Giant stars, according to our understanding, erupt in dramatic supernovas when they die. However, astronomers have discovered that some massive stars simply vanish, leaving no trace behind. It's like they're not giant stars, but misplaced keys!
A recent study sheds light on this mystery. Researchers, led by Dr. Alejandro Vigna-Gómez, propose that some stars meet their demise with a whimper, not a bang.
Their evidence comes from a binary system named VFTS 243 in the Large Magellanic Cloud. This system consists of a black hole and a companion star, but with no signs of a past supernova – an explosion that typically accompanies a black hole's birth.
"Imagine witnessing a giant star collapse," explains Dr. Vigna-Gómez. "It might simply vanish, leaving no bright supernova to light up the sky."
He continues, "Astronomers have observed such disappearances recently. While we can't confirm a connection, our findings on VFTS 243 offer a strong explanation."
Supernovas from massive stars (eight times the Sun's mass or more) are chaotic events. The star's outer layers explode outward, forming a vast dust and gas cloud. The core, crushed by gravity, transforms into a super-dense neutron star or black hole.
These collapsed cores can travel if the supernova is uneven, propelling them through space. We can sometimes track their path back to the explosion debris, but over time, this material disperses. However, the kick itself leaves a long-lasting signature.
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| A not-to-scale artist's impression of the VFTS 243 system and its home in the Tarantula Nebula |
VFTS 243 is intriguing. It has a massive star (25 times the Sun's mass) and a black hole (10 times the Sun's mass). The black hole is invisible, but its presence is revealed by the companion star's orbit.
This orbit is nearly circular, and the system's movement suggests the black hole received no powerful kick from a supernova. This aligns with the initial suspicions of the researchers who discovered the black hole in 2022.
Mounting evidence suggests that massive stars can directly collapse into black holes, bypassing the supernova stage. VFTS 243 provides the strongest support for this theory yet.
"VFTS 243 is the best example we have of a stellar black hole formed through a complete collapse, without a supernova," says Dr. Irene Tamborra, co-author of the study. "This validates our models and paves the way for further research on stellar collapse and evolution."
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