Related papers: Structure and Evolution of Pre-Main Sequence Stars
Emission mechanism of the magnetars is still controversial while various observational and theoretical studies have been made. In order to investigate mechanisms of both the persistent X-ray emission and the burst emission of the magnetars,…
Stellar masses are a fundamental property to understand models of pre-main sequence evolution, but their values derived from Hertzsprung-Russell (HR) diagrams are strongly model dependent. We benchmark pre-main sequence stellar evolutionary…
The combination of photometry, spectroscopy and spectropolarimetry of the chemically peculiar stars often aims to study the complex physical phenomena such as stellar pulsation, chemical inhomogeneity, magnetic field and their interplay…
The bright maser emission produced by several molecular species at centimeter to long millimeter wavelengths provides an essential tool for understanding the process of massive star formation. Unimpeded by the high dust optical depths that…
We address the origin of the observed bimodal rotational distribution of stars in massive young and intermediate age stellar clusters. This bimodality is seen as split main sequences at young ages and also has been recently directly…
The 6.7 GHz methanol maser emission, a tracer of forming massive stars, sometimes shows enigmatic periodic flux variations over several 10-100 days. In this Letter, we propose that this periodic variations could be explained by the…
X-ray spectroscopy is a sensitive probe of stellar winds. X-rays originate from optically thin shock-heated plasma deep inside the wind and propagate outwards throughout absorbing cool material. Recent analyses of the line ratios from…
Context: The pre-main sequence evolution is often simplified by choosing classical initial models. These have large initial radii and sufficient uniform contraction to make them fully convective. Contrary to that, real stars are born as…
We present the ASCA results of intermediate-mass pre-main-sequence stars (PMSs), or Herbig Ae/Be stars (HAeBes). Among the 35 ASCA pointed-sources, we detect 11 plausible X-ray counterparts. X-ray luminosities of the detected sources in the…
X-ray emission from stars has origins as diverse as the stars themselves: accretion shocks, shocks generated in wind-wind collisions, or release of magnetic energy. Although the scenarios responsible for X-ray emission are thought to be…
Angular momentum is a key property regulating star formation and evolution. However, the physics driving the distribution of the stellar rotation rates of early-type main-sequence stars is as yet poorly understood. Using our catalog of…
We present Halpha spectropolarimetry of a large sample of pre-main sequence (PMS) stars of low and intermediate mass, and argue that the technique is a powerful tool in studying the circumstellar geometry around these objects. For the…
Understanding the collapse of clouds and the formation of protoplanetary disks is essential to understanding the formation of stars and planets. Infall and accretion, the mass-aggregation processes that occur at envelope and disk scales,…
We report the discovery of extended X-ray emission within the young star cluster NGC 602 in the Wing of the Small Magellanic Cloud (SMC) based on observations obtained with the Chandra X-ray Observatory. X-ray emission is detected from the…
Numerous investigations on the fundamental properties of low-mass stars using eclipsing binaries indicate a strong discrepancy between theory and observations that is still awaiting explanation. Current models seem to predict radii for…
Many gamma-ray bursts are followed by periods of extended emission. At least in some cases, the burst afterglow may be powered by a rapidly rotating, highly-magnetised neutron star, which spins down due to electromagnetic and gravitational…
Precise measurements of the fundamental properties of low-mass stars and brown dwarfs are key to understanding the physics underlying their formation and evolution. While there has been great progress over the last decade in studying the…
The magnetic activity of late-type MS stars is characterized by different regimes, and their activity levels are well described by Ro, the ratio between P_rot and the convective turnover time. Very young PMS stars show, similarly to MS…
The X-ray colors and X-ray-to-optical luminosity ratios (L_X/L_B) of 61 early- type galaxies observed with the ROSAT PSPC are determined. The colors indicate that the X-ray spectral properties of galaxies vary as a function of L_X/L_B. The…
The X-ray and gamma-ray spectrum of rotation-powered millisecond pulsars is investigated in a model for acceleration and pair cascades on open field lines above the polar caps. Although these pulsars have low surface magnetic fields, their…