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.
A fossilised remnant of the early Milky Way harbouring stars of hugely different ages has been revealed by an international team of astronomers. Terzan 5 resembles a globular cluster, but is unlike any other cluster known. It contains stars remarkably similar to the most ancient stars in the Milky Way and bridges the gap in understanding between our galaxy’s past and its present.
Galactic arms, sunflowers and whirlpools are only a few examples of nature’s apparent preference for spirals. A beautiful example is Messier 63, nicknamed the Sunflower Galaxy, its winding arms shining bright due to the presence of recently formed, blue–white giant stars and clusters, readily seen in this NASA/ESA Hubble Space Telescope image.
The first use of adaptive optics to measure the Hubble constant appears to confirm a discrepancy in cosmologists’ understanding of how fast the universe is expanding.
