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by Enrique Sacristán
March 19
2018
from
SINC Website
Spanish version
At a time when modern humans were beginning to leave Africa
and the
Neanderthals were living on our planet,
Scholz's star approached less than a light-year.
José A.
Peñas/SINC
New
Evidences of the Passage of the Scholz's star
About 70,000
years ago,
when the human
species was already on Earth,
a small reddish
star approached our solar system
and
gravitationally disturbed comets and asteroids.
Astronomers from
the Complutense University of Madrid
and the
University of Cambridge
have verified
that the movement of some of these objects
is still marked
by that stellar encounter.
At a time when modern humans were beginning to leave Africa and the
Neanderthals were living on our planet,
Scholz's star - named after German
astronomer Ralf-Dieter Scholz who discovered it - approached
less than a light-year from the Sun.
Nowadays it is almost 20
light-years away, but 70,000 years ago it entered the
Oort cloud, a reservoir of
trans-Neptunian objects located at the confines of the solar system.
This discovery was made public in 2015 by a team of astronomers led
by Professor Eric Mamajek of the University of Rochester
(USA).
The details of that
stellar flyby (The
Closest known Flyby of a Star to the Solar System), the
closest documented so far, were presented in The Astrophysical
Journal Letters.
Now two astronomers from the Complutense University of Madrid
(Spain), the brothers Carlos and Raúl de la Fuente Marcos,
together with the researcher Sverre J. Aarseth of the
University of Cambridge (United Kingdom), have analyzed for the
first time the nearly 340 objects of the solar system with
hyperbolic orbits (very open V-shaped, not the typical
elliptical), and in doing so they have detected that the trajectory
of some of them is influenced by the passage of Scholz's star.
"Using numerical
simulations we have calculated the radiants or positions in the
sky from which all these hyperbolic objects seem to come,"
explains Carlos de la Fuente Marcos, who together with the other
coauthors publishes the results (Where
the Solar System meets the Solar Neighborhood) in the
MNRAS Letters journal.
"In principle," he adds, "one would expect those positions to be
evenly distributed in the sky, particularly if these objects
come from the Oort cloud; however, what we find is very
different: a statistically significant accumulation of radiants.
The pronounced
over-density appears projected in the direction of the
constellation of Gemini, which fits the close encounter with
Scholz's star."
The moment in which this
star passed close to us and its position during prehistory coincide
with the data of the new investigation and in those of Mamajek and
his team.
"It could be a
coincidence, but it is unlikely that both location and time are
compatible," says De la Fuente Marcos, who points out that their
simulations suggest that Scholz's star approached even more than
the 0.6 light-years pointed out in the 2015 study as the lower
limit.
The close fly-by of this
star 70,000 years ago did not disturb all the hyperbolic objects of
the solar system, only those that were closest to it at that time.
"For example, the
radiant of the famous interstellar
asteroid 'Oumuamua is in the constellation of Lyra
(the Harp), very far from Gemini, therefore it is not part of
the detected over-density," says De la Fuente Marcos.
He is confident that new
studies and observations will confirm the idea that a star passed
close to us in a relatively recent period.
Scholz's star is actually a binary system formed by a small red
dwarf, with about 9% of the mass of the Sun, around which a much
less bright and smaller brown dwarf orbits.
It is likely that our
ancestors saw its faint reddish light in the nights of prehistory.
Artist's conception of Scholz's star
and its
brown dwarf companion (foreground)
during
its flyby of the solar system 70,000 years ago.
The Sun
(left, background)
would
have appeared as a brilliant star.
The
pair is now about 20 light years away.
Michael
Osadciw/University of Rochester
References
C. de la Fuente
Marcos, R. de la Fuente Marcos, S. J. Aarseth - "Where the Solar
system meets the solar neighborhood: patterns in the
distribution of radiants of observed hyperbolic minor bodies" -
MNRAS Letters, 2018.
https://doi.org/10.1093/mnrasl/sly019
http://adsabs.harvard.edu/abs/2018MNRAS.476L...1D
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