Evolution of the Lithium Abundance of Solar-Type Stars. X. Does Accretion Affect the Lithium Dispersion in the Pleiades?

2002 ◽  
Vol 124 (5) ◽  
pp. 2799-2812 ◽  
Author(s):  
B. S. Wilden ◽  
Burton F. Jones ◽  
D. N. C. Lin ◽  
David R. Soderblom
Keyword(s):  
Lithium Abundance ◽  
Solar Type

scholarly journals Lithium Abundance of the Solar-Type Superflare Stars

2017 ◽  
Author(s):  
Satoshi Honda ◽  
Yuta Notsu ◽  
Hiroyuki Maehara ◽  
Shota Notsu ◽  
Takuya Shibayama ◽  
...  
Keyword(s):  
Lithium Abundance ◽  
Solar Type

scholarly journals Transport Phenomena and Light Element Abundances in the Sun and Solar Type Stars

2000 ◽  
Vol 198 ◽  
pp. 470-475
Author(s):  
Sylvie Vauclair
Keyword(s):  
Diffusion Processes ◽  
Light Element ◽  
The Sun ◽  
Mixing Processes ◽  
Lithium Abundance ◽  
Solar Convection Zone ◽  
Element Abundances ◽  
Solar Convection ◽  
Halo Stars ◽  
Solar Type

The observations of light elements in the Sun and Solar type stars give special clues for understanding the hydrodynamical processes at work in stellar interiors. In the Sun 7Li is depleted by 140 while 3He has not increased by more than ≅ 10% in 3 Gyrs. Meanwhile the inversion of helioseismic modes lead to a precision on the sound velocity of about 1%. The mixing processes below the solar convection zone are constrained by these observations. Lithium is depleted in most Pop I solar type stars. In halo stars however, the lithium abundance seems constant in the “spite plateau” with no observed dispersion, which is difficult to reconcile with the theory of diffusion processes. In the present paper, the various relevant observations will be discussed. It will be shown that the μ-gradients induced by element settling may help solving the ‘lithium paradox’.

scholarly journals Evidence for Lithium Destruction and Synthesis in Main-Sequence and Subgiant Stars of about Solar Mass

1968 ◽  
Vol 1 ◽  
pp. 233-236
Author(s):  
M. W. Feast
Keyword(s):  
Main Sequence ◽  
Solar Mass ◽  
Lithium Abundance ◽  
Solar Type ◽  
Subgiant Stars

Herbig’s extensive work on lithium abundances in solar-type stars on and near the main sequence, suggested to him that for these stars the lithium abundance might be some simple, decreasing function of age. If this were the full story we should expect a low lithium abundance in subgiants of about solar mass. However, already in Herbig’s work there were one or two stars with lithium abundance about 10 times the Greenstein-Richardson solar value whose trigonometrical parallaxes showed them to be possible subgiants. Other subgiants with high lithium abundances have been found by Wallerstein and at Pretoria. These results suggest that solar-mass stars are able to synthesise fresh lithium in or just prior to their subgiant phase.

scholarly journals On the Link Between Rotation and Lithium in Giant stars

2000 ◽  
Vol 198 ◽  
pp. 500-501
Author(s):  
J. R. De Medeiros ◽  
J. D. Nascimento ◽  
S Sankarankutty ◽  
J. M. Costa ◽  
J. R. P. Da Silva ◽  
...  
Keyword(s):  
Spectral Type ◽  
Lithium Content ◽  
Late Type ◽  
Lithium Abundance ◽  
Root Cause ◽  
Giant Stars ◽  
Evolved Stars ◽  
Solar Type ◽  
Type Giant ◽  
The Relationship

Late-type evolved stars are well known for the decrease with age of their rotation and lithium abundance. However, the root cause of this property as well as the relationship between rotation and lithium content in these stars are not yet completely established. In the present work, we study the link between rotation and lithium abundances in solar-type giant stars on the basis of a large sample of 380 stars of spectral type F, G and K.

scholarly journals 3D non-LTE corrections for Li abundance and 6Li/7Li isotopic ratio in solar-type stars

2018 ◽  
Vol 618 ◽  
pp. A16 ◽  
Author(s):  
G. Harutyunyan ◽  
M. Steffen ◽  
A. Mott ◽  
E. Caffau ◽  
G. Israelian ◽  
...  
Keyword(s):  
Spectral Synthesis ◽  
Isotopic Ratio ◽  
Stellar Atmospheres ◽  
Line Profiles ◽  
Solar Mass ◽  
Lithium Abundance ◽  
Dwarf Stars ◽  
Link Type ◽  
Solar Type ◽  
The Impact

