APOD: 2025 August 4 Б Blue Arcs Toward Andromeda
Credit & Copyright: Ogle et
al.
Explanation:
What are these gigantic blue arcs near the Andromeda Galaxy (M31)?
Discovered in 2022 by amateur astronomers, the faint arcs -- dubbed
SDSO 1
-- span nearly the same angular size as M31 itself.
At first, their origin was a mystery: are they actually
near the Andromeda Galaxy,
or alternatively near to our Sun?
Now, over 550 hours of combined exposure
and a collaboration between amateur and
professional astronomers has revealed strong evidence
for their true nature: SDSO 1 is not
intergalactic, but a new class of
planetary nebula within our galaxy.
Dubbed a Ghost Planetary Nebula (GPN), SDSO 1
is the first recognized member of a new subclass of faded
planetary nebulas, along with seven others also
recently identified.
Shown in blue are extremely faint
oxygen emission from the shock waves, while the
surrounding red
is a hydrogen-emitting trail that indicates the GPN's age.
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.
