Mad Galaxy Man previously wrote:
This one seems to me to be the best candidate for a genuine Vertical Dust Chimney on Greg's exposure:
Attachment 147685
If that is the NGC 6231 / Scorpius OB1 complex in the mid-plane of the Milky Way beneath the dust chimney, then this would be a plausible candidate for the source of one or more energetic events that could project dust and gas far above the plane of the Milky Way; this is a very large concentration of supermassive stars, and it could well have hosted one or more supernovae.
Quote:
Originally Posted by gregbradley
Great detective work. It sounds plausible.
Greg.
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Greg,
Bad galaxy man's further cogitations:
It looks like the RCW108 (Ara OB1) star-forming complex (associated with a two degree scale HII region that looks like a ghostly version of Eta Car. Nebula) is also aligned with the hypothetical dust ejection in a dust chimney, but this OB association is currently very much less active than the NGC 6231 complex (see: 2005, A&A, 433, 955).
The appearance of the very-large-scale giant dust rift ("equatorial dust band") on the Scutum side of the Milky Way looks very different from the appearance of this dust chimney. This vertical "dust chimney" could be a feature that exits at (very roughly) a right angle to the plane of the Milky Way Galaxy, which could indicate ejection of gas in this direction, while (in contrast) the gigantic dust rift on the other side could conceivably be
bent away from the principal plane of the Milky Way; I am very familiar with a wide variety of bends and warps that are observed in the disks of many spiral galaxies.....in fact, the
majority of spiral galaxies are
not planar and have some bending of the disk....I have previously discovered that, statistically speaking and looking at the galaxy population as a whole, dust lanes are the most likely features in galaxies to be bent away from the principal plane by tidal forces.
Given that deep imaging surveys of our own Galaxy by professional astronomers often limit themselves to fields that are near to the plane of the Milky Way, your deep exposures of the band of the Milky Way give a unique perspective; there is always a potential for discoveries far from the principal plane, as the focus of professional astronomers' attention seems to be the plane itself.
On the whole I would say that the "vertical" dust chimney morphology in our own Galaxy is less pronounced than in some other spiral galaxies where this dust morphology is very obvious; in general, non-dwarf spiral galaxies with a higher rate of massive star formation tend to have more of the "vertical" dust chimneys and plumes. A classic case of a disk with a higher star formation rate than the Milky Way Galaxy is NGC 891, and NGC 891 has impressive dust structures at right angles to its plane.
Nick Risinger's impressive 360 degree image of the Milky Way may perhaps provide a further perspective on the dust which
at least apparently extends far away from the plane of our Galaxy;
http://apod.nasa.gov/apod/ap110520.html
Looking at the entire band of the Milky Way seems to put the size of the dust features into perspective.
Considering the Milky Way band as a spiral galaxy in its entirety, the Milky Way is obviously a
small-bulged galaxy with a
thin disk, but I do agree with you that there is evidence for dust stretching a long way from its plane.
Best Regards,
Robert Lang