Astronomers using the Wide Field Imager camera on the MPG/ESO 2.2-m telescope at ESO’s La Silla Observatory have snapped a spectacular new image of a Messier object known as M47, or Messier 47.
Star cluster Messier 47. Image credit: ESO.
Messier 47, also known as NGC 2422, is an open star cluster located in the constellation Puppis, about 1,600 light-years away.
It is dominated by a sprinkling of brilliant blue stars but also contains a few contrasting red giant stars.
Although it is bright and easy to see, Messier 47 is one of the least densely populated open clusters.
Only around 50 stars are visible in a region about 12 light-years across, compared to other similar objects which can contain thousands of stars.
The bright blue and white colors of these stars are an indication of their temperature, with hotter stars appearing bluer and cooler stars appearing redder.
There are also a few bright red stars in the picture – these are red giant stars that are further through their short life cycles than the less massive and longer-lived blue stars.
By chance Messier 47 appears close in the sky to another contrasting star cluster – Messier 46.
Messier 47 is relatively close, but Messier 46 is located around 5,500 light-years away and contains a lot more stars, with at least 500 stars present. Despite containing more stars, it appears significantly fainter due to its greater distance.
Messier 46 could be considered to be the older sister of Messier 47, with the former being about 300 million years old compared to the latter’s 78 million years.
Consequently, many of the most massive and brilliant of the stars in Messier 46 have already run through their short lives and are no longer visible, so most stars within this older cluster appear redder and cooler.
