A newly released image of 30 Doradus, also known as the Tarantula Nebula, shows wispy, spiderweb-like strands of gas revealing a dramatic battle between gravity and stellar energy that could give astronomers an idea of how massive stars have shaped this star-forming region and why they continue to do so to be born in this molecular cloud.
Located 170,000 light-years from Earth, the high-resolution image of the Tarantula Nebula is composed of data collected by the Atacama Large Millimeter/submillimeter Array (ALMA). Located in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, the Tarantula Nebula is one of the most luminous star-forming regions in our galactic backyard. It’s also one of the most active in terms of the birth of new stars – some of which have a mass more than 150 times that of the Sun. At the heart of the Large Magellanic Cloud lies a star-forming site that has produced 800,000 stars – half a million of which are hot, young, and massive stars.
This makes the nebula a prime target for researchers wanting to study star formation, and it has another unique property that makes it an exciting vantage point for research studies.
“What makes 30 Doradus unique is that it is close enough for us to study in detail how stars form, and yet its properties are similar to those found in very distant galaxies when the universe was young,”” European Space Agency (ESA) scientist Guido De Marchi, a scientist with the European Space Agency and co-author of a paper describing the work, said in the statement. “Thanks to 30 Doradus, we can study how stars formed 10 billion years ago, when most stars were born.”
The struggle for the birth of more massive stars
The “push and pull” observed by the researchers is generated by the energy provided by its vast stellar population and gravity, with the former tearing gas clouds into strand-like fragments, thus slowing star formation, and the latter attempting to gather gas clouds together to form form stars.
“These fragments could be the remnants of once-larger clouds, shredded by the tremendous energy released by young and massive stars, a process called feedback,” says Tony Wong, a professor in the University of Astronomy Department Illinois at Urbana -Champaign in a press release from the European Southern Observatory (ESO). (opens in new tab).
The results also showed that despite intense stellar feedback, gravity is still shaping the nebula – located 170,000 light-years from Earth and adjacent to the Milky Way – and driving the continued formation of massive stars.
This contradicts previous consensus on such star-forming regions, which suggests that tenuous strands of gas, such as seen in the Tarantula Nebula, should be perturbed by this feedback too much to allow gravity to pull them together and form new stars.
“Our results suggest that even with very strong feedbacks, gravity can exert a strong influence and lead to continued star formation,” Wong continued.
Clump by clump, watching the spider web of the tarantula
Given its properties, it is not surprising that the Tarantula Nebula has been well studied. What makes this new research different is that previous studies have focused mostly on its center – the location of the densest gas and therefore fastest star formation – astronomers know that stars are also being formed in other regions of the nebula this team is collecting high up has resolution observations of a large region of the Tarantula Nebula, rather than focusing on its heart. With this global approach to the nebula in mind, they then dipped it into clumps that revealed a surprising pattern.
“We used to think of interstellar gas clouds as having bloated or rounded structures, but it is becoming increasingly clear that they are filiform or filiform,” Wong said in a National Radio Astronomy Observatory (NRAO) news release. (opens in new tab). “When we divided the cloud into clumps to measure differences in density, we found that the densest clumps are not placed randomly, but are highly organized on these filaments.”
Focusing on the light emitted by carbon monoxide gas allowed researchers to map the large, cold gas clouds in the Tarantula Nebula that are collapsing and forming young stars. They also observed how these gas clouds change as these young stars release tremendous amounts of energy.
“We expected that parts of the cloud closest to the young massive stars would show the clearest signs of gravity being overcome by feedbacks,” Wong said. (opens in new tab) “We found instead that gravity is still important in these feedback-prone regions — at least for parts of the cloud that are dense enough.”
Overlaying the data collected by ALMA with an infrared image of the Tarantula Nebula with bright stars and glowing hot gas from the Very Large Telescope and the Infrared Survey Telescope for Astronomy (VIS (opens in new tab)TA) creates a composite image showing the extent of its gas clouds and their distinct web-like shape.
While the team’s findings provide an indication of how gravity affects star-forming regions, the research is still a work in progress. “There is much more to be done with this fantastic dataset, and we are releasing it publicly to encourage other researchers to do new research,” concluded Wong.
Future studies will also focus on the differences between the Milky Way and the Tarantula Nebula, including star formation rates — while our galaxy is constantly forming stars, the Tarantula Nebula does so in “boom-and-bust” cycles.
Research on the Tarantula Nebula was presented June 15 at the 240th American Astronomical Society (AAS) meeting in Pasadena, California. The results are also presented in an article in the Astrophysical Journal.
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