Small Region of Sky Source of Mysterious, Energetic Blasts

Astronomers have identified source as a supermassive, unknown star cluster containing some of the most massive stars in the Milky Way 

Hidden within the region inset in the small square lie some of the rarest, most massive stars in the galaxy.
Hidden within the region inset in the small square lie some of the rarest, most massive stars in the galaxy. More than a dozen red supergiant stars. Credit: NASA/ESA/STScI

Space news (unknown X-ray and gamma-ray sources) – 2/3 of the way to the core of the Milky Way or 18,900 light-years (5,800 parsecs) from Earth toward the constellation Scutum in the Bermuda Triangle of the Milky Way – 

For years, astronomers studied a small region of the sky called the Bermuda Triangle known for mysterious, highly energetic blasts of X-rays and gamma rays looking for clues to the source. The identity of the source was finally determined around 2005 as an unknown, hefty star cluster containing some of the rarest and most massive stars in the Milky Way. More than a dozen red supergiant stars, supermassive stars that are destroyed when a star goes supernova, within a million years time.  

This color composite image compiled by the Spitzer Space Telescope highlights the colors of the cosmos. Credit: NASA/ESA/STScI
This color composite image compiled by the Spitzer Space Telescope highlights the dazzling color palette of the cosmos. Credit: NASA/ESA/STScI

Astronomers detected 14 gigantic, red supergiant stars bloated to beyond 100 times their original size hidden within a star cluster estimated to be over 20 times the average size. Their outer envelopes of hydrogen bloated to beyond bursting, these behemoth stars are destined to end their days in one of the most energetic events in the cosmos a supernova. Destined to spread the elements of creation throughout the galaxy in a titanic explosion more energetic than the output of the entire Milky Way. 

“Only the most massive clusters can have lots of red supergiants because they are the only clusters capable of making behemoth stars,” explains Don Figer led scientists for the study. “They are good signposts that allow astronomers to predict the mass of the cluster. This observation also is a rare chance to study huge stars just before they explode. Normally, we don’t get to see stars before they pop off.” 

This very colorful artist's impression of the stars within this unknown star cluster. CreditNASA/ESA/STScI
This very colorful artist’s impression of the 14 red supergiant stars within this unknown star cluster. CreditNASA/ESA/STScI

What’s next for the team?

Red supergiant stars were indeed rare during the human journey to the beginning of space and time. Only about 200 such titanic stars have been identified among the hundreds of millions detected in the Milky Way. Finding 14 of these behemoth stars relatively close to Earth is an opportunity for astronomers to study their life cycle in greater detail. An opportunity Figer and his team at the Space Telescope Science Institute (STScI) in Baltimore plan on taking full advantage of during the years ahead. 

At the same time, Figer and his team of space scientists plan on studying an additional 130 supermassive star cluster candidates from the newly found clusters compiled in the Two Micron All Sky Survey catalog. “We can only see a small part of our galaxy in visible light because a dusty veil covers most of our galaxy,” Figer said. “I know there are other massive clusters in the Milky Way that we can’t see because of the dust. My goal is to find them using infrared light, which penetrates the dusty veil.” 

“Mysterious X-ray and gamma ray source explained!” 

“Now, we search for new cosmic mysteries to unveil!”

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Learn more about red supergiant stars

Read about the Nuclear Star Cluster, the Milky Way’s densest star cluster.

Learn more about the giant star blowing a huge bubble of gas.

Read about astronomers discovering superstar binary systems like Eta Carinae are more common than first thought.

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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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