Recent asteroseismic analyses indicate the presence of strong (B  10 G) magnetic fields in the cores of many red giant stars. Here, we examine the implications of these results for the evolution of stellar magnetic fields, and we make predictions for future observations. Those stars with suppressed dipole modes indicative of strong core fields should exhibit moderate but detectable quadrupole ...

With the advent of surveys generating multi-epoch photometry and the discovery of large numbers of variable stars, the classification of these stars has to be automatic. We have developed such a classification procedure for about 1700 stars from the variable star catalogue of ASAS 1-2 (All Sky Automated Survey, Pojmański 2000) by selecting the periodic ones and by applying an unsupervised Bayes...

We present multi-wavelength observations of the northern population of ω Cen from the main-sequence turn-off to high on the red giant branch. We show that the best information about the metallicity and age of the stars can be gained from combining vby, B-I and V-I colors (in the absence of spectroscopy). We confirm our results for the main-sequence turn-off stars: there is at least a 3 Gyr age ...

We have obtained spectra for 50 candidate red giants in Andromeda II, a dwarf spheroidal companion of M31, using the Low Resolution Imaging Spectrometer on the Keck II telescope. After eliminating background galaxies and Galactic foreground stars, we are left with a sample of 42 red giants for which membership in Andromeda II can be established unambiguously from radial velocities. Line indices...

Recent asteroseismic advances have allowed for direct measurements of the internal rotation rates of many sub-giant and red giant stars. Unlike the nearly rigidly rotating Sun, these evolved stars contain radiative cores that spin faster than their overlying convective envelopes, but slower than they would in the absence of internal angular momentum transport. We investigate the role of interna...

Context. About 0.2-2% of giant stars are Li-rich, whose lithium abundance (A(Li)) is higher than 1.5 dex. Among them, near 6% super Li-rich with A(Li) exceeding 3.2 Meanwhile, the formation mechanism these and giants still under debate. Aims. Considering compact He core red giants, attention paid to effect element diffusion on A(Li). In particular, when flash occurs, makes thermohaline mixing z...

ABSTRACT Lithium abundances for red giants in the GALAH DR3 survey are studied. The rare examples of Li-enriched stars with A(Li) ≥1.5 confirmed to be He-core burning belonging or evolved from clump similar masses and metallicity: M ≃ 1.1 ± 0.2 M⊙ [Fe/H] −0.3 0.3. Li enrichment over abundance present a star’s predecessor at tip giant branch likely occurs all these stars. Examination elemental (...

Context. So far, red giant oscillations have been studied from radial velocity and/or light curve variations, which reveal frequencies of the oscillation modes. To characterise radial and non-radial oscillations, line profile variations are a valuable diagnostic. Here we present for the first time a line profile analysis of pulsating red giants, taking into account the small line profile variat...

We present an R = 45,000 Keck spectrum of the microlensed Galactic bulge G-dwarf OGLE-2006-BLG-265, which has high (∼ 60) signal-to-noise ratio despite its short (15 min) exposure time because the source was magnified by A ∼ 135. While it is very metal-rich ([Fe/H]=0.56), the higher temperature of this star compared with the luminous red giants usually measured in the bulge gives its spectrum m...