相关论文: Chemical Fractionation and Abundances in Coronal P…
Studies of element abundances in stars are of fundamental interest for their impact in a wide astrophysical context, from our understanding of galactic chemistry and its evolution, to their effect on models of stellar interiors, to the…
We report a detailed analysis of the coronal abundance of 4 stars with varying levels of activity and with accurately known photospheric abundances. The coronal abundance is determined here using a line flux analysis and a full…
Following the Chandra Orion Ultradeep Project (COUP) observation, we have studied the chemical composition of the hot plasma in a sample of 146 X-ray bright pre-main sequence stars in the Orion Nebula Cluster. We report measurements of…
The determination of chemical abundances in star-forming galaxies and the study of their evolution on cosmological timescales are powerful tools for understanding galaxy formation and evolution. This contribution presents the latest results…
The determination of chemical abundances from stellar spectra is considered a mature field of astrophysics. Digital spectra of stars are recorded and processed with standard techniques, much like samples in the biological sciences.…
X-ray emission from stars in the cool half of the Hertzsprung-Russell diagram is generally attributed to the presence of a magnetic corona that contains plasma at temperatures exceeding 1 million K. Coronae are ubiquitous among these stars,…
Star-forming regions show a rich and varied chemistry, including the presence of complex organic molecules - both in the cold gas distributed on large scales, and in the hot regions close to young stars where protoplanetary disks arise.…
The horizon for studies of element abundances has expanded dramatically in the last ten years. Once the domain of astronomers concerned chiefly with stars and nearby galaxies, this field has now become a key component of observational…
The measurement of chemical abundances in planetary nebulae in nearby galaxies is now relatively straightforward. The challenge is to use these chemical abundances to infer the chemical evolution of their host galaxies. At this point, our…
Chemical abundances provide important clues to the evolution of galaxies. Ionized nebulae are one of the main sources of chemical abundance measurements, especially in external galaxies. Studies of H II regions have shown that the overall…
The chemical abundances in the atmosphere of a star provide unique information about the gas from which that star formed, and, modulo processes that are not important for the vast majority of stars, such as mass transfer in close binary…
In stellar astrophysics, the study of the atmospheres of early-type stars plays a very special role. The atmospheres of these stars display a variety of different phenomena, such as the presence of large magnetic fields, strong surface…
Young stars show a variety of highly energetic phenomena, from accretion and outflow processes to hot coronal plasmas confined in their outer atmosphere, all regulated by the intense stellar magnetic fields. Many aspects on each of these…
The chemical composition of solar and stellar atmospheres differs from that of their photospheres. Abundances of elements with low first ionization potential (FIP) are enhanced in the corona relative to high FIP elements with respect to the…
The determination of chemical abundances in star-forming galaxies and the study of their evolution on cosmological timescales are powerful tools for understanding galaxy formation and evolution. This contribution presents the latest results…
Most of the ordinary matter in the local Universe has not been converted into stars but resides in a largely unexplored diffuse, hot, X-ray emitting plasma. It pervades the gravitational potentials of massive galaxies, groups and clusters…
We present some recent highlights and prospects for the study of hot astrophysical plasmas. Hot plasmas can be studied primarily through their X-ray emission and absorption. Most astrophysical objects, from solar system objects to the…
As building blocks of dust, rocky planets, and even complex life, the chemical elements heavier than hydrogen (H) and helium (He) - called "metals" in astronomy - play an essential role in our Universe and its evolution. Up to Fe and Ni,…
Since stellar populations enhance particular element abundances according to the yields and lifetimes of the stellar progenitors, the chemical evolution of galaxies serves as one of the key tools that allows the tracing of galaxy evolution.…
Coronae exist in most astrophysical objects: stars, accretion disks, and individual galaxies and clusters of galaxies. Coronae in these varied systems have some common properties: 1) hydrostatic equilibrium in background gravity is a good…