# BD +26°730 suspected back in 1981

## 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?

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?

_________________

Thanks,

CarpD (^_^)

**marasama**- SuperEarth
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## Re: BD +26°730 suspected back in 1981

*deleted*

Last edited by Darkness nova on 18th November 2008, 4:09 pm; edited 1 time in total

**Darkness nova**- Asteroid
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## Re: BD +26°730 suspected back in 1981

0.0002 solar masses is the

f(

Where f(

From the paper:

*mass function*, not the companion mass. Mass function is defined asf(

*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:

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).If the orbit is viewed edge-on, and if we assume the primary has a mass of ~0.8M_{⊙}, then the unseen secondary must be substellar (~0.05M_{⊙}). 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 velocityv(equator) ~25 km s^{-1}. The fact we observevsini≲15 km s^{-1}impliesi≲35°

...

We note that ifi=30°, the implied secondary massM_{2}is 0.1M_{⊙}...

**Lazarus**- dF star
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