Friday, 10 August 2018

IC4954/5: Shedding the birth veil

Some six degrees north of the famous Dumbbell Nebula, at the border between the constellations of Vulpecula and Cygnus, dwells a small star cluster. Roslund 4 is not all that difficult to observe, in spite of its considerable distance of 6,000 light-years, and should already be visible through a three-inch telescope given good sky conditions. 

A bigger challenge is the surrounding nebulosity (IC4954 - IC4955) which reflects the light of the stars in this cluster, born out of it hardly 4 million years ago. The young, hot stars have fired up nuclear fusion at full power and the ensuing radiation, up to 3,000 times solar, is currently blasting the nebula away. The sharp edge where the stellar wind's hitting the nebula actually serves as a very convenient yard stick with which we can measure the expansion speed of the nebula. It is estimated that within the next 6 million years the nebula, still containing about 60 solar masses of matter, will have dissolved completely. 

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