PACS images of GJ 581 cropped to ± 50 arcsec from the star, at 70, 100 and 160 μm from top to bottom, respectively. In the left-hand column, the raw images show that the main emission is centrally located about the star position (image center) and that there are several point-sources in the field, barely detected at 70 μm, significantly at 100 μm, and more prominently at 160 μm, as expected for submillimeter background galaxies. In Sect. 4, we show that the main emission is extended and centered on the star position, as expected for a debris disk, and mingles with a background source ~11 arcsec toward the northwest. The panels in the middle column are the photosphere-subtracted images. The panels in the right-hand column show the best subtraction (lowest residuals) of a two-point source model, which assumes that there is no debris disk around GJ 581 but an extra background source located exactly behind the star in addition to the N W source. This model is rejected because of the systematic residuals left, indicative of an extended structure, especially at 70 and 100 μm. At each wavelength, the contours levels of the three images are the same and correspond to 1, 2, 3, 9, 15σ₀ (σ₀ = 0.0135 mJy/1′′ pixel) at 70 μm, 1, 2, 3, 6, 9, 12, 15σ₀ (σ₀ = 0.0094 mJy/1′′ pixel) at 100 μm, and 1, 2, 3, 5, 7, 9, 11σ₀ (σ₀ = 0.0251 mJy/2′′ pixel) at 160 μm. The coordinates of the image center provided in the labels correspond to the star position at epoch of observation (July 29th–August 1st 2011). The hatched circles are the beam FWHMs: 5.6, 6.8, and 11.4 arcsec at 70, 100, and 160 μm, respectively.