TY - JOUR

T1 - On a rapid lithium enrichment and depletion of K giant stars

AU - De La Reza, R.

AU - Drake, N. A.

AU - Da Silva, L.

AU - Torres, C. A.O.

AU - Martin, E. L.

PY - 1997/1/1

Y1 - 1997/1/1

N2 - A model scenario has recently been introduced by de la Reza and colleagues to explain the presence of very strong Li lines in the spectra of some low-mass K giant stars. In this scenario all ordinary, Li-poor, K giants become Li rich during a short time (∼105 yr) when compared to the red giant phase of 5 × 107 yr. In this "Li period," a large number of the stars are associated with an expanding thin circumstellar shell supposedly triggered by an abrupt internal mixing mechanism resulting in a surface new 7Li enrichment. This Letter presents nearly 40 Li-rich K giants known up to now. The distribution of these Li-rich giants, along with 41 other observed K giants that have shells but are not Li rich, in a color-color IRAS diagram confirms this scenario, which indicates, also as a new result, that a rapid Li depletion takes place on a timescale of between ∼103 and 105 yr. This model explains the problem of the presence of K giants with far-infrared excesses presented by Zuckerman and colleagues. Other present and future tests of this scenario are briefly discussed.

AB - A model scenario has recently been introduced by de la Reza and colleagues to explain the presence of very strong Li lines in the spectra of some low-mass K giant stars. In this scenario all ordinary, Li-poor, K giants become Li rich during a short time (∼105 yr) when compared to the red giant phase of 5 × 107 yr. In this "Li period," a large number of the stars are associated with an expanding thin circumstellar shell supposedly triggered by an abrupt internal mixing mechanism resulting in a surface new 7Li enrichment. This Letter presents nearly 40 Li-rich K giants known up to now. The distribution of these Li-rich giants, along with 41 other observed K giants that have shells but are not Li rich, in a color-color IRAS diagram confirms this scenario, which indicates, also as a new result, that a rapid Li depletion takes place on a timescale of between ∼103 and 105 yr. This model explains the problem of the presence of K giants with far-infrared excesses presented by Zuckerman and colleagues. Other present and future tests of this scenario are briefly discussed.

KW - Infrared: stars

KW - Stars: circumstellar matter

KW - Stars: evolution

KW - Stars: late-type

KW - Stars: mass loss

UR - http://www.scopus.com/inward/record.url?scp=21744461412&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:21744461412

VL - 482

SP - L77-L80

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 PART II

ER -