T CrB photometry and spectra

We aim to derive a robust estimate of the most important parameters describing the physical nature of T CrB, trace the accretion history onto its white dwarf, and account for the unexpected delay in the occurrence of the new outburst: the SAP prior to 1946 was brighter, and it was followed by the nova eruption within 6 months from its conclusion.

This time the 2015-2023 SAP has been fainter and two years past its conclusion no new eruption has yet taken place. Between 2005-2025, a period covering SAP and the preceding quiescence, we collected a massive amount of photometric and spectroscopic observations at optical wavelengths, that we have analyzed together with the abundant ultraviolet observations available in the archive of the Swift satellite. Guided by the results of the orbital solution and in particular by the radiative modeling to which we subjected the whole set of available data, we found for T CrB a binary period of 227.556 days, an inclination of 61 deg, and masses of 1.35 and 0.93 Msun for the white dwarf and the M3III companion, respectively, making mass transfer dynamically stable.