ORIGIN OF LITHIUM ENRICHMENT IN K GIANTS

AbstractAt McDonald Observatory we have been monitoring the relative radial velocities of a sample of K giants. The technique employed uses the telluric O2 lines near 6300 Å as a reference for measuring the stellar line shifts. We demonstrate that precisions of 10 m s−1 are possible with this technique. We present radial velocity data covering a 2 year time span for α Boo, α Tau, and β Gem. All of these stars show both long term variations (~ several hundred days) with a peak-to-peak amplitude of about 400 m s−1 and short term variations (~ few days) with a peak-to-peak amplitude of about 100 m s−1. The long term variations may be due to the rotational modulation of surface active regions whereas the short term variations may be indicative of pulsations.

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Hydrogeological constraints for the genesis of the extreme lithium enrichment in the Salar de Atacama (NE Chile): A thermohaline flow modelling approach

The Science of The Total Environment ◽

10.1016/j.scitotenv.2020.139959 ◽

2020 ◽

Vol 739 ◽

pp. 139959

Author(s):

M.A. Marazuela ◽

C. Ayora ◽

E. Vázquez-Suñé ◽

S. Olivella ◽

A. García-Gil

Keyword(s):

Flow Modelling ◽

Thermohaline Flow ◽

Lithium Enrichment ◽

Modelling Approach

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Detect the density profile with LAMOST K giants

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317008651 ◽

2017 ◽

Vol 13 (S334) ◽

pp. 387-388

Author(s):

Yan Xu ◽

Chao Liu

Keyword(s):

Density Distribution ◽

Power Law ◽

Density Profile ◽

Milky Way ◽

Galactic Center ◽

Fitting Method ◽

Stellar Halo ◽

Model Independent ◽

Power Law Index ◽

K Giants

AbstractThe density distribution of the Milky Way halo is detected with 5351 LAMOST DR3 metal poor K giants using a nonparametric method. The nonparametric fitting method is a model independent way to estimate the halo density distribution while to a large extent avoiding the influence of the halo substucture. We show that the K giants density profile can be fitted well by single power law. We found no indication of a break in the power law index. The powerlaw index n = 5.0−0.64+0.64. The data show that the stellar halo is flattened at smaller radii, and becomes more spherical farther from the Galactic center. The flattening q(r=15Kpc)is about0.64, q(20Kpc) is about 0.8, q(30Kpc) is about 0.96.

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Short Period Oscillations in Acturus, Aldebaran, and Pollux

Symposium - International Astronomical Union ◽

10.1017/s0074180900035166 ◽

1988 ◽

Vol 132 ◽

pp. 291-294

Author(s):

Peter H. Smith ◽

Robert S. McMillan

Keyword(s):

Time Series ◽

Preliminary Analysis ◽

Time Series Data ◽

Careful Analysis ◽

Series Data ◽

Short Period ◽

Stellar Velocity ◽

Clean Algorithm ◽

K Giants

A total of 48 nights of time series data have been obtained for the K giants: Arcturus, Pollux, and Aldebaran. A careful analysis of both single and multi–night sets using the earth's motion as a velocity calibrator has yielded stellar velocity time series accurate to ± 3 m/s per observation. Periodogram analyses of these sets have revealed the existence of oscillations with periods near 2.5 hrs and amplitudes of ± 5 m/s for both Pollux and Aldebaran, but not for Arcturus. Preliminary analysis of a 5-night set for Pollux using the CLEAN algorithm suggests at least three modes separated by about 35 microHertz.

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Li Enrichment, Mass Loss, and CN Abundances in High Rotating K Giants

Symposium - International Astronomical Union ◽

10.1017/s0074180900195658 ◽

2004 ◽

Vol 215 ◽

pp. 242-243

Author(s):

N. A. Drake ◽

R. de la Reza ◽

L. da Silva ◽

D. L. Lambert

Keyword(s):

Mass Loss ◽

Spectral Resolution ◽

High Spectral Resolution ◽

Mixing Process ◽

Stellar Activity ◽

New Models ◽

Low Mass ◽

K Giants

High rotating low-mass K giants can be considered as interesting new “laboratories” for studies of the mixing process and mass loss. By means of high spectral resolution observations of some rapidly rotating K giants we found a series of connections between rotation, stellar activity, high Li abundance and mass loss. These giants show low 14N and high 13C enrichment. Nearly half of them are Li rich. This frequency is much higher than the ~ 2% corresponding to common, low rotating K giants. They are also the most suitable objects to test new models of rotation-induced mixing or planet engulfing scenarios.

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