Spectral atlas of dwarf novae in outburst

Up to now, only a very small number of dwarf novae have been studied during their outburst state (~30 per cent in the Northern hemisphere). In this paper we present the first comprehensive atlas of outburst spectra of dwarf novae. We study possible correlations between the emission and absorption lines seen in the spectra and some fundamental parameters of the binaries. We find that out of the 48 spectra presented, 12 systems apart from IP Peg show strong HeII in emission: SS Aur, HL CMa, TU Crt, EM Cyg, SS Cyg, EX Dra, U Gem, HX Peg, GK Per, KT Per, V893 Sco, IY UMa, and 7 others less prominently: FO And, V542 Cyg, BI Ori, TY Psc, VZ Pyx, ER UMa, and SS UMi. We conclude that these systems are good targets for finding spiral structure in their accretion discs during outburst if models of Smak (2001) and Ogilvie (2001) are correct. This is confirmed by the fact that hints of spiral asymmetries have already been found in the discs of SS Cyg, EX Dra and U Gem.Comment: 16 pages, 14 figures. To be published in MNRA

Tracing the spiral arms in IP Pegasi

We report the analysis of time-resolved spectroscopy of IP Pegasi in outburst with eclipse mapping techniques to investigate the location and geometry of the observed spiral structures. We were able to obtain an improved view of the spiral structures with the aid of light curves extracted in velocity bins matching the observed range of velocities of the spiral arms combined with a double default map tailored for reconstruction of asymmetric structures. Two-armed spiral structures are clearly seen in all eclipse maps. The arms are located at different distances from the disc centre. The “blue” arm is farther out in the disc (R = 0.55 ± 0.05 R L1 ) than the “red” arm (R = 0.30 ± 0.05 R L1 ). There is evidence that the velocity of the emitting gas along the spiral pattern is lower than the Keplerian velocity for the same disc radius. The discrepancy is smaller in the outer arm (measured velocities 10–15 per cent lower than Keplerian) and is more significant in the inner arm (observed velocities up to 40 per cent lower than Keplerian). We measured the opening angle of the spirals from the azimuthal intensity distribution of the eclipse maps to be φ = 25◦ ± 3◦ . A comparison with similar measurements on data at different outburst stages reveals that the opening angle of the spiral arms in IP Peg decreases while the outbursting accretion disc cools and shrinks, in agreement with the expected evolution of a tidally driven spiral wave. The sub-Keplerian velocities along the spiral pattern and the clear correlation between the opening angle of the spirals and the outburst stage favors the interpretation of these asymmetric structures as tidally-induced spiral shocks

Promoting Resources Through Physical Library Displays

Physical Library resource displays offer an effective, low-cost means of publicising relevant resources to user groups and enhancing library spaces. This paper discusses the experience of using displays in academic libraries to prominently highlight a wider range of resources, which might not otherwise be used by students and the potential this offers to improve the level of work they produce. The formation of teams to create, plan, maintain and document resource displays at Leeds Beckett University Library has provided an opportunity for members of staff across the Library to work together using knowledge and creativity to enhance the overall student experience. Displays have provided opportunities for the Library to create closer links within the university and work with external organisations. Gathering detailed usage statistics and providing opportunities for users to interact with displays and offer feedback, has contributed to a better understanding of the study areas and themes which students respond to. Future directions are explored to further develop the Library display as a tool for connecting with users, including closer linking of physical displays with online resources and personalising display experiences to specific student groups and reading lists

Revealing the Archetype: The Journey of a Trecento Madonna and Child at the National Museum of Scotland

The National Museums Scotland Madonna and Child project sought to uncover and document the history of a fine polychrome wood carving attributed to The Master of the Gualino St Catherine and to prepare it for display. A new body of knowledge has been assembled by the interdisciplinary team. The conservation treatment was informed by this work and led to further discoveries: the removal of overpaint exposing a previously hidden underdrawing. The ethics of the treatment decisions, including the removal of the Christ Child’s 1960s’ fingers required team dialogue and was opened up for the public to respond to in a series of blogs. The discovery of a rich polychromy including gold and glazed tin has led to further plans to produce a 3-D colour reconstruction. The collaborations developed during this project will facilitate future joint ventures for polychrome sculpture in Scottish collections