Context. Convective motions in solar-type stellar atmospheres induce Doppler shifts that affect the strengths and shapes of spectral absorption lines and create slightly asymmetric line profiles. One-dimensional (1D) local thermodynamic equilibrium (LTE) studies of elemental abundances are not able to reproduce this phenomenon, which becomes particularly important when modeling the impact of isotopic fine structure, like the subtle depression created by the 6Li isotope on the red wing of the Li I resonance doublet line. Aims. The purpose of this work is to provide corrections for the lithium abundance, A(Li), and the 6Li/7Li isotopic ratio that can easily be applied to correct 1D LTE lithium abundances in G and F dwarf stars of approximately solar mass and metallicity for three-dimensional (3D) and non-LTE (NLTE) effects. Methods. The corrections for A(Li) and 6Li/7Li are computed using grids of 3D NLTE and 1D LTE synthetic lithium line profiles, generated from 3D hydro-dynamical CO5BOLD and 1D hydrostatic model atmospheres, respectively. For comparative purposes, all calculations are performed for three different line lists representing the Li I λ670.8 nm spectral region. The 3D NLTE corrections are then approximated by analytical expressions as a function of the stellar parameters (Teff, log ℊ, [Fe/H], ν sin i, A(Li), 6Li/7Li). These are applied to adjust the 1D LTE isotopic lithium abundances in two solar-type stars, HD 207129 and HD 95456, for which high-quality HARPS observations are available. Results. The derived 3D NLTE corrections range between −0.01 and +0.11 dex for A(Li), and between −4.9 and −0.4% for 6Li/7Li, depending on the adopted stellar parameters. We confirm that the inferred 6Li abundance depends critically on the strength of the Si I 670.8025 nm line. Our findings show a general consistency with recent works on lithium abundance corrections. After the application of such corrections, we do not find a significant amount of 6Li in any of the two target stars. Conclusions. In the case of 6Li/7Li, our corrections are always negative, showing that 1D LTE analysis can significantly overestimate the presence of 6Li (up to 4.9% points) in the atmospheres of solar-like dwarf stars. These results emphasize the importance of reliable 3D model atmospheres combined with NLTE line formation for deriving precise isotopic lithium abundances. Although 3D NLTE spectral synthesis implies an extensive computational effort, the results can be made accessible with parametric tools like the ones presented in this work.

scholarly journals Exploiting kinematics and UBVIc photometry to establish high fidelity membership of the open cluster Blanco 1

2007 ◽  
Vol 3 (S248) ◽  
pp. 490-491
Author(s):  
P. A. Cargile ◽  
D. J. James ◽  
I. Platais ◽  
J.-C. Mermilliod ◽  
C. Deliyannis ◽  
...  
Keyword(s):  
High Precision ◽  
Open Cluster ◽  
High Fidelity ◽  
Wide Field ◽  
Proper Motions ◽  
Lithium Abundance ◽  
Kinematic Data ◽  
Internal Mixing ◽  
Solar Type ◽  
Bona Fide

AbstractWe present the results of a wide-field, high-precision UBVIc CCD photometric survey of the Galactic open cluster Blanco 1. Standardized photometry was acquired using the Y4Kcam on the SMARTS 1m telescope at CTIO. We have also determined new high-precision proper motions (σμ = 0.3 mas yr−1) over an eight square degree area down to V = 16.5. Combined with 1D kinematic data, our survey yields a complete list of cluster members down to ~ 0.5 M⊙ and new high-fidelity color-magnitude diagrams are presented for Blanco 1. Having established a bona fide membership catalog, astrophysical characteristics of solar-type cluster members such as X-ray activity and lithium abundance have been studied to gain more insights in the process of internal mixing and convection. Our new results should also help to better understand its peculiar location in the Milky Way and to unravel its dynamical history.

A Search for Dyson Spheres around Late-Type Stars in the Solar Neighborhood II

1997 ◽  
Vol 161 ◽  
pp. 707-709 ◽  
Author(s):  
Jun Jugaku ◽  
Shiro Nishimura
Keyword(s):  
Solar Neighborhood ◽  
The Sun ◽  
Late Type ◽  
Solar Type

AbstractWe continued our search for partial (incomplete) Dyson spheres associated with 50 solar-type stars (spectral classes F, G, and K) within 25 pc of the Sun. No candidate objects were found.

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