The luminous blue variable ( LBV ) RMC 143 is located in the outskirts of the 30 Doradus complex , a region rich with interstellar material and hot luminous stars .
We report the 3 \sigma sub-millimetre detection of its circumstellar nebula with ALMA .
The observed morphology in the sub-millimetre is different than previously observed with HST and ATCA in the optical and centimetre wavelength regimes .
The spectral energy distribution ( SED ) of RMC 143 suggests that two emission mechanisms contribute to the sub-mm emission : optically thin bremsstrahlung and dust .
Both the extinction map and the SED are consistent with a dusty massive nebula with a dust mass of 0.055 \pm 0.018 ~ { } M _ { \odot } ( assuming \kappa _ { 850 } = 1.7 cm ^ { 2 } g ^ { -1 } ) .
To date , RMC 143 has the most dusty LBV nebula observed in the Magellanic Clouds .
We have also re-examined the LBV classification of RMC 143 based on VLT/X-shooter spectra obtained in 2015/16 and a review of the publication record .
The radiative transfer code CMFGEN is used to derive its fundamental stellar parameters .
We find an effective temperature of \sim 8500 K , luminosity of log ( L / L _ { \odot } ) = 5.32 , and a relatively high mass-loss rate of 1.0 \times 10 ^ { -5 } ~ { } M _ { \odot } yr ^ { -1 } .
The luminosity is much lower than previously thought , which implies that the current stellar mass of \sim 8 ~ { } M _ { \odot } is comparable to its nebular mass of \sim 5.5 ~ { } M _ { \odot } ( from an assumed gas-to-dust ratio of 100 ) , suggesting that the star has lost a large fraction of its initial mass in past LBV eruptions or binary interactions .
While the star may have been hotter in the past , it is currently not hot enough to ionize its circumstellar nebula .
We propose that the nebula is ionized externally by the hot stars in the 30 Doradus star-forming region .