Observations of Five Southern-Hemisphere Cataclysmic Binary Stars
Abstract
We present observations and analyses of five little-studied cataclysmic binary stars in the southern celestial hemisphere. Our new observations are from the South African Astronomical Observatory. The objects and salient results are as follows: (i) 6dF0752-54 is a dwarf nova with an orbital period Porb = 5.05 hr that shows a contribution from a mid-M type secondary in its mean spectrum. (ii) J0916-26 had been suspected of being a magnetic CV with an eclipse period of 3.37 hr. Our spectrum corroborates this classification. (iii) GSC 08944 is a novalike variable with Porb = 3.80 hr. Archival photometry also shows a persistent photometric period near 4.03 hr, apparently from a positive super- hump. Its emission line behavior is consistent with an SW Sextantis-type novalike. (iv) MGAB-V253, also Gaia20eys, had been identified as a short-period eclipsing novalike with Porb = 1.44 hr. Our spectrum shows shows broad emission lines consistent with this, and the extensive TESS data show a persistent modulation near 1.35 hr, evidently a negative superhump. It is less luminous than most novalikes, but significantly brighter than quiescent dwarf novae with comparably short periods. (v) Finally, DDE 45 shows a complicated variability history, cycling rapidly between high and low states for a time and more recently showing outbursts resembling a U Gem-type dwarf nova. We find a 2.07 hr radial velocity period, which also appears in archival TESS photometry. The emission lines are double-peaked, with an orbital S-wave similar to low-inclination dwarf novae. To be published in Astronomical Journal.
Cite
@article{arxiv.2511.12762,
title = {Observations of Five Southern-Hemisphere Cataclysmic Binary Stars},
author = {John R. Thorstensen and Annabelle E. Niblett and Shreya Gandhi and Lauren P. Zanarini and Gavin D. Goss and Arnav Singh and Divik Verma and Ryan C. Hickox and Emmanuel A. Durodola and Jiaqi Martin Ying},
journal= {arXiv preprint arXiv:2511.12762},
year = {2025}
}