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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 β{sub p} = –52° ± 6° and β{sub 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 {sub *}) 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 {sub *}. 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.

Authors:
; ;  [1];  [2];  [3];  [4]; ;  [5];  [6];  [7];  [8]
  1. Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
  3. Department of Astronomy and Astrophysics, University of California Santa Cruz, Santa Cruz, CA 95064 (United States)
  4. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
  5. Institut d'Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août 17, Bat. B5C, Liège 1 (Belgium)
  6. Observatoire Astronomique de lÚniversité de Genève, Chemin des Maillettes 51, Sauverny CH-1290 (Switzerland)
  7. Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)
  8. Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94551 (United States)
Publication Date:
OSTI Identifier:
22357129
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 785; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BANANAS; BINARY STARS; COMPARATIVE EVALUATIONS; ECLIPSE; EQUATIONS; EVOLUTION; GEOMETRY; ORBITS; ROTATION; SKY; SPIN; STARS; VELOCITY

Citation Formats

Albrecht, Simon, Winn, Joshua N., Triaud, Amaury, Torres, Guillermo, Fabrycky, Daniel C., Setiawan, Johny, Gillon, Michaël, Jehin, Emmanuel, Queloz, Didier, Snellen, Ignas, and Eggleton, Peter. The BANANA project. V. Misaligned and precessing stellar rotation axes in CV Velorum. United States: N. p., 2014. Web. doi:10.1088/0004-637X/785/2/83.
Albrecht, Simon, Winn, Joshua N., Triaud, Amaury, Torres, Guillermo, Fabrycky, Daniel C., Setiawan, Johny, Gillon, Michaël, Jehin, Emmanuel, Queloz, Didier, Snellen, Ignas, & Eggleton, Peter. The BANANA project. V. Misaligned and precessing stellar rotation axes in CV Velorum. United States. doi:10.1088/0004-637X/785/2/83.
Albrecht, Simon, Winn, Joshua N., Triaud, Amaury, Torres, Guillermo, Fabrycky, Daniel C., Setiawan, Johny, Gillon, Michaël, Jehin, Emmanuel, Queloz, Didier, Snellen, Ignas, and Eggleton, Peter. Sun . "The BANANA project. V. Misaligned and precessing stellar rotation axes in CV Velorum". United States. doi:10.1088/0004-637X/785/2/83.
@article{osti_22357129,
title = {The BANANA project. V. Misaligned and precessing stellar rotation axes in CV Velorum},
author = {Albrecht, Simon and Winn, Joshua N. and Triaud, Amaury and Torres, Guillermo and Fabrycky, Daniel C. and Setiawan, Johny and Gillon, Michaël and Jehin, Emmanuel and Queloz, Didier and Snellen, Ignas and Eggleton, Peter},
abstractNote = {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{sub p} = –52° ± 6° and β{sub 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 {sub *}) 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 {sub *}. 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.},
doi = {10.1088/0004-637X/785/2/83},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 785,
place = {United States},
year = {2014},
month = {4}
}