All Figures

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{H3242f1.eps} \end{figure}$ Figure 1: Johnson H images of double nuclei in four merger candidates. The ESO numbers are indicated. ESO/MPI 2.2-m telescope.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{H3242f2.eps} \end{figure}$ Figure 2: The distribution of the comparison galaxies in radial velocity and absolute magnitude, M_B. M_B is based on total magnitudes obtained from LEDA, corrected for galactic extinction. The triangles are galaxies in the additional sample discussed in Sect. 3.4. The solid line marks the m_B=14.5 magnitude limit.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f3.eps} \end{figure}$ Figure 3: The luminosity function (LF) of the comparison sample (solid histogram). The vertical bars are the errors based on Poisson statistics. The hatched line illustrates how the LF would change if the galaxy population was influenced by mergers according to the observational results by Le Fèvre et al. (2000). The solid line is the LF of field galaxies according to Ramella et al. (1999).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{H3242f4.eps} \end{figure}$ Figure 4: The distribution of the isolated galaxies of the Karachentseva (1973, 1997) sample in the radial velocity-M_V plane. The solid line marks the m_V=15.7 magnitude limit.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f5.eps} \end{figure}$ Figure 5: The L(V) luminosity functions our sample (solid line) and Karachentsevas sample of isolated galaxies (hatched line). The V magnitudes of our sample are based on the B magnitudes obtained from LEDA combined with our B-V colours and a correction of 0.2 mag to compensated for the difference in galactic extinction between our sample and Karachentsevas sample and 0.5 mag which is the approximate difference in zeropoint between the LEDA and the Karachentseva total V magnitude scales. The two distributions have been adjusted to agree at the central magnitude bin.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f6.eps}\end{figure}$ Figure 6: The U-B/B-V diagram of the galaxies in the present study based on the photoelectric photometry, corrected for galactic extinction (Burstein & Heiles 1984). The filled symbols are the components of interacting pairs, stars are merger candidates and squares are the galaxies of the comparison sample. The apertures used in the photometry correspond roughly to the effective diameter. For comparison the evolutionary tracks of galaxies with two different star formation histories are displayed, a 100 Myr burst (hatched line) and continuous star formation (dotted line). We assumed a Salpeter IMF and solar abundancies (from Zackrisson et al. 2001). The straight arrow is the reddening vector and the cross corresponds to 1 $\sigma$ errors.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{H3242f7.eps} \end{figure}$ Figure 7: The cumulative distributions of U-B and B-V. The full-drawn line are the interacting and merging galaxies and the hatched line is the comparison sample.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{H3242f8.eps} \end{figure}$ Figure 8: Arp galaxies with available photometry in NED (filled dots), corrected for galactic extinction (Burstein & Heiles 1984). The error bars are observational mean errors obtained from NED. The small hatched box indicates the location of normal Hubble galaxies (de Vaucouleurs 1977). The size of the box corresponds to 3 standard deviations from the mean colours. The larger solid box is the Hubble box with a size corresponding to 3 times the median value of the observational mean errors of the Arp sample. The long arrow is the reddening vector.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{H3242f9.eps}\end{figure}$ Figure 9: Arp galaxies also shown in Fig. 6 (filled dots), corrected for galactic extinction (Burstein & Heiles 1984). For comparison the evolutionary tracks of galaxies with three different star formation histories are displayed, an exponentially decaying star formation rate with a timescale of 1 Gyr (full drawn line) a 100 Myr burst followed by passive evolution (hatched line) and continuous star formation (dotted line). The start and end of the tracks are marked with arrows. We assumed a Salpeter IMF and solar abundancies (from Zackrisson et al. 2001). The straight arrow is the reddening vector.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{H3242f10.eps} \end{figure}$ Figure 10: The m₃₉₀₀-m₄₁₅₀ colour plotted against the equivalent width of H $\alpha$ . The symbols are the same as in Fig. 6.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{H3242f11.eps} \end{figure}$ Figure 11: The m₃₉₀₀-m₄₁₅₀/m₄₁₅₀-m₅₅₀₀ two-colour diagram. The symbols are the same as in Fig. 6.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{H3242f12.eps} \end{figure}$ Figure 12: The frequency distribution of the [OIII] $\lambda$ 5007/H $\beta$ line ratio and the equivalent width in H $\alpha$ . The solid line is the interacting and merging galaxies and the hatched line is the comparison sample (only 3 galaxies in the upper diagram). Corrections for Galactic extinction have been applied.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f13.eps} \end{figure}$ Figure 13: The J-H/H-K two-colour diagram. The symbols are the same as in Fig. 6. The position of red supergiant stars has been indicated with the hatched line marked RSG. The cross at the lower left indicates 1 $\sigma$ errors.