Tuesday, December 20, 2016

multi-star Messier 47 (Halifax)

While the sky was full of Moon, I wanted to have a go at the multi-star systems in Messier 47. I sent the Burke-Gaffney telescope on a mission. It brought back some stars from Puppis.

multi-star systems in Messier 47 luminance

Luminance only, 3 seconds subexposures, 6 stacked shots. FITS Liberator, Paint.NET. North is up; east is left.

In the middle of loose open cluster M47 is HD 60997 or Σ1121. The A and B stars are the brightest, slightly left or east of centre, and touching in this image. They appear equally bright. A is eastward; B is westward. C is the rather faint star south-east of AB and perfectly in-line. D is the medium bright star due east of A. E is south-west of B showing a bit brighter than C but less than D. Where's F? G is the bright star due north of AB. SkyTools shows this star more eastward. Either its moved to the west or the AB stars have shifted east. H looks the same brightness as D, is opposite D, to the west of A. The I star might be the same magnitude as A or B and is north-east of G. Finally the J star is quite far north, slightly more than the AB-G separation, and slightly to the west, almost opposite C.

Huh. F is the faint star beyond B, slightly in-line with AB, just over half-way to the mid-bright star HD 60968. It seems to be slightly brighter than C.

I had viewed Messier 47 back in March 2013 but had rushed. I had not noted all the stars of the system nor their colours. I look forward to drawing out the hues in colour data.

To the right or west of Struve 1121 is the multi-star system V378 Pup or A3092 or ADS6208. The C, D, E, and F stars are easily spotted. The bright point is the A star (at magnitude 5.7) with the very faint (mag 12.2) B star close by, lost in the glare perhaps. C and D and E appear the same brightness. C is close to AB, to the north-east. D is well-away, to the north-east of C whereas E is to the north-west, about 2/3rds the AB-D separation. F is the faint star between D and E, almost in-line.

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Tried coaxing V378 B out by dramatically stretching with the x^1/5 function. No joy.

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