Orbital Period Variation of the Low Mass Ratio Contact Binary HN UMa: O–C Analysis Based on TESS, SuperWASP and Ground Data

Year 2025, Volume: 11 Issue: 3, 309 - 317, 30.09.2025

Muhammed Faruk Yıldırım

https://doi.org/10.28979/jarnas.1746977

Abstract

The orbital period (OP) variation of the low-mass ratio contact HN Ursae Majoris (UMa) stellar system has been studied in detail for the first time using data from the Transiting Exoplanet Survey Satellite (TESS) and the Super Wide-Angle Search for Planets (SuperWASP) as well as data collected from the literature. We focused on determining the eclipse times (ET) from the light curves (LC) and constructed the O–C diagram from these times. The results obtained indicate the presence of OP variations in the system, where the OP of HN UMa decreases, and this ratio is calculated as dP/dt = –1.74  10-7 days/year. Energy and material transfer from the more mass star to the less mass one was proposed as the reason for the OP decrease, and this ratio was obtained as 3.03  10-8 Mʘ/year. Furthermore, a sinusoidal variation was also observed, and it was hypothesized that a possible third object or magnetic activity could cause this variation. The Js/Jo ratio for HN UMa was calculated as 0.215, and the values of qins and ains were determined as 0.036 and 2.21, respectively. In light of these findings, it can be said that the HN UMa system remains stable for the time being. The findings are likely to contribute to the understanding of the evolutionary processes in low-mass ratio binary systems.

Keywords

W UMa type systems , orbital period change , energy and material transfer , HN UMa

