Which ancestor of mine is this oil painting showing?
I think it is either Heimann JARISLOWSKY, born in Konigsberg in 1812 and died just short of his 100th birthday.  Or is it his father, Aaron JARISLOWSKY born in 1792?  
It is a small oil painting, with no indication of the artist's name.  

Any ideas where I could begin to identify the sitter and what was the occasion ?

Margaret Levin
London UK 

I ran this thru Googleimages.  Many very similar paintings but none like yours. Value ranged from $79.00 to almost $10,000 USA Dollars.  . Do you know the provenance of the painting?  Assuming no signature of the artist?
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Sandra Parker

Thanks for looking through Googleimages.  Any consensus on the artist ?  Heimann J died in Breslau, 
No signature. The frame has been taken off.
My questions are  more about why and where and when was this painting done; who is the person;  was the hat a sign of wealth; or  position in the community; what fur is it made of  ?  Was this portrait commissioned to mark a special birthday ?  For his 70th birthday, his 7 children gave him  a silver tree with their names engraved on it.

Margaret Levin

Have you thought about consulting with any of the auction houses that specialize in Judaica? They may be able to help you narrow down the year, region, possibly the artist, and the social conventions regarding individual Jewish portraits of the era. 
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Felice Bogus
Raleigh, NC

Have you noticed the name n the bottom left of the frame? It looks like Fevt,  which may mean something to you or to an expert and he;lp to date it..
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Eva Lawrence
St Albans, UK.