NGC 654,VdB6,LDN 1332,1334,1337 (Cassiopeia)
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Antonio F. Sánchez
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NGC 654,VdB6,LDN 1332,1334,1337 (Cassiopeia) * August-September 2014 * ASA N12 astrograph (f/3.6,1078mm) * DDM85 mount * FLI ML8300 at -25ºC * Optec LRGB filter set * L.520m R:180m G:160m B:210m * Unguided *NGC 654 is a young cluster,with an age of about 14 million years.The cluster`s 80 measured members (7th magnitude and fainter) appear in little clumps scattered across a mere 6´of sky,or 14 lightyears. Astronomers have taken keen interest in NGC 654 because of it displays nonuniform extinction across its face,with stars reddened by about 1 magnitude on average.Color excess indicates the amount of interstellar reddening suffered by the light from the star when it passes through dust in space.Data from Indian Astronomer Biman J. Medhi and colleagues (2008), show evidence for the presence of at least two layers of dust along the line of sight to the cluster, which lies at a distance of about 7800 light-years.The 7th magnitude yellow supergiant star HD 10494 is a likely member of this cluster with a recessional velocity of about 31km/sec.They estimate the distances to the two dust layers to be about 652 and 3300 light-years, placing the clouds much closer to the Sun than the cluster.The foreground dust grains,appear to be responsible,then, for the nonuniform extinction towards the cluster,whose least reddened stars lie close to the cluster center.VdB 6 is a little reflection nebula. The star wrapped in vdB 6 is listed as HIP 8074 of magnitude 9.66, located in the Perseus arm, which gives the nebula a distinctly bluish color.Credits: Stephen James O´Meara"Deep-Sky Companions:The Secret Deep, Vol 4"Italian Wikipedia
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