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Астронет: Астрономическая картинка дня Высокоскоростные облака и Млечный Путь http://www.variable-stars.ru/db/msg/1162749/eng |
Credit & Copyright: B. Wakker
(U. Wisconsin-Madison) et al.,
NASA
Explanation:
Where are these gas clouds going so quickly?
High velocity clouds (HVCs) of gas
have been seen for decades but their origins and
destinations have remained mysterious.
Recent measurements have now placed at least
one of these clouds in the halo of our
Milky Way Galaxy, while other measurements
have determined the relative abundance of cloud elements.
Of the two clouds measured, each appears to have a
chemical abundance consistent with a different origin.
One HVC has been measured to have very few heavy elements
("low metallically") compared to neighboring stars,
while another HVC has been inferred to have a
heavy element abundance more typical of neighboring stars.
Hypotheses are therefore being investigated that
some HVCs are local gas remnants being
pushed away from our Galaxy by
supernova explosions, while other
HVCs are ancient
dwarf galaxy
remnants falling toward our Galaxy.
The latter possibility is particularly
interesting as it might help explain how our
Galaxy can continue to
make stars at the observed rate.
Fast moving HVCs are circled in the above false-color mosaic.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.