To the naked eye, most stars in the heavens appear to be making a solitary journey through the cosmos. In reality, more than half of the stars have companion stars that can sometimes be seen through a telescope, and other times can only be detected spectroscopically or by measuring minute changes in position or fluctuations in brightness which reveal that there is a stellar partner. In the case of the image above, there is no question that this is a unique binary star system. Cor Caroli, which means “Heart of Charles”, was named after England’s King Charles the 1st, shortly after he was killed during the English Revolution. This radiant Binary system shown above, is actually 2 stars which lie only 19 arcseconds apart, but are easily discernable in this image: Alpha-1 and Alpha-2 Canes Venaticorum. These stars are part of the constellation Canes Venatici, the Hunting Dogs and lie perpendicular and south of the Big Dippers handle. The system is dominated by the peculiar blue/white A0 Alph-2 star. It has a magnitude of 2.9 and far outshines the Alpha-1 6th magnitude F class star. The larger of the 2 shines with the luminosity of 83 Suns.
What is peculiar about Cor Caroli is that the main star is considered to be a magnetic star. In fact, it has the strongest magnetic field of any known hydrogen fusing star. Most planets that are geologically active, such as the earth, as well as stars, have a magnetic field that is generated internally. Our Suns magnetic field is only a few times stronger than that of our earth. Cor Caroli’s magnetic field however is over 1500 times stronger than that of our planet earth. This exceptional strong magnetic field is believed to be responsible for excessive stellar spots, which are believed to be responsible for it’s periodic variability in brightness. In fact, this star is the prototype for a class of variable stars called the Alpha Canes Venaticorum Variables, which have strong magnetic fields and similar periodicity.
Date: March 2009
Location: Starlodge Observatory
Scope: Planewave CDK 12.5
Camera: SBIG STL-11000