APOD: 2020 September 3 – A Halo for Andromeda

APOD: 2020 September 3 – A Halo for Andromeda<br />

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2020 September 3

See Explanation.  Clicking on the picture will download
the highest resolution version available.

A Halo for Andromeda
Digital Illustration Credit:

J. DePasquale and E. Wheatley
(STScI) and Z. Levay


M31, the Andromeda Galaxy, is the closest large spiral galaxy to
our Milky Way.

Some 2.5 million light-years distant it shines in Earth’s night sky as a
small, faint, elongated cloud just visible to the unaided eye.

Invisible to the eye though, its enormous halo of hot ionized gas is
represented in purplish hues for
this digital illustration
of our neighboring galaxy
above rocky terrain.

Mapped by Hubble Space Telescope observations of the
absorption of ultraviolet light against
distant quasars, the extent and make-up of Andromeda’s gaseous halo has been
recently determined by the AMIGA project.

A reservoir of material for future star formation,
Andromeda’s halo of diffuse
plasma was measured
to extend around 1.3 million light-years or more from the galaxy.

That’s about half way to the Milky Way,
likely putting it in contact with the diffuse gaseous halo of our own

Tomorrow’s picture: pixels in space

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Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell (UMCP)
NASA Official: Phillip Newman
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