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arXiv · 0706.2325

The Monitor project: JW 380 -- a 0.26, 0.15 Msol pre main sequence eclipsing binary in the Orion Nebula Cluster

Jonathan Irwin·Suzanne Aigrain·Simon Hodgkin·Keivan G. Stassun·Leslie Hebb·Mike Irwin·Estelle Moraux·Jerome Bouvier·Aude Alapini·Richard Alexander·D. M. Bramich·Jon Holtzman·Eduardo L. Martin·Mark J. McCaughrean·Frederic Pont·P. E. Verrier·Maria Rosa Zapatero Osorio
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Abstract

We report the discovery of a low-mass (0.26 +/- 0.02, 0.15 +/- 0.01 Msol) pre-main-sequence eclipsing binary with a 5.3 day orbital period. JW 380 was detected as part of a high-cadence time-resolved photometric survey (the Monitor project) using the 2.5m Isaac Newton Telescope and Wide Field Camera for a survey of a single field in the Orion Nebula Cluster (ONC) region in V and i bands. The star is assigned a 99 per cent membership probability from proper motion measurements, and radial velocity observations indicate a systemic velocity within 1 sigma of that of the ONC. Modelling of the combined light and radial velocity curves of the system gave stellar radii of 1.19 +0.04 -0.18 Rsol and 0.90 +0.17 -0.03 Rsol for the primary and secondary, with a significant third light contribution which is also visible as a third peak in the cross-correlation functions used to derive radial velocities. The masses and radii appear to be consistent with stellar models for 2-3 Myr age from several authors, within the present observational errors. These observations probe an important region of mass-radius parameter space, where there are currently only a handful of known pre-main-sequence eclipsing binary systems with precise measurements available in the literature.

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Jonathan Irwin, Suzanne Aigrain, Simon Hodgkin, Keivan G. Stassun, Leslie Hebb, Mike Irwin, Estelle Moraux, Jerome Bouvier, Aude Alapini, Richard Alexander, D. M. Bramich, Jon Holtzman, Eduardo L. Martin, Mark J. McCaughrean, Frederic Pont, P. E. Verrier, Maria Rosa Zapatero Osorio. 2007-06-15. The Monitor project: JW 380 -- a 0.26, 0.15 Msol pre main sequence eclipsing binary in the Orion Nebula Cluster. https://doi.org/10.1111/j.1365-2966.2007.12117.x

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