AnIUESpectroscopic Study of the Ultra–Short‐Period Dwarf Nova T Leonis in Outburst

TheIUEarchive contains numerous low‐resolution spectra of dwarf novae in outburst but relatively little synthetic spectral analyses of them using realistic accretion disk models with spectral lines. We have examined a series of previously unstudied archivalIUElow‐resolution short‐wavelength prime spectra of the SU UMa–type ultra–short‐period dwarf nova T Leonis, obtained continuously through a single dwarf nova outburst. We describe its outburst spectra, characterizing its metallic absorption‐line spectrum and the shape of its energy distribution. We estimate a terminal wind velocity of 2500 km s−1and report possible evidence of wind variability on timescales of roughly 2 hr, although orbital phase variations cannot be ruled out. We have constructed a grid of optically thick accretion disk models for white dwarf masses 0.6 and 1.0M ⊙, accretion rates 10−11–10−7 M ⊙yr−1, and disk inclination angles of 40° and 80°. We carry out preliminary synthetic accretion disk spectral fitting of T Leo and present the results. Our best‐fitting model to a co‐addition of three spectra with similar S/N yields \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $M_{\mathrm{WD}\,}=0.6\,M_{\odot }$ \end{document} , \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $i\simeq 40$ \end{document} °, \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsx