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The nucleosynthesis of heavy elements in low-mass AGB stars
We take 13C(α,n)16O as neutron source, allowfor variation of the mass of the nucleus with thermal pulse number andadopt the unbranched s process path from 56Fe to210Bi in an attempt to explain the overabundance of heavyelements in MS and S stars. We found stars with larger masses havelarger dilution factors because of a stronger convection and that thesestars fall in four different regions in the abundance diagram, thusenabling a rough estimate of the mass to be made. We show that, for a2.5 Msolar star, the third dredge-up stops after a certain number ofpulses because of the formation of a hollow shell structure, so the starwill show no Tc and this can account for the existence of binary systemsconsisting of a ``Tc-no'' AGB star with a main-sequence star companion.
| The heavy elements nucleosynthesis in the low mass AGB stars.
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| Photoelectric observations of lunar occultations. X
Photoelectric occulation results for 461 events observed during 15months are reported. They include 77 reappearances, 4 determinations ofangular diameter, 38 analyses of double or multiple stars including twopreviously unknown bright stars, and 8 previously known bright double ormultiple stars.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Yilanci |
| Sað Açýklýk: | 16h38m34.74s |
| Yükselim: | -18°49'32.5" |
| Görünürdeki Parlaklýk: | 6.992 |
| Uzaklýk: | 213.22 parsek |
| özdevim Sað Açýklýk: | -10.6 |
| özdevim Yükselim: | -12.9 |
| B-T magnitude: | 8.892 |
| V-T magnitude: | 7.149 |
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