Archive for the ‘Focus On’ Category

Focus On: Messier 80

Monday, October 9th, 2017


Messier 80, aka M80, is a globular cluster located nearly 33,000-light-years away, towards the constellation Scorpius. While most of the stars in this cluster are of similar age – about 13-billion years – scientists have noted a large number of younger “blue stragglers” within the cluster’s core. M80 also contains many bright red-giants, which you can see in greater detail by clicking on the Hubble image at left.


Globular clusters are dense collections of tens-of-thousands to hundreds-of-thousands of gravitationally-bound stars. They include the oldest stars in a galaxy and orbit the galactic core as a halo system. Our Milky Way has about 150 known globular clusters; larger galaxies can contain hundreds and even thousands of globular clusters. With upwards of 200,000 stars, our subject cluster, M80, is one of the most densely populated globulars in our galaxy. A few globulars, like M13 and Omega Centauri, contain even more stars.

Blue stragglers, like those found in M80, are younger main-sequence stars that are more massive and luminous than the general population of a cluster. The prevailing theory for their existence centers around the interactions between two or more cluster stars, resulting in the consequential transference of materials from one star to another.

Red-giants are older main-sequence stars with vastly inflated, thus cooler but brighter, atmospheres and lower masses. Our own Sun will someday expand into a red-giant star, engulfing the inner planets as it undergoes the hydrogen shell fusion stage.

The entire collection of M80’s stars spans some 96-light-years across. It has an apparent diameter of 10′, an apparent magnitude of 7.8, and appears as a distinctly fuzzy ball of light through a telescope or higher-powered binoculars. You can find this celestial gem about 4-degrees NW of bright red Antares (or between the scorpion’s bright red eye and its famous claw,) anytime that Scorpius is visible in your local sky. While you’re looking for M80, check-out another globular beauty, Messier 4, closer to Antares.

** ESO and HST offer some stunning images of globular (and open) clusters, here and here. **