A UV-to-NIR Study of Molecular Gas in the Dust Cavity around RY Lupi

Abstract

We present a study of molecular gas in the inner disk (r< 20 {au}) around RY Lupi, with spectra from HST-COS, HST-STIS, and VLT-CRIRES. We model the radial distribution of flux from hot gas in a surface layer between r = 0.1-10 au, as traced by Lyα-pumped H<SUB>2</SUB>. The result shows H<SUB>2</SUB> emission originating in a ring centered at ∼3 au that declines within r < 0.1 au, which is consistent with the behavior of disks with dust cavities. An analysis of the H<SUB>2</SUB> line shapes shows that a two-component Gaussian profile ({FWHM}}<SUB>broad</SUB>,{{{H}}}<SUB>2</SUB>}=105 +/- 15 {km} {{{s}}}<SUP>-1</SUP>{FWHM}}<SUB>narrow</SUB>,{{{H}}}<SUB>2</SUB>}=43+/- 13 {km} {{{s}}}<SUP>-1</SUP>) is statistically preferred to a single-component Gaussian. We interpret this as tentative evidence for gas emitting from radially separated disk regions (< {r}<SUB>broad</SUB>,{{{H}}}<SUB>2</SUB>}> ∼ 0.4+/- 0.1 {au};< {r}<SUB>narrow</SUB>,{{{H}}}<SUB>2</SUB>}> ∼ 3+/- 2 {au}). The 4.7 μm <SUP>12</SUP>CO emission lines are also well fit by two-component profiles (< {r}<SUB>broad</SUB>,{CO}}> =0.4+/- 0.1 {au};< {r}<SUB>narrow</SUB>,{CO}}> =15+/- 2 {au}). We combine these results with 10 μm observations to form a picture of gapped structure within the mm-imaged dust cavity, providing the first such overview of the inner regions of a young disk. The HST SED of RY Lupi is available online for use in modeling efforts.