Three Luminous Blue Variables ( LBVs ) are located in and near the Quintuplet Cluster at the Galactic Center : the Pistol star , G0.120-0.048 , and qF362 .
We present imaging at 19 , 25 , 31 , and 37 \mu m of the region containing these three LBVs , obtained with SOFIA using FORCAST .
We argue that the Pistol and G0.120-0.048 are identical “ twins ” that exhibit contrasting nebulae due to the external influence of their different environments .
Our images reveal the asymmetric , compressed shell of hot dust surrounding the Pistol Star and provide the first detection of the thermal emission from the symmetric , hot dust envelope surrounding G0.120-0.048 .
However , no detection of hot dust associated with qF362 is made .
Dust and gas composing the Pistol nebula are primarily heated and ionized by the nearby Quintuplet Cluster stars .
The northern region of the Pistol nebula is decelerated due to the interaction with the high-velocity ( 2000 km/s ) winds from adjacent Wolf-Rayet Carbon ( WC ) stars .
From fits to the spectral energy distribution ( SED ) of the Pistol nebula with the DustEM code we determine that the Pistol nebula is composed of a distribution of very small , transiently-heated grains ( 10 - \sim 35 \AA ) having a total dust mass of 0.03 M _ { \odot } , and that it exhibits a gradient of decreasing grain size from the south to the north due to differential sputtering by the winds from the WC stars .
The total IR luminosity of the Pistol nebula is 5.2 \times 10 ^ { 5 } L _ { \odot } .
Dust in the G0.120-0.048 nebula is primarily heated by the central star ; however , the nebular gas is ionized externally by the Arches Cluster .
Unlike the Pistol nebula , the G0.120-0.048 nebula is freely expanding into the surrounding medium .
A grain size distribution identical to that of the non-sputtered region of the Pistol nebula satisfies the constraints placed on the G0.120-0.048 nebula from DustEM model fits to its SED and implies a total dust mass of 0.021 M _ { \odot } .
The total IR luminosity of the G0.120-0.048 nebula is \sim 10 ^ { 5 } L _ { \odot } .
From Paschen- \alpha and 6 cm observations we determine a total gas mass of 9.3 M _ { \odot } and 6.2 M _ { \odot } for the Pistol and G0.120-0.048 nebulae , respectively .
Given the independent dust and gas mass estimates we find that the Pistol and G0.120-0.048 nebulae exhibit similar gas-to-dust mass ratios of 310 ^ { +77 } _ { -52 } and 293 ^ { +73 } _ { -101 } , respectively .
Both nebulae share identical size scales ( \sim 0.7 pc ) which suggests that they have similar dynamical timescales of \sim 10 ^ { 4 } yrs , assuming a shell expansion velocity of v _ { \mathrm { exp } } = 60 km/s .