References

• L. B. Lucy, The structure of contact binaries, The Astrophysical Journal 151 (1968) 1123–1136.
• L. Binnendijk, The orbital elements of W Ursae Majoris systems, Vistas in Astronomy 12 (1970) 217–256.
• L. Li, F. Zhang, Z. Han, D. Jiang, T. Jiang, The evolutionary status of W Ursae Majoris-type systems, Monthly Notices of the Royal Astronomical Society 387(1) (2008) 97–104.
• K. Stepien, Evolutionary status of late-type contact binaries, Acta Astronomica 56 (2006) 199–218.
• K. Yakut, P. P. Eggleton, Evolution of close binary systems, The Astrophysical Journal 629(2) (2005) 1055–1074.
• R. F. Webbink, Contact binaries, 3D stellar evolution, in: S. Turcotte, S. C. Keller, R. M. Cavallo (Eds), ASP Conference Proceedings, Livermore, California (2002) 76–87.
• M. F. Yıldırım, A comprehensive photometric analysis of the shallow contact binary IR Vir, New Astronomy 111 (2024) id.102252.
• ESA, The Hipparcos and Tycho catalogues, ESA Hipparcos Space Astrometry-1200 (1997) ISBN: 9290923997.
• S. M. Rucinski, C. C. Capobianco, W. Lu, H. DeBond, J. R. Thomson, S. W. Mochnacki, R. M. Blake, W. Ogłoza, G. Stachowski, P. Rogoziecki, Radial velocity studies of close binary stars. VIII, The Astronomical Journal 125(6) (2003) 3258–3264.
• D. Pourbaix, A. A. Tokovinin, A. H. Batten, F. C. Feke, W. I. Hartkopf, H. Levato, N. I. Morrell, G. Torres, S. Udry, SB9: The ninth catalogue of spectroscopic binary orbits, Astronomy and Astrophysics 424(2) (2004) 727–732.
• S. O. Selam, Key parameters of W UMa-Type contact binaries discovered by HIPPARCOS, Astronomy and Astrophysics 416(3) (2004) 1097–1105.
• S. Zola, J. M. Kreiner, B. Zakrzewski, D. P. Kjurkchieva, D. V. Marchev, A. Baran, S. M. Rucinski, W. Ogloza, M. Siwak, D. Koziel, M. Drozdz, B. Pokrzywka, Physical parameters of components in close binary systems: V, Acta Astronomica 55 (2005) 389–405.
• W. B. Lee, H. I. Kim, Y. W. Kang, K. D. Oh, Low mass ratio contact binary systems HN UMa and II Uma III, Journal of Astronomical and Space Sciences 23(3) (2006) 189–198.
• D. Kjurkchieva, D. Marchev, New radial-velocity-curve solution of the eclipsing star HN UMa, Bulgarian Astronomical Journal 17 (2011) 96–100.
• G. R. Ricker, J. N. Winn, R. Vanderspek, D. W. Latham, G. A. Bakos, J. L. Bean, Z. K. Berta-Thompson, T. M. Brown, L. Buchhave, N. R. Butler, R. P. Butler, W. J. Chaplin, D. B. Charbonneau, J. C. Dalsgaard, M. Clampin, D. Deming, J. P. Doty, N. D. Lee, C. Dressing, E. W. Dunham, J. Villasenor, Transiting Exoplanet Survey Satellite (TESS), Journal of Astronomical Telescopes, Instruments, and Systems 1(1) (2015) 014003.
• O. W. Butters, R. G. West, D. R. Anderson, A. C. Cameron, W. I. Clarkson, B. Enoch, C. A. Haswell, C. Hellier, K. Horne, Y. Joshi, S. R. Kane, T. A. Lister, P. F. L. Maxted, N. Parley, D. Pollacco, B. Smalley, R. A. Street, I. Todd, P. J. Wheatley, D. M. Wilson, The first WASP public data release, Astronomy and Astrophysics 520 (2010) L10 4pp.
• A. Barbara, Mikulski Archive for Space Telescopes (MAST) (2025), [https://archive.stsci.edu](https://archive.stsci.edu), Accessed Jun 2025.
• A. Paschke, L. Brat, O-C Gateway, a collection of minima timings, Open European Journal on Variable Stars 23 (2006) 13–15.
• J. Eastman, B. S. Siverd, Achieving better than 1 minute accuracy in the heliocentric and barycentric Julian dates, Publications of the Astronomical Society of the Pacific 122(894) (2010) 935.
• S. B. Qian, Y. G. Yang, B. Soonthornthum, L. Y. Zhu, J. J. He, J. Z. Yuan, Deep, low mass ratio overcontact binary systems. III. CU Tauri and TV Muscae, The Astronomical Journal 130(1) (2005) 224–233.
• M. F. Yıldırım, Orbital period changes of selected two semi-detached binaries, Journal of Advanced Research in Natural and Applied Sciences 8(2) (2022) 237–245.
• M. F. Yıldırım, In-depth analysis of the light curve and first orbital period of contact binary GM Dra, New Astronomy 121 (2025) id.102445.
• P. Zasche, A. Liakos, P. Niarchos, M. Wolf, V. Manimanis, K. Gazeas, Period changes in six contact binaries: WZ And, V803 Aql, DF Hya, PY Lyr, FZ Ori, and AH Tau, New Astronomy 14(2) (2009) 121–128.
• J. H. Applegate, A mechanism for orbital period modulation in close binaries, The Astrophysical Journal 385 (1992) 621–629.
• A. F. Lanza, M. Rodono, Gravitational quadrupole-moment variations in active binaries, Astronomische Nachrichten 323(3-4) (2002) 424–431.
• A. F. Lanza, M. Rodono, Orbital period modulation and quadrupole moment changes in magnetically active close binaries, Astronomy and Astrophysics 349 (1999) 887–897.
• A. F. Lanza, Internal stellar rotation and orbital period modulation in close binary systems, Monthly Notices of the Royal Astronomical Society 369(4) (2006) 1773–1779.
• O. Latkovic, A. Ceki, S. Lazarevic, Statistics of 700 individually studied W UMa stars, The Astrophysical Journal Supplement Series 254(1) (2021) 10.
• M. F. Yıldırım, Investigation of the stability of the extreme low mass ratio contact binaries SX Crv and XX Sex, which are analysed photometrically, Advances in Space Research 74(8) (2024) 4223–4234.
• M. Yıldız, Origin of W UMa-type contact binaries ages and orbital evolution, Monthly Notices of the Royal Astronomical Society 437(1) (2014) 185–194.
• P. Hut, Stability of tidal equilibrium, Astronomy and Astrophysics 92(1-2) (1980) 167–170.
• Y. G. Yang, S. B. Qian, Deep, low mass ratio overcontact binary systems. XIV. A statistical analysis of 46 sample binaries, The Astronomical Journal 150(3) (2015) 69.
• F. A. Rasio, The minimum mass ratio of W Ursae Majoris binaries, The Astrophysical Journal Letters 444(1) (1995) L41–L43.
• L. Li, F. Zhang, The dynamical stability of W Ursae Majoris-type systems, Monthly Notices of the Royal Astronomical Society 369(4) (2006) 2001–2004.
• S. S. Wadhwa, A. D. Horta, M. D. Filipovic, N. F. H. Tothill, B. Arbutina, J. Petrovic, G. Djurasevi, ZZ Piscis Austrinus (ZZ PsA): A bright red nova progenitor and the instability mass ratio of contact binary stars, Monthly Notices of the Royal Astronomical Society 501(1) (2021) 229–235.