(DIR) Home
'God's Hand' interstellar cloud reaches for the stars in new dark
energy camera image (video)
(HTM) Source
----------------------------------------------------------------------
The Dark Energy Camera (DECam) has captured an ominous and ghostly
hand reaching from the Milky Way from a distant edge-on spiral galaxy.
But don't panic; despite its nickname, "God's Hand," there is nothing
supernatural about this structure — yet that doesn't make it any less
awe-inspiring.
God's Hand is actually a cometary globule officially known as CG 4. It
is located around 1,300 light-years from Earth within our Milky Way
galaxy and seen in the constellation Puppis. Cometary globules are a
hard-to-detect subclass of so-called Bok globules, which are isolated
and dense clouds of gas and dust surrounded by hot, ionized material.
Despite their name, cometary globules have nothing to do with comets.
The moniker actually comes from the fact that these nebulas have had
material dragged away from them, creating a long tail that resembles
the characteristic tail of a comet.
**Related:** Dark Energy Camera captures record-breaking image of a
dead star's scattered remains
The cometary globule God's Hand as seen by the Dark Energy Camera.
(Image credit: CTIO/NOIRLab/DOE/NSF/AURA)
Cometary globules remain somewhat mysterious because the cause of
their structure hasn't yet been definitively determined. Scientists
hypothesize that the structure of cometary globules could be created
by stellar winds that flow from the hot, massive stars surrounding
them, or from the supernovas that occur when these stars die.
## Reach for the skies!
CG 4's distinctive tail, which helps define it as a cometary nebula,
is an 8 light-year-long faint tendril of gas and dust with a 1.5
light-year-wide tip. This feature is stunningly apparent in the images
from the DECam, an instrument located on the Victor M. Blanco 4-meter
Telescope at the Cerro Tololo Inter-American Observatory, which is
located at an altitude of 7,200 feet (2,200 meters) above Chile.
Images like this one may finally help crack the mystery of cometary
globule and Bok nebula creation.
Bok clusters weren't discovered by astronomers until the mid-1970s,
evading detection for so long because of how faint they are and the
fact that their tails are shrouded by stellar dust that prevents light
from passing through it.
Breaking space news, the latest updates on rocket launches,
skywatching events and more!
To see through this dust, the DECam is outfitted with a Hydrogen-alpha
filter that allows it to image ionized hydrogen. In the image of the
God's hand globule, this matter is seen as a red glow within CG 4, its
"claw," and outlining its edge. Ionized hydrogen and its glow is
created when this element is bombarded by intense radiation from
nearby mass stars, stripping away electrons or "ionizing" the gas.
A close-up of CG 4 aligning with the edge-on spiral galaxy ESO 257-19
(PGC 21338), the two are actually 100 million light-years apart. Near
the head of the cometary globule are two young stellar objects (YSOs).
(Image credit: CTIO/NOIRLab/DOE/NSF/AURA)
The lobster-claw-like head of CG 4 appears in the image to be reaching
out for the spiral galaxy ESO 257-19 (PGC 21338), which is seen edge-
on from our perspective on Earth. Though the galaxy may appear about
to be gripped by God's Hand or a cosmic lobster claw, it is safe from
harm, located around 100 million light-years from CG 4.
Even if ESO 257-19 were closer to CG 4 (and not an entire galaxy and
thus vastly bigger than CG 4), it would be safe from the grasp of this
celestial God's Hand, because the same radiation that is ionizing the
'Hand's' hydrogen is also disintegrating its structure. Despite this,
there is still enough gas and dust within CG 4 to form several new
sun-sized stars.
Bok nebula are found throughout our galaxy, but the majority of them,
like CG 4 and 30 others, are located within the Gum Nebula, also known
as "Gum 12." This is a huge cloud of gas around 1,400 light-years away
that is spread across the constellations Puppis and Vela. Gum 12 is
thought to be the expanding remnants of a massive star that died in a
supernova explosion around a million years ago.
The Gum nebula, home to many Bok nebulas, seen over the Atacama Desert
in Northern Chile. (Image credit: P. Horálek/ESO)
Scientists suggest two mechanisms that could create a cometary globule
such as CG 4. One of these occurs when stellar winds and radiation
from massive stars 'sculpt' gas and dust into a comet-like shape; the
other is that they could be spherical nebulas that may have been
disrupted by a nearby supernova explosion.
The tails of the cometary globules within Gum 12 appear to be pointing
away from the Vela supernova and the rapidly spinning neutron star
pulsar at the heart of this nebula. The star that collapsed to create
this pulsar must have been massive, and thus, it could have been its
stellar winds before its death that sculpted the cometary nebula of
Gum 12.
_Join our Space Forums to keep talking space on the latest missions,
night sky and more! And if you have a news tip, correction or comment,
let us know at: community@space.com._
______________________________________________________________________
Served by Flask-Gopher/2.2.1