Related papers: Explaining UXOR variability with self-shadowed dis…
Protoplanetary discs, when externally irradiated by Far Ultraviolet (FUV) photons from OBA-type stars, lose material through photoevaporative winds, reducing the amount of material available to form planets. Understanding the link between…
We study the origin of tail-like structures recently detected around the disk of SU Aurigae and several FU~Orionis-type stars. Dynamic protostellar disks featuring ejections of gaseous clumps and quiescent protoplanetary disks experiencing…
FU Orionis objects are low-mass pre-main sequence stars characterized by dramatic outbursts of several magnitudes in brightness. These outbursts are linked to episodic accretion events in which stars gain a significant portion of their…
Context. FU Orionis is the archetypal FUor star, a subclass of young stellar object (YSO) that undergo rapid brightening events, often gaining 4-6 magnitudes on timescales of days. This brightening is often associated with a massive…
It is now widely accepted that most ultraluminous X-ray sources (ULXs) are binary systems whose large (above $10^{39}$ erg s$^{-1}$) apparent luminosities are explained by super-Eddington accretion onto a stellar-mass compact object. Many…
We present multi-wavelength long-term monitoring observations of V635 Cas, the optical counterpart to the transient X-ray pulsar 4U0115+63. The evolution of emission lines and photometric magnitudes indicates that the Be star undergoes…
The FU Orionis (FUor) or EX Orionis (EXor) phenomenon has attracted increasing attention in recent years and is now accepted as a crucial element in the early evolution of low-mass stars. FUor and EXor eruptions of young stellar objects…
In order to study the growth and evolution of circumstellar disks around classical Be stars, we analyze optical time-series photometry from the KELT survey with simultaneous infrared and visible spectroscopy from the APOGEE survey and BeSS…
We present a comprehensive study of the variability properties of young disk-bearing stars in the Taurus star-forming region, paralleling our previous investigation in rho Oph and Upper Sco. A sample of 99 confirmed Taurus association…
The [Ne II] fine-structure emission line at 12.8 micron has been detected in several young stellar objects (YSO) spectra. This line is thought to be produced by X-ray irradiation of the warm protoplanetary disk atmospheres, however the…
The dipper subclass of YSOs are characterised by frequent dips in their light curves. Irregular dippers do not show periodic signatures and have dips accounting for significant proportions of their photospheric flux. Given the short…
We simulate the polarized radiative transfer in vicinities of the UX Ori type stars during their minima. Our model of an eclipse by an extended disc perturbation generalizes the compact gas-dust cloud eclipse model. We apply the radiative…
Context: To follow the early evolution of stars we need to understand how young stars accrete and eject mass. It is generally assumed that the FU Orionis phenomenon is related to the variations in the disk accretion, but many questions…
In the classical grouping of large magnitude episodic variability of young accreting stars, FUORs outshine their stars by a factor of $\sim$ 100, and can last for up to centuries; EXORs are dimmer, and last months to a year. A disc Hydrogen…
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…
With the Keck Interferometer, we have studied at 2 um the innermost regions of several nearby, young, dust depleted "transitional" disks. Our observations target five of the six clearest cases of transitional disks in the Taurus/Auriga…
We report new Spitzer Space Telescope observations from the IRAC and MIPS instruments of the young (~ 3 Myr) sigma Orionis cluster. We identify 336 stars as members of the cluster using optical and near-infrared color magnitude diagrams.…
Context. Episodic accretion in young stellar objects (YSOs) is thought to play a critical role in addressing the "luminosity problem" associated with star formation. However, optical surveys tend to bias against sources that are heavily…
We identify a high frequency of Type 1 XUV disks, reflecting recent outer disk star formation, in a sample of 31 E/S0s with stellar masses primarily below M_* ~ 4 x 10^10 M_sun. Our ~40% identification rate is roughly twice the 20% fraction…
Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability.…