UMD-led group utilized NASA’s SOFIA telescope to catch high-resolution information of a star nursery in the Milky Way.
University of Maryland scientists developed the very first high-resolution picture of a broadening bubble of hot plasma and ionized gas where stars are born. Previous low-resolution images did not plainly reveal the bubble or expose how it broadened into the surrounding gas.
The scientists utilized information gathered by the Stratospheric Observatory for Infrared Astronomy (SOFIA) telescope to evaluate among the brightest, most huge star-forming areas in the Milky Way galaxy. Their analysis revealed that a single, broadening bubble of warm gas surrounds the Westerlund 2 star cluster and negated earlier research studies recommending there might be 2 bubbles surrounding Westerlund 2. The scientists likewise recognized the source of the bubble and the energy driving its growth. Their outcomes were released in The Astrophysical Journal on June 23, 2021.
“When massive stars form, they blow off much stronger ejections of protons, electrons and atoms of heavy metal, compared to our sun,” stated Maitraiyee Tiwari, a postdoctoral partner in the UMD Department of Astronomy and lead author of the research study. “These ejections are called stellar winds, and extreme stellar winds are capable of blowing and shaping bubbles in the surrounding clouds of cold, dense gas. We observed just such a bubble centered around the brightest cluster of stars in this region of the galaxy, and we were able to measure its radius, mass and the speed at which it is expanding.”
The surface areas of these broadening bubbles are made from a thick gas of ionized carbon, and they form a sort of external shell around the bubbles. New stars are thought to form within these shells. But like soup in a boiling cauldron, the bubbles confining these star clusters overlap and intermingle with clouds of surrounding gas, making it difficult to differentiate the surface areas of private bubbles.
Tiwari and her associates developed a clearer image of the bubble surrounding Westerlund 2 by determining the radiation given off from the cluster throughout the whole electro-magnetic spectrum, from high-energy X-rays to low-energy radio waves. Previous research studies, which just radio and submillimeter wavelength information, had actually produced low-resolution images and did disappoint the bubble. Among the most crucial measurements was a far-infrared wavelength given off by a particular ion of carbon in the shell.
“We can use spectroscopy to actually tell how fast this carbon is moving either towards or away from us,” stated Ramsey Karim (M.S. ’19, astronomy), a Ph.D. trainee in astronomy at UMD and a co-author of the research study. “This technique uses the Doppler effect, the same effect that causes a train’s horn to change pitch as it passes you. In our case, the color changes slightly depending on the velocity of the carbon ions.”
By identifying whether the carbon ions were approaching or far from Earth and integrating that info with measurements from the remainder of the electro-magnetic spectrum, Tiwari and Karim had the ability to produce a 3D view of the broadening stellar-wind bubble surrounding Westerlund 2.
In addition to discovering a single, excellent wind-driven bubble around Westerlund 2, they discovered proof of brand-new stars forming in the shell area of this bubble. Their analysis likewise recommends that as the bubble broadened, it burst on one side, launching hot plasma and slowing growth of the shell approximately a million years back. But then, about 200,000 or 300,000 years back, another brilliant star in Westerlund 2 developed, and its energy re-invigorated the growth of the Westerlund 2 shell.
“We saw that the expansion of the bubble surrounding Westerlund 2 was reaccelerated by winds from another very massive star, and that started the process of expansion and star formation all over again,” Tiwari stated. “This suggests stars will continue to be born in this shell for a long time, but as this process goes on, the new stars will become less and less massive.”
Tiwari and her associates will now use their technique to other brilliant star clusters and warm gas bubbles to much better comprehend these star-forming areas of the galaxy. The work belongs to a multi-year NASA-supported program called 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.
Additional co-authors of the term paper from UMD’s Department of Astronomy consist of Research Scientists Marc Pound and Mark Wolfire and Adjunct Professor Alexander Tielens. This work was supported by the NASA-funded FEEDBACK job (Award No. SOF070077). The material of this post does not always show the views of this company.