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More success for Herschel July 11, 2009

Posted by Sarah in new astronomy, pics, science, space.
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After the early sneak preview from the PACS instrument on board the recently launched Herschel infrared space telescope, more images have now been released from its other instruments, SPIRE and HIFI. The above image shows images taken with the IR imager and spectrometer SPIRE of nearby galaxy M74 at 250 micron. The amount of detail visible in the images is really great, particularly as all the image reconstruction software hasn’t even been optimised yet. We may be very used to seeing spectacularly detailed images from Hubble, but achieving these resolutions at Herschel’s far-infrared wavelengths is very new.

Because of diffraction, the resolution of an image scales linearly with the wavelength of the light for a given telescope size (in the absence of the Earth’s atmosphere, which tends to interfere!) – so as the wavelengths get longer, the image gets fuzzier. Hubble observes the Universe at wavelengths around 1000 times shorter than Herschel and is therefore capable of imaging at much higher resolution (i.e. more detail is visible) from the outset. At the same time, the comparison in the image above with the Spitzer space telescope, whose mirror is only a fifth of the the size of Herschel’s, shows the gains to be made with a larger telescope size at a given wavelength.  Even though optical and infrared astronomy are often placed under the same header, the technology required to produce images in the infrared is a little different, more challenging to produce and therefore pricier – particularly at the far-infrared wavelengths where Herschel operates.

The Herschel science team also published some images from the telescope’s third instrument, the high-resolution spectrometer HIFI. The picture on the left shows an overlay of HIFI high-resolution spectra of newly forming stars in giant molecular cloud DR21 on mid-infrared Spitzer images of the region.

In summary, all the news from Herschel is good! I look forward to much more new science from it, and congratulations to all the teams who’ve been working hard to make this happen.

The ESA webpage with more details of these images is here. The CoolCosmos site at Caltech gives an excellent and accessible overview of infrared astronomy.

Update 11/07/09: Watch a video of the Herschel/PACS team as they receive the beautiful picture of M51 from the telescope, here. Great stuff!

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