The banana project. III. spin-orbit alignment in the long-period eclipsing binary NY cephei

Simon Albrecht*, Joshua N. Winn, Joshua A. Carter, Ignas A.G. Snellen, Ernst J.W. De Mooij

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Binaries are not always neatly aligned. Previous observations of the DI Her system showed that the spin axes of both stars are highly inclined with respect to one another and the orbital axis. Here, we report on a measurement of the spin-axis orientation of the primary star of the NY Cep system, which is similar to DI Her in many respects: it features two young early-type stars (∼6 Myr, B0.5V+B2V), in an eccentric and relatively long-period orbit (e = 0.48, P = 15d. 3). The sky projections of the rotation vector and the spin vector are well aligned (βp = 2° ± 4°), in strong contrast to DI Her. Although no convincing explanation has yet been given for the misalignment of DI Her, our results show that the phenomenon is not universal, and that a successful theory will need to account for the different outcome in the case of NY Cep.

Original languageEnglish
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 10 Jan 2011
Externally publishedYes


  • Stars: early-type
  • Stars: formation
  • Stars: individual (NY Cep)
  • Stars: kinematics and dynamics
  • Stars: rotation
  • Techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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