An A&A preprint on ArXiv today discusses the recent super-active phase SAP of T CrB.
The SAP lasted between 2015 and 2023, during which T was about three-quarters of a magnitude brighter than normal. A similar SAP was observed prior to the 1946 eruption.
The authors find that the SAP was triggered in the inner part of the accretion disc, increasing the disc temperature and the mass accretion rate at the white dwarf surface. The higher temperature should have further enhanced the mass transfer and sustained the SAP.
The SAP abruptly stopped in 2023, implying that the disc has returned to a quiet phase. At this time accretion dropped to a very low level. Recently T has been gradually brightening again and accretion has picked up. Note that when sufficient material has accumulated on the surface of the white dwarf, it triggers the thermonuclear runaway that appears as a nova eruption.
