HRD of the stars studied in this work for a heliocentric distance of 5 kpc. The MSP and VPHAS sources are represented by the golden-filled circles, while the 0.10, 0.25, 0.5, and 1.0 Myr PARSEC isochrones (40 − 120 M_⊙ mass range) are shown by the dashed gray, red, blue, and green lines, respectively. Based on their position in this diagram, they are all very young massive stars, probably much younger than 1 Myr. The observed positions of the VPHAS sources #1273 and #1338 indicate that they are very massive main sequence stars with theoretical initial masses in the range 60 − 80 M_⊙, similar to those of sources MSP182, MSP183, and MSP199 that are placed in the Westerlund 2 cluster center (for more on this subject, see the main text).