KIC 1718290: A HELIUM-RICH V1093-Her-LIKE PULSATOR ON THE BLUE HORIZONTAL BRANCH
- Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium)
- Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma (Spain)
- Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom)
- Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States)
- Department of Physics, Astronomy, and Materials Science, Missouri State University, Springfield, MO 65897 (United States)
- Dr. Karl Remeis-Observatory and ECAP, Astronomisches Inst., FAU Erlangen-Nuremberg, Sternwartstr. 7, D-96049 Bamberg (Germany)
We introduce the first g-mode pulsator found to reside on the classical blue horizontal branch. One year of Kepler observations of KIC 1718290 reveals a rich spectrum of low-amplitude modes with periods between 1 and 12 hr, most of which follow a regular spacing of 276.3 s. This mode structure strongly resembles that of the V1093 Her pulsators, with only a slight shift toward longer periods. Our spectroscopy, however, reveals KIC 1718290 to be quite distinct from the sdB stars that show V1093 Her pulsations, which all have surface gravities higher than log g = 5.1 and helium abundances depleted by at least an order of magnitude relative to the solar composition. We find that KIC 1718290 has T{sub eff} = 22,100 K, log g = 4.72, and a super-solar helium abundance (log N{sub He}/N{sub H} = -0.45). This places it well above the extreme horizontal branch, rather on the very blue end of the classical horizontal branch, where shell hydrogen burning is present. We conclude that KIC 1718290 must have suffered extreme mass loss during its first giant stage, but not sufficient to reach the extreme horizontal branch.
- OSTI ID:
- 22047705
- Journal Information:
- Astrophysical Journal Letters, Vol. 753, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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