Ellipsoidal modulation and multi-wavelength activity in the pre-cataclysmic binary RX J1553.0+4457
Abstract
RX J1553.0+4457 (TMTS J15530469+4457458) is a detached post-common-envelope binary containing a cool white dwarf and an active late-type companion. We present a multi-wavelength study combining BOOTES multi-band photometry, six sectors of public TESS full-frame imaging, Einstein Probe/FXT X-ray observations, CAFOS optical spectroscopy, and archival ultraviolet-to-mid-infrared photometry. The BOOTES data reveal two short optical flares separated by about 3 h, with amplitudes of roughly 1-1.5 mag and faster decay at shorter wavelengths. The combined TESS light curve shows a stable signal at P = 0.083782 d, consistent with the first harmonic of the known spectroscopic orbital period, and its folded morphology indicates ellipsoidal modulation from a tidally distorted late-type companion rather than an irradiation-dominated waveform. TESS flare energetics lie in the active M-dwarf regime. The Einstein Probe/FXT spectra show a factor of about 4 decline in the 0.3-10 keV flux, mainly associated with decreasing emission measures. The broadband SED is reproduced by a cool white dwarf plus a late-type M dwarf, with no clear hot-continuum or mid-infrared excess. RX J1553.0+4457 is therefore best interpreted as a detached pre-cataclysmic binary whose rapid optical variability is dominated by magnetic activity and whose orbital modulation is ellipsoidal, although a weak wind-fed or intermittent accretion contribution remains possible.
Cite
@article{arxiv.2605.02796,
title = {Ellipsoidal modulation and multi-wavelength activity in the pre-cataclysmic binary RX J1553.0+4457},
author = {S. -Y. Wu and M. Gritsevich and Q. -H. Lao and A. J. Castro-Tirado and Z. Li and Y. -D. Hu and I. Pérez-García and R. Sánchez-Ramírez and N. Castro-Segura and E. J. Fernández-García and M. D. Caballero-García and S. Guziy and I. Olivares and J. D. Sakowska and G. García-Segura and D. Hiriart and W. H. Lee and P. J. Meintjes and H. J. van Heerden and A. Martín-Carrillo and L. Hanlon and A. Maury and L. Hernández-García and I. M. Carrasco-García and S. Castillo-Carrión and A. Castellón and S. B. Pandey and C. J. Pérez del Pulgar and A. J. Reina and J. -M. Bai and Y. -F. Fan and C. -J. Wang and Y. -X. Xin and D. -R. Xiong and X. -H. Zhao and J. Mao and B. -L. Lun and K. Ye and C. -Z. Cui and A. F. Valeev and B. -B. Zhang and T. -R. Sun},
journal= {arXiv preprint arXiv:2605.02796},
year = {2026}
}
Comments
16 pages, 10 figures, 6 tables. Updated title, author list, abstract, and minor textual revisions