We propose to observe a 3x3 oversampled map of the Planetary Nebula NGC 7009. The wavelength of the observation is centered on the 69micron band of crystalline silicate forsterite. This observation will strengthen the results obtained for the PN NGC 6543 (GT1_bdevries_1, PI: B.L. de Vries). For NGC 6543 we have already seen that the forsterite is confined to the inner part of the outflow, therefor linked to the denser last mass-loss phase. NGC 7009 is similar to NGC 6543 in size and age. Combining the observations of NGC 7009 with NGC 6543 will help to further investigate the dust-formation in the circumstellar environment of evolved stars and look at the link with mass-loss and possibly binarity. The total observing time is 2.1h
THROES: a caTalogue of HeRschel Observations of Evolved Stars. I. PACS range spectroscopy . Ramos-Medina J. et al. . Astronomy & Astrophysics, Volume 611, id.A41, 38 pp. . 611 . 10.1051\/0004-6361\/201731940 . 2018A&A...611A..41R ,
Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.