Category: Hubble

Astronomers released this beautiful photograph of the grand spiral design galaxy, M81, captured by the Hubble Space Telescope. Although it looks like a single image, it was actually constructed by stitching together many images on computer, using three different wavelengths of light.

M81 is located about 11.6 million light-years in the constellation of Ursa Major. We’re fortunate that it’s turned at an oblique angle towards the Earth, so we can see a full view of the spiral structure. Hubble’s view of M81 is so crisp and clear that individual stars can be resolved, as well as open clusters and globular star clusters.

The older, redder stars are contained around the galaxy’s central bulge, and it has regions of star formation along its spiral arms. Astronomers suspect that its recent nearby encounter with another galaxy (M82) unleashed the period of star formation about 300 million years ago.

The image was released as part of the Americal Astronomical Society Meeting in Honolulu, which is currently going on in Hawaii.

Original Source: Hubble News Release

Astronomers have long believed that globular star clusters formed out of a single cloud of dust and gas. All the stars in the cluster should be roughly the same age. But new observations from the Hubble Space Telescope show this isn’t always the case – in cluster NGC 2808, there were three distinct periods of star formation.

Globular star clusters are some of the most ancient objects in the Universe, forming shortly after their parent galaxies came together. They’re compact swarms with hundreds of thousands of stars held together by mutual gravity. The traditional view is that these clusters formed together, from the same material, at the same time, and then evolved together over time.

These new Hubble observations show that there are clearly three different populations of stars in globular cluster NGC 2808. All of the stars formed within 200 million years of each other. Each generation contains a different mix of chemicals, with increasing quantities of helium.

One theory is that the clusters hung onto large quantities of gas, beyond that initial period of star formation. Some event, or shockwaves from supernovae might have collapsed this gas, mixing in heavier elements to create additional stars. Another possibility is that NGC 2808 isn’t a globular cluster at all, but an ancient dwarf galaxy that was stripped of most of its material when it was captured by the Milky Way.

Original Source: Hubble News Release