The blue straggler V106 in NGC 6791: a prototype progenitor of old single giants masquerading as young.

K Brogaard; S M Christiansen; F Grundahl; A Miglio; R G Izzard; T M Tauris; E L Sandquist; D A Vandenberg; J Jessen-hansen; T Arentoft; H Bruntt; S Frandsen; J A Orosz; G A Feiden; R Mathieu; A Geller; M Shetrone; N Ryde; D Stello; I Platais; S Meibom

doi:10.1093/mnras/sty2504

The blue straggler V106 in NGC 6791: a prototype progenitor of old single giants masquerading as young.

K Brogaard, S M Christiansen, F Grundahl, A Miglio, R G Izzard, T M Tauris, E L Sandquist, D A Vandenberg, J Jessen-hansen, T Arentoft, H Bruntt, S Frandsen, J A Orosz, G A Feiden, R Mathieu, A Geller, M Shetrone, N Ryde, D Stello, I PlataisS Meibom

Physics and Astronomy

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Abstract

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∼1.67M_⊙, more massive than the cluster turn-off, with R_p∼1.91R_⊙ and T_eff = 7110 ± 100 K. The secondary component is highly oversized and overluminous for its low mass with M_s∼0.182M_⊙, R_s∼0.864R_⊙ 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 over-massive 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.

Original language	English
Journal	Monthly Notices of the Royal Astronomical Society
Early online date	18 Sept 2018
DOIs	https://doi.org/10.1093/mnras/sty2504
Publication status	E-pub ahead of print - 18 Sept 2018

Keywords

stars: fundamental parameters
stars: individual: V106
binaries: close
blue stragglers
white dwarfs

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K_Brogaard_et_al_The_blue_straggler_V106_in_NGC_6791_Monthly_Notices_of_the_Royal_Astronomical_Society_2018
Checked for eligibility: 09/10/2018 This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record: K Brogaard, S M Christiansen, F Grundahl, A Miglio, R G Izzard, T M Tauris, E L Sandquist, D A VandenBerg, J Jessen-Hansen, T Arentoft, H Bruntt, S Frandsen, J A Orosz, G A Feiden, R Mathieu, A Geller, M Shetrone, N Ryde, D Stello, I Platais, S Meibom; The blue straggler V106 in NGC 6791: A prototype progenitor of old single giants masquerading as young., Monthly Notices of the Royal Astronomical Society, , sty2504, https://doi.org/10.1093/mnras/sty2504 is available online at: https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/sty2504/5101456
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https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/sty2504/5101456Licence: None: All rights reserved

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Brogaard, K., Christiansen, S. M., Grundahl, F., Miglio, A., Izzard, R. G., Tauris, T. M., Sandquist, E. L., Vandenberg, D. A., Jessen-hansen, J., Arentoft, T., Bruntt, H., Frandsen, S., Orosz, J. A., Feiden, G. A., Mathieu, R., Geller, A., Shetrone, M., Ryde, N., Stello, D., ... Meibom, S. (2018). The blue straggler V106 in NGC 6791: a prototype progenitor of old single giants masquerading as young. Monthly Notices of the Royal Astronomical Society. Advance online publication. https://doi.org/10.1093/mnras/sty2504

@article{c78e99950a71406aa9ab3a2ac41acae2,

title = "The blue straggler V106 in NGC 6791: a prototype progenitor of old single giants masquerading as young.",

abstract = "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 Mp∼1.67M⊙, more massive than the cluster turn-off, with Rp∼1.91R⊙ and Teff = 7110 ± 100 K. The secondary component is highly oversized and overluminous for its low mass with Ms∼0.182M⊙, Rs∼0.864R⊙ and Teff = 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 over-massive 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. ",

keywords = "stars: fundamental parameters, stars: individual: V106, binaries: close, blue stragglers, white dwarfs",

author = "K Brogaard and Christiansen, {S M} and F Grundahl and A Miglio and Izzard, {R G} and Tauris, {T M} and Sandquist, {E L} and Vandenberg, {D A} and J Jessen-hansen and T Arentoft and H Bruntt and S Frandsen and Orosz, {J A} and Feiden, {G A} and R Mathieu and A Geller and M Shetrone and N Ryde and D Stello and I Platais and S Meibom",

year = "2018",

month = sep,

day = "18",

doi = "10.1093/mnras/sty2504",

language = "English",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "SIPRI/Oxford University Press",

}

Brogaard, K, Christiansen, SM, Grundahl, F, Miglio, A, Izzard, RG, Tauris, TM, Sandquist, EL, Vandenberg, DA, Jessen-hansen, J, Arentoft, T, Bruntt, H, Frandsen, S, Orosz, JA, Feiden, GA, Mathieu, R, Geller, A, Shetrone, M, Ryde, N, Stello, D, Platais, I & Meibom, S 2018, 'The blue straggler V106 in NGC 6791: a prototype progenitor of old single giants masquerading as young.', Monthly Notices of the Royal Astronomical Society. https://doi.org/10.1093/mnras/sty2504

TY - JOUR

T1 - The blue straggler V106 in NGC 6791

T2 - a prototype progenitor of old single giants masquerading as young.

AU - Brogaard, K

AU - Christiansen, S M

AU - Grundahl, F

AU - Miglio, A

AU - Izzard, R G

AU - Tauris, T M

AU - Sandquist, E L

AU - Vandenberg, D A

AU - Jessen-hansen, J

AU - Arentoft, T

AU - Bruntt, H

AU - Frandsen, S

AU - Orosz, J A

AU - Feiden, G A

AU - Mathieu, R

AU - Geller, A

AU - Shetrone, M

AU - Ryde, N

AU - Stello, D

AU - Platais, I

AU - Meibom, S

PY - 2018/9/18

Y1 - 2018/9/18

N2 - 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 Mp∼1.67M⊙, more massive than the cluster turn-off, with Rp∼1.91R⊙ and Teff = 7110 ± 100 K. The secondary component is highly oversized and overluminous for its low mass with Ms∼0.182M⊙, Rs∼0.864R⊙ and Teff = 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 over-massive 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.

AB - 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 Mp∼1.67M⊙, more massive than the cluster turn-off, with Rp∼1.91R⊙ and Teff = 7110 ± 100 K. The secondary component is highly oversized and overluminous for its low mass with Ms∼0.182M⊙, Rs∼0.864R⊙ and Teff = 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 over-massive 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.

KW - stars: fundamental parameters

KW - stars: individual: V106

KW - binaries: close

KW - blue stragglers

KW - white dwarfs

U2 - 10.1093/mnras/sty2504

DO - 10.1093/mnras/sty2504

M3 - Article

SN - 0035-8711

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

ER -

The blue straggler V106 in NGC 6791: a prototype progenitor of old single giants masquerading as young.

Abstract

Keywords

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