ORIGIN OF LITHIUM ENRICHMENT IN K GIANTS

Journal Article · Sun Mar 20 04:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/730/1/L12· OSTI ID:21560433

Kumar, Yerra Bharat; Reddy, Bacham E ^[1]; Lambert, David L ^[2]

---

1. Indian Institute of Astrophysics, Bengaluru 560034 (India)
2. McDonald Observatory, University of Texas, Austin, TX 78712 (United States)

In this Letter, we report on a low-resolution spectroscopic survey for Li-rich K giants among 2000 low-mass (M {<=} 3 M{sub sun}) giants spanning the luminosity range from below to above the luminosity of the clump. Fifteen new Li-rich giants including four super Li-rich K giants (log {epsilon}(Li) {>=}3.2) were discovered. A significant finding is that there is a concentration of Li-rich K giants at the luminosity of the clump or red horizontal branch. This new finding is partly a consequence of the fact that our low-resolution survey is the first large survey to include giants well below and above the red giant branch (RGB) bump and clump locations in the H-R diagram. Origin of the lithium enrichment may be plausibly attributed to the conversion of {sup 3}He via {sup 7}Be to {sup 7}Li by the Cameron-Fowler mechanism but the location for the onset of the conversion is uncertain. Two possible opportunities to effect this conversion are discussed: the bump in the first ascent of the RGB and the He-core flash at the tip of the RGB. The finite luminosity spread of the Li-rich giants serves to reject the idea that Li enhancement is, in general, a consequence of a giant swallowing a large planet.

• OSTI ID: 21560433
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 730; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALKALI METALS
ELEMENTS
ENRICHMENT
GIANT STARS
LITHIUM
LUMINOSITY
METALS
OPTICAL PROPERTIES
ORIGIN
PHYSICAL PROPERTIES
STARS