APOD: Grand Spiral Galaxy NGC 7424 (2013 Jan 08)

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APOD Robot
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APOD: Grand Spiral Galaxy NGC 7424 (2013 Jan 08)

Post by APOD Robot » Tue Jan 08, 2013 5:05 am

Image Grand Spiral Galaxy NGC 7424

Explanation: The grand, winding arms are almost mesmerizing in this face-on view of NGC 7424, a spiral galaxy with a prominent central bar. About 40 million light-years distant in the headlong constellation Grus, this island universe is also about 100,000 light-years across making it remarkably similar to our own Milky Way. Following along the winding arms, many bright clusters of massive young stars can be found. The star clusters themselves are several hundred light-years in diameter. And while massive stars are born in the arms of NGC 7424, they also die there. Notably, this galaxy was home to a powerful stellar explosion, supernova SN 2001ig, which faded well before the above image was recorded.

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Ann
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Re: APOD: Grand Spiral Galaxy NGC 7424 (2013 Jan 08)

Post by Ann » Tue Jan 08, 2013 6:25 am

This is a great APOD! I love how the fine colors help us assess the nature of this galaxy.

Note the yellow population of NGC 7424. This is the old, stable population, billions of years old. NGC 7424 is strongly yellow in the bar and between the bar and the innermost arms, but it is also quite yellow below the lower innermost arm. There is what looks like a long, soft "arc" of yellowness below that innermost arm. It is as if we were looking at a broad yellow arm, made up almost exclusively of an old yellow population.

Look closely, and you'll see a similar broad soft arm above the upper innermost arm, too. This broad soft arm is fainter than the "yellow arm" below, and upper soft arm is not quite as yellow. Note, however, how regular these two soft broad arms are.

By contrast, the star forming arms and areas are all "Sturm und Drang" and rock and roll, wild and crazy and irregular. Clearly these are a recent addition to the galaxy, and the soft broad arms represent the underlying mass distribution and rotation of the galaxy. The bright starforming areas are extremely bright, but not so massive. Luminosity increases exponentially with mass in stars, so that a few massive stars can outshine millions of low-mass stars whose combined mass is thousands or millions of times greater than the cluster of hot brilliant stars.

This galaxy looks very "wind-blown" to me. Its original structure seems to be relatively unchanged, but wildfires rage on the surface of it, creating turmoil and fireworks and weird shapes primarily beyond the well-established old spiral structure.

Ann
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Re: APOD: Grand Spiral Galaxy NGC 7424 (2013 Jan 08)

Post by Boomer12k » Tue Jan 08, 2013 12:17 pm

A Grand Galaxy indeed, a veritable spinning fireworks display on a cosmic level.

Gorgeous Photo, Thanks.

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Re: APOD: Grand Spiral Galaxy NGC 7424 (2013 Jan 08)

Post by Anthony Barreiro » Tue Jan 08, 2013 6:37 pm

Wow, our long-lost twin! This is a beautiful and interesting picture.

Grus is too far south to be seen from my mid-northern latitude. Wikipedia says that NGC 7424 is 11th magnitude and 9.5 x 8.1 arcminutes across. The Messier spiral galaxies are mostly 8th to 10th magnitude. I wonder how NGC 7424 would appear visually in my biggest telescope, 203 mm aperture. Would you see an undifferentiated faint fuzzy, maybe a brighter core surrounded by fuzz, or would you be able to detect spiral structure and brighter knots in the spiral arms? If you've observed this object, I would love to hear what it looks like.
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Re: APOD: Grand Spiral Galaxy NGC 7424 (2013 Jan 08)

