Tanda Li

THE CONTRIBUTIONS OF INTERACTIVE BINARY STARS TO DOUBLE MAIN-SEQUENCE TURNOFFS AND DUAL RED CLUMP OF INTERMEDIATE-AGE STAR CLUSTERS

Double or extended main-sequence turnoffs (DMSTOs) and dual red clump (RC) were observed in intermediate-age clusters, such as in NGC 1846 and 419. The DMSTOs are interpreted as that the cluster has two distinct stellar populations with differences in age of about 200-300 Myr but with the same metallicity. The dual RC is interpreted as a result of a prolonged star formation. Using a stellar population-synthesis method, we calculated the evolution of a binary-star stellar population. We found that binary interactions and merging can reproduce the dual RC in the color-magnitude diagrams of an intermediate-age cluster, whereas in actuality only a single population exists. Moreover, the binary interactions can lead to an extended main-sequence turnoff (MSTO) rather than DMSTOs. However, the rest of the main sequence, subgiant branch, and first giant branch are hardly spread by the binary interactions. Part of the observed dual RC and extended MSTO may be the results of binary interactions and mergers.

Solar Models with Revised Abundance

We present new solar models in which we use the latest low abundances and further include the effects of rotation, magnetic fields, and extra-mixing processes. We assume that the extra-element mixing can be treated as a diffusion process, with the diffusion coefficient depending mainly on the solar internal configuration of rotation and magnetic fields. We find that such models can well reproduce the observed solar rotation profile in the radiative region. Furthermore, the proposed models can match the seismic constraints better than the standard solar models, also when these include the latest abundances, but neglect the effects of rotation and magnetic fields.

Stellar parameters and seismological analysis of the star 18 Scorpii

Aims. We constructed models of the structure and evolution of the stars including diffusion and extra-mixing caused by rotation to estimate stellar parameters of the solar twin 18 Scorpii. Methods. Based on the classical observed features, we considered three additional constraints, i.e., lithium abundance log N(Li), rotational period P eq, and average large frequency separation �� ν� , by combing stellar models with observations to determine stellar parameters and the possible evolutionary status of 18 Scorpii. Results. More accurate results of mass and age were found by our model than in previous studies. We estimate that the mass and

LITHIUM ABUNDANCE AS A PREDICTOR OF MASS AND AGE IN SOLAR-ANALOG STARS

In order to estimate the mass and age of stars, we construct a grid of stellar models for eight solar-analog stars including diffusion and rotation-induced mixing for the given ranges of stellar mass, metallicity, and rotational rate. By combining stellar models with observational data including lithium abundance, we obtain more accurate estimations of mass and age for solar-analog stars. The results indicate that stars HIP 56948, HIP 73815, and HIP 78399 are three possible solar twins. Furthermore, we find that lithium depletion due to extra-mixing in solar analogs strongly depends on mass, metallicity, and rotational history. Therefore, lithium abundance can be used as a good constraint in stellar modeling.

Asteroseismology of 1523 misclassified red giants using Kepler data

We analysed solar-like oscillations in 1523

ASTEROSEISMIC ANALYSIS OF THE CoRoT TARGET HD 49933

\textit{Kepler}

EFFECTS OF MAGNETIC FIELDS ON LITHIUM EVOLUTION IN F AND G STARS

red giants which have previously been misclassified as subgiants, with predicted

Mass and age of red giant branch stars observed with LAMOST and Kepler

\nu_{\rm max}

LOFAR Discovery of the Fastest-spinning Millisecond Pulsar in the Galactic Field

values (based on the Kepler Input Catalogue) between 280

Stellar parameters of main sequence turn-off star candidates observed with LAMOST and Kepler

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