by APOD Robot » Tue Feb 06, 2018 5:06 am
Galaxy NGC 474: Shells and Star Streams
Explanation: What's happening to galaxy NGC 474? The multiple layers of emission appear strangely complex and unexpected given the relatively featureless appearance of the
elliptical galaxy in less deep images. The cause of the shells is currently unknown, but possibly
tidal tails related to debris left over from absorbing numerous small galaxies in the past billion years. Alternatively the
shells may be like ripples in a pond, where the ongoing collision with the spiral galaxy just above
NGC 474 is causing
density waves to ripple through the galactic giant. Regardless of the actual cause, the
featured image dramatically highlights the increasing consensus that at least some elliptical
galaxies have formed in the recent past, and that the outer halos of most
large galaxies are not really smooth but have complexities induced by frequent
interactions with -- and accretions of --
smaller nearby galaxies. The halo of our own
Milky Way Galaxy is
one example of such
unexpected complexity. NGC 474 spans about 250,000
light years and lies about 100 million light years distant toward the constellation of the Fish (
Pisces).
[/b]
[url=https://apod.nasa.gov/apod/ap180206.html][img]https://apod.nasa.gov/apod/calendar/S_180206.jpg[/img] [size=150]Galaxy NGC 474: Shells and Star Streams[/size][/url]
[b] Explanation: [/b] What's happening to galaxy NGC 474? The multiple layers of emission appear strangely complex and unexpected given the relatively featureless appearance of the [url=http://en.wikipedia.org/wiki/Elliptical_galaxy]elliptical galaxy[/url] in less deep images. The cause of the shells is currently unknown, but possibly [url=https://apod.nasa.gov/apod/ap100926.html]tidal tails[/url] related to debris left over from absorbing numerous small galaxies in the past billion years. Alternatively the [url=https://apod.nasa.gov/apod/ap021111.html]shells[/url] may be like ripples in a pond, where the ongoing collision with the spiral galaxy just above [url=http://adsabs.harvard.edu/abs/1999IAUS..186..191T]NGC 474[/url] is causing [url=http://www.youtube.com/watch?v=c5Us-jonCLA]density waves[/url] to ripple through the galactic giant. Regardless of the actual cause, the [url=http://www.cfht.hawaii.edu/HawaiianStarlight/AIOM/English/2013/Images/Jul-Image2012-CFHT-Coelum.jpg]featured image[/url] dramatically highlights the increasing consensus that at least some elliptical [url=http://asterisk.apod.com/viewtopic.php?f=24&t=18005]galaxies[/url] have formed in the recent past, and that the outer halos of most [url=https://apod.nasa.gov/apod/ap061011.html]large galaxies[/url] are not really smooth but have complexities induced by frequent [url=https://www.youtube.com/watch?v=Su4gI2CApcQ]interactions[/url] with -- and accretions of -- [url=http://en.wikipedia.org/wiki/Local_Group]smaller nearby galaxies[/url]. The halo of our own [url=http://en.wikipedia.org/wiki/Milky_Way_galaxy]Milky Way Galaxy[/url] is [url=https://apod.nasa.gov/apod/ap050529.html]one example[/url] of such [url=https://utbblogs.com/wp-content/uploads/2014/10/toilet-paper-mess-01.jpg]unexpected complexity[/url]. NGC 474 spans about 250,000 [url=http://chandra.harvard.edu/photo/cosmic_distance.html]light years[/url] and lies about 100 million light years distant toward the constellation of the Fish ([url=http://en.wikipedia.org/wiki/Pisces_%28constellation%29]Pisces[/url]).
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