Multi-mission observations of the old nova GK Per during the 2015 outburst
GK Per, a classical nova of 1901, is thought to undergo variable mass accretion onto a magnetized white dwarf (WD) in an intermediate polar system (IP). We organized a multi-mission observational campaign in the X-ray and ultraviolet (UV) energy ranges during its dwarf nova (DN) outburst in 2015 Mar...
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| Autores principales: | , , , |
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| Formato: | CONF |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_18248039_v_n_p_Zemko |
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| Sumario: | GK Per, a classical nova of 1901, is thought to undergo variable mass accretion onto a magnetized white dwarf (WD) in an intermediate polar system (IP). We organized a multi-mission observational campaign in the X-ray and ultraviolet (UV) energy ranges during its dwarf nova (DN) outburst in 2015 March-April. Comparing data from quiescence and near outburst, we have found that the maximum plasma temperature decreased from 26 to 16 keV. This is consistent with the previously proposed scenario of increase in mass accretion rate while the inner radius of the magnetically disrupted accretion disk shrinks, thereby lowering the shock temperature. A NuS-TAR observation also revealed a high-amplitude WD spin modulation of the very hard X-rays, suggesting an obscuration of the lower accretion pole and an extended shock region on the WD surface. In the Chandra observation with the High Energy Transmission Gratings (HETG), we detected prominent emission lines, where the ratios of H-like to He-like transition for each element indicate a much lower temperature than the underlying continuum. We suggest that the X-ray spectrum in the 0.8-2 keV range results from emission from different regions of collisionally ionized plasma with a possible contribution from photoionization processes. © Copyright owned by the author(s) under the terms of the Creative Commons. |
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