TY - JOUR

T1 - Rapidly rotating lithium-rich K giants

T2 - The new case of the giant PDS 365

AU - Drake, Natalia A.

AU - De la Reza, Ramiro

AU - Da Silva, Licio

AU - Lambert, David L.

PY - 2002/5/1

Y1 - 2002/5/1

N2 - PDS 365 is a newly detected, rapidly rotating (v sin i = 20 km s -1), single, low-mass giant star that with HD 233517 and HD 219025 forms a remarkable ensemble of single K giants with the unique properties of rapid rotation, very strong Li lines, an asymmetrical Hα profile, and a large far-infrared excess. Their v sin i values are between 18 and 23 km s -1, and their LTE Li abundances, log ε(Li), are between 2.9 and 3.9. Detailed analysis of PDS 365 reveals it to be a ∼1 M⊙ giant with a value of 12C/13C approximately equal to 12. A clear relation between high rotational velocities and very high Li abundances for K giant stars is found only when asymmetrical Ha profiles and large far-infrared excesses are present. If we consider single K giants, we find that among rapid (v sin i ≥ 8 km s-1) rotators, a very large proportion (∼50%) are Li-rich giants. This proportion is in contrast with a very low proportion (∼2%) of Li-rich stars among the much more common slowly rotating K giants. This striking difference is discussed in terms of proposed mechanisms for Li enrichment.

AB - PDS 365 is a newly detected, rapidly rotating (v sin i = 20 km s -1), single, low-mass giant star that with HD 233517 and HD 219025 forms a remarkable ensemble of single K giants with the unique properties of rapid rotation, very strong Li lines, an asymmetrical Hα profile, and a large far-infrared excess. Their v sin i values are between 18 and 23 km s -1, and their LTE Li abundances, log ε(Li), are between 2.9 and 3.9. Detailed analysis of PDS 365 reveals it to be a ∼1 M⊙ giant with a value of 12C/13C approximately equal to 12. A clear relation between high rotational velocities and very high Li abundances for K giant stars is found only when asymmetrical Ha profiles and large far-infrared excesses are present. If we consider single K giants, we find that among rapid (v sin i ≥ 8 km s-1) rotators, a very large proportion (∼50%) are Li-rich giants. This proportion is in contrast with a very low proportion (∼2%) of Li-rich stars among the much more common slowly rotating K giants. This striking difference is discussed in terms of proposed mechanisms for Li enrichment.

KW - Circumstellar matter

KW - Stars: abundances

KW - Stars: activity

KW - Stars: chemically peculiar

KW - Stars: individual (PDS 365)

KW - Stars: mass loss

KW - Stars: rotation

UR - http://www.scopus.com/inward/record.url?scp=0038009455&partnerID=8YFLogxK

U2 - 10.1086/339968

DO - 10.1086/339968

M3 - Article

AN - SCOPUS:0038009455

VL - 123

SP - 2703

EP - 2714

JO - Astronomical Journal

JF - Astronomical Journal

SN - 0004-6256

IS - 5 1757

ER -