Context. Future astrometric missions such as SIM PlanetQuest need very stable reference stars. K giants have large luminosities, which place them at large distances and thus the jitter of their photocenters by companions is relatively small. Therefore K giants would be best suited as references. To confirm this observationally a radial velocity survey is performed to quantify the level of intri...

Atmospheric parameters (Teff , log g), and radial velocities are derived for twelve candidate blue horizontal branch (HB) stars in the globular clusters 47 Tuc and NGC 362, which so far have been known to contain primarily red HB stars. The spectroscopic targets were selected from the catalog of hot stars detected in these clusters at 1600 Å using the Ultraviolet Imaging Telescope (UIT). Spectr...

The red giant branch (RGB) of globular clusters (GCs) is home to some exotic stars, which may provide clues on the formation multiple stellar populations in GCs. It well known that binary interactions are responsible for many stars. Thus, it important understand what fraction stars RGB GCs result interactions. In this paper, we performed a population synthesis study track number post-binary-int...

We developed, tested and validated a new Fast, Robust Automated (FRA) tool to detect solar-like oscillations. FRA is based on the detection measurement of frequency maximum oscillation power $\nu_{max}$, without relying regular spacing guide search. applied pipeline 254 synthetic spectra representative TESS red giants, as well 1689 giants observed by Kepler 2344 TESS. obtain consistency rate fo...

We investigate the expected increase in the rotation rate of post-main-sequence stars as they expand and ingest orbiting planets. This phenomenon is expected to occur when the stellar radius becomes larger than the planet’s periastron distance. We calculate the expected frequency of planet ingestion during the red giant, horizontal branch (HB), and early asymptotic giant branch phases for plane...

A recent spectroscopic survey has shown that the lithium abundances in low-mass red-clump stars are higher than theoretical prediction. Motivated by their finding, we implemented effects of additional energy losses induced neutrino magnetic moments on stellar evolution models. It is found red giants increase because finite neutrinos enhance efficiency deep mixing and 7 Be conveyed from hydrogen...

I present details of the variations of several hundred red giant stars on time scales of a few hours to a few days from Hubble Space Telescope (HST) observations of a low-extinction galactic bulge sample from an intensive seven day campaign. Variations in the red giants are shown to be a strong function of position within the color-magnitude diagram (CMD) in accord with general expectations fro...

Context. Globular clusters (GCs) in the outer halo are important probes of the composition and origin of the Galactic stellar halo. Aims. We derive chemical element abundance ratios in red giants belonging to the remote (R ∼90 kpc) GC Pal 3 and compare our measurements to those for red giant stars in both inner and outer halo GCs. Methods. From high-resolution spectroscopy of four red giants, o...

We have used the High Resolution Camera (HRC-I) of the Chandra X-Ray Observatory to search for coronal (T 106 K) emission from the archetype ‘‘ noncoronal ’’ red giants Arcturus ( Bootis=HD 124897, K1 III) and Aldebaran ( Tauri=HD 29139, K5 III). Our program follows up previous detections of ultraviolet coronal proxies such as C iv 1548 (T 1 105 K) and O vi 1031 (T 3 105 K). The deep ( 19 ks) H...

The behaviour of the ∆ν=2 CO bands around 2.3 μm was examined by comparing observed and synthetic spectra in stars in globular clusters of different metallicity. Changes in the C/C isotopic ratio and the carbon abundances were investigated in stars from 3500–4900 K in the galactic globular clusters M71, M5, M3 and M13, covering the metallicity range from –0.7 to –1.6. We found relatively low ca...