SRGA J115215.0$-$510656: an unusual long-period eclipsing dwarf nova with disc wind signatures
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| Main Authors: | , , , , , , , , , , , |
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| Format: | Preprint |
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2026
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| author | Rawat, Nikita Buckley, David A. H. Thorstensen, John R. Knigge, Christian Tampo, Yusuke Potter, Stephen B. Bhardwaj, Anupam Scaringi, Simone Mereminskiy, Ilya A. Pandey, Jeewan C. Rao, Srinivas M Lutovinov, Alexander A. |
| author_facet | Rawat, Nikita Buckley, David A. H. Thorstensen, John R. Knigge, Christian Tampo, Yusuke Potter, Stephen B. Bhardwaj, Anupam Scaringi, Simone Mereminskiy, Ilya A. Pandey, Jeewan C. Rao, Srinivas M Lutovinov, Alexander A. |
| contents | We present the first detailed optical study of the cataclysmic variable SRGA J115215.0$-$510656, based on new time-resolved photometric and spectroscopic observations complemented by long-baseline Transiting Exoplanet Survey Satellite (TESS) data. The TESS light curve reveals deep, recurring eclipses consistent with a high-inclination geometry and an orbital period of 0.43567659(9)d. The eclipse morphology during outburst is consistent with a possible 'inside-out' type outburst and supports classification of the system as a U Gem-type dwarf nova. By combining eclipse phase width and ellipsoidal modulation, we constrain the system geometry to a narrow locus in the $(q,i)$ plane, with allowed mass ratios $0.28 \lesssim q \lesssim 0.84$ and inclinations $i$ $\simeq$75$-$84$^{\circ}$. The persistence of single-peaked Balmer lines during outburst, together with strong He II emission and a flattened Balmer decrement, points towards emission arising in a disc wind or vertically extended regions above the disc. Absorption features from a late-type secondary star (approximately K3) are detected, contributing roughly 30 per cent of the red optical flux. Comparison with main-sequence expectations suggests that the donor star is moderately inflated, consistent with a mildly evolved secondary. With its long orbital period, modest outburst amplitude, and emission-line characteristics, SRGA J115215.0$-$510656 appears to be a rare and compelling example of a bright, long-period dwarf nova whose optical properties are influenced by disc-wind processes during outburst. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_26702 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | SRGA J115215.0$-$510656: an unusual long-period eclipsing dwarf nova with disc wind signatures Rawat, Nikita Buckley, David A. H. Thorstensen, John R. Knigge, Christian Tampo, Yusuke Potter, Stephen B. Bhardwaj, Anupam Scaringi, Simone Mereminskiy, Ilya A. Pandey, Jeewan C. Rao, Srinivas M Lutovinov, Alexander A. Solar and Stellar Astrophysics We present the first detailed optical study of the cataclysmic variable SRGA J115215.0$-$510656, based on new time-resolved photometric and spectroscopic observations complemented by long-baseline Transiting Exoplanet Survey Satellite (TESS) data. The TESS light curve reveals deep, recurring eclipses consistent with a high-inclination geometry and an orbital period of 0.43567659(9)d. The eclipse morphology during outburst is consistent with a possible 'inside-out' type outburst and supports classification of the system as a U Gem-type dwarf nova. By combining eclipse phase width and ellipsoidal modulation, we constrain the system geometry to a narrow locus in the $(q,i)$ plane, with allowed mass ratios $0.28 \lesssim q \lesssim 0.84$ and inclinations $i$ $\simeq$75$-$84$^{\circ}$. The persistence of single-peaked Balmer lines during outburst, together with strong He II emission and a flattened Balmer decrement, points towards emission arising in a disc wind or vertically extended regions above the disc. Absorption features from a late-type secondary star (approximately K3) are detected, contributing roughly 30 per cent of the red optical flux. Comparison with main-sequence expectations suggests that the donor star is moderately inflated, consistent with a mildly evolved secondary. With its long orbital period, modest outburst amplitude, and emission-line characteristics, SRGA J115215.0$-$510656 appears to be a rare and compelling example of a bright, long-period dwarf nova whose optical properties are influenced by disc-wind processes during outburst. |
| title | SRGA J115215.0$-$510656: an unusual long-period eclipsing dwarf nova with disc wind signatures |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2604.26702 |