by Passant Rabie
A rendition of the area surrounding the Local Void,
with our galaxy at the center of the three arrows.
(Image credit: R. Brent Tully)
the local void
Astronomers mapped out the
- an extensive, empty region
of space that borders the Milky Way - revealing new details about
the structure of our cosmic neighborhood.
Although it was discovered more than 30 years ago, the Local Void's
exact size and shape have remained a bit of a mystery.
The new study,
mapped the size and shape of the cosmic void using
observations of the movement of galaxies to create a 3D map of the
local universe, showing how the Local Void becomes "emptier" as the
universe expands, officials with the University of Hawaii's
Institute for Astronomy said in a statement.
Local Void was discovered in 1987
Brent Tully, an astronomer at the University of Hawaii who
is also the lead author of the new study, and
an astrophysicist at the National Radio Astronomy Observatory in
The pair noted that while
the Milky Way is surrounded by other galaxies and cosmic structures,
our galaxy also sits at the edge of a large, empty region.
However, it was difficult to observe the Local Void since it is
located behind the center of the Milky Way from our perspective here
For this study (Cosmicflows-3
- Cosmography of the Local Void), the team measured the
motion of 18,000 galaxies to develop a map that shows the boundaries
between where matter is present and where it is absent in order to
outline the edge of the Local Void.
Measuring the empty region in our cosmic neighborhood helps weigh in
on a longstanding astronomical mystery.
While we know that the
universe is expanding, scientists have wondered why the Milky Way,
our largest neighboring galaxy Andromeda and smaller surrounding
galaxies deviate from the speed of expansion by 1.3 million mph (600
kilometers per second).
Galaxies tend to move towards denser areas in the universe, pulled
by the gravity of surrounding bodies in space, while moving away
from the less populated regions.
Therefore, the study
found that at least half of this deviation is a combination of the
gravitational tug by
the Virgo Cluster, a nearby cluster
of galaxies, and the expansion of the Local Void as it grows emptier
while the universe continues to expand, according to the statement.
The study (Cosmicflows-3
- Cosmography of the Local Void) was published July 22
The Astrophysical Journal.