What is going on in galaxy M87?
Research shows that a high-speed explosion of gas in galaxy M87 is making stars new, but no one knows how. A nova is born after a star known as a dense white dwarf receives gas from an orbiting star. As the white dwarf’s strong gravity squeezes the gas, it heats up and explodes, but both stars survive the violence. In fact, the same star becomes new again and again over millions of years. Recent observations indicate that these explosions accounted for a large part, and perhaps most, of the universe’s lithium supply.
Nova outbursts erupt in our galaxy and other galaxies, including the giant elliptical M87, whose fast-moving jet of gas is fed by the black hole at the center of the galaxy. Now, data from the Hubble Space Telescope shows that there are too many of these explosions in M87, researchers report in a study posted Sept. 28 on arXiv.org.
Alec Lessing, a student at Stanford University, Michael Shara, an astronomer at the American Museum of Natural History in New York, and their colleagues used the telescope to locate 135 novae in M87, whose jet is several thousand light years away. long The galaxy itself is located 54 million light years from Earth, at the heart of the nearest galaxy cluster, Virgo.
After detecting the novae, the team plotted their location in the galaxy. “It was overwhelming,” Shara says of the storyline. “The novae seemed to be mostly concentrated on the jet.” Dividing the galaxy into 10 equal sectors, the astronomers found that 25 explosions occurred in the jet, while only 10 to 16 explosions occurred in the other sectors of the galaxy. According to the researchers, the chance that this is just a statistical fluke is only about 0.3 percent. “I was really surprised,” says Massimo Della Valle, an astronomer at Italy’s National Institute of Astrophysics in Naples, who was not involved in the new study. “If these objects are new, the jet must be responsible somehow.” Perhaps, he says, the jet is pushing interstellar gas onto white dwarf stars in new systems, increasing the amount of material adhering to the stars’ surfaces. As a result, white dwarfs explode more often than usual, which explains the excessive increase in novae along the jet. According to Shara, the jet itself does not appear to be producing enough gas or radiation to explain the explosions. “The jet is to blame, but we just don’t know why or how,” he says. “It somehow causes novae to propagate in this sector, but whether that’s because it somehow triggers novae, or creates novae — by adding them there — or some other process … we don’t know.” For more clues, Shara hopes to use Hubble to study other galaxies similar to M87 to see if their jets are accompanied by such explosions.
Related Articles:
https://hubblesite.org/contents/media/images/2000/20/968-Image.html
https://www.space.com/m87-galaxy-first-3d-map-hubble-keck
https://www.britannica.com/place/Virgo-A
https://hubblesite.org/contents/media/images/2008/30/2391-Image.html
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