Primary driver of VY Scl low states

Determine whether changes in the mass-transfer rate from the donor star are the primary driver of low states in VY Scl variables, or whether alternative physical mechanisms produce these brightness declines.

Background

The paper describes the prevailing interpretation of VY Scl fading episodes as consequences of abrupt reductions in the donor-star mass-transfer rate, potentially caused by starspots near the inner Lagrangian point or by changes in the outer disk rim that disrupt irradiation feedback. It notes, however, that current observations do not compellingly support this explanation, leaving the physical origin of low states unresolved and motivating the proposed dynamics-driven disk-collapse scenario.

References

However, since current observations do not provide compelling support for this interpretation, whether changes in the mass transfer rate are indeed the primary driver of the low states remains an open question, and alternative physical mechanisms cannot yet be excluded.

— Dynamically driven collapse of a thermally stable accretion disk in a nova-like system  (2608.27878 - Li et al., 28 Aug 2026) in Section 1, Introduction

However, the physical mechanism responsible for this transition is still unclear.

— Dynamically driven collapse of a thermally stable accretion disk in a nova-like system  (2608.27878 - Li et al., 28 Aug 2026) in Section 3.3, Discussion, “A dynamics-driven morphological cycle of the accretion disk,” stage D