Re: [APML] Going Deep on M27

["Richard Crisp" <rdcrisp@earthlink.net>]

----- Original Message ----- 
From: "Stuart Heggie" <stuart.j.heggie@sympatico.ca>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Saturday, August 13, 2005 5:24 AM
Subject: Re: [APML] Going Deep on M27


> Rob, it is a beautiful shot! The colours are very rich. A few of us 
> locally have been debating the colour of M27 and we will take a big nod 
> from you on that issue. Thanks!


one easy way to end the debate is to shoot them in tricolor narrowband. You 
get to write your own score.....


>
> Stuart
>>
>> From: "Robert Gendler" <robgendler@worldnet.att.net>
>> Date: 2005/08/12 Fri PM 09:43:40 EST
>> To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
>> Subject: [APML] Going Deep on M27
>>
>> Hi all,
>> Here's a deep image of M27 using recent data acquired
>> from New Mexico and h-alpha data from connecticut.
>> Some information on the M27 is below the image link.
>> http://www.robgendlerastropics.com/M27NM.html
>>
>> M27 has the distinction of being the first planetary nebula ever 
>> discovered.
>> Messier's description of it as an "oval nebula without stars" was 
>> followed
>> by John Herschel's comparison to a dumbbell which later became its 
>> popular
>> name. The brightest part of the nebula is about 6 arc minutes (2.4 light
>> years) wide but a faint outer shell exists extending to 15 arc minutes. 
>> The
>> nebula is apparently expanding at a rate of 6.8 arc seconds per century.
>> This value leads to a calculated age of 3000 to 4000 years. The central 
>> star
>> is a white dwarf with a temperature of 85,000 degrees K. High energy
>> radiation from the dead star is absorbed by the gases of the nebula and
>> reemitted predominantly (about 90%) in green light at 500.7 nm due to
>> ionized oxygen. Other less abundant elements also present in the 
>> expanding
>> shell include hydrogen, helium, nitrogen and neon.
>>
>>
>>
>> Studies of M27 reveal a complex triple shell structure uncommon among
>> planetary nebulae. The outermost shell has a very low surface brightness 
>> and
>> a complex structure. It is recorded well only through narrowband filters 
>> and
>> probably represents gases expelled during earlier mass ejection periods 
>> of
>> the dying star. The elliptical shape of M27 is due to viewing the nebula 
>> at
>> its equatorial plane as most planetary nebulae have a cylindrical bilobed
>> shape.
>>
>>
>>
>>
>>
>> Rob Gendler
>> email: robgendler@att.net
>> Web Site: http://www.robgendlerastropics.com
>>
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>
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