Radial velocities from the 2.1 m telescope at McDonald Observatory supplemented with radial velocities from the coudé feed telescope at KPNO provide new precise orbits for the double-lined spectroscopic binaries RR Lyn ( A3/A8/A6 ) , 12 Boo ( F8IV ) , and HR 6169 ( A2V ) .
We derive orbital dimensions ( a _ { 1 } \sin i and a _ { 2 } \sin i ) and minimum masses ( m _ { 1 } \sin ^ { 3 } i and m _ { 2 } \sin ^ { 3 } i ) with accuracies of 0.06 to 0.9 % .
The three systems , which have V magnitudes of 5.54 , 4.83 , and 6.42 , respectively , are all sufficiently bright that they are easily within the grasp of modern optical interferometers and so afford the prospect , when our spectroscopic observations are complemented by interferometric observations , of fully-determined orbits , precise masses , and distances .
In the case of RR Lyn , which is also a detached eclipsing binary with a well-determined orbital inclination ( i = 87 \fdg 45 \pm 0 \fdg 11 ; Khaliullin et al .
2001 ) , we are able to determine the semimajor axis of the relative orbit , a = 29.32 \pm 0.04 R _ { \odot } , primary and secondary radii of 2.57 \pm 0.02 R _ { \odot } and 1.59 \pm 0.03 R _ { \odot } , respectively ; and primary and secondary masses of 1.927 \pm 0.008 M _ { \odot } and 1.507 \pm 0.004 M _ { \odot } , respectively .
Comparison of our new systemic velocity determination , \gamma = -12.03 \pm 0.04 km s ^ { -1 } , with the earlier one of Kondo ( 37 ) , \gamma = -11.61 \pm 0.30 km s ^ { -1 } , shows no evidence of any change in the systemic velocity in the 40 years separating the two measurements , a null result that neither confirms nor contradicts the presence of the low-mass third component proposed by Khaliullin & Khaliullina ( 32 ) .
Our spectroscopic orbit of 12 Boo is more precise that that of Boden et al .
( 11 ) but confirms their results about this system .
Our analysis of HR 6169 has produced a major improvement in its orbital elements .
The minimum masses of the primary and secondary are 2.20 \pm 0.01 and 1.64 \pm 0.02 M _ { \sun } , respectively .
Although all three systems have eccentric orbits , the six components of the systems are either pseudosynchronously rotating or very nearly so .