Object of the Week, January 31 2021 - NGC 1491, the "Fossil Footprint Nebula"
Name: NGC 1491 = Sh 2-206 = LBN 705
RA: 04 31 16
Dec: +51 18 34
Constellation: Perseus
Size: ~ 5'x4' (central bubble), ~ 25'x25' (outer regions LBN 705)
High in the sky between the stars Capella and Mirfak we found the nebula complex of NGC 1491. Discovered by William Herschel at 1790 indicates, that this nebula was and is a target for us visual observer.
Deep photographs show a large, around 25'x25' nebula, mainly shining in red but also blue colors. Looking somewhat deeper shows an open structure around the blue (O5) 11mag star BD +50 886 which ionized with its strong stellar winds mainly the center of the nebula [1]. This process creates an interesting combination of an "elephant's trunk" like ionization front 1.1' west and a thin shock front only 0.2' west of the star.
For us observer the nebula is in fact small but bright and especially the center is shining in the [OIII] band [2]. So, a 4-inch telescope could show the nebula at all. The first structures within the ionization front is in reach of an 14-inch telescope or maybe smaller. Unfortunately I could not pick up the shock front with my 27-inch, but maybe someone else was more successful?
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