Saturday 14 October 2017

NGC7789: Caroline's Rose

Discovered by Caroline Herschel in 1783, NGC7789 is one of autumn's finest jewels. Notwithstanding its considerable distance of 7,600 light-years, this open cluster appears so brightly in the constellation of Cassiopeia that it can almost be seen with the naked eye under a perfect sky. Being extremely rich and dense, the cluster's gravity has been able so far to keep most of its stars together during its already fairly long existence of 1.6 billion years. Since more massive stars burn their fuel more quickly, many of its bigger members have already left their main-sequence, "adult" life and have evolved into helium-fusing red giants. 

It was quite a challenge to sketch and it took me two full observing nights and a week behind the pc to obtain this result. So I hope that you'll appreciate the effort. The cluster's nickname "Caroline's Rose" comes from the many dark dust-lanes which cut through the cluster and give the impression of flower petals, or of indeed a rose. 

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