Mario Juric talks with
ScienceWatch.com and answers a few questions about
this month's Fast Breaking Paper in the field of Space
Science. The author has also sent along images of his
work.
Article Title: The milky way tomography with SDSS.
I. Stellar number density distribution
Authors: Juric,
M, et al.
Journal: ASTROPHYS J
Figure 1:
False-color stellar number density in
slices parallel to the Galactic plane (red
-- areas many of stars, blue -- areas with
few stars). The distance from the plane
varies from 17.5 kpc (top left) to 6 kpc
(bottom right). The circles visualize the
expected axial symmetry of the Galaxy, and
the origin marks the location of the
Galactic center. The Sun is at X=8000, Y=0
parsecs (1 parsec equals 3.26 light years).
Note the strong asymmetry with respect to
the Y=0 line, caused by the red "blob" at
X~6000,Y~4000. This is the newly discovered
"Virgo Overdensity," likely a remnant of a
merger of a smaller satellite galaxy with
the Milky Way.
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Figure 2:
Figure 2:
Another way of visualizing the Virgo
Overdensity: A false-color depiction of
stellar number density in a shell 35-52
thousand light years from Earth. Red are
the areas with many stars, while blue areas
have few stars. Noticable in the picture
are the Virgo Overdensity as a red blob in
the upper left quadrant near the edge of
the surveyed sky, and another stream of
stars in the first quadrant that overlaps
the Virgo Overdensity, the Sagittarius
Stream. Both of these structures are
thought to be remnants of mergers of
smaller satellite galaxies with the Milky
Way.
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Figure 3:
Figure 3:
The volume of space in and around the Milky
Way that has been surveyed by the SDSS and
studied in this paper (artistic depiction
of the Milky Way disk courtesy of NASA).
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