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arXiv · 2606.01867

LAMOST J010103.13+275449.6: A New Binary Exhibiting a Switch in Photometric Period from 1.7216\,d to 0.8444\,d

Y. H. Chen
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Abstract

LAMOST J010103.13+275449.6 is bright with an apparent magnitude of 10.764 in the SDSS $g$ band. We searched for two low resolution spectra from LAMOST, apparent magnitudes from GALEX, Pan-STARRS, 2MASS, and WISE, X-ray data from XMM-Newton, and light curve from TESS. It is very interesting that the photometric period of light curve switch from 1.7216\,d to 0.8444\,d. In previous large sample statistical studies, it was identified as an eclipsing binary, a rotational variable star, or an emission line star. The ultraviolet excess in 2006 from GALEX, the hard X-ray emission in 2016 from XMM-Netwon, the high amplitude photometric variability in 2019 from TESS, together with the nearly featureless photospheric spectra in 2011 and 2015 from LAMOST, collectively reduce the likelihood of the rapidly rotating single star magnetic activity scenario. The spectral fitting for the two main-sequence components shows that the system is a main-sequence binary consisting of F and G type stars. Mathematical modeling suggests that, with a 1.7216\,d orbital period and tidal locking of the companion, the period switching of the light curve can be semi-quantitatively explained by orbital motion, involving a large spot at the substellar point in the early phase and small spots at both the substellar and antipodal points in the later phase. The binary parameters are preliminary with large uncertainties and more in-depth studies can be carried out in the future based on more spectra that may be released by LAMOST.

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Y. H. Chen. 2026-06-01. LAMOST J010103.13+275449.6: A New Binary Exhibiting a Switch in Photometric Period from 1.7216\,d to 0.8444\,d. https://arxiv.org/abs/2606.01867

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