All Figures

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{5099fig1.eps} \end{figure}$ Figure 1: The December 2004 low resolution spectrograms of the four luminous variable stars in M 33. From the bottom: the Hubble-Sandage variables A, B, C, and the Romano's star GR 290. For three stars two individual spetrograms taken at diferent times (see Table 1) are shown. Ordinates are log fluxes in cgs units with a vertical shift for GR 290 and Var A. Spectral artifacts are marked with an asterisk.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=12.4cm,clip]{5099fig2.eps} \end{figure}$ Figure 2: Cima Ekar spectrograms of the LBVs Var C, Var B, and GR 290, and of the Ofpe/WN9 star UIT3 in M 33. Ordinates are fluxes normalized to the continuum, with offsets for Var B, GR 290, and UIT3. For the LBV stars, we used the combination of two spectra, taking away the artifacts. Some line identification is given (see also Figs. 5 and 6). The 4600-4686 Å feature in UIT3 and GR 290 is indicated. The wavelength position of the He I and Fe II emission lines is marked with vertical bars and stars, respectively.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{5099fig3.eps} \end{figure}$ Figure 3: Comparison of the Hubble-Sandage Var A spectrum with that of three standard supergiant stars. The Var A spectrum has been corrected for $A_{\rm V}=0.7$ . The Asiago not dereddened spectrum of the M-type star M 33a-460 (Massey 1998) is also shown. Ordinates are Log fluxes plus a constant.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.1cm,clip]{5099fig4.eps} \end{figure}$ Figure 4: The energy distribution of Var A. Both the B and V photometric observations and the calibrated spectrum are shown. For better clarity on the plot, the spectral portions inside the B and V bands have been cut. The 2MASS ${\it J H K}$ photometry, referred to December 1997, is also reported. Ordinates are log fluxes (in erg cm^-2 s^-1 Å^-1) corrected for an E_B-V = 0.22. A correction factor has been applied to the spectrum in order to fit with the B V mag. The optical-near IR energy distribution is fitted by a combination of 6500 K and 1350 K black body spectra. The optical-near IR photometric data from Humphreys et al. (1987) are shown for comparison (open triangles).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7cm]{5099fig5.eps} \end{figure}$ Figure 5: Comparison of the Loiano ( bottom) and Asiago ( middle) spectra of Var C with that of the B[e] star HD 45677 (FS CMa, top). The Asiago spectrum is the combination of the two December 2004 observations. Ordinates are fluxes normalized to the continuum, with an offset of +0.3 for HD 45677 and of -0.1 for the Loiano spectrum of Var C. The main Fe II and [Fe II] emission lines or blends identified in Var C are marked below the spectrum.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{5099fig6.eps} \end{figure}$ Figure 6: Comparison of the December 2004 spectra of GR 290 and UIT3. Ordinates are Log fluxes normalized to the continuum, with a slight upward offset for UIT3. Some line identification is indicated. Note the nearly equal strength of the hydrogen and He I emission lines in GR 290 and UIT3. A portion of the January 2005 grism 7 spectrum of GR 290 is also plotted below the December 2004 spectrum to show the [N II] 6584 Å and N II 6610 Å lines in the red wing of H $\alpha$ .
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=6.5cm,clip]{5099fig7.eps} \end{figure}$ Figure 7: The spectrum of GR 290 taken at different epochs during 2003-2005. From bottom to top: 2 February 2003, 14 February 2004, 6 December 2004, 16 January 2005. Ordinates are fluxes normalized to the continuum, with vertical offsets.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5099fig8.eps} \end{figure}$ Figure 8: The multifrequency (B: circles, V: triangles, R: squares) light curve of GR 290 during 2003-2005. The vertical bars at the top of the figure indicate when spectroscopic observations were made.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5099fig9.eps} \end{figure}$ Figure 9: The energy distribution of GR 290. Both the December 2004 ${\it UBVRI}$ photometric observations (squares with error bars) and the calibrated spectrum (the upper spectrogram in Fig. 1) are shown. The 2MASS J H photometry and the K upper flux limit, referred to as December 1997, are also reported (circles). Ordinates are log fluxes (in erg cm^-2 s^-1 Å^-1) corrected for an E_B-V = 0.22. The 30 000 K black body distribution normalized to the visual is shown for comparison.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.1cm,clip]{5099fg10.eps} \end{figure}$ Figure 10: The H-R diagram showing the location of the 4 studied variables. The dashed lines represent the approximate path covered back and forth by the stars during their light history, assuming constant bolometric luminosity, with the crosses marking their present state (see Table 4). For Var A we used the bolometric magnitude derived by Humphreys et al. (1987) from the IR. The M 33 distance modulus of 24.8 has been assumed for all the stars. The empirical upper luminosity boundary (from Humphreys et al. 1987) is shown as a dotted line. The evolutionary tracks for massive stars with mass loss and solar composition are from Chieffi & Limongi (2006).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{5099fig3.eps} \end{figure}$	Figure 3: Comparison of the Hubble-Sandage Var A spectrum with that of three standard supergiant stars. The Var A spectrum has been corrected for $A_{\rm V}=0.7$ . The Asiago not dereddened spectrum of the M-type star M 33a-460 (Massey 1998) is also shown. Ordinates are Log fluxes plus a constant.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=6.5cm,clip]{5099fig7.eps} \end{figure}$	Figure 7: The spectrum of GR 290 taken at different epochs during 2003-2005. From bottom to top: 2 February 2003, 14 February 2004, 6 December 2004, 16 January 2005. Ordinates are fluxes normalized to the continuum, with vertical offsets.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5099fig8.eps} \end{figure}$	Figure 8: The multifrequency (B: circles, V: triangles, R: squares) light curve of GR 290 during 2003-2005. The vertical bars at the top of the figure indicate when spectroscopic observations were made.
Open with DEXTER