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arXiv · 2403.03065

Tight stellar binaries favour active longitudes at sub- and anti-stellar points

Ritika Sethi·David V. Martin
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Abstract

Stellar binaries are ubiquitous in the galaxy and a laboratory for astrophysical effects. We use TESS to study photometric modulations in the lightcurves of 162 unequal mass eclipsing binaries from the EBLM (Eclipsing Binary Low Mass) survey, comprising F/G/K primaries and M-dwarf secondaries. We detect modulations on 81 eclipsing binaries. We catalog the rotation rates of the primary star in 69 binaries and discover 17 ellipsoidal variables. In a large portion (at least $\sim 51\%$) of our sample, we detect photometric modulations consistent with two over-densities of spots on the primary star that are roughly $180^{\circ}$ apart. We show that these so-called active longitudes are preferentially at the sub- and anti-stellar points on the primary star. Physically, this means that the spots on the primary star preferentially face directly towards and away from the secondary star.

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Ritika Sethi, David V. Martin. 2024-03-05. Tight stellar binaries favour active longitudes at sub- and anti-stellar points. https://arxiv.org/abs/2403.03065

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