Arp 240: A Bridge between Spiral Galaxies from Hubble
Explanation:
Why is there a bridge between these two spiral galaxies?
Made of gas and stars, the bridge provides strong evidence that these two
immense star systems have passed close to each other and experienced
violent tides induced by mutual gravity.
Known together as
Arp 240 but individually
as
NGC 5257 and
NGC 5258,
computer modelling and the ages of star clusters
indicate that the two galaxies completed a first passage
near each other only about 250 million years ago.
Gravitational tides not only pulled away matter,
they compress gas and so caused star formation in both galaxies and the
unusual bridge.
Galactic mergers are thought to be common, with Arp 240 representing a
snapshot
of a brief stage in this
inevitable process.
The Arp 240
pair are about 300 million
light-years distant and can be seen with a
small telescope toward the constellation of
Virgo.
Repeated
close passages should ultimately result in a
merger and with the emergence of a
single combined galaxy.
Free Download:
APOD 2017 Calendar: NASA Images
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
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A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
