Science & Technology

SOFIA Captures First Clear View of a Boiling Cosmic Cauldron Where Stars Are Born

A group led by UMD astronomers created the primary clear picture of an increasing bubble of stellar fuel the place stars are born utilizing knowledge from NASA’s SOFIA telescope on board a closely modified 747 jet as seen right here on this artist’s rendering. Credit score: Artist Rendering by Marc Pound/UMD

UMD-led group used NASA’s SOFIA telescope to seize high-resolution particulars of a star nursery within the Milky Means.

College of Maryland researchers created the primary high-resolution picture of an increasing bubble of scorching plasma and ionized fuel the place stars are born. Earlier low-resolution pictures didn’t clearly present the bubble or reveal the way it expanded into the encompassing fuel.

The researchers used knowledge collected by the Stratospheric Observatory for Infrared Astronomy (SOFIA) telescope to research one of the brightest, most large star-forming areas within the Milky Means galaxy. Their evaluation confirmed that a single, increasing bubble of heat fuel surrounds the Westerlund 2 star cluster and disproved earlier research suggesting there could also be two bubbles surrounding Westerlund 2. The researchers additionally recognized the supply of the bubble and the power driving its enlargement. Their outcomes have been revealed in The Astrophysical Journal on June 23, 2021.

“When large stars kind, they blow off a lot stronger ejections of protons, electrons and atoms of heavy steel, in comparison with our solar,” mentioned Maitraiyee Tiwari, a postdoctoral affiliate within the UMD Division of Astronomy and lead writer of the research. “These ejections are referred to as stellar winds, and excessive stellar winds are succesful of blowing and shaping bubbles within the surrounding clouds of chilly, dense fuel. We noticed simply such a bubble centered across the brightest cluster of stars on this area of the galaxy, and we have been in a position to measure its radius, mass and the pace at which it’s increasing.”

The surfaces of these increasing bubbles are made of a dense fuel of ionized carbon, and so they kind a sort of outer shell across the bubbles. New stars are believed to kind inside these shells. However like soup in a boiling cauldron, the bubbles enclosing these star clusters overlap and intermingle with clouds of surrounding fuel, making it onerous to tell apart the surfaces of particular person bubbles.

The RCW 49 galactic nebula pictured above is one of the brightest star-forming areas within the Milky Means. By analyzing the motion of carbon atoms in an increasing bubble of fuel surrounding the Westerlund 2 star cluster inside RCW 49, a UMD-led group of researchers have created the clearest picture thus far of a stellar-wind pushed bubble the place stars are born. Credit score: NASA/JPL-Caltec/E.Churchwell (College of Wisconsin)

Tiwari and her colleagues created a clearer image of the bubble surrounding Westerlund 2 by measuring the radiation emitted from the cluster throughout your entire electromagnetic spectrum, from high-energy X-rays to low-energy radio waves. Earlier research, which solely radio and submillimeter wavelength knowledge, had produced low-resolution pictures and didn’t present the bubble. Among the many most vital measurements was a far-infrared wavelength emitted by a particular ion of carbon within the shell.

“We are able to use spectroscopy to really inform how briskly this carbon is shifting both in the direction of or away from us,” mentioned Ramsey Karim (M.S. ’19, astronomy), a Ph.D. scholar in astronomy at UMD and a co-author of the research. “This system makes use of the Doppler impact, the identical impact that causes a practice’s horn to vary pitch because it passes you. In our case, the colour modifications barely relying on the speed of the carbon ions.”

By figuring out whether or not the carbon ions have been shifting towards or away from Earth and mixing that info with measurements from the remainder of the electromagnetic spectrum, Tiwari and Karim have been in a position to create a 3D view of the increasing stellar-wind bubble surrounding Westerlund 2.

Along with discovering a single, stellar wind-driven bubble round Westerlund 2, they discovered proof of new stars forming within the shell area of this bubble. Their evaluation additionally means that because the bubble expanded, it broke open on one aspect, releasing scorching plasma and slowing enlargement of the shell roughly a million years in the past. However then, about 200,000 or 300,000 years in the past, one other vibrant star in Westerlund 2 advanced, and its power re-invigorated the enlargement of the Westerlund 2 shell.

“We noticed that the enlargement of the bubble surrounding Westerlund 2 was reaccelerated by winds from one other very large star, and that began the method of enlargement and star formation over again,” Tiwari mentioned. “This means stars will proceed to be born on this shell for a very long time, however as this course of goes on, the brand new stars will grow to be much less and fewer large.”

Tiwari and her colleagues will now apply their methodology to different vibrant star clusters and heat fuel bubbles to raised perceive these star-forming areas of the galaxy. The work is an element of a multi-year NASA-supported program referred to as FEEDBACK.

Reference: “SOFIA FEEDBACK Survey: Exploring the Dynamics of the Stellar-wind-driven Shell of RCW 49” by Tiwari, M., Karim, R., Pound, M. W., Wolfire, M., Jacob, A., Buchbender, C., Güsten, R., Guevara, C., Higgins, R. D., Kabanovic, S., Pabst, C., Ricken, O., Schneider, N., Simon, R., Stutzki, J., Tielens, A. G. G. M., 23 June 2021, The Astrophysical Journal.
DOI: 10.3847/1538-4357/abf6ce

Extra co-authors of the analysis paper from UMD’s Division of Astronomy embrace Analysis Scientists Marc Pound and Mark Wolfire and Adjunct Professor Alexander Tielens. This work was supported by the NASA-funded FEEDBACK undertaking (Award No. SOF070077). The content material of this text doesn’t essentially replicate the views of this group.

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