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We report on NICER and MAXI observations of a long-duration thermonuclear X-ray burst and a subsequent outburst-like X-ray flare from the neutron star low-mass X-ray binary MAXI J0911─655. Prior to the burst, the source was in a persistent low/hard state with a power-law-dominated spectrum (Γ ∼ 1.7) and a mass accretion rate of ∼1% of the Eddington limit. The long burst, detected by MAXI on 2020 May 22 (MJD 58991.7101), was rapidly followed up by NICER. From time-resolved spectroscopy of the cooling tail, we estimate an exponential decay time of ≍43 minutes, the ignition column depth of ≍0.1 × 10<SUP>12</SUP> g cm<SUP>−2</SUP>, the burst fluence of ≍1.1 × 10<SUP>−4</SUP> erg cm<SUP>−2</SUP>, and the total energy release of ≍1.2 × 10<SUP>42</SUP> erg. Approximately 1 day after the burst onset, the 0.5─10 keV light curve unexpectedly rebrightened, initiating an outburst-like flare. During the peak of this flare, the persistent power-law flux increased from its preburst level of ∼0.27 × 10<SUP>−9</SUP>─1.4 × 10<SUP>−9</SUP> erg cm<SUP>−2</SUP> s<SUP>−1</SUP>. This flux enhancement was accompanied by significant spectral softening, with the photon index increasing to Γ ∼ 2.2. Subsequently, the flux decayed and the source returned to its baseline low/hard state. The observed timescales and energetics suggest that intense irradiation from the long burst amplified the ongoing thermal─viscous accretion process. This heating drove an inside-out heating front that temporarily enhanced the mass accretion rate, providing compelling observational evidence of a thermonuclear burst directly modulating the accretion dynamics of its surrounding disk.

Persistent, low-luminosity low-mass X-ray binaries offer a unique opportunity to study accretion in this poorly understood regime as well as to unveil new members of the ultracompact X-ray binary (UCXB) family, which are characterised by orbital periods (P<SUB>orb</SUB>) shorter than ∼80 min. We report on a NuSTAR archival observation that, for the first time above 10 keV, spatially resolves the Galactic Centre pair SLX 1744−299 and SLX 1744−300. We find SLX 1744−300 to be slightly brighter, with a flux ratio of ∼1.15, increasing to ∼1.3 when extrapolated to 0.5─10 keV. Both the timing (root-mean-square variability) and spectral properties (well described in both cases by a thermal Comptonisation model) indicate that the systems were in the hard state. The two sources, however, display markedly different behaviour throughout the observation. SLX 1744−299 shows a gradual flux decline consistent with a decrease in the mass-accretion rate, whereas SLX 1744−300 remains steady but exhibits two short-recurrence Type-I X-ray bursts indicative of mixed H and He burning. Combining our results with previously reported upper limits on the distance, we derived low persistent X-ray luminosities of L<SUB>X</SUB> ≲ 1.1 × 10<SUP>36</SUP> erg s<SUP>−1</SUP> and L<SUB>X</SUB> ≲ 2.6 × 10<SUP>36</SUP> erg s<SUP>−1</SUP> (3─78 keV) for SLX 1744−299 and SLX 1744−300, respectively. The corresponding mass-accretion rates, when compared with the critical values from the disc instability model, favour P<SUB>orb</SUB> ≲ 90 min and P<SUB>orb</SUB> ≲ 105─155 min. Although both limits are formally compatible with the UCXB regime, the case of SLX 1744−299 appears significantly more compelling, also considering the previously reported intermediate-duration burst.