In our star formation group meeting this afternoon, one object that came up was the Polaris Flare. Up until now I’ve only heard of this object in passing, but it is going to be mapped by Herschel so I thought I’d take a closer look.

The image below shows how it looks in the far-infrared using IRAS data from Chromoscope. I have drawn on the stars of Ursa Minor as a guide and also placed a green box around the footprint of the Herschel data. You can see the ‘flare’ as the arch of material streaming up and way from the central ‘blob’ where Polaris lies. Being an astronomer requires so much technical jargon!

The Polaris Flare was discovered in 1990 by Heithausen and Thaddeus who mapped the region in CO. It is a molecular cloud complex at a distance of 110 parsec. The flare appears to surround the star Polaris – the North Star – but in reality the two may not be related. Herschel mapped it as part of the science demonstration phase of operations and the images were shown at the Herschel meeting held in Madrid before Christmas. This was the same meeting that showed off the amazing Herschel data of the Rosette region.

The black-and-white image at the top (RSS readers click here), available as part of Alain Abergel’s talk, shows a chunk of the Polaris flare and reveals its delicate, cirrus structure. This image is from the SPIRE instrument and shows data at 250 microns. What you’re seeing is fairly cold dust in the interstellar medium (the material that lies between stars and is involved in their evolution).

A portion of the flare was mapped as a taster for one of the Herschel key projects: Evolution of Interstellar Dust (the footprint of the Herschel data is shown above as a green box). This is a group researching the structure and properties of the interstellar medium in different environments. One interesting thing to note is that this image – which is actually generated from a very high resolution set of data – contains a whole lot of something very different to cirrus nebulosity.

If you were to zoom in to a small portion of the image and change the contrast so that the background was revealed, as is done in the image below, then you would see a lot of small speckly dots. There are hundreds of thousands of them speckling the background of the whole molecular complex. These objects are galaxies. Lying far beyond the nebula itself, but ever-present in this far-infrared data, such a backdrop is rather confusing when you are trying to measure the properties of the nebula itself. This is a problem that star-formers will have to overcome in order to make detailed analyses of images like this.

Conversely of course, astronomers studying galaxies will wish the nebula was the thing that was removed. Astronomy is a very murky business indeed.