相关论文: Chemically peculiar stars on the pre-main sequence
Context: Homogeneous investigations of red giant stars in open clusters contribute to studies of internal evolutionary mixing processes inside stars, which are reflected in abundances of mixing-sensitive chemical elements like carbon,…
Aims. Magnetic and abundance maps of chemically peculiar (CP) stars, derived with the help of Zeeman Doppler mapping, have invariably been used as arguments against theories, in particular atomic diffusion theory. We intend to expose the…
Young A-type stars in the pre--main-sequence (PMS) evolutionary phase are particularly interesting objects since they cover the mass range (1.5-4 solar ma sses) which is most sensitive to the internal conditions inherited during the…
We present a comprehensive analysis of BRITE photometry for 85 chemically peculiar stars, aimed at refining or determining their rotational periods. Utilizing a uniform Lomb-Scargle-based pipeline, we derived significant periods for 47…
Investigating chemically peculiar pulsating stars is crucial for understanding the pulsation driving mechanism in detail. To reveal the true peculiarity properties of stars detailed spectroscopic analysis is essential. Therefore, in this…
Magnetic, chemically peculiar stars are known for exhibiting surface abundance inhomogeneities (chemical spots) that lead to photometric and spectroscopic variability with the rotation period. It is commonly assumed that the surface…
The chemical abundance patterns of the oldest stars in the Galaxy are expected to contain residual signatures of the first stars in the early universe. Numerous studies attempt to explain the intrinsic abundance scatter observed in some…
Since the end of 2018, the Transiting Exoplanet Survey Satellite (TESS) provides high-quality space data on stellar photometry to the astronomical community. We present the results of an analysis of TESS photometric data for known slowly…
The chemical evolution of pre-stellar cores during their transition to a protostellar stage is not yet fully understood. Detailed chemical characterizations of these sources are needed to better define their chemistry during star formation.…
Based on the spectrum fitting method applied to CI 5380, NI 7486, and OI 6156-8 lines, we determined the abundances of C, N, and O for 100 mostly A-type main-sequence stars (late B through early F at 11000K>Teff>7000K) comprising normal…
The first massive stars triggered the onset of chemical evolution by releasing the first metals (elements heavier than helium) in the Universe. The nature of these stars and how the early chemical enrichment took place is still largely…
Chemically peculiar (CP) stars are unique natural laboratories for investigation of the microscopic diffusion processes of chemical elements. The element segregation under the influence of gravity and radiation pressure leads to the…
We propose a new chemical evolution model aimed at explaining the chemical properties of globular clusters (GC) stars. Our model depends upon the existence of (i) a peculiar pre-enrichment phase in the GC's parent galaxy associated with…
Observations of nearby star forming clouds with imaging X-ray telescopes have revealed that X-ray emission is elevated $10^1-10^4$ above main sequence levels in low-mass pre-main sequence (PMS) stars. The variability and spectral X-ray…
A recent analysis of high precision photometry obtained using the Kepler spacecraft has revealed two surprising discoveries: (1) over 860 main sequence A-type stars -- approximately 40% of those identified in the Kepler field -- exhibit…
A significant fraction of massive main-sequence stars show strong, large-scale magnetic fields. The origin of these fields, their lifetimes, and their role in shaping the characteristics and evolution of massive stars are currently not well…
Stellar members of binary systems are formed from the same material, therefore they should be chemically identical. However, recent high-precision studies have unveiled chemical differences between the two members of binary pairs composed…
Many chemically peculiar (CP) stars, especially the magnetic CP2 stars, show a flux depression at 5200A. The "Delta a" photometric System takes advantage of this characteristic to detect these objects in an efficient way. In addition, it is…
Procedure and results of computations of stellar model atmospheres and spectral energy distributions are discussed. Model atmospheres of some chemically peculiar stars are computed taking into account detailed information about their…
Studies of stellar magnetism at the pre-main sequence phase can provide important new insights into the detailed physics of the late stages of star formation, and into the observed properties of main sequence stars. This is especially true…