Herschel image of supernova remnant W44
This image shows the supernova remnant W44 (SNR W44), a prime example of the interaction between the remains of a supernova and the dense interstellar material around it. The image is based on data gathered with ESA's Herschel space observatory at far-infrared wavelengths.
The image shows SNR W44's asymmetric expanding shell, which can be seen as the large violet bubble with filamentary texture occupying the left half of the image. The shell is about 100 light-years across and, just above the centre of the image, it is impacting the arc-shaped bright feature to the right – an HII region known as G34.8-0.7.
Observations at X-ray wavelengths have highlighted that the remnant's expanding shell is filled with hot, X-ray emitting gas. Hence, SNR W44 is classified as a mixed-morphology supernova remnant.
Around 10 000 light-years from us, SNR W44 is located in the molecular cloud complex known as W48, a rich star-forming region where a multitude of massive stars are being born. Two HII regions stand out in violet in the image, showing the intense activity of star formation in W48: G035.1387-00.7622 in the upper part of the image to the right, and G35.0-0.5 just to the right of the image centre. The bright flecks scattered across the image are denser clumps in the turbulent cloud medium and are the seeds of future massive stars. In the lower left corner of the image, the diffuse glow corresponds to emission from warm dust in the Galactic Plane, the disc-like structure that contains most of the stars and star-forming clouds in our Galaxy, the Milky Way.