Face-on starburst spiral galaxy MCG+07-33-027 lies 300 million light-years from Earth in the constellation of Hercules. Click the image for a full-size version. Image credit: ESA/Hubble & NASA and N. Grogin (STScI).This image was taken by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), and shows a starburst galaxy named MCG+07-33-027. This galaxy lies some 300 million light-years away from us, and is currently experiencing an extraordinarily high rate of star formation — a starburst. Normal galaxies produce only a couple of new stars per year, but starburst galaxies can produce a hundred times more than that! As MCG+07-33-027 is seen face-on, the galaxy’s spiral arms and the bright star-forming regions within them are clearly visible and easy for astronomers to study.
In order to form newborn stars, the parent galaxy has to hold a large reservoir of gas, which is slowly depleted to spawn stars over time. For galaxies in a state of starburst, this intense period of star formation has to be triggered somehow — often this happens due to a collision with another galaxy. MCG+07-33-027, however, is special; while many galaxies are located within a large cluster of galaxies, MCG+07-33-027 is a field galaxy, which means it is rather isolated. Thus, the triggering of the starburst was most likely not due to a collision with a neighbouring or passing galaxy and astronomers are still speculating about the cause.
This NASA/ESA Hubble Space Telescope image shows the galaxy Messier 94, which lies in the small northern constellation of Canes Venatici (the Hunting Dogs), about 16 million light-years away. Within the bright ring or starburst ring around Messier 94, new stars are forming at a high rate and many young, bright stars are present within it.
This colourful bubble is a planetary nebula called NGC 6818, also known as the Little Gem Nebula, discovered by William Herschel in 1787. It is located in the constellation of Sagittarius, roughly 6,000 light-years away from us. The rich glow of the cloud is just over half a light-year across.
Astronomers using observations from the NASA/ESA Hubble Space Telescope and NASA’s Chandra X-ray Observatory have studied how dark matter in clusters of galaxies behaves when the clusters collide. The results show that dark matter interacts with itself even less than previously thought, and narrows down the options for what this mysterious substance might be.
