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Contains:  NGC 6946
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NGC 6946, 





    
        

            Algorab
NGC 6946

NGC 6946

Technical card

Resolution: 2000x2000

Dates:April 16, 2018April 17, 2018April 18, 2018April 19, 2018April 20, 2018April 21, 2018

Frames:
Baader 36mm Ha 7nm: 61x180" bin 1x1
Baader 36mm L: 101x180"
Baader 36mm Blue: 69x180" bin 1x1
Baader 36mm Red: 70x180" bin 1x1
baader 36mm Green: 70x180" bin 1x1

Integration: 18.6 hours

Avg. Moon age: 3.14 days

Avg. Moon phase: 13.74%

Astrometry.net job: 2025554

RA center: 308.720 degrees

DEC center: 60.154 degrees

Pixel scale: 0.657 arcsec/pixel

Orientation: 83.478 degrees

Field radius: 0.258 degrees

Locations: Säule, Siegen, NRW, Germany

Description

Some interesting infos about this object, found at http://www.gemini.edu/node/116

“In order to sustain this rate of supernova activity, massive, quickly evolving stars must form or be born at an equally rapid rate in NGC 6946,” said Gemini North Associate Director, Jean-René Roy. “Its stars are exploding like a string of firecrackers!”

Astronomers speculate that if just a million years of this galaxy’s history were compressed into a time-lapse movie lasting a few seconds, there would be nearly constant outbursts of light as new stars flare into view, while old ones expire in spectacular explosions. Over the past century, eight supernovae have exploded in the arms of this stellar metropolis, occurring in 1917, 1939, 1948, 1968, 1969, 1980, 2002, and 2004. This makes NGC 6946 the most prolific known galaxy for supernovae during the past 100 years.

By comparison, the average rate for such catastrophic stellar outbursts in the Milky Way is about one per century, and only four have been recorded over the last thousand years. The last known supernova went off in our galaxy in the constellation Ophiuchus in 1604.

Yet, it is the ubiquitous occurrence of starbirth throughout NGC 6946 and not its supernovae that lend this galaxy its blazingly colorful appearance. For reasons not completely understood, it experiences a much higher rate of star formation than all the large galaxies in our local neighborhood. The prodigious output of stellar nurseries in this galactic neighbor eventually leads to accelerated numbers of supernova explosions.

Starbirth regions exist in most galaxies, particularly in spirals, and are obvious as clouds of predominantly hydrogen gas called H II regions. These areas coalesce over millions of years to form stars. Young, hot, massive stars formed in these regions emit copious amounts of ultraviolet radiation, which strip the electrons from hydrogen atoms in which they are embedded. When these ionized hydrogen atoms re-associate with electrons they radiate in a deep red color (at a wavelength of 656.3 nanometers) as the electrons transition back to lower energy levels.

[...]

NGC 6946 lies between 10 and 20 million light-years away on the border between the constellations of Cepheus and Cygnus, and was discovered by Sir William Herschel (1738-1822) on September 9, 1798. It continues to fascinate astronomers, who estimate that it contains about half as many stars as the Milky Way. They often use it to study and characterize the evolution of massive stars and the properties of interstellar gas. As viewed in the new Gemini optical image, we see only the “tip of the iceberg” of this galaxy. Its optical angular diameter is about 13 arcminutes, but viewed at radio wavelength at the frequency of neutral hydrogen (1420 Mhz or 21-cm line), it extends considerably more than the angular diameter of the Moon.

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Algorab
Algorab
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    Original
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  • Final
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color changes

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crop on 6946

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NGC 6946, 





    
        

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In these public groups

ZWO ASI1600MM/QHY163M