Simeis 147 (SH2-240) in Hydrogen Alpha

Simeis 147

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Copyright Steve Cannistra

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FOV: approximately 3.9
x 3.9 degrees (two panel mosaic)
RA (J2000): 05h 43m 12s
Dec (J2000): +28 degrees 17' 00"
Position Angle: +0 degrees

Simeis 147 is a very faint, very large supernova remnant in Taurus that is expanding at a rate of 1000 kilometers/second.  It covers an area of over 3 degrees of sky and is just barely included in this two frame mosaic using the STL11K in combination with the FSQ106 scope.  Simeis 147 is a result of a supernova explosion that occurred approximately 30,000 years ago, and the remaining pulsar has been recently identified.  A supernova results from a massive star (at least 8 solar masses) that has used up most of its elements through fusion, converting hydrogen to helium, oxygen, silicon, sulfur, calcium, gold, and eventually iron.  Iron is not a viable fuel for fusion (it requires too much energy), meaning that this element represents the end of the line for a dying star.  Without the outward force of fusion-induced radiation, the star collapses under its own gravity, resulting in a massive explosion and release of radiation, some of which we see as visible light.  The stellar remnant of a supernova explosion is a neutron star or a black hole (depending upon the size of the residual star).  If the residual star is between 1.44 and 3 solar masses, it forms a neutron star (which is also known as a pulsar, as is the case for Simeis 147).  If it is greater than 3 solar masses, it forms a black hole.  I will eventually add color to this image, but thought that I would post the hydrogen alpha version first since it contains a great deal of interesting detail.

Photographic Details:
Date:  Ha- October 22, 2007 (bottom half); December 13, 2008 (top half).  The years are correct- I did not get a chance to acquire the top half of this image until now!
Scope:  Takahashi FSQ106 at f5 on the Takahashi NJP Mount
Autoguider:  SBIG ST-402 with 60mm guidescope, focal length 227mm
Camera:  STL11K -20C
Baader 7nm Ha filter, 50.8mm unmounted
Exposures:  Ha for each half was 210'; Total exposure 7 hours
Post-processing:  Calibrated, aligned, and Sigma Clip combined in Maxim, followed by DDP in ImagesPlus (IP).  Further processing in Photoshop CS (16 bit format)

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