NASA, JPL-Caltech, Susan Stolovy (SSC/Caltech) et al.
- A NASA photo captured the center of the Milky Way galaxy in infrared light.
- The image shows the galactic center in unprecedented detail, but NASA's upcoming James Webb Space Telescope (JWST) will produce even better photos.
- JWST's powerful infrared cameras might even capture the disk of hot matter swirling around the supermassive black hole at the galaxy's center.
- Future images of the galaxy's center could help scientists answer questions about how the Milky Way formed and how it evolves over time.
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The center of the Milky Way is a crowded hub of millions of stars, bathed in harsh ultraviolet and X-ray radiation and swirling around a black hole as massive as 4 million suns.
A shroud of dust and gas makes it difficult to see all that activity, but NASA's Spitzer telescope cut through the fog with infrared sensors in 2006, producing an unprecedented image. The agency republished that photo (shown above) on Wednesday in order to highlight how much more we'll be able to see with its next venture.
That project, the James Webb Space Telescope (JWST), is slated to launch in 2021. It will use more advanced infrared cameras to image the galaxy while in Earth's orbit and be able to capture dimmer stars and smaller details than Spitzer can.
"Even one image from Webb will be the highest-quality image ever obtained of the galactic center," Roeland van der Marel, an astronomer who worked on JWST's imaging tools, said in a press release.
Such images could help answer some of scientists' biggest questions about how the galaxy formed and how it evolves over time.
Spitzer imaged the Milky Way's center like never before
The Spitzer photo is a mosaic of smaller shots showing the galactic center in infrared light, with wavelengths 10 times longer than what the human eye can see. Infrared vision enabled Spitzer's cameras to see past the clouds of interstellar dust that block visible light between Earth and the center of the galaxy 26,000 light-years away.
In the image, cooler old stars appear in blue at the edges, while massive young stars burn a hot red hue. Stars on the far sides of the image are 900 light-years apart.
The horizontal streak of brighter stars across the center of the image is the plane of the Milky Way. The galaxy's center is the bright white spot in the middle of the photo — that's where hot massive stars crowd together.
Somewhere in that center lies a supermassive black hole. Tiny stars are forming just a few light-years out of its grasp, even though scientists previously thought that environment would be too harsh for gas clouds to collapse into stars. They hope JWST can offer clues about how stars form there.
Around the galactic plane, meanwhile, clouds of interstellar dust swirl. Scientists think these clouds were shaped by streams of charged particles, or "wind," from massive stars.
JWST could photograph the galaxy's black hole in new detail
The upcoming telescope is fully assembled and now faces a long testing process in Northrop Grumman's California facilities before its launch date on March 30, 2021.
JWST will study every phase of the universe's history in order to learn about how the first stars and galaxies formed, how planets are born, and where there might be life in the universe. A 21-foot-wide folding beryllium mirror will help the telescope observe faraway galaxies in detail and capture extremely faint signals within our own galaxy.
Thanks to new infrared technology, JWST could provide an unprecedented view of the supermassive black hole at the Milky Way's center, which is called Sagittarius A* (pronounced "A-star") or Sgr A*.
Black holes' intensely strong gravitational pull means even light can't escape, so it's impossible to image them. Scientists can, however, look at the disk of hot fast-spinning material circling the drain, just outside the point of no return.
That's how the Event Horizon Telescope (EHT) team took the first-ever photo of a black hole in April. Researchers hope to use the JWST to do the same for the black hole at the center of our galaxy. So far, no one has seen it.
"Detecting the disk around Sagittarius A* with Webb would be a home run," Torsten Böker, a JWST astronomer, said in the release.
Event Horizon Telescope Collaboration
Such imaging could help answer questions about how the galaxy and its black hole formed, including a classic chicken-or-egg dilemma.
"Does the black hole come first and stars form around it? Do stars gather together and collide to form the black hole? These are questions we want to answer," Jay Anderson, another JWST scientist, said in the release.
Read more: A huge explosion sliced through our galaxy just 3.5 million years ago, as human ancestors walked the Earth. Scientists think it was nuclear activity in the black hole at the Milky Way's center.
In another avenue for investigation, Scientists think that every galaxy has a black hole at its center, and studies have shown that each black hole's mass is related to the total mass of the surrounding stars. But nobody knows why. JWST researchers plan to look for clues.
Another team seeks to film the galaxy's central black hole
The international team of scientists that captured the first image of a black hole is also planning to point telescopes at the center of our galaxy — this time, to film video.
"We can see the black hole evolve in real time," Shep Doeleman, an astronomer who leads the global EHT team, previously told Business Insider. "We can see how it evolves with the galaxy. We can even test Einstein's gravity in completely different ways by looking at the orbits of matter — not light, but matter — around the black hole."
Doeleman expects to make the first grainy videos available to the public in the next five years. Eventually, he said, space-based telescopes like JWST will lend their incredibly precise lenses to the venture as well.
"So many interesting, strange things happen at the centers of galaxies," Marcia Rieke, who oversees the development of the JWST infrared camera, said in the release. "We want to find out what's happening in our own."