Related papers: Evolution of X-ray Activity in <25 Myr Old Pre-Mai…
Mass accretion onto (proto-)stars at high accretion rates > 10^-4 M_sun/yr is expected in massive star formation. We study the evolution of massive protostars at such high rates by numerically solving the stellar structure equations. In…
We present a multi-wavelength study of three star forming regions, spanning the age range 1-14 Myr, located between the 30 Doradus complex and supernova SN1987A in the Large Magellanic Cloud (LMC). We reliably identify about 1000 pre-main…
Protoplanetary disks in dense, massive star-forming regions are strongly affected by their environment. How this environmental impact changes over time is an important constraint on disk evolution and external photoevaporation models. We…
We explore the empirical power-law relationship between X-ray luminosity (Lx) and total surface magnetic flux (Phi), established across solar magnetic elements, time- and disk-averaged emission from the Sun, older active stars, and…
Low-mass stars are currently the most promising targets for detecting and characterizing habitable planets in the solar neighborhood. However, the ultraviolet (UV) radiation emitted by such stars can erode and modify planetary atmospheres…
This white paper is motivated by open questions in star formation, which can be uniquely addressed by high resolution X-ray imaging and require an X-ray observatory with large collecting area along good spectral resolution. A complete…
Recently much progress has been made in probing the embedded stages of massive star formation, pointing to formation scenarios akin to a scaled up version of low-mass star formation. However, the latest stages of massive star formation have…
Formation of massive stars by accretion requires a high accretion rate of > 10^-4 M_sun/yr to overcome the radiation pressure barrier of the forming stars. Here, we study evolution of protostars accreting at such high rates, by solving the…
We analyse pre-Main Sequence evolutionary tracks for low mass stars with masses $m \le 1.4 \msol$ based on the Baraffe et al. (1998) input physics. We also extend the recent Chabrier et al. (2000) evolutionary models based on dusty…
(abridged) Thus far our impressions regarding the evolutionary time scales for young circumstellar disks have been based on small number statistics. Over the past decade, however, in addition to precision study of individual star/disk…
Late in their evolution, massive stars may undergo periods of violent instability and mass loss, but the mechanism responsible for these episodes has not been identified. We study one potential contributor: the development of local…
We study the properties of powerful X-ray flares from 161 pre-main sequence (PMS) stars observed with the Chandra X-ray Observatory in the Orion Nebula region. Relationships between flare properties, protoplanetary disks and accretion are…
Stellar ages are extremely difficult to determine and often subject to large uncertainties, especially for field low-mass stars. We plan to carry out a calibration of the decrease in high-energy emissions of low-mass GKM stars with time,…
Low-mass young stellar objects are powerful emitters of X-rays that can ionize and heat the disks and the young planets they harbour. The X-rays produce molecular ions that affect the chemistry of the disk atmospheres and their…
Studies of the formation and evolution of young stars and their disks rely on the knowledge of the stellar parameters of the young stars. The derivation of these parameters is commonly based on comparison with photospheric template spectra.…
Observational data on the dust content of circumstellar disks show that the median dust content in disks around pre-main sequence stars in nearby star forming regions seem to increase from about 1 Myr to about 2 Myr, and then decline with…
Recent numerical simulations have shown that the unstable disk within the central regime of the primordial gas cloud fragments to form multiple protostars on several scales. Their evolution depends on the mass accretion phenomenon,…
We have studied the young low-mass pre-main sequence (PMS) stellar population associated with the massive star-forming region DR 21 by using archival X-ray Chandra observations and by complementing them with existing optical and IR surveys.…
Direct imaging has revealed exoplanet systems hosting multiple wide-orbit Super-Jupiters, where planet-planet interactions can shape their long-term dynamical evolution. These strong perturbations may lead to orbital instability, raising…
We present population synthesis models of viscous protoplanetary disks subject to mild external far-ultraviolet (FUV) radiation fields ($F_{\rm UV}=1\text{-}100\,$G$_0$). Our simulations focus on gas disk evolution, exploring stellar masses…