Herschel gets the rosette

Herschel image of the Rosette Nebula
Rosette Nebula as seen by Herschel. Image credit: ESA / PACS and SPIRE consortia / HOBYS Key Programme consortium

A new image of the Rosette Nebula as seen by Herschel has been released by ESA.  The three-colour image combines data from PACS at 70 microns (red) and 170 microns (green) with data from SPIRE at 250 microns (blue).  The blue material is warmer, and the red cooler - but all still at temperatures below about 40 Kelvin (-233oC).

The Rosette Nebula is a cloud of dust containing enough gas and dust to make about 10,000 stars like out Sun.  In the centre of the nebul, and off to the right hand side of this image, is a cluster of hot, bright young stars.  These are warming up the surrounding gas and dust, making it appear bluer.  The small, bright white regions are cocoons of dust in which huge stars are currently being born.  These "protostars", each one of which will probably become a star up to ten times more massive than the Sun, are heating up the surrounding gas and dust and making it clow brighter.  The smaller, redder dots on the left side and near the centre of the image also contain protostars, but these are smaller, and will go on to form stars much like our Sun.

Just as the centre of the nebula contains bright young stars, in a few tens or hundreds of millions of years these stars will have died, but the protostars will have evolved into fully-fledged stars in their own right.  In this way, the star formation will move outwards through the nebula.  To show this in context, the image below shows the Herschel image overlaid on an image taken by the Isaac Newton Telescope, on La Palma, which shows the hydrogen glowing in the nebula itself.

This image was taken as part of the "Herschel imaging survey of OB Young Stellar objects", or HOBYS for short.  The hottest and brightest stars are called "OB stars", and this project is targetting the formation and evolution of these giants.  While less common than their lighter, fainter siblings such as our Sun, OB stars provide a lot of light and can have a significant impact on their environment.  After a few million years, when they have consumed their vast amounts of fuel, these stars will die in supernovae, distributing their material throughout the neighbourhood and seeding further generations of stars.

The video below shows the Herschel image overlaid on an image taken in visbile light.  The background image, taken by Rob Gendler, is taken in "hydrogen alpha", which means that it excludes most of the light except that emitted by hydrogen.  Some of the features are visible in both images, particularly nearer the centre of the nebula.  However, what is glowing in infrared light as seen by Herschel is dark and opaque in visble light.

Higher resolution versions of the animations can be downloaded in Quicktime and AVI formats.

Image credits: ESA / SPIRE and PACS consortia / HOBYS Key Project Consortium (overlaid image) ; Robert Gendler (background image)


Click here for more download options of the image from the ESA website.