CPD–82 291: Multi-sector TESS Photometry and SED Analysis of an Active Eclipsing Binary
Abstract
We present a multi-sector TESS photometric and spectral energy distribution analysis of the eclipsing binary CPD–82 291 (RX J0853.1–8244). Eight TESS sectors reveal well-defined eclipses and substantial, changing out-of-eclipse modulation. The asymmetries are reproduced by different surface-brightness configurations at different epochs, consistent with strong and evolving stellar activity, although the fitted circular regions are not unique maps of individual starspots. A detached-binary light-curve model yields an orbital inclination of i≃82.°1 and a photometric mass ratio of qphot ≃ 0.464. Without a spectroscopic radial-velocity orbit, the mass ratio and absolute parameters are model dependent rather than dynamical measurements. Combining the light-curve geometry with the SED radius scale and Gaia distance gives R1 ≃ 1.25 R⊙ and R2 ≃ 3.70 R⊙; the corresponding model-inferred masses remain substantially less secure than the dimensionless light-curve parameters. The stellar photospheres reproduce the observed SED from the optical region through WISE W4, with no statistically significant mid-infrared excess. The only positive long-wavelength deviation is a low-significance 60 μm measurement, while the 90 μm result is an upper limit. A cool circumbinary-dust model can reproduce this tentative signal, but such a component is not required by the photometry, and its inferred mass and radial extent are non-unique and strongly model dependent. Evolutionary tracks place the primary close to the zero-age main sequence and the secondary well above the main-sequence locus. However, the absence of radial velocities and spectroscopic youth indicators, together with Gaia astrometry inconsistent with Chamaeleon I membership, prevents a secure pre-main-sequence classification. CPD–82 291 is therefore best regarded as an active eclipsing binary with uncertain evolutionary status and only a marginal far-infrared indication that could be reproduced by cool circumstellar material.