Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{natta-fig1.ps} \end{figure}$ Figure 1: Location of the sample objects in the HR diagram. Filled dots are objects in $\rho$ Oph, open squares objects in Cha I. The tracks are from D'Antona and Mazzitelli (1997) and their unpublished 1998 update.
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In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{natta-fig2.ps} \end{figure}$ Figure 2: Normalized average H $\alpha$ profiles for the 5 objects with broad lines. The solid curves are the observed profiles, the dashed ones are the model fits. For Cha H $\alpha$ 2, the dotted lines shows a model with an ad hoc temperature profiles (see text).The stellar continuum has been subtracted.
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In the text

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{natta-fig3.ps} \end{figure}$ Figure 3: Accretion rate as a function of the H $\alpha$ full width at 10% peak intensity. Dots (full and open) and pentagons are objects with mass $\protect\la$ 0.23 $M_\odot$ . Full dots are from this paper, open dots from Muzerolle et al. (2003); for both samples $\dot M_{\rm ac}$ has been derived from model-fits of the H $\alpha$ profiles. Pentagons are substellar objects for which $\dot M_{\rm ac}$ has been obtained from veiling measurements (Muzerolle et al. 2003, 2000; White & Basri 2003; Barrado y Navascués et al. 2004). The small dots at Log $\dot M_{\rm ac}$ = -12are VLMOs with no evidence of accretion (37 in total); the value of the accretion rate is the model-determined upper limit. Squares are TTS (mass $\protect\ga$ 0.3 $M_\odot$ ) for which accretion rates have been measured from veiling. Most are TTS in Taurus-Auriga ( $\dot M_{\rm ac}$ from Gullbring et al. 1998, H $\alpha$ widths from Edwards et al. 1994). We have also added TW Hya (Muzerolle et al. 2000) and GN Tau from White & Basri (2003). The dashed line shows the best-fitting relation (Eq. (1)). The four connected squares show the 10% full width of H $\alpha$ H $\beta$ , H $\gamma$ and H $\delta$ for DF Tau from Edwards et al. (1994); H $\alpha$ is the narrowest of the four.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{natta-fig4.ps} \end{figure}$ Figure 4: Near-IR spectra of objects with Pa $\beta$ ( top panel) or Br $\gamma$ ( bottom panel) detection.
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In the text

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{natta-fig5.ps} \end{figure}$ Figure 5: Pa $\beta$ luminosity as a function of $L_{\rm ac}$ . The dots are the VLMOs from this paper. The squares are T Tauri stars in Taurus-Auriga from Muzerolle et al. (1998). The dashed line is the best-fitting relation (Eq. (2)).
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{natta-fig6.ps} \end{figure}$ Figure 6: H $\alpha$ variability in $\rho$ Oph-102 and $\rho$ Oph-032.
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In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{natta-fig7.ps} \end{figure}$ Figure 7: NaD lines in $\rho$ Oph-102.
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{natta-fig8.ps} \end{figure}$ Figure 8: Accretion rate as a function of the mass of the central object. Filled dots and squares are VLMOs in $\rho$ Oph and Cha I, respectively, from this paper; $\dot M_{\rm ac}$ has been determined from L(Pa $\beta$ ) as described in Sect. 3.3. Arrows are 3 $\sigma$ upper limits. Open squares are objects in Cha I from Gómez & Persi (2001) with Pa $\beta$ emission, where $\dot M_{\rm ac}$ has been determined from L(Pa $\beta$ ). Objects in IC 348 (Muzerolle et al. 2003) are shown by diamonds, in TW Hya (Muzerolle et al. 2000) by pentagons, in Taurus (White & Ghez 2001; White & Basri 2003; Muzerolle et al. 2003) by crosses. We do not plot objects from the literature with no detected accretion.
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{natta-fig1.ps} \end{figure}$	Figure 1: Location of the sample objects in the HR diagram. Filled dots are objects in $\rho$ Oph, open squares objects in Cha I. The tracks are from D'Antona and Mazzitelli (1997) and their unpublished 1998 update.
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$\begin{figure} \par\includegraphics[width=7.7cm,clip]{natta-fig2.ps} \end{figure}$	Figure 2: Normalized average H $\alpha$ profiles for the 5 objects with broad lines. The solid curves are the observed profiles, the dashed ones are the model fits. For Cha H $\alpha$ 2, the dotted lines shows a model with an ad hoc temperature profiles (see text).The stellar continuum has been subtracted.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{natta-fig4.ps} \end{figure}$	Figure 4: Near-IR spectra of objects with Pa $\beta$ ( top panel) or Br $\gamma$ ( bottom panel) detection.
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$\begin{figure} \par\includegraphics[width=8.2cm,clip]{natta-fig5.ps} \end{figure}$	Figure 5: Pa $\beta$ luminosity as a function of $L_{\rm ac}$ . The dots are the VLMOs from this paper. The squares are T Tauri stars in Taurus-Auriga from Muzerolle et al. (1998). The dashed line is the best-fitting relation (Eq. (2)).
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$\begin{figure} \par\includegraphics[width=8.3cm,clip]{natta-fig6.ps} \end{figure}$	Figure 6: H $\alpha$ variability in $\rho$ Oph-102 and $\rho$ Oph-032.
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$\begin{figure} \par\includegraphics[width=8.4cm,clip]{natta-fig7.ps} \end{figure}$	Figure 7: NaD lines in $\rho$ Oph-102.
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