Related papers: F stars: A challenge to stellar evolution
Binary F stars exhibit large brightness anomaly, which is defined here as the difference between the absolute magnitude from the uvby photometry and the actual absolute magnitude of the star. We have found that the anomaly inversely…
Rotation has a number of important effects on the evolution of stars. Apart from structural changes because of the centrifugal force, turbulent mixing and meridional circulation caused by rotation can dramatically affect a star's chemical…
We provide a status report on the determination of stellar ages from asteroseismology for stars of various masses and evolutionary stages. The ability to deduce the ages of stars with a relative precision of typically 10 to 20% is a unique…
Stellar evolution models are a cornerstone of young star astrophysics, which necessitates that they yield accurate and reliable predictions of stellar properties. Here, I review the current performance of stellar evolution models against…
The field of exoplanet research has revitalized interest in M dwarfs, which have become favorite targets of Doppler and transit surveys. Accurate measurements of their basic properties such as masses, radii, and effective temperatures have…
Calibrating the ages, masses, and radii of stars on the upper main sequence depends heavily on accurate measurements of the effective temperature ($T_\mathrm{eff}$) and surface gravity ($\log g$). These parameters are difficult to obtain…
We have compared the kinematics and metallicity of the main sequence binary and single {\it uvby} F stars from the {\it HIPPARCOS} catalog to see if the populations of these stars originate from the same statistical ensemble. The velocity…
In this review, I will discuss a few problems which point to the need for improved stellar evolution models of halo stars. Current stellar evolution models do not match the observed $^7$Li abundance patterns, suggesting that the input…
Age is a fundamental stellar property, yet for many stars it is difficult to reliably determine. For M dwarfs it has been notoriously so. Due to their lower masses, core hydrogen fusion proceeds at a much slower rate in M dwarfs than it…
In this last decade, our knowledge of evolutionary and structural properties of stars of different mass and chemical composition is significantly improved. This result has been achieved as a consequence of our improved capability in…
A significant fraction of stars in globular clusters (about 70%-85%) exhibit peculiar chemical patterns with strong abundance variations in light elements along with constant abundances in heavy elements. These abundance anomalies can be…
We present $\gtrsim 15,000$ metal-rich (${\rm [Fe/H]}>-0.2$dex) A and F stars whose surface abundances deviate strongly from Solar abundance ratios and cannot plausibly reflect their birth material composition. These stars are identified by…
Rotation is of key importance for the evolution of hot massive stars, however, the rotational velocities of these stars are difficult to determine. Based on our own data for 31 Galactic O stars and incorporating similar data for 86 OB…
The impact of new stellar evolution models with rotation on the predictions of population synthesis models is discussed. Massive rotating stars have larger convective cores than their non-rotating counterparts, and their outer layers are…
Stellar magnetic activity decays over the main-sequence life of cool stars due to the stellar spin-down driven by magnetic braking. The evolution of chromospheric emission is well-studied for younger stars, but difficulties in determining…
Open and globular star clusters have served as benchmarks for the study of stellar evolution due to their supposed nature as simple stellar populations of the same age and metallicity. After a brief review of some of the pioneering work…
We derive the effective temperatures and gravities of 461 OB stars in 19 young clusters by fitting the H-gamma profile in their spectra. We use synthetic model profiles for rotating stars to develop a method to estimate the polar gravity…
Aims. We aim to describe the pre-main sequence and main-sequence evolution of X-ray and extreme-ultaviolet radiation of a solar mass star based on its rotational evolution starting with a realistic range of initial rotation rates. Methods.…
M-dwarf stars are prime targets for exoplanet searches because of their close proximity and favorable properties for both planet detection and characterization. However, the potential habitability and atmospheric characterization of these…
High precision photometry and spectroscopy of low-mass stars reveal a variety of properties standard stellar evolution cannot predict. Rotation, an essential ingredient of stellar evolution, is a step towards resolving the discrepancy…