Our discovery of 1SWASP J093010.78+533859.5 as a probable doubly eclipsing quadruple system , containing a contact binary with P \sim 0.23 d and a detached binary with P \sim 1.31 d , was announced in 2013 .
Subsequently , Koo et al .
confirmed the detached binary spectroscopically , and identified a fifth set of static spectral lines at its location , corresponding to an additional non-eclipsing component of the system .
Here we present new spectroscopic and photometric observations , allowing confirmation of the contact binary and improved modelling of all four eclipsing components .
The detached binary is found to contain components of masses 0.837 \pm 0.008 and 0.674 \pm 0.007 M _ { \sun } , with radii of 0.832 \pm 0.018 and 0.669 \pm 0.018 R _ { \sun } and effective temperatures of 5185 _ { -20 } ^ { +25 } and 4325 _ { -15 } ^ { +20 } K , respectively ; the contact system has masses 0.86 \pm 0.02 and 0.341 \pm 0.011 M _ { \sun } , radii of 0.79 \pm 0.04 and 0.52 \pm 0.05 R _ { \sun } , respectively , and a common effective temperature of 4700 \pm 50 K. The fifth star is of similar temperature and spectral type to the primaries in the two binaries .
Long-term photometric observations indicate the presence of a spot on one component of the detached binary , moving at an apparent rate of approximately one rotation every two years .
Both binaries have consistent system velocities around -11 to -12 km s -1 , which match the average radial velocity of the fifth star ; consistent distance estimates for both subsystems of d = 78 \pm 3 and d = 73 \pm 4 pc are also found , and , with some further assumptions , of d = 83 \pm 9 pc for the fifth star .
These findings strongly support the claim that both binaries – and very probably all five stars – are gravitationally bound in a single system .
The consistent angles of inclination found for the two binaries ( 88.2 \pm 0.3 °and 86 \pm 4 ° ) may also indicate that they originally formed by fragmentation ( around 9–10 Gyr ago ) from a single protostellar disk , and subsequently remained in the same orbital plane .