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(NASA/JPL-Caltech/UCLA) |
A new model of star formation supports the theory that most, if not all, stars are born in a litter with at least one sibling.
Our own
star at the centre of the Solar System is likely no exception, and some
astronomers believe the Sun's doppelganger is to blame for the extinction of
the dinosaurs.
Two
researchers from UC Berkeley and the Harvard-Smithsonian Astrophysical
Observatory found in 2017 that all Sun-like stars are likely formed with a
companion after analysing data from a radio survey done on a dust cloud in the
Perseus constellation.
In June
2017, UC Berkeley astronomer Steven Stahler said, "We ran a series of
statistical models to see if we could account for the relative populations of
young single stars and binaries of all separations in the Perseus molecular
cloud, and the only model that could reproduce the data was one in which all
stars form initially as wide binaries."
For years,
astronomers have debated if our galaxy's enormous number of binary and triple
star systems are formed near to one another or if they collide after they've
formed.
The 'born
together' hypothesis has long been the most popular, and simulations created in
recent decades have demonstrated that practically all stars are born as
multiples that spin away on their own.
Unfortunately,
empirical evidence supporting these models has been scarce, which makes this
new work so fascinating.
"Our research advances our understanding of both how binaries develop and the role binaries play in early star evolution," Stahler added.
The
researchers studied the radio waves leaking out of a dense cocoon of dust some
600 light-years away that contains an entire nursery of budding stars as part
of the VLA nascent disc and multiplicity study (VANDAM for short).
The VANDAM
survey allowed for a census of stars less than half a million years old, known
as Class 0 stars (or "babies" in star parlance), and stars between
500,000 and 1 million years old, known as Class 1.
The
scientists discovered 45 single stars, 19 binary star systems, and five star
systems with more than two stars using data on the morphologies of the
surrounding cloud of dust.
While
their findings suggested that all stars are born as binaries, they revised
their conclusion to accommodate for model constraints by stating that most
stars generated inside the dense centres of dust clouds are born with a
partner.
Stahler said at the time, "I believe we have the strongest evidence to date for such a statement."
When the
researchers examined the distances between the stars, they discovered that all
binaries separated by 500 AU or more were Class 0 and aligned with the axis of
the egg-shaped cloud surrounding them.
At roughly
200 AU, Class 1 stars, on the other hand, tended to be closer together and not
aligned with their 'egg's' axis.
"We don't know exactly what that implies yet," said Sarah Sadavoy of the Harvard-Smithsonian Astrophysical Observatory, "but it isn't random and must tell something about the way wide binaries arise."
Where is
ours, if most stars are born with a partner?
A distance
of 500 AU is approximately 0.008 light-years, or little less than three
light-days. Neptune is around 30 AU away, the Voyager 1 probe is just under 140
AU away, and the nearest known star, Proxima Centauri, is 268,770 AU away.
So, if the
Sun has a twin, it's probably certainly not visible from our area.
However,
there is a theory that our Sun has a twin that visits every now and then to
spice things up.
This
hypothetical troublemaker has been given the name Nemesis and has been posited
as the cause of a 27-million-year cycle of extinctions on Earth, including the
one that wiped out most of the dinosaurs.
Richard
Muller, an astronomer at the University of California, Berkeley, proposed 23
years ago that a red dwarf star 1.5 light-years away could travel through the
icy outer reaches of our Solar System on a regular basis, stirring up material
with its gravity and knocking a few more space boulders our way.
Other
abnormalities on the outside of our Solar System, such as the strange, broad
orbit of the dwarf planet Sedna, could be explained by a dim passing star like
a brown dwarf.
There's no
indication of Nemesis, but a long-lost binary companion for our Sun would be a
good fit.
"We're suggesting that, sure, there was probably a Nemesis a long time ago," Stahler said.
In which
case, it appears that our Sun would have gathered the most of the dust and gas,
leaving its twin dark and stunted.
It's
understandable that it's irritated.
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