Helix Nebula

The spectral energy distribution of WD 2226-210 superposed on an image of the Helix Nebula from Hubble Space Telescope

The spectral energy distribution of WD 2226-210 superposed on an image of the Helix Nebula from Hubble Space Telescope. The plot combines optical, infrared, and millimeter photometry, the Spitzer mid-infrared spectrum, and upper limits from WISE, Spitzer, SOFIA, Herschel, and ALMA. Models of the white dwarf photosphere (solid) and IR excess showing good fits to the data detections (circles) and upper limits (triangles). Helix Nebula image credit: NOIRLab; SED credit: J. P. Marshall.