THE BANANA PROJECT. V. MISALIGNED AND PRECESSING STELLAR ROTATION AXES IN CV VELORUM

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 beta sub(p) = -52[degrees] + or - 6[degrees] an...

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Bibliographic Details
Published in:The Astrophysical journal 2014-04, Vol.785 (2), p.1-11
Main Authors: Albrecht, Simon, Winn, Joshua N, Torres, Guillermo, Fabrycky, Daniel C, Setiawan, Johny, Gillon, Michael, Jehin, Emmanuel, Triaud, Amaury, Queloz, Didier, Snellen, Ignas, Eggleton, Peter
Format: Article
Language:English
Subjects:
Angular momentum
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Aérospatiale, astronomie & astrophysique
BANANAS
binaries: eclipsing
BINARY STARS
COMPARATIVE EVALUATIONS
ECLIPSE
EQUATIONS
EVOLUTION
GEOMETRY
Mathematical analysis
ORBITS
Physical, chemical, mathematical & earth Sciences
Physique, chimie, mathématiques & sciences de la terre
ROTATION
SKY
Space science, astronomy & astrophysics
SPIN
STARS
stars: early-type
stars: formation
stars: individual: CV Velorum DI Herculis EP Crucis
stars: kinematics and dynamics
stars: rotation
Stellar rotation
techniques: spectroscopic
Vectors (mathematics)
VELOCITY
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Summary: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 beta sub(p) = -52[degrees] + or - 6[degrees] and beta sub(s) = 3[degrees] + or - 7[degrees] 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 (v sin i sub([sstarf])) over the last 30 yr, leading to a model in which the primary star's obliquity is approximately 65[degrees], 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 v sin i sub([sstarf]). 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.
ISSN:0004-637X
1538-4357
1538-4357
DOI:10.1088/0004-637X/785/2/83