Context . We present an analysis of mid- and far-infrared ( IR ) spectrum and spectral energy distribution ( SED ) of the luminous blue variable ( LBV ) R71 in the Large Magellanic Cloud ( LMC ) . Aims . This work aims to understand the overall contribution of high-mass LBVs to the total dust-mass budget of the interstellar medium ( ISM ) of the LMC and compare this with the contribution from low-mass asymptotic giant branch ( AGB ) stars .
As a case study , we analyze the SED of R71 . Methods . We compiled all the available photometric and spectroscopic observational fluxes from various telescopes for a wide wavelength range ( 0.36 – 250 \mu m ) .
We determined the dust composition from the spectroscopic data , and derived the ejected dust mass , dust mass-loss rate , and other dust shell properties by modeling the SED of R71 .
We noted nine spectral features in the dust shell of R71 by analyzing Spitzer Space Telescope spectroscopic data .
Among these , we identified three new crystalline silicate features .
We computed our model spectrum by using 3D radiative transfer code MCMax . Results . Our model calculation shows that dust is dominated by amorphous silicates , with some crystalline silicates , metallic iron , and a very tiny amount of polycyclic aromatic hydrocarbon ( PAH ) molecules .
The presence of both silicates and PAHs indicates that the dust has a mixed chemistry .
We derived a dust mass of 0.01 M _ { \odot } , from which we arrive at a total ejected mass of \approx 5 M _ { \odot } .
This implies a time-averaged dust mass-loss rate of 2.5 \times 10 ^ { -6 } M _ { \odot } yr ^ { -1 } with an explosion about 4000 years ago .
We assume that the other five confirmed dusty LBVs in the LMC loose mass at a similar rate , and estimate the total contribution to the mass budget of the LMC to be \approx 10 ^ { -5 } M _ { \odot } yr ^ { -1 } , which is comparable to the contribution by all the AGB stars in the LMC . Conclusions . Based on our analysis on R71 , we speculate that LBVs as a class may be an important dust source in the ISM of the LMC .