by Ann » Wed Apr 07, 2021 4:43 am
How interesting! NGC 1947 is like a future, "spent" version of active galaxy
Cen A!
Both Cen A and NGC 1947 are products of galactic collisions. A small gas-rich galaxy has collided with a larger elliptical galaxy.
In Cen A, the collision probably happened
relatively recently. The crash created huge amounts of very thick dark dust and reasonably high levels of star formation (blue stars at upper right and lower left). Cen A also has an active black hole with a jet, probably because the collision has been feeding material into the galactic center. The jet is seen better
here.
NGC 1947, by contrast, is "spent". Its dust lanes are thinning like the hairs of a man going bald, and there are no young blue stars associated with the dust lanes.
But we can still see how the dust lanes appear to be "orbiting" around the elliptical galaxy's equator, as if they were rings of Saturn. The dust lanes of NGC 1947 appear to be wind-blown, too, as if they are being drawn out and stretched by the rotation of the elliptical galaxy. The galaxy, or at the very least the dust lanes, seem to be rotating "clockwise".
Another similar galaxy is
NGC 1316. But here the dust lanes are more chaotic.
Ann
[float=left][img3="Cen A. Photo: ESO."]https://cdn.eso.org/images/screen/eso0005b.jpg[/img3][/float][float=right][img3="NGC 1947. Image Credit: ESA/Hubble & NASA, D. Rosario; Acknowledgment: L. Shatz."]https://apod.nasa.gov/apod/image/2104/NGC1947potw2051a_1024.jpg[/img3][/float]
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How interesting! NGC 1947 is like a future, "spent" version of active galaxy [url=https://en.wikipedia.org/wiki/Centaurus_A#/media/File:ESO_Centaurus_A_LABOCA.jpg]Cen A[/url]!
Both Cen A and NGC 1947 are products of galactic collisions. A small gas-rich galaxy has collided with a larger elliptical galaxy.
In Cen A, the collision probably happened [b][i]relatively[/i][/b] recently. The crash created huge amounts of very thick dark dust and reasonably high levels of star formation (blue stars at upper right and lower left). Cen A also has an active black hole with a jet, probably because the collision has been feeding material into the galactic center. The jet is seen better [url=https://chandra.harvard.edu/photo/2014/cena/]here[/url].
NGC 1947, by contrast, is "spent". Its dust lanes are thinning like the hairs of a man going bald, and there are no young blue stars associated with the dust lanes.
But we can still see how the dust lanes appear to be "orbiting" around the elliptical galaxy's equator, as if they were rings of Saturn. The dust lanes of NGC 1947 appear to be wind-blown, too, as if they are being drawn out and stretched by the rotation of the elliptical galaxy. The galaxy, or at the very least the dust lanes, seem to be rotating "clockwise".
Another similar galaxy is [url=https://apod.nasa.gov/apod/ap210126.html]NGC 1316[/url]. But here the dust lanes are more chaotic.
Ann