Looking deep into the Cat's Eye with Herschel/PACS
An overlay of a snapshot of individual PACS spectra for a line of ionized nitrogen (all taken
simultaneously with the PACS spectrometer) on the dust continuum as observed with
the PACS photometer. A near-infrared image taken by the Spitzer Space Observatory
illustrates the inner region of the nebula that was covered by the PACS measurements.
The lower part of the figure shows a comparison of the spatial distribution of
two different spectral lines: ionized nitrogen and neutral oxygen. The spectral intensity
distributions were reconstructed from a mosaic of 9 such snapshots, spatially sligthly
displaced against each other.
The two lines obviously originate from different
components within the object - where the ionised nitrogen emission is brightest,
there is a "hole" in the neutral oxygen. This is seen most clearly in the 2-colour
composite image at the lower right corner (neutral oxygen is shown in green, ionized nitrogen
After the surprising success of the earlier "sneak preview" of the PACS
photometer - a spectacular far-infrared colour image of the
Whirlpool Galaxy M51 - the first light observation of the spectrometer
part of the instrument was carried out on June 23.
The first object the telescope was pointed at with the PACS spectrometer
was the planetary nebula NGC 6543 in the constellation of Draco, also known
as the Cat's Eye Nebula, which was first discovered by William Herschel in 1786.
Already, these very first data fulfill the expectations of the PACS-Team at MPE
at this point and are of unprecedented sensitivity. The enormoue effort that went into the
development of PACS is beginning to pay off now.
"A lot of excitement is ahead of us"