Astronomy & Astrophysics

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$\begin{figure} \par\includegraphics[width=14cm,clip]{5719fig1.eps}\end{figure}$ Figure 1: Left: SED predicted by the "puffed-up'' rim model used to normalise the K-band continuum visibility. The contributions of the A star (long-dashed line), the K3 star (dotted line) and the rim (short dashed line) are shown (see the text for the stellar parameters). The observations are from 2MASS (filled circles), Hipparcos (filled squares), and Malfait et al. (1998) (empty circles). An extinction of $A_{\rm v} = 0.31$ (van den Ancker et al. 1998) has been used to correct the data for interstellar absorption. Center: comparison of ${\rm Br}\gamma$ observed with AMBER in the photometric channels (solid line) and ISAAC (dotted line); the dashed line shows the ISAAC spectrum smoothed to the spectral resolution of AMBER. Right: visibility of HD 104237 as a function of wavelength. The continuum has been normalised using the star + rim model, as described in the text. The vertical line shows the ${\rm Br}\gamma$ wavelength.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.85cm,clip]{5719fig2.ps}\end{figure}$ Figure 2: Comparison between the observed visibilities (empty square with error bars) and the predictions (solid curves) of the simple geometrical models for the ${\rm Br}\gamma$ emission (sketched in the same panels). The observed visibilities are scaled to match the continuum value predicted by the "puffed-up'' inner rim model (Isella & Natta 2005) as described in Sect. 2. The continuum emission arises both from the stellar photosphere ( ${\approx }$ $20\%$ ) and from the dusty disk inner rim, located at the dust evaporation distance $R_{\rm rim}=0.45$ AU and which appears as the bright gray scale ring. The ${\rm Br}\gamma$ emission regions are shown as grid surfaces. The three panels illustrate the different models discussed in Sect. 3: the upper panel represents the magnetospheric accretion model in which the ${\rm Br}\gamma$ emission originates very close to the star, inside the corotational radius $R_{\rm corot}=$ 0.07 AU; in the middle panel the ${\rm Br}\gamma$ emission originates between $R_{\rm corot}$ and the rim radius $R_{\rm rim}=$ 0.45 AU, representing the gas within the disk model; the bottom panel shows the outflowing wind model, in which the emission is confined close to the inner rim, between $\sim$ 0.2 AU and $\sim$ 0.5 AU.
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In the text