**Table 7:** The five known binaries in Sco OB2 with an orbital period less than two days. Columns 1-3 list the primary star, the primary spectral type, and the measured orbital period. Columns 4 and 5 list the primary mass estimate as derived from the V-band magnitude, under the assumption that the mass ratio is $q\approx 0$ and q=1, respectively. Columns 6 and 7 list extremes for the semi-major axis of the binary, as derived using Kepler's third law, under the assumption of a mass ratio $q\approx 0$ (6th column), and q=1 (7th column). Finally, Cols. 8 and 9 list the subgroup of which the binary is a member and the reference for the orbital period. It is possible that a small number of closer, yet undiscovered binaries exist in Sco OB2.
Member	Spectral	P	$M_1~({M}_\odot)$		$a~({R}_\odot)$		Subgroup	Reference
HIP	type	day	( $q\approx 0$ )	(q=1)	( $q\approx 0$ )	(q=1)
74449	B3 IV	0.90	5.2	4.0	6.8	7.8	UCL	Buscombe & Kennedy (1962)
77911	B9 V	1.26	3.5	2.2	7.5	8.0	US	Levato et al. (1987)
78265	B1 V	1.57	10.9	8.3	12.6	14.5	US	Levato et al. (1987)
74950	B9 IV	1.85	4.2	3.2	10.2	11.8	UCL	Andersen et al. (1993)
77858	B5 V	1.92	4.5	3.4	10.7	12.3	US	Levato et al. (1987)

Source LaTeX | All tables | In the text