Hubble Discovery: ‘Monster Stars’ Found In Incredibly Dense Stellar Cluster

“Monster stars” have been found by British astronomers that defy scientific explanation, demanding that those who study the stars redefine what they know about enormous stars and their proximity to each other. In fact, there are so many of these “monster stars” about 170,000 light years away, scientists are hard-pressed to explain why they exist at all.

NPR reported March 19, that astronomers using the Hubble Space Telescope have found a crowded field of super-massive and super-luminous stars in the Tarantula Nebula, which is located inside the Large Magellanic Cloud, the larger of the two smaller galaxies nearest the Milky Way.

These “monster stars” are found in star cluster R136, which already is home to the most massive star yet discovered in all of space: R126a1, a star that registers over 250 times the solar mass of the Sun. The stars are packed in so closely that astronomers had to combine images taken from the Hubble Space Telescope with ultraviolet light data from an imaging spectrograph on the telescope itself, University of Sheffield’s Prof. Paul Crowther explained in a statement, giving due credit to the space telescope’s contributions to the observations.

NASA's Hubble Space Telescope [Image via European Space Agency/Wikimedia Commons/CC BY 3.0]“The ability to distinguish ultraviolet light from such an exceptionally crowded region into its component parts, resolving the signatures of individual stars, was only made possible with the instruments aboard Hubble,” Crowther said in a statement (per

Within the tightly clustered stars, the British astronomers detected nine that were at least 30 million times more luminous than the Sun. Crowther told BBC News that the stars are all close to their “Eddington limit,” which is the point where a stellar object becomes so massive that it begins to tear itself apart. He noted that the “monster stars” were shedding roughly the mass of the Earth in gaseous material each month.

“In just a tiny bit of this satellite galaxy, we see perhaps a couple of dozen stars with more than a 100 solar masses, of which nine are in a tight core just a few light-years across,” Prof. Crowther told BBC News. “But that two dozen number – that’s probably more than are in the entire Milky Way Galaxy for this type of star.”

Of the nine “monster stars,” four stars are 150 times the mass of the Sun. Five are more than 100 times as massive.

Note: Four of the stars, along with R126a1, were found in 2010, using data from a telescope in Chile. The current work by Crowther and company, whose work was published Thursday in Monthly Notices of the Royal Astronomical Society, was a continuation of the work the same group began half a decade ago. Their work was facilitated by the Hubble Space Telescope and its array of detection instruments.

Saida Caballero-Nieves of Sheffield’s Astronomy and Physics Department, and co-author of the study, pointed out that current understanding of binary star merger could not explain the proximity of so many massive bright stars.

“There have been suggestions that these monsters result from the merger of less extreme stars in close binary systems. From what we know about the frequency of massive mergers, this scenario can’t account for all the really massive stars that we see in R136, so it would appear that such stars can originate from the star formation process.”

Crowther told BBC News that that the dying of the binary formations would produce black holes, which would some day merge into a single massive black hole. The black holes created would then emit gravitational waves. He noted that the recent discovery of gravitational waves likely came from a pair of 30-solar mass black, which, he believes, were formed from 100-solar mass stars.

Star-forming Region R136 With Young Stars
(Image via NASA, ESA, F. Paresce (INAF-IASF, Bologna, Italy), R. O'Connell (University of Virginia, Charlottesville), and the Wide Field Camera 3 Science Oversight Committee/Wikimedia Commons/Public Domain)

NPR noted that NASA said in a statement released in 2009, along with a stunning photo of the R136 star cluster taken by the Hubble Space Telescope, that the stars’ luminosity provided a glimpse into their future. Although presently somewhat young on the cosmic scale of things, burning brightly meant a relatively short life, with the “stars destined to pop off, like a string of firecrackers, as supernovas in a few million years.”

[Image via Shutterstock]