Dr David Moriarty was the author on this publication in the Journal of the American Association of Variable Star Observers in 2015.


TW Crucis is a W-type W UMa contact eclipsing binary that has not been studied in detail since discovery in 1926. During 5 seasons from 2011 to 2015, photometric CCD observations were obtained mostly in the V passband, but also some light curves in B and I passbands. The period was found to be 0.3881444 ± 0.0000006 days, which is not substantially different from the original period of 0.3881358 days. There were slight variations in the period from cycle to cycle and year to year, which are most likely due to asymmetry in the light curves caused by star spots. A preliminary model of the light curves indicates the mass ratio may be about 0.67, inclination 70.8° and fillout factor 0.11. As no spectra are available, the range in B-V and V-I colour indices of 0.82 – 0.87 and 0.87 – 0.92 respectively were used to estimate the effective temperatures for the modelling, based on the spectral types of K0 – K2. The spectral type may be earlier, if the colour indices are affected by interstellar reddening. Star spots, which changed over short period cycles and were required to obtain good fits of the models to the light curves, indicate the stars are magnetically active.

The model has been updated with radial velocity data.  Models of several of the binary systems have been prepared with Binary Maker; the Sun is shown as an orange circle to the scale of each binary system.  View the model animation here:


Moriarty, D.J.W. 2015.
Period Analysis, Photometry and Astrophysical Models of the Eclipsing Binary TW Crucis. Journal of the American Association of Variable Star Observers. 43: 151-157.
Web site: https://app.aavso.org/jaavso/article/3115/

Link to Publication