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TESS Dates An Ancient
Collision With Our Galaxy
TESS
Spacecraft Credit: NASA
A single bright star in the constellation of
Indus, visible from the southern hemisphere, has revealed new
insights on an ancient collision that our galaxy the Milky Way
underwent with another smaller galaxy called Gaia-Enceladus early
in its history.
An international team of scientists led by the
University of Birmingham adopted the novel approach of applying the
forensic characterization of a single ancient, bright star called
ν Indi as a probe of the history of the Milky Way.
Stars carry "fossilized records" of their histories and hence the
environments in which they formed. The team used data from
satellites and ground-based telescopes to unlock this information
from ν Indi. Their results are published in the
journalNature Astronomy.
The star was aged using its natural
oscillations (asteroseismology), detected in data collected by
NASA's recently launched
Transiting Exoplanet Survey Satellite (TESS). Launched
in 2018, TESS is surveying stars across most of the sky to search
for planets orbiting the stars and to study the stars themselves.
When combined with data from the
European Space Agency (ESA) Gaia Mission, the detective
story revealed that this ancient star was born early in the life of
the Milky Way, but the Gaia-Enceladus collision altered its motion
through our Galaxy.
Bill Chaplin, Professor of Astrophysics at the
University of Birmingham and lead author of the study said: "Since
the motion of ν Indi was affected by the Gaia-Enceladus collision,
the collision must have happened once the star had formed. That is
how we have been able to use the asteroseismically-determined age
to place new limits on when the Gaia-Enceladus event occurred."
Co-author Dr Ted Mackereth, also from
Birmingham, said: "Because we see so many stars from
Gaia-Enceladus, we think it must have had a large impact on the
evolution of our Galaxy. Understanding that is now a very hot topic
in astronomy, and this study is an important step in understanding
when this collision occurred."
Bill Chaplin added: "This study demonstrates
the potential of asteroseismology with TESS, and what is possible
when one has a variety of cutting-edge data available on a single,
bright star"
The research clearly shows the strong potential of the TESS program
to draw together rich new insights about the stars that are our
closest neighbors in the Milky Way. The research was funded by the
Science and Technology Facilities Council and the
European Research Council through the
Asterochronometry Project
Source: University of Birmingham
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