Star Clusters of Unimaginable Size Exist in the Universe

Understanding how large star clusters form could tell us more about star formation when the universe was young

The Tarantula nebula in full glory
The Tarantula nebula in full glory

Astronomers news (2013-10-14) – Tonight we’ll journey to the truly titanic 30 Doradus nebula (also called the Tarantula nebula), 170 light-years away in the Large Magellanic Cloud, aboard the Hubble Space Telescope. The Large Magellanic Cloud is a smaller satellite galaxy to the Milky Way, where astronomers recently discovered something they suspected about the formation of larger star clusters.

Using Hubble’s Wide Field Camera 3, we’ll be able to look at images of the Tarantula nebula filled with startling reds, greens and blues, which indicates to astronomers the elemental composition of the  stars in the region. Blue light is from the hottest, most massive stars astronomers have found to date. Red light is from fluorescing hydrogen gas, while green light is the glow of oxygen.

Every element on the periodic table gives off light with a specific signature upon fluorescing. Scientists use this knowledge to analyze the light reaching Hubble’s Wide Field Camera 3 from the Tarantula nebula to determine the elemental composition of the stars in the region .They hope to use this knowledge to answer questions they have concerning star formation when the universe was still in its infancy.

30 Doradus is full of red, blue and yellow light
30 Doradus is full of red, blue and green light

NASA astronomers see something different going on in 30 Doradus

We’ll specifically journey to a region of the 30 Doradus nebula where astronomers recently discovered a pair of star clusters which they first thought was a single star cluster, is in fact a pair of star clusters in the initial stages of merging into a larger star cluster. Astronomers now think the merging of star clusters could help explain the abundance of large star clusters throughout the visible universe.

Lead scientist Elena Sabbi of the Space Telescope Science Institute in Baltimore, Maryland and her team first started looking at the region to find runaway stars. Runaway stars are fast-moving stars that have been kicked out of the stellar nursery where they first formed. Astronomers found the region surrounding 30 Doradus has a large number of runaway stars, which according to current star formation theories could not have formed at their present location. Astronomers now believe the runaway stars outside 30 Doradus could have been ejected out of the region at high speed due to dynamic interactions with other stellar bodies as the two star clusters merge into one larger star cluster.

This image of 30 Doradus makes one feel small
This image of 30 Doradus makes one feel small

Astrophysicists and astronomers started looking for clues

The first clue to the true nature of the event astronomers were viewing was the fact that parts of the star cluster varied in age by about 1 million years. Upon further study the team noticed the distribution of low-mass stars detected by Hubble were not spherical in shape as astronomers expected, but resembled the elongated shape of two merging galaxies. Now astronomers are studying this region of space and time to find clues to help them understand the way larger star clusters are formed in the universe. They also hope this discovery will help determine interesting and enlightening facts concerning the formation of star clusters when the universe was still young.

Astronomers are also looking further at this region of space and time to find other star clusters in the process of merging in the 30 Doradus nebula. They plan on using the ability of the James Webb Space Telescope to detect infrared light , once it comes on line, to take a closer look at areas within the Tarantula nebula where they think stars hidden within cocoons of dust are blocked from the view of telescopes and instruments detecting visible light.

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