BD +26°730 suspected back in 1981

Boy, this is an old paper. It state that there is suspected companion to BD +26°730
http://adsabs.harvard.edu/abs/1981ApJ...249..662

http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BD+%2B26+730
AND
http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD%20283750b (probably a BD)

Turns out, they knew this back in 1981 or earlier.
Mass constrained at.
-- mass of companion, 0.0002Ms if viewed edge-on
-- mass of companion, ~0.05 if rotation of the primary is synchornous which is the case for nearly all BY Dra system

It also stated that EQ Vir is similar in the Hα emission variability. I wonder if that means that EQ Vir should be looked at more?

*deleted*

0.0002 solar masses is the mass function, not the companion mass. Mass function is defined as

f(m) = (m sin i)³ / (M + m)²

Where f(m) is the mass function, M is the primary mass and m is the secondary mass.

From the paper:

Quote :

If the orbit is viewed edge-on, and if we assume the primary has a mass of ~0.8 M_⊙, then the unseen secondary must be substellar (~0.05 M_⊙). However, if the rotation of the primary is synchronous with the orbit (as is the case for nearly all BY Dra systems) then we expect a rotation velocity v (equator) ~25 km s^-1. The fact we observe v sin i≲15 km s^-1 implies i≲35°
...
We note that if i=30°, the implied secondary mass M₂ is 0.1M_⊙...

So a stellar companion, not substellar. See also this table from Cuntz, Saar and Musielak (2000), where the true mass is given as 132 Jupiter masses (well into the stellar regime).