Ha loops in the core of M31 (David Ellison)

Ha loops in the core of M31

This is a pure Ha image of M31 showing loops of Ha emission around the core of the galaxy.

The difference in the core structure is just 47 ADU compared to a total light level of over 8000 ADU in the narrow band Ha image, so it represents less than 0.6% of the light from the 4 hour Ha exposure.

The image was produced from 2 sets of narrow band exposures, A red continuum filter is a 5nm narrow band filter that just misses the Ha band. Subtracting the RC from the Ha leaves pure Ha.

The loops probably represent "stellar streams", loops of star forming regions originating from previous galactic collisions. There is a similar loop pattern in VDB152 which can be seen in the APOD for 31OCT2012. You can go to pod.nasa.gov and search for that date. There is a description of stellar streams at et.m.wikipedia.org. There is a description of the double nucleus in the Andromeda Galaxy at hubblesite.org/newscenter/archive/releases/1993/18/text, and a Hubble photograph of the double nucleus, APOD, 11OCT96. Jon Talbot also has an image showing these loops on his site at starscapeimaging.com/resources/m31_Ha3nm_1210_50.jpg.

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Distribution of astrophotographers

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	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

Distribution of subject types

This table shows the distribution of awards per subject type, compared to the popularity of images of that subject type.
	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
Noctilucent clouds
Landscape

Distribution of data sources

This table shows the distribution of awards per data source, compared to the popularity of images acquired from that data source.
	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown

The “AstroBin Image of the Day and Top Picks”, or IOTD/TP, is a long-running system to promote beautiful, interesting, peculiar, or otherwise amazing astrophotographs, with a focus on technical excellence. Learn more.

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