Evidence for mass accretion driven by spiral shocks onto the white dwarf in SDSS J123813.73–033933.0
| Autor: | Roger D. Pickard, Elmé Breedt, Daniel E. Reichart, A. Aungwerojwit, Matthias R. Schreiber, Christian Knigge, Boris T. Gänsicke, D. de Martino, Anna F. Pala, B. Monard, Steven G. Parsons, V. S. Dhillon, Rod Stubbings, T. R. Marsh, Gary Poyner, P. Godon, Peter Nelson, Franz-Josef Hambsch, Paula Szkody, Lian-Tao Wang, John D. Landstreet, G. Myers, Dean M. Townsley, J. J. Hermes |
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| Přispěvatelé: | GBR |
| Rok vydání: | 2018 |
| Předmět: |
Physics
Brightness Very Large Telescope 010308 nuclear & particles physics Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Cataclysmic variable star White dwarf Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Orbital period Light curve 01 natural sciences Photometry (optics) Amplitude Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Astrophysics::Galaxy Astrophysics QB |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 483:1080-1103 |
| ISSN: | 1365-2966 0035-8711 1745-3933 |
| DOI: | 10.1093/mnras/sty3174 |
| Popis: | We present high-time-resolution photometry and phase-resolved spectroscopy of the short-period ($P_\mathrm{orb} = 80.52\,\mathrm{min}$) cataclysmic variable SDSS J123813.73-033933.0, observed with the $\mathit{Hubble}$ $\mathit{Space}$ $\mathit{Telescope}$ $\mathit{(HST)}$, the $\mathit{Kepler/K2}$ mission and the Very Large Telescope (VLT). We also report observations of the first detected super-outburst. SDSS J1238-0339 shows two types of variability: quasi-regular brightenings recurring every $\simeq 8.5$ h during which the system increases in brightness by $\simeq 0.5$mag, and a double hump quasi-sinusoidal modulation at the orbital period. The detailed $\mathit{K2}$ light curve reveals that the amplitude of the double-humps increases during the brightenings and that their phase undergoes a $\simeq 90^{\circ}$ phase shift with respect to the quiescent intervals. The $\mathit{HST}$ data unambiguously demonstrate that these phenomena both arise from the heating and cooling of two relatively large regions on the white dwarf. We suggest that the double-hump modulation is related to spiral shocks in the accretion disc resulting in an enhanced accretion rate heating two localised regions on the white dwarf, with the structure of the shocks fixed in the binary frame explaining the period of the double humps. The physical origin of the 8.5 h brightenings is less clear. However, the correlation between the observed variations of the amplitude and phase of the double-humps with the occurrence of the brightenings is supportive of an origin in thermal instabilities in the accretion disc. Comment: 26 pages, 22 figures. MNRAS, in press |
| Databáze: | OpenAIRE |
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