Ejected mass in FQ Cir’s nova outbursts

Determine the ejected mass (M_ejecta) in classical nova eruptions of FQ Circini with usable accuracy sufficient to compare against the inter-eruption accreted mass (M_accreted), in order to assess whether the white dwarf grows or erodes over time.

Background

Assessing whether a white dwarf can approach the Chandrasekhar limit requires knowing if it retains more mass than it ejects over repeated nova cycles. The authors emphasize that traditional methods for estimating M_ejecta suffer from 2–3 orders of magnitude uncertainty and explicitly note that no usable measurement exists for FQ Cir (and rapid recurrent novae).

A reliable determination of M_ejecta for FQ Cir would constrain mass-retention efficiency and help clarify whether HMCVs with ONe cores can reach conditions for AIC.

References

The huge problem with checking whether $M_{\rm ejecta}$ is more-or-less than $M_{\rm accreted}$ is that all the usual and traditional methods for estimating $M_{\rm ejecta}$ have 2--3 orders-of-magnitude real uncertainty. Importantly, for M31N 2008-12a, we have no measure of $M_{\rm ejecta}$ to any useable accuracy, and the same is true for all the RRNe and FQ Cir.

— FQ Circini: An Ordinary Nova with a High-mass B1 V(n)(e) Companion Whose Decretion Disk Transfers Mass to the White Dwarf via Roche-Lobe Overflow  (2511.16594 - Schaefer et al., 20 Nov 2025) in Section 4 (Supernova Progenitor?)

During classical nova eruptions, the WD loses mass, and between recurrent nova eruptions it gains mass through accretion; whether a nova WD mass overall increases or decreases over its life-time is, however, still a matter of debate.

— The instantaneous mass accretion rate of novae in quiescence: - an archival ultraviolet optical spectral analysis  (2608.18037 - Godon et al., 18 Aug 2026) in Section 1, Introduction