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In the southern constellation of Fornax is an eclipsing binary, called UZ For, that consists of two small stars, a white dwarf and a red dwarf, that orbit their common barycentre in just a couple of hours. Their separation is so small that the whole system would fit within our own Sun!
The white dwarf, more massive despite its much smaller size (a teaspoon full of its matter would weigh about 5 tons), is constantly accreting material from its companion, and in the region where the material falls temperatures of millions of Kelvin are generated, causing the emission of a powerful X-ray flux which irradiates all of the surrounding space.
UZ For is now making the news because from recent photometric observations made with the Southern African Large Telescope by an international team of astronomers, and analysed together with other similar observations by other groups over a period of 27 years, a strange phenomenon has been noticed. The timing of mutual eclipses of the two dwarfs (about one per hour) appear to suffer periodic modifications of up to 60 seconds, which seem to be consistent with two long period perturbations of length 16 and 5.25 years.
According to the astronomers involved (including Stephen B. Potter, Encarni Romero–Colmenero and Gavin Ramsay), the scenario which best describes the observed discrepancies is one in which two giant planets orbit around the pair of dwarfs in 16 and 5.25 years, having masses of at least 6.3 and 7.7 jovian masses.
This would make UZ For an extremely unusual planetary system, but it doesn't stop there.
The two planet hypothesis, in fact, would only explain the time anomalies if the most external of the two were in an extremely elliptical orbit, which would be very unstable, making this unlikely. Potter and colleagues attribute the residuals in the eclipse timings either to other planets in orbit around the dwarfs (further out or much less massive) or to a complex magnetic cycle on the red dwarf, or a combination of both.
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