Astronomers using the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST) instrument onboard NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) have mapped the inner 600 light-years of our Milky Way Galaxy — home to a warm, turbulent interstellar medium that is unlike any other part of the Galaxy.
This composite image shows dense swirls of gas and dust in the central region of our Milky Way Galaxy. The image spans 600 light-years across and is helping astronomers learn how many massive stars are forming in the Galactic center. New data from SOFIA taken at 25 and 37 microns, shown in blue and green, are combined with data from ESA’s Herschel Space Observatory, shown in red (70 microns), and NASA’s Spitzer Space Telescope, shown in white (8 microns). Image credit: NASA / SOFIA / JPL-Caltech / ESA / Herschel.
The Milky Way’s central region has significantly more of the dense gas and dust that are the building blocks for new stars compared to other parts of the Galaxy. Yet, there are 10 times fewer massive stars born here than expected.
Understanding why this discrepancy exists has been difficult because of all the dust between Earth and the Galactic core getting in the way — but observing with infrared light offers a closer look at the situation.
“It’s incredible to see our Galactic center in detail we’ve never seen before,” said Dr. James Radomski, a Universities Space Research Association scientist at the SOFIA Science Center, NASA’s Ames Research Center.
“Studying this area has been like trying to assemble a puzzle with missing pieces. The SOFIA data fills in some of the holes, putting us significantly closer to having a complete picture.”
The new FORCAST/SOFIA data illuminate structures indicative of star birth near the Quintuplet Cluster and warm material near the Arches Cluster that could be the seeds for new stars.
Seeing these warm features in high resolution may help astronomers explain how some of the most massive stars in the Milky Way managed to form so close to each other, in a relatively small region, despite the low birthrate in the surrounding areas.
“Understanding how massive star birth happens at the center of our own Galaxy gives us information that can help us learn about other, more distant galaxies,” said Caltech astronomer Dr. Matthew Hankins.
“Using multiple telescopes gives us clues we need to understand these processes, and there’s still more to be uncovered.”
The new map from SOFIA also shows the material that may be feeding the ring around Sagittarius A*, the supermassive black hole at the Milky Way’s center.
“The ring is about 10 light-years in diameter and plays a key role in bringing matter closer to the black hole, where it may eventually be devoured,” the researchers said.
“The origin of this ring has long been a puzzle for scientists because it may be depleted over time, but the SOFIA data reveal several structures which could represent material being incorporated into it.”
Dr. Hankins and his colleagues presented the new results January 7 at the 235th Meeting of the American Astronomical Society in Honolulu, Hawai’i.
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M. Hankins et al. 2020. SOFIA/FORCAST Galactic Center Legacy Survey: Overview and First Results. 235th AAS Meeting, abstract # 336.02
