Hardness ratios of sources in HM1 for MOS1 (left), MOS2 (middle), and pn (right). Different types of sources are distinguished by symbols. The massive, blue stars are shown with blue filled symbols (triangle for the known binary, circles for the others). The low-mass FK stars are shown with green open triangles. The other X-ray bright objects (i.e., with at least 500 EPIC counts) with and without 2MASS counterparts are displayed as cyan crosses and black stars, respectively. The remaining, faint sources are represented by red asterisks (see top of the figure − error bars are not shown for the other sources), and potentially spurious sources are not shown. WR87 is the hardest massive star. The color version of this figure is available online.