Three-dimensional models of astronomical objects can be ridiculously
complex. They can range from black holes that light doesn't even escape to
the literal size of the Universe and everything in between.
But not every object has received the attention needed to develop a complete
model of it, but we can officially add another highly complex model to our
lists.
Astronomers at the University of Arizona have developed a model of VY Canis
Majoris, a red hypergiant that is quite possibly the largest star in the
Milky Way. And they're going to use that model to predict how it will die.
How red hypergiants die has been a matter of some debate recently.
Initially, astronomers thought they simply exploded into a supernova, as so
many other stars do.
However, more recent data show a significant lack of supernovae compared to
the numbers that would be expected if red hypergiants themselves we to
explode that way.
The going theory now is that they are more likely to collapse into a black
hole, which is much harder to observe directly than the initially suggested
supernovae.
It remains unclear what precisely the characteristics of the stars that
would evolve into black holes are; and to find out, it would be beneficial
to have a model.
Enter the team from UA. They picked VY Canis Majoris as an excellent
stand-in for the type of red hypergiants they were interested in learning
more about.
The star itself is massive, ranging from 10 AU to 15 AU (astronomical units)
in size. And it is only 3,009 light-years away from Earth as it is. This
makes VY Canis Majoris, which resides in the southern constellation Canis
Major, fascinating to observers.
Its sheer size and proximity to our Solar System make it an excellent
observational candidate. With good observational data, astronomers can see
the breathtaking complexity of what the star's surface actually looks
like.
One of the fundamental processes in a star's death is mass loss. Typically,
this happens when gas and dust are blown evenly out of the star's
photosphere. However, on VY Canis Majoris, there are massive features that
are similar to Earth's coronal arcs but a billion times more massive.
The UA researchers used time on ALMA to collect radio signals of the
material that is blasted into space as part of these eruptions.
That material, including sulfur dioxide, silicon dioxide, and sodium
chloride, would allow them to detect the speed at which it moves, rather
than just the static presence of other ejecta, such as dust.
To do so, they had to align all 48 dishes of ALMA and collect over a
terabyte of data to get the correct information.
Processing all that collected data can be pretty challenging, and they are
still working on some of it. Still, they had enough so far to present their
findings to the American Astronomical Society in mid-June.
When they have even more data, they'll be able to describe an even better
model of what one of the largest stars in the galaxy looks like.
And someday, far in the future, that model of what will happen to a red
hypergiant might just get a chance to be tested when VY Canis Majoris
finally, officially, dies.
Reference:
A. P. Singh et al, Molecules and Outflows in NML Cygni: New Insights from a
1 mm Spectral Line Survey, The Astrophysical Journal Letters (2021).
DOI: 10.3847/2041-8213/ac2c7c
This article was originally published by Universe Today. Read the
original article.
Tags:
Space & Astrophysics