Post by neufer » Tue Jan 08, 2013 9:08 pm

http://en.wikipedia.org/wiki/NGC_7424 wrote:
<<NGC 7424 is a barred spiral galaxy located 37.5 million light-years away in the southern constellation Grus (the Crane). Its structure and diameter (about 100,000 light-years) make it similar to our own galaxy, the Milky Way. It is called a "grand design" galaxy because of its well defined spiral arms. One supernova and two ultraluminous X-ray sources have been discovered in NGC 7424. In May and June 2002 Roberto Soria and his colleagues at the Harvard-Smithsonian Center for Astrophysics discovered two Ultraluminous X-ray sources (ULXs) with the Chandra X-ray Observatory. ULXs are objects that emit tremendous amounts of X-rays (> 1032 watts or 1039 erg/s), assuming they radiate isotropically (the same in all directions). This amount is larger than currently understood stellar processes (including supernovae) but smaller than the amount of X-rays emitted by active galactic nuclei, which accounts for their alternate name, Intermediate-luminosity X-ray Objects (IXOs). The source designated ULX1 was found in a relatively empty interarm region, far from any bright clusters or star-forming complexes, and showed a 75% increase in X-ray luminosity over the course of 20 days. ULX2 was found in an exceptionally bright young stellar complex, and showed an order of magnitude increase over the same time period.>>
http://apod.nasa.gov/apod/ap050330.html wrote:
Explanation: In visual appearance, M74 is a nearly perfect face-on spiral galaxy, about 30 million light-years away toward the constellation Pisces. The red blotches seen in this composite view are ultraluminous x-ray sources (ULXs) mapped by the Chandra X-ray Observatory. The ULXs are so called because they actually do radiate 10 to 1,000 times more x-ray power than "ordinary" x-ray binary stars, which harbor a neutron star or stellar mass black hole. In fact, watching these ULXs change their x-ray brightness over periods of 2 hours or so, astronomers conclude that ULXs could well be intermediate mass black holes -- black holes with masses 10,000 times or so greater than the Sun, but still much less than the million solar mass black holes which lurk in the centers of large spiral galaxies. How did these intermediate mass black holes get there? One intriguing suggestion is that they are left over from the cores of much smaller galaxies that are merging with spiral galaxy M74.
Art Neuendorffer

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Re: APOD: Grand Spiral Galaxy NGC 7424 (2013 Jan 08)

Post by saturno2 » Tue Jan 08, 2013 11:45 pm

NGC 7424
Particularly striking is prominent central bar.
It seems that the rotating speed is " very slow ", the spiral arms not follow one aerodynamic line, out of its lane.

Sa Ji Tario

Re: APOD: Grand Spiral Galaxy NGC 7424 (2013 Jan 08)

Post by Sa Ji Tario » Sun May 27, 2018 12:54 pm

[float=] :P [/float]

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Re: APOD: Grand Spiral Galaxy NGC 7424 (2013 Jan 08)

Post by BDanielMayfield » Mon May 28, 2018 2:09 pm

Anthony Barreiro wrote:
Tue Jan 08, 2013 6:37 pm
Wow, our long-lost twin! This is a beautiful and interesting picture.

Grus is too far south to be seen from my mid-northern latitude. Wikipedia says that NGC 7424 is 11th magnitude and 9.5 x 8.1 arcminutes across. The Messier spiral galaxies are mostly 8th to 10th magnitude. I wonder how NGC 7424 would appear visually in my biggest telescope, 203 mm aperture. Would you see an undifferentiated faint fuzzy, maybe a brighter core surrounded by fuzz, or would you be able to detect spiral structure and brighter knots in the spiral arms? If you've observed this object, I would love to hear what it looks like.
Welcome back Anthony.

I think your much more likely to get an answer to your questions on S&T 's observer's page.

Bruce
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Re: APOD: Grand Spiral Galaxy NGC 7424 (2013 Jan 08)

Post by neufer » Mon May 28, 2018 5:10 pm

BDanielMayfield wrote:
Mon May 28, 2018 2:09 pm
Anthony Barreiro wrote:
Tue Jan 08, 2013 6:37 pm

Wow, our long-lost twin! This is a beautiful and interesting picture.

Grus is too far south to be seen from my mid-northern latitude. Wikipedia says that NGC 7424 is 11th magnitude and 9.5 x 8.1 arcminutes across. The Messier spiral galaxies are mostly 8th to 10th magnitude. I wonder how NGC 7424 would appear visually in my biggest telescope, 203 mm aperture. Would you see an undifferentiated faint fuzzy, maybe a brighter core surrounded by fuzz, or would you be able to detect spiral structure and brighter knots in the spiral arms? If you've observed this object, I would love to hear what it looks like.
Welcome back Anthony.
Hate to bring you down, Bruce, but this is an old thread and Anthony posted to it back on Jan 08, 2013.
Art Neuendorffer