A dying galaxy near the Milky Way appears to be sowing the seeds of its own rebirth and may hold the secret to the apparent reincarnation of several other similar galaxies. The phoenix-like process may also help resolve a longstanding mystery about missing dark matter clumps near the Milky Way.About 20 small galaxies are known to exist around our galaxy. Most fall into two main categories: dwarf spheroidals, which are dead because they lack the gas needed for making new stars, and dwarf irregulars, which have plenty of gas and show signs of ongoing star formation.
Some astronomers have suggested that dwarf galaxies can switch back and forth between the two types by dying and being reborn repeatedly. In the dwarf irregular phase, abundant gas fuels rapid star formation. But the newly formed stars then sterilise the galaxy when some of them explode as supernovae and blow away its gas. The galaxy’s gravity later pulls the gas back in to fuel a new cycle of star formation.
Now, new observations have bolstered that idea by showing that a gas cloud expelled from one such galaxy is moving slowly enough that it will eventually revive the galaxy by falling back into it and triggering new star formation.
Light Cue 23
Notes from the Drafting Table
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The text of Light Cue 23 by Lucas Krech is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
Based on a work at lucaskrech.com.
