All Figures

$\begin{figure} \includegraphics[angle=-90,width=12cm,clip]{5908-f1.ps} \end{figure}$ Figure 1: A partial ring of very red stars is seen in this J+H+ $K_{\rm s}$ image of M 33, secured from a special set of 2MASS observations wherein the integration time was increased by a factor of six. The ring is seen to full advantage with a simple ellipsoid model subtracted. Black areas are those of excess emission while white areas correspond to areas of deficit emission. The northern plume or arc spans up to 5' in width and is located at a radius of 2 to 3 disk scale lengths (or 12 to 18 arcmin). An ellipse (of semi-major axis 16 arcmin) is drawn to pass through the arcs; North is up and and East to the left.
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In the text

$\begin{figure} \includegraphics[width=12cm,clip]{5908-f2.eps}\end{figure}$ Figure 2: The positions of the seven stars listed in Table 1 are indicated by plus signs; the stars lie in the northern swath of carbon bearing stars identified photometrically in an earlier study (Block et al. 2004). Spectra of these stars (see Fig. 3) were secured using the Keck I telescope in Hawaii. Also observed with its twin sister telescope, Keck II, are two stars which lie 0.5 degrees away from the centre of M 33 in an area identified by a white circle. These outlying stars are representative of a very red family identified in near-infrared imaging with the Hale 5 m reflector at Mount Palomar. In this DSS image, North is up and East is to the left.
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In the text

$\begin{figure} \par\includegraphics[width=13cm,clip]{5908-f3.eps} \end{figure}$ Figure 3: Spectra of the seven stars seen in Fig. 2, secured using the Keck I telescope. All C stars candidates are very red, with $J-K_{\rm s} >2$ mag; their individual colors are listed in Table 1. The coordinates of each star are indicated in each panel. Tick marks identify the prominent CN bands found in each star, shortward of 7000 Å and 8000 Å and longward of 9000 Å. Each star is spectroscopically confirmed to belong to the thermally-pulsing asymptotic giant branch carbon star family.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{5908-f4.ps}\end{figure}$ Figure 4: Spectra with the Keck II telescope, of two stars 0.5 degree ( $\sim$ 5 scalelengths) away from the centre of M 33 (the field circled in Fig. 2), centered at approximately RA(2000)=1h34m21s and Dec(2000 $)=31^{\circ }$ 08'45 $\hbox{$.\!\!^{\prime\prime}$ }$ 7. The dominant CN absorption features are clearly evident and betray the signature of TP-AGB carbon stars.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{5908-f5.ps}\end{figure}$ Figure 5: The topmost panel shows a dust emissivity 8 $\mu$ m radial profile. In the middle panel is shown the amplitude of the Fourier m=2 mode as a function of radius. The local peak at r=14' coincides with the inner radial limit of the arcs. The outer spiral arms or "arcs'' correspond to the higher m=2 amplitude between 14 and 18 arcmin. The phase of the m=2 component is presented in the lower panel. We see a change of phase in the dust emissivity distribution at 18 arcmin, at the outer boundary of the outer spirals, precisely the same radius where Corbelli & Schneider (1997) find a warp in HI.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{5908-f4.ps}\end{figure}$	Figure 4: Spectra with the Keck II telescope, of two stars 0.5 degree ( $\sim$ 5 scalelengths) away from the centre of M 33 (the field circled in Fig. 2), centered at approximately RA(2000)=1h34m21s and Dec(2000 $)=31^{\circ }$ 08'45 $\hbox{$.\!\!^{\prime\prime}$ }$ 7. The dominant CN absorption features are clearly evident and betray the signature of TP-AGB carbon stars.
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