<\/p>\n The team of astronomers used TESS<\/a> to observe starquakes rippling through the red giant of Gaia BH2. Just as seismic waves can be used to probe the interior of Earth, starquakes can be employed by astrophysicists to investigate below the surface layers of stellar bodies, right down to their cores.<\/p>\n Best picks for you<\/p>\n “Just like seismologists use earthquakes to study Earth’s interior, we can use stellar oscillations to understand what\u2019s happening inside distant stars,” team leader Daniel Hey, a scientist at the University of Hawaii Institute for Astronomy (IfA), said in a statement. <\/a>“These vibrations told us something unexpected about this star\u2019s history.”<\/p>\n Red giant star is younger than it looks<\/p>\n Hey and colleagues were surprised when they took a close look at the composition of this red giant star, finding it to be packed with heavy elements, or “alpha-rich.” This is something common to more ancient stars. However, the starquakes<\/a> observed by TESS suggest that the star is only 5 billion years old.<\/p>\n For context, our 4.6 billion-year-old star, the sun, will only reach its red giant phase when it runs out of hydrogen in its core in around 5 billion years.<\/p>\n “Young, alpha-rich stars are quite rare and puzzling,” Hey continued. “The combination of youth and ancient chemistry suggests this star didn\u2019t evolve in isolation. It likely acquired extra mass from a companion, either through a merger or by absorbing material when the black hole formed.”<\/p>\n This isn’t the only puzzle surrounding this red giant, either.<\/p>\n \n An image of the Milky Way showing the location of the first two black holes discovered by Gaia including Gaia BH2 which has a red giant companion. (Image credit: ESA\/Gaia\/DPAC; CC BY-SA 3.0 IGO, CC BY-SA 3.0 IGO)<\/p>\n Observing the red giant using ground-based instruments, scientists found that it is rotating once every 398 Earth days, which is much faster than isolated red giants of similar ages normally spin. That rapid spin hints at the fact that it may have merged with another star in its distant history, or that it once interacted with the massive star that died to birth its black hole companion.<\/p>\n “If this rotation is real, it can’t be explained by the star\u2019s birth spin alone,” team member Joel Ong, a NASA Hubble Fellow at IfA, said in the statement. “The star must have been spun up through tidal interactions with its companion, which further supports the idea that this system has a complex history.”<\/p>\n Don’t miss these<\/p>\n![\"An](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/12\/8NfTeeKZMC5qHX2XuxKGBN.jpeg\")
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