Bogumił Pilecki, Dariusz Graczyk, Wolfgang Gieren, Grzegorz Pietrzyński, Ian B. Thompson, Radosław Smolec, Andrzej Udalski, Igor Soszyński, Piotr Konorski, Mónica Taormina, Alexandre Gallenne, Dante Minniti, Márcio Catelan

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


We present here the first spectroscopic and photometric analysis of the double-lined eclipsing binary containing the classical, first-overtone (FO) Cepheid OGLE-LMC-CEP-2532 (MACHO 81.8997.87). The system has an orbital period of 800 days and the Cepheid is pulsating with a period of 2.035 days. Using spectroscopic data from three high-class telescopes and photometry from three surveys spanning 7500 days, we are able to derive the dynamical masses for both stars with an accuracy better than 3%. This makes the Cepheid in this system one of a few lassical Cepheids with an accurate dynamical mass determination (M1 = 3.90 +:0.10 MM). The companion is probably slightly less massive (3.82 ±0.10 MM ), but may have the same mass within errors (M2 M1 = 0.981 ±0.015). The system has an age of about 185 million years and the Cepheid is in a more advanced evolutionary stage. For the first time precise parameters are derived for both stars in this system. Due to the lack of the secondary eclipse for many years, not much was known about the Cepheids companion. In our analysis, we used extra information from the pulsations and the orbital solution from the radial velocity curve. The best model predicts a grazing secondary eclipse shallower than 1 mmag, hence undetectable in the data, about 370 days after the primary eclipse. The dynamical mass obtained here is the most accurate known for a FO Cepheid and will contribute to the solution of the Cepheid mass discrepancy problem.

Original languageEnglish
Article number29
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 10 Jun 2015


  • binaries: eclipsing
  • galaxies: individual (LMC)
  • stars: oscillations
  • stars: variables: Cepheids

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'THE ARAUCARIA PROJECT: The FIRST-OVERTONE CLASSICAL CEPHEID in the ECLIPSING SYSTEM OGLE-LMC-CEP-2532'. Together they form a unique fingerprint.

Cite this