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The lithium in weak G-band stars
Available data on Li abundance and CH band weakness in weak G-band starsindicates the existence of a linear relationship between Li and carbonabundance. Weak G-band stars with a high Li abundance are least depletedin C, and weak G-band stars with a relatively low Li abundance have avery low abundance of C. Li production seems to be a necessity after thestar leaves the main sequence and reaches the giant branch, probably byspallation reactions on the surface. Then mixing due to meridionalcirculation on the giant branch might bring out the CN-processedmaterial to the surface, at the same time destroying the surface Li.Thus, both C and Li abundances are depleted together.
| Further spectroscopic evidence bearing on the M22-Omega Centauri comparison
Spectroscopic observations made at CTIO of stars from the giant-branchtip to well below the horizontal-branch level on the subgiant branch ofM22 (alpha = 18h 33m.3, delta = -23 deg 58 min/1950/, l = 9 deg, b = 8deg) provide identification of 15 new radial-velocity members, includinga second giant CH star (IV-24) and a possible subgiant CH star (III-32).In general, M22 stars show a marked range of CN strengths. These andother recent results seem consistent with the suggestion that M22 mayshare, albeit in a weaker form, some of the distinguishing anomalies ofOmega Cen.
| The lithium abundance in weak-G band stars
Lithium abundances are derived for ten weak-G band giants. The stars arefound to have at least normal lithium abundances, and may have enhancedlithium relative to normal giants of similar temperature. Also, broadlines found in the G5 giant HR 1023 can be interpreted as rotation witha variable radial velocity of amplitude 17 + or - 5 km/sec. Possibleinterpretations of these results are discussed.
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Osservazione e dati astrometrici
| Costellazione: | Acquario |
| Ascensione retta: | 21h51m33.58s |
| Declinazione: | -07°24'14.3" |
| Magnitudine apparente: | 8.903 |
| Distanza: | 884.956 parsec |
| Moto proprio RA: | -4.5 |
| Moto proprio Dec: | -1.3 |
| B-T magnitude: | 10.093 |
| V-T magnitude: | 9.002 |
Cataloghi e designazioni:
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