A scientific study that begins, “The Sun is formidable and destroying it is generally considered to be a difficult problem,” has got to be something to adore. The study in question investigates whether the Sun may be harboring a black hole and if doing so would have destroyed the Sun by now, rather than serving as a prelude for a Bond villain.
Science fiction authors are occasionally recognized by scientists as the original creators of concepts that have been later proven to have scientific value. It’s less common to get inspiration from music, especially from 90s songs. However, Dr. Earl Bellinger of the Max Planck Institute for Astrophysics was first motivated to consider the possibility that such objects may exist by the song Black Hole Sun by Soundgarden.
In supernova explosions, stars with masses greater than 25 times that of the Sun collapse, producing stellar black holes. Bellinger might have easily concluded that “Black hole, (former) Sun” was accurate science by just adding a word to the title. Rather, he recruited eight coworkers to join him in the investigation to see if a black hole could exist within an otherwise normal star.
They believe the answer is yes, which is surprising.
It may seem absurd to consider that things whose most evident feature is that they shine might be overcoming that force to light the universe, given that black holes are known to have such intense gravitational fields that even light cannot escape from them. But quasars are far brighter, driven by supermassive black holes in their centers.
Stephen Hawking himself proposed the possibility of a primordial black hole in the Sun’s core. Bellinger and colleagues have investigated how stars might evolve if this theory were accurate, but the proposal was never very successful.
The study’s theoretical foundation is the notion that several tiny black holes with masses comparable to the Moon or less were created in the initial seconds following the Big Bang. The idea that black holes the size of an asteroid would still be there, traveling about the cosmos, is completely unsettling. The tiniest black holes would dissipate.
These primordial black holes may be so numerous that they account for a portion of the universe’s missing dark matter. The majority of the holes would be around the stars; they are so well-hidden that we haven’t found one yet. However, if one were to penetrate into the gas cloud where a star is developing, it may end up in the core of the star.
The goal of the experiment was to determine what would happen if this were genuine and, if so, whether we might see any impacts.
The study determined that black holes with masses less than the asteroid Psyche would not have any detectable impacts from the outside. The impacted region would be so tiny that an outside observer could never differentiate stars with and without such black holes, even though they would devour nearby parts of the star.
But things would be different at the bigger end of the mass range that the authors find believable. The fusion processes that provide the star’s energy would be gradually shut off as the black hole slowly consumed the star from the inside out, resembling some kind of horrible parasite. As a result, when stars with comparable mass and age become (slightly) brighter, the star would fade.
In 100 million years, the Sun would lose around half of its brightness if it had a Black Hole with a mass that was presently a millionth of that of the Sun—roughly three times that of Mars. But after that, the star’s primary energy source would shift from nuclear fusion to black hole accretion, causing it to get brighter. Prematurely, the star would burst into a red giant and exhibit certain characteristics that would disclose its actual makeup.
Compared to previous red giants, it would, for starters, have a higher surface helium content and would never grow to the same size—the Sun would only expand to Mercury’s orbit, not nearly to Earth’s.
The scientists suggest that stars of this type might be members of the class of stars known as red stragglers, which are brighter than subgiants yet have colors that are just as red as red giants. If true, their vibration should differ from that of stars with no internal mystery, which might be investigated in further research. Such a star will eventually be devoured and become a naked black hole, its mass greater than its initial mass but not quite as great as those resulting from supernova explosions.
The precise specifics rely on the masses of the surrounding star and the original black hole, as well as the amount of heavier elements (known as metals to stellar astronomers) in the star. Although there are too many options to address them all, the study takes into consideration a number of eventualities.
We may assess the possibility of such black hole stars occurring by searching for evidence of primordial black holes elsewhere, in addition to examining stars for the distinctive characteristics the authors anticipate. Thus far, we have identified four black hole mergers with a single component that had sufficiently low mass to suggest that it originated in the early universe, however none of them are definitively proven examples.
Many low-mass microlensing events from objects of the suitable mass have also been observed, but as of right now, it is impossible to differentiate the majority from planets that are free-floating.