Brown dwarf or Hot Jupiter as 3rd body in eclipsing binary A

Sounds intriguing!

Preliminary results for the triple system AV CMi

Quote :

ts periodwas found to be  0.52 days. It is very difficult to conclude which componentis eclipsed by the third body, since both of them have the same temperature.The 2.6% flux drop of the eclipsing binary indicates that the size of the thirdbody is probably very small, and that is the reason we cannot observe its eclipse,but only its transit. Spectroscopic observations are certainly needed in order to:i) derive the mass ratio of the components of the eclipsing pair, ii) define thespectral types of all the components of the triple system, and iii) detect peri-odic shifts in the radial velocity curves due to the existence of the third body.Moreover, additional photometric observations in I-filter during the transits willhelp to determine the period of the third body with higher accuracy. To sumup, the preliminary results of the present analysis show that the third body issmall and cool and it has an internal and eccentric orbit. These characteristicslead us to suggest that the third body is probably a brown dwarf or a massive Hot Jupiter(!), but its nature requires further study.

So...

The binary orbital period is 2.3 days, which puts the components very close together, yet there is apparently in this system a third object, which is not in circumbinary orbit but in an S-type orbit of period 0.52 days around one of the componets.

Rather an extreme system, no? Have to wonder whether that Kepler "circumbinary planet" curve may also be an example of this class of system...

Yeah, indeed quite extreme. The 3rd object would have to have an extremely short orbital period I would guess, < 1 d?

If the 3rd body's orbit is not coplanar with the system orbit, then that would quickly destabilize, right?

If the 3rd body's orbit is coplanar with the system orbit, then it should transit both stars, negating any sufficiently large eccentricity in the third body's orbit, which one would think might be fatal in such a cramped space.

Transits of the host star would be at regular intervals. Transits of the other star are guaranteed regardless of the third body's orbital parameters, but they would occur sporadically without a resonant effect which might be nice for system stability.

This also would open an important question about the planetary orbits in binary systems, both in tight both in wide ones.

It would seem planets may find different configurations the binary nature of primary could not affect.

This could also be the case of the controversial unseen third body of Sirius or Nu Octantis...