The banana project. V. Misaligned and precessing stellar rotation axes in CV Velorum

Simon Albrecht; Joshua N. Winn; Guillermo Torres; Daniel C. Fabrycky; Johny Setiawan; Michaël Gillon; Emmanuel Jehin; Amaury Triaud; Didier Queloz; Ignas Snellen; Peter Eggleton

doi:10.1088/0004-637X/785/2/83

The banana project. V. Misaligned and precessing stellar rotation axes in CV Velorum

Simon Albrecht, Joshua N. Winn, Guillermo Torres, Daniel C. Fabrycky, Johny Setiawan, Michaël Gillon, Emmanuel Jehin, Amaury Triaud, Didier Queloz, Ignas Snellen, Peter Eggleton

Research output: Contribution to journal › Article › peer-review

45 Scopus citations

Abstract

As part of the Binaries Are Not Always Neatly Aligned project (BANANA), we have found that the eclipsing binary CV Velorum has misaligned rotation axes. Based on our analysis of the Rossiter-McLaughlin effect, we find sky-projected spin-orbit angles of β_p = -52° ± 6°and β_s = 3°± 7°for the primary and secondary stars (B2.5V + B2.5V, P = 6.9 days). We combine this information with several measurements of changing projected stellar rotation speeds (vsin i _*) over the last 30 yr, leading to a model in which the primary star's obliquity is ≈65°, and its spin axis precesses around the total angular momentum vector with a period of about 140 yr. The geometry of the secondary star is less clear, although a significant obliquity is also implicated by the observed time variations in the vsin i _*. By integrating the secular tidal evolution equations backward in time, we find that the system could have evolved from a state of even stronger misalignment similar to DI Herculis, a younger but otherwise comparable binary.

Original language	English (US)
Article number	83
Journal	Astrophysical Journal
Volume	785
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/785/2/83
State	Published - Apr 20 2014
Externally published	Yes

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

Keywords

binaries: eclipsing
stars: early-type
stars: formation
stars: individual (CV Velorum, DI Herculis, EP Crucis)
stars: kinematics and dynamics
stars: rotation
techniques: spectroscopic

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10.1088/0004-637X/785/2/83

Cite this

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title = "The banana project. V. Misaligned and precessing stellar rotation axes in CV Velorum",

abstract = "As part of the Binaries Are Not Always Neatly Aligned project (BANANA), we have found that the eclipsing binary CV Velorum has misaligned rotation axes. Based on our analysis of the Rossiter-McLaughlin effect, we find sky-projected spin-orbit angles of βp = -52° ± 6°and βs = 3°± 7°for the primary and secondary stars (B2.5V + B2.5V, P = 6.9 days). We combine this information with several measurements of changing projected stellar rotation speeds (vsin i *) over the last 30 yr, leading to a model in which the primary star's obliquity is ≈65°, and its spin axis precesses around the total angular momentum vector with a period of about 140 yr. The geometry of the secondary star is less clear, although a significant obliquity is also implicated by the observed time variations in the vsin i *. By integrating the secular tidal evolution equations backward in time, we find that the system could have evolved from a state of even stronger misalignment similar to DI Herculis, a younger but otherwise comparable binary.",

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author = "Simon Albrecht and Winn, {Joshua N.} and Guillermo Torres and Fabrycky, {Daniel C.} and Johny Setiawan and Micha{\"e}l Gillon and Emmanuel Jehin and Amaury Triaud and Didier Queloz and Ignas Snellen and Peter Eggleton",

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T1 - The banana project. V. Misaligned and precessing stellar rotation axes in CV Velorum

AU - Albrecht, Simon

AU - Winn, Joshua N.

AU - Torres, Guillermo

AU - Fabrycky, Daniel C.

AU - Setiawan, Johny

AU - Gillon, Michaël

AU - Jehin, Emmanuel

AU - Triaud, Amaury

AU - Queloz, Didier

AU - Snellen, Ignas

AU - Eggleton, Peter

PY - 2014/4/20

Y1 - 2014/4/20

N2 - As part of the Binaries Are Not Always Neatly Aligned project (BANANA), we have found that the eclipsing binary CV Velorum has misaligned rotation axes. Based on our analysis of the Rossiter-McLaughlin effect, we find sky-projected spin-orbit angles of βp = -52° ± 6°and βs = 3°± 7°for the primary and secondary stars (B2.5V + B2.5V, P = 6.9 days). We combine this information with several measurements of changing projected stellar rotation speeds (vsin i *) over the last 30 yr, leading to a model in which the primary star's obliquity is ≈65°, and its spin axis precesses around the total angular momentum vector with a period of about 140 yr. The geometry of the secondary star is less clear, although a significant obliquity is also implicated by the observed time variations in the vsin i *. By integrating the secular tidal evolution equations backward in time, we find that the system could have evolved from a state of even stronger misalignment similar to DI Herculis, a younger but otherwise comparable binary.

AB - As part of the Binaries Are Not Always Neatly Aligned project (BANANA), we have found that the eclipsing binary CV Velorum has misaligned rotation axes. Based on our analysis of the Rossiter-McLaughlin effect, we find sky-projected spin-orbit angles of βp = -52° ± 6°and βs = 3°± 7°for the primary and secondary stars (B2.5V + B2.5V, P = 6.9 days). We combine this information with several measurements of changing projected stellar rotation speeds (vsin i *) over the last 30 yr, leading to a model in which the primary star's obliquity is ≈65°, and its spin axis precesses around the total angular momentum vector with a period of about 140 yr. The geometry of the secondary star is less clear, although a significant obliquity is also implicated by the observed time variations in the vsin i *. By integrating the secular tidal evolution equations backward in time, we find that the system could have evolved from a state of even stronger misalignment similar to DI Herculis, a younger but otherwise comparable binary.

KW - binaries: eclipsing

KW - stars: early-type

KW - stars: formation

KW - stars: individual (CV Velorum, DI Herculis, EP Crucis)

KW - stars: kinematics and dynamics

KW - stars: rotation

KW - techniques: spectroscopic

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ER -

The banana project. V. Misaligned and precessing stellar rotation axes in CV Velorum

Abstract

All Science Journal Classification (ASJC) codes

Keywords

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