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The blue straggler ...
Abstract
Ämnesord
Stäng
- We determine the properties of the binary star V106 in the old open cluster NGC 6791. We identify the system to be a blue straggler cluster member by using a combination of ground-based and Kepler photometry and multi-epoch spectroscopy. The properties of the primary component are found to be M-p similar to 1.67 M-circle dot, more massive than the cluster turn-off, with R-p similar to 1.91 R-circle dot and T-eff = 7110 +/- 100 K. The secondary component is highly oversized and overluminous for its low mass with M-s similar to 0.182 M-circle dot, R-s similar to 0.864 R-circle dot, and T-eff = 6875 +/- 200 K. We identify this secondary star as a bloated (proto) extremely low-mass helium white dwarf. These properties of V106 suggest that it represents a typical Algol-paradox system and that it evolved through a mass-transfer phase, which provides insight into its past evolution. We present a detailed binary stellar evolution model for the formation of V106 using the MESA code and find that the mass-transfer phase only ceased about 40 Myr ago. Due to the short orbital period (P = 1.4463 d), another mass-transfer phase is unavoidable once the current primary star evolves towards the red giant phase. We argue that V106 will evolve through a common-envelope phase within the next 100 Myr and merge to become a single overmassive giant. The high mass will make it appear young for its true age, which is revealed by the cluster properties. Therefore, V106 is potentially a prototype progenitor of old field giants masquerading as young.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- binaries: close
- blue stragglers
- stars: fundamental parameters
- stars: individual V106
- white dwarfs
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- ref (ämneskategori)
- art (ämneskategori)
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Brogaard, K.
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Christiansen, S. ...
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Grundahl, F.
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Miglio, A.
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Izzard, R. G.
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Tauris, T. M.
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visa fler...
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Sandquist, E. L.
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VandenBerg, D. A ...
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Jessen-Hansen, J ...
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Arentoft, T.
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Bruntt, H.
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Frandsen, S.
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Orosz, J. A.
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Feiden, Gregory ...
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Mathieu, R.
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Geller, A.
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Shetrone, M.
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Ryde, N.
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Stello, D.
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Platais, I.
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Meibom, S.
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