Within the Milky Way galaxy, it is estimated that between 100 billion and 400 billion stars
exist and astronomers have recently announced that they may have discovered one of the smallest
of them. A white dwarf star that is of a similar size to our Moon yet is heavier than the sun.
Your watching V101 Science and this is your Space Fix.
Dubbed the "very special" star by some, this white dwarf has a mass greater than that of
the sun, all compressed into a body that is slightly bigger than the moon, making it the
most massive white dwarf known, but also the smallest.
White dwarfs are usually about the size of Earth and are the cool, dim cores of long-dead
stars that have exhausted their fuel and shed their outer layers into space.
About 97 percent of all-stars will ultimately become white dwarfs at the end of their lives.
The sun, for example, will one day share the same fate and evolve into one of these smouldering
corpses in around 5 to 10 billion years from now.
This particular dead star is named ZTF J1901+1458 and is located around 130 light-years away
in the constellation of Aquila. Its diameter is much smaller than the Earth
however, at only 2670 miles, or 4296 kilometres, yet crammed into this moon-sized space, is
1.35 times the mass of the sun. Scientists are not 100% certain how this rare
star formed, but it does appear that it was created from two ancient stars, that likely
grew old together and exhausted their fuel supplies, before evolving into white dwarfs.
Over time the pair spiralled closer and closer, until they ultimately merged, becoming one.
If the parent stars had too much mass, then they would have exploded in what is called
a type 1a supernova, destroying both of them, however, it seems that in this case, they
didn't, instead, they came together, creating
the most massive of all the white dwarfs discovered
so far. Likely because they were both below a certain mass threshold.
This process of merging causes the rare white dwarf to inherit its parents combined spin
speed, resulting in the unusual star rotating on its axis at a violent pace, around one
revolution every seven minutes. As an example, the sun takes 27 days to complete a single
rotation. This rapid spin also helps boost its intense
magnetic field, which is nearly 1 billion times stronger than the Suns. It may be small,
but this white dwarf is immensely powerful. It was discovered using a host of telescopes
that helped analyse the dead star.
But It was initially spotted by the Zwicky Transient Facility at the Palomar Observatory
in California, which is a telescope, that scans the entire northern sky every two nights
looking for cosmic bodies that blink, move or change in brightness.
So what will become of this bizarre white dwarf? Well, the so-called, very special star,
could be on the verge of collapse. Researchers think that the star has enough
mass to possibly evolve into an even smaller, even denser object, called a neutron star.
Neutron stars typically form when a star much more massive than our sun explodes as a supernova,
leaving behind a tiny, super-dense object. They can range from 1.4 times the mass of
the sun, up to about twice as much, all of which is squeezed into a star that's only
around 12 miles or 20 kilometres across, or about the size of a city. One tablespoon of
a star like this would weigh more than A billion tons here on Earth.
If the hypothesis is correct, and this newly found small but massive white dwarf is on
the verge of collapsing even further and becoming one of these bizarre objects, then this could
mean that many other neutron stars throughout the universe formed in this previously unknown
way. However, just like all new scientific discoveries,
more questions are raised than answered and so we will have to wait until further studies
have been completed before we can really start to understand the smallest, yet most massive
white dwarf star in the universe discovered so far.
So what did you think of this bizarre dead star? Let me know in the comment section below.
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