Absolute Dimensions of the Eccentric Eclipsing Binary V541 Cygni

Guillermo Torres, Chima D. McGruder, Robert J. Siverd, Joseph E. Rodriguez, Joshua Pepper, Daniel J. Stevens, Keivan G. Stassun, Michael B. Lund, David James

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12 Scopus citations


We report new spectroscopic and photometric observations of the main-sequence, detached, eccentric, double-lined eclipsing binary V541 Cyg (P = 15.34 days, e = 0.468). Using these observations together with existing measurements, we determine the component masses and radii to better than 1% precision: M1 = 2.335+0.017 -0.013 Mo, M2 =2.260+0.016 -0.013 Mo, R1 =1.859+0.012 -0.009 Ro , and R2 =1.808+0.015 -0.013 Ro. The nearly identical B9.5 stars have estimated effective temperatures of 10650 ±200 K and 10350 ±200 K. A comparison of these properties with current stellar evolution models shows excellent agreement at an age of about 190 Myr and [Fe/H] ≈ -0.18. Both components are found to be rotating at the pseudo-synchronous rate. The system displays a slow periastron advance that is dominated by general relativity (GR), and has previously been claimed to be slower than predicted by theory. Our new measurement ω =0.859+0.042 -0.017, deg century-1, has an 88% contribution from GR and agrees with the expected rate within the uncertainties. We also clarify the use of the gravity darkening coefficients in the light-curve fitting Eclipsing Binary Orbit Program (EBOP), a version of which we use here.

Original languageEnglish (US)
Article number177
JournalAstrophysical Journal
Issue number2
StatePublished - Feb 20 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.


  • binaries: eclipsing
  • stars: evolution
  • stars: fundamental parameters
  • stars: individual (V541 Cyg)
  • techniques: photometric


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