
We present K-band polarimetric images of several massive young stellar objects at resolutions $\sim$ 0.1-0.5 arcsec. The polarization vectors around these sources are nearly centro-symmetric, indicating they are dominating the illumination…
Characterization of the properties of young brown dwarfs are important to constraining the formation of objects at the extreme low-mass end of the IMF. While young brown dwarfs share many properties with solar-mass T Tauri stars,…
Classical T Tauri stars are young low-mass systems still accreting material from their disks. These systems are dynamic on timescales of hours to years. The observed variability can help us infer the physical processes that occur in the…
We review recent advances in our understanding of the innermost regions of the circumstellar environment around young stars, made possible by the technique of long baseline interferometry at infrared wavelengths. Near-infrared observations…
Magnetic activity changes the gravito-acoustic modes of solar-like stars and in particular their frequencies. There is an angular-degree dependence that is believed to be caused by the non-spherical nature of the magnetic activity in the…
High precision photometry and spectroscopy of low-mass stars reveal a variety of properties standard stellar evolution cannot predict. Rotation, an essential ingredient of stellar evolution, is a step towards resolving the discrepancy…
Magnetic braking causes the spin-down of single stars as they evolve on the main sequence. Models of magnetic braking can also explain the evolution of close binary systems, including cataclysmic variables. The well-known period gap in the…
We revisit the nature of large dips in flux from extinction by dusty circumstellar material that is observed by Kepler for many young stars in the Upper Sco and $\rho$ Oph star formation regions. These young, low-mass "dipper" stars are…
The unusual properties of transition objects (young stars with an optically thin inner disc surrounded by an optically thick outer disc) suggest that significant disc evolution has occured in these systems. We explore the nature of these…
We present a study of the scaling properties of bipolar outflows, generic to the circumstellar environment of young stellar objects, and which are generally believed to be magnetohydrodynamically driven. Our work consists of a multifractal…
The disks that orbit young stars are the essential conduits and reservoirs of material for star and planet formation. Their structures, meaning the spatial variations of the disk physical conditions, reflect the underlying mechanisms that…
The long-term evolution of stellar orbits bound to a massive centre is studied in order to understand the cores of star clusters in central regions of galaxies. Stellar trajectories undergo tiny perturbation, the origin of which is twofold:…
We characterize the kinematics, morphology, stellar populations and star formation histories of a sample of massive compact galaxies in the nearby Universe, which might provide a closer look to the nature of their high redshift (z > 1.0)…
(Abridged) In this review we focus on the observations and theory of the formation of early disks and outflows, and their connections with the first phases of planet formation. Large rotationally supported circumstellar disks, although…
Young stars form on a wide range of scales, producing aggregates and clusters with various degrees of gravitational self-binding. The loose aggregates have a hierarchical structure in both space and time that resembles interstellar…
The kinematics of newly-formed star clusters are interesting both as a probe of the state of the gas clouds from which the stars form, and because they influence planet formation, stellar mass segregation, cluster disruption, and other…
We review recent progress in high-resolution imaging of scattered light from disks around young stellar objects. Many new disks have been discovered or imaged in scattered light, and improved instrumentation and observing techniques have…
Debris disks are tenuous, dust-dominated disks commonly observed around stars over a wide range of ages. Those around main sequence stars are analogous to the Solar System's Kuiper Belt and Zodiacal light. The dust in debris disks is…