M 52 an open cluster but how far is it?

M 52
3x5 minute exposure, Stromgren y
© Billy Vazquez

M 52 discovered by Messier in 1774 is shown here in an unguided co-added 3x5 minutes Stromgren y filtered exposures.   This image is part of a battery of tests I am excercising on the observatory in preparation for a a new science run that will use Stromgren filters for stellar and luminosity classification.   I am glad to report that the Stromgren y filter which peaks exactly where the Johnson V filter does, is performing well in initial tests.   It is also an opportuinity for you to glimpse at a cluster with a controversial history about its true distance.  Reports vary considerably in the literature and mostly attributed to interstellar extinction.

M36 - An Open Cluster in Auriga

©Billy Vazquez @ VAO Webster, NY  9/11/2011

The open cluster M36 was discovered by Giovanni Batista Hodierna, an Italian astronomer of the 17th century. Rediscovered by Charles Messier as entry number 36 in his catalog.

©Billy Vazquez @ VAO Webster, NY  9/11/2011

The cluster is rather young with an approximate age of 25 million years and it is roughly at a distance at 4,000 light years.  The brightest stars on the image are of spectral type B.




This means these stars have temperatures that reach up to 33,000 K.  These stars are also very fast spinners.   You might ask how do we know they are fast rotators?   The key is on a technique called spectroscopy which breaks the light of the stars into its different emission and absorption lines and from the width of these lines we can tell the rotation speed.  

The image was taken from my observatory and it is a LRGB color combined image.  3 x 5 minutes exposures over each Johnson filter and 15 minutes exposure over a luminance (IR Blocking) filter.