8/7/2023 0 Comments B1 archiver pupIt was found to have a 100.4 min period, which was the shortest known period at the time ( van Gent 1931). The star VV Pup was recognised very early on as a periodic variable star from the analysis of photographic plates taken at the now defunct Union Observatory (Johannesburg, South Africa). Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This confirms previous statements suggesting that present instability models are unable to explain the full QPO characteristics within the parameters commonly known for polars. Detailed hydrodynamical numerical simulations of the post-shock accretion region with parameters consistent with VV Pup demonstrate that the expected frequencies from radiative instability are identical for X-rays and optical regime at values ν ∼ 40–70 Hz, more than one order magnitude higher than observed. No significant X-ray QPOs are detected with an amplitude upper limit of ∼30% in the range 0.1–5 Hz. ![]() The detailed X-ray orbital light curve displays a short Δ ϕ ≃ 0.05 ingress into self-eclipse of the active pole, indicative of an accretion shock height of ∼75 km. The X-ray Multi-mirror Mission XMM (0.5–10 keV) observation provides the first accurate estimation of the hard X-ray component with a high kT ∼ 40 keV temperature and confirms the high extreme ultraviolet (EUV)-soft/hard ratio in the range of 4−15 for VV Pup. Mean orbitally-averaged power spectra during the bright phase show a rather broad excess with a quality factor Q = ν/Δ ν = 5−7 but smaller data segments commonly show a much higher coherency with Q up to 30. QPOs are detected in the three filters at a mean frequency of ∼0.7 Hz with a similar amplitude ∼1%. Quasi-periodic oscillations (QPOs) are clearly detected in the optical during the source bright phase intervals when the accreting pole is visible, confirming the association of the QPOs with the basis of the accretion column. An analysis of a long 50 ks XMM-Newton observation of the source, retrieved from the database, is also provided. We present high time resolution optical photometric data of the polar VV Puppis obtained simultaneously in three filters ( u′, HeII λ4686, r′) with the ULTRACAM camera mounted at the ESO-VLT telescope. ![]() Instituto de Astrofisica de Canarias, 38205 La Laguna, Tenerife, Spain South African Astronomical Observatory, PO Box 9, Observatory 7935 Cape Town, South Africaĭepartment of Astronomy, University of Cape Town, Rondebosch 7700, Cape Town, South Africaĭepartment of Physics, University of Warwick, Coventry CV4 7AL, UKĭepartment of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK ![]() Dhillon 7 ,8ĭépartement d’Astrophysique-Laboratoire AIM, CEA/Irfu, 91191 Gif-sur-Yvette, FranceĮ-mail: de Paris, UMR 8102-CNRS, Université Paris-Diderot, 92190 Meudon, France ![]() Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes
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