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Credit: G. R. Meurer
(Johns Hopkins U.),
C. Carignan (U. Montreal), S. Beaulieu and K. Freeman (MSSSO),
Radio Image:
ATCA,
Optical Image:
AAT
Explanation:
How do you find a nearly invisible galaxy?
Pictured above is the blue compact dwarf (BCD) galaxy NGC 2915. In visible light, shown above in yellow,
this galaxy appears to be a normal
dwarf galaxy,
as indicated by the yellow smudge in the image center.
Yet when imaged in a very specific color,
shown in blue, a whole
spiral galaxy appears.
This specific color is in the
radio band
and is preferentially emitted by neutral
hydrogen atoms. Much about
BCD galaxies remains mysterious,
such as how the neutral hydrogen obtained its shape,
what drives current star formation,
and why there is so much
dark matter.
NGC 2915 is located at the relatively nearby distance of 15 million light-years
- just outside our
Local Group of Galaxies.
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NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day