NGC 7419, Open Star Cluster
The star cluster NGC 7419 is located at a distance of 9,500 light years in the constellation Cepheus and was found by F.W. Herschel in 1787.
With an apparent magnitude of 13mag it is relatively faint and therefore rather an object for medium sized telescopes with more than 10" aperture.
The cluster is very massive with a total mass of 7,000 to 10,000 solar masses. From the apparent diameter and the distance the true diameter
can be determined to 17 light years. With an age of 14 million years NGC 7419 is still quite young and contains accordingly many young, hot
stars.
Studying the individual cluster members is not easy because the light is weakened by dust by up to 6 magnitudes - which especially affects the
hot, blue stars. The hottest ones belong to spectral class B2 and reach a temperature of up to 26,000 Kelvin at their surface, which means they
are "blue giant stars". This type of star alone accounts for 1,200 solar masses. Unusual is the fact that in NGC 7419, despite its young age,
already 5 red giant stars have been discovered. The brightest one is named "MY Cep" - not to be confused with "My Cephei". Despite its high
luminosity of more than 100,000 suns it reaches only an apparent brightness of 14.4 to 15.3mag, which changes in irregular intervals. The red
giant has a surface temperature of cool 3,000 Kelvin and therefore belongs to the spectral class M7.5.
----------------------------------------------------------------------------------------------------------------------------------------------
In a 20 inch Dobsonian NGC 7419 offers a wonderful sight. At low magnification, the cluster is easily seen with indirect vision as a brighter,
grainy patch of light.
The cluster appears most beautiful at 270x. There are about 35-40 faint single stars visible. The cluster is not completely resolved, but the
background is still slightly grainy and from time to time fainter stars flash out. Most noticeable are two bright stars to the west of the cluster,
the brighter of which shines in a distinct yellow hue.
