Everything dies eventually, even the brightest stars. In fact, the brightest stars live the shortest lives.
They use up all the hydrogen they have in just a few million years, and then explode as bright supernovae.
The remnants of their cores collapse into a neutron star or black hole. These small, dark objects litter our galaxy like a cosmic graveyard.
Both neutron stars and stellar black holes are difficult to detect. Neutron stars are only 15 kilometers in diameter, and unless their magnetic poles are aligned so that we can see them as pulsars, they will usually be overlooked.
Stellar black holes are even smaller and emit no light of their own. Most would only be observed when they pass between us and a more distant star, he writes ScienceAlert.
What’s hiding in the cosmic graveyard?
We haven’t observed enough stellar remnants to create an observed map of their general location, but a recent study published in Monthly Notices of the Royal Astronomical Society shaped where we might find them.
The researchers analyzed the distribution of stars in our current galaxy and simulated how stellar debris might be drawn and deflected by stellar interactions. Because these stars are typically older than the current stars in the galaxy, they have had more time to move onto new orbital paths.
Stellar remnants experience, statistically speaking, a kind of blur effect on their position. The distribution of these stars lies in a plane three times thicker than that of the visible Milky Way. But the team discovered one aspect of their distribution that was surprising.
About a third of these dead old stars are ejected from the galaxy. In their model, a third of the stars had a close stellar encounter that gave them such a speed boost that they would eventually escape the Milky Way’s gravitational pull.
What happens to dead stars in our galaxy?
This means that over time the Milky Way “evaporates”, or loses mass, which is unexpected. We know that small groups of stars, such as globular clusters, can evaporate, but the Milky Way is much more massive, so we might think that long-term evaporation would be minimal.
Another surprising aspect of the model is that these stellar remnants are fairly evenly distributed throughout the Milky Way.
In the case of the Sun, the most probable distance of the nearest stellar remnant is about 65 light years.
As more observatories, such as the Rubin Observatory, become operational, it may be possible to capture such events and discover where these stellar remnants actually reside. Then we will finally be able to see the true galactic world around us.