The Red Spider Nebula

The Red Spider Nebula: Surfing in Sagittarius - not for the fainThe Red Spider Nebula, located some 3,000 light-years away in the constellation of Sagittarius, is a warm planetary nebula that contains one of the hottest stars known. The star’s powerful stellar winds generate 100 billion km high shock waves that sculpt the twin-lobed nebula. The waves are caused by supersonic shocks formed when the local gas is compressed and heated in front of the rapidly expanding lobes. The atoms caught in the shock emit the radiation seen in this image.

Image Credit: ESA

NGC 278

Cassiopeia’s unusual residentNGC 278 may look serene, but it isn’t. The galaxy is currently undergoing an terrific burst of star formation. The blue knots speckling the galaxy’s spiral arms mark clumps of hot newborn stars. However, NGC 278’s star formation is very unusual. It does not extend all across the galaxy to its outer edges but is only taking place within an inner ring roughly 6500 light-years across. The galaxy’s center is bright, but its extremities are much darker. This odd configuration may have been caused by a merger with a smaller, gas-rich galaxy which ignited the center of NGC 278 while the dusty remains of the smaller galaxy were dispersed into the galaxy’s outer regions. Whatever happened, such a ring of star formation, called a nuclear ring, is extremely rare in galaxies without bars at their centers.

Image Credit: ESA / NASA


Starburst galaxy Messier 94This is the galaxy Messier 94 which lies about 16 million light-years away. Within the bright ring around Messier 94, new stars are forming at a high rate, so many that that feature is called a starburst ring. This peculiarly-shaped star-forming region is likely the result of a pressure wave going outwards from the galactic center, compressing the gas and dust in the outer region. The compression causes the gas to collapse into denser clouds, and gravity pulls the gas and dust together inside the clouds until temperature and pressure are high enough for stars to be born.

Image Credit: ESA / NASA