R CrB (R Coronae Borealis)
Abstract:
"The Coronae Borealis stars are one of the longest known classes of variable star. They fade dramatically and unpredictably by factors of up to one thousand within a few weeks. Over succeeding months, they gradually recover their original brightness. This spectacular fading is caused by the formation of sooty dust clouds above the surface of the star. The surfaces of CB stars are unusually poor in hydrogen, and rich in carbon and nitrogen, which implies that they are the remnants of evolved stars".
A lot has been going on with R CrB, John Toone reported it varying between 6.1 to 6.4mag in June 2007 whereas it had been at a point of 5.9mag in March to May 2007. A sudden fading is now expected so I will report when this happens to any great extent, Des Loughney in Scotland has reported as I type that it is now down to 6.73.
Keep an watch on this one.
Regards
"The Coronae Borealis stars are one of the longest known classes of variable star. They fade dramatically and unpredictably by factors of up to one thousand within a few weeks. Over succeeding months, they gradually recover their original brightness. This spectacular fading is caused by the formation of sooty dust clouds above the surface of the star. The surfaces of CB stars are unusually poor in hydrogen, and rich in carbon and nitrogen, which implies that they are the remnants of evolved stars".
A lot has been going on with R CrB, John Toone reported it varying between 6.1 to 6.4mag in June 2007 whereas it had been at a point of 5.9mag in March to May 2007. A sudden fading is now expected so I will report when this happens to any great extent, Des Loughney in Scotland has reported as I type that it is now down to 6.73.
Keep an watch on this one.
Regards
posted by Peter Little at
06:40
1 Comments:
I've been following R CrB from Tabuk in Saudi Arabia since April 2007, and up till June 23rd it was normal. The following night it had faded to 6m.2 and the night after that it was down to 6m.3. It then recovered. I contacted Guy Hurst at the time but we decided not to issue a general alert. R CrB has a propensity towards mini-fades and this could be just another. We decided to wait and see. Very soon afterwards it faded again, but the light-curve zig-zaged up and down on almost a daily basis. It was as if the star could not make up its mind. However the general trend was downwards, and it faded below 7m.0. This has now continued and I last saw it (July 29th., 2007) at 8m.3
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