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{H3242f14.eps} \end{figure}$ Figure 14: a) The distribution of the IRAS temperatures based on the 60 and 100 $\mu$ fluxes. b) The IRAS luminosities in solar units. c) The ratio between the FIR luminosity and the blue luminosity. The solid line is the interacting and merging galaxies and the dotted line is the comparison sample.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{H3242f15.eps} \end{figure}$ Figure 15: NGC 1487 in B filter. The size of the field is $2.2\hbox {$^\prime $ }\times 2.2\hbox {$^\prime $ }$ . North is up, east is to the left. ESO/MPI 2.2-m telescope, La Silla.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{H3242f16.eps} \end{figure}$ Figure 16: NGC 1487 in H filter. The size of the field is $2.2\hbox {$^\prime $ }\times 2.2\hbox {$^\prime $ }$ . North is up, east is to the left. ESO/MPI 2.2-m telescope, La Silla.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{H3242f17.eps} \end{figure}$ Figure 17: The correlation between the FIR luminosity and a few optical/near-IR parameters. The symbols are the same as in Fig. 6.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{H3242f18.eps} \end{figure}$ Figure 18: The correlation between the FIR temperature index f₆₀/f₁₀₀ and a few optical/near-IR parameters. The symbols are the same as in Fig. 6.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f19.eps} \end{figure}$ Figure 19: The correlation between absolute magnitude and FIR luminosity. The symbols are the same as in Fig. 6. The solid lines are the linear regression lines and the dotted line the symmetry line.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f20.eps} \end{figure}$ Figure 20: The Q1 parameter (Dahari & de Robertis 1988) versus various star formation parameters for our sample of interacting galaxies. Symbols as in Fig. 4. Increasing strength of interaction $\rightarrow$ higher Q1 value. No value of the parameter can be derived for most of the merger candidates (stars) which have been placed at Q1=3 for comparison.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{H3242f21.eps} \end{figure}$ Figure 21: The Q2 parameter (Dahari & de Robertis 1988) versus various star formation parameters for our sample of interacting galaxies. Symbols as in Fig. 4. Increasing strength of interaction $\rightarrow$ higher Q2 value. No value of the parameter can be derived for most of the merger candidates (stars) which have been placed at Q2=0 for comparison.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f22.eps} \end{figure}$ Figure 22: The relation between total gas mass and FIR/B luminosity ratio for the sample galaxies.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{H3242f23.eps}\end{figure}$ Figure 23: The relation between total gas mass and FIR luminosity for the sample galaxies. Upper and lower limits are marked with arrows. The solid line shows the slope of the $\cal M$ (HI+H $_2) \propto$ $L_{\rm FIR}$ , arbitrarily shifted to fit the data.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{H3242f1.eps} \end{figure}$	Figure 1: Johnson H images of double nuclei in four merger candidates. The ESO numbers are indicated. ESO/MPI 2.2-m telescope.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{H3242f2.eps} \end{figure}$	Figure 2: The distribution of the comparison galaxies in radial velocity and absolute magnitude, M_B. M_B is based on total magnitudes obtained from LEDA, corrected for galactic extinction. The triangles are galaxies in the additional sample discussed in Sect. 3.4. The solid line marks the m_B=14.5 magnitude limit.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f3.eps} \end{figure}$	Figure 3: The luminosity function (LF) of the comparison sample (solid histogram). The vertical bars are the errors based on Poisson statistics. The hatched line illustrates how the LF would change if the galaxy population was influenced by mergers according to the observational results by Le Fèvre et al. (2000). The solid line is the LF of field galaxies according to Ramella et al. (1999).
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{H3242f4.eps} \end{figure}$	Figure 4: The distribution of the isolated galaxies of the Karachentseva (1973, 1997) sample in the radial velocity-M_V plane. The solid line marks the m_V=15.7 magnitude limit.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{H3242f7.eps} \end{figure}$	Figure 7: The cumulative distributions of U-B and B-V. The full-drawn line are the interacting and merging galaxies and the hatched line is the comparison sample.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{H3242f10.eps} \end{figure}$	Figure 10: The m₃₉₀₀-m₄₁₅₀ colour plotted against the equivalent width of H $\alpha$ . The symbols are the same as in Fig. 6.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{H3242f11.eps} \end{figure}$	Figure 11: The m₃₉₀₀-m₄₁₅₀/m₄₁₅₀-m₅₅₀₀ two-colour diagram. The symbols are the same as in Fig. 6.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{H3242f12.eps} \end{figure}$	Figure 12: The frequency distribution of the [OIII] $\lambda$ 5007/H $\beta$ line ratio and the equivalent width in H $\alpha$ . The solid line is the interacting and merging galaxies and the hatched line is the comparison sample (only 3 galaxies in the upper diagram). Corrections for Galactic extinction have been applied.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f13.eps} \end{figure}$	Figure 13: The J-H/H-K two-colour diagram. The symbols are the same as in Fig. 6. The position of red supergiant stars has been indicated with the hatched line marked RSG. The cross at the lower left indicates 1 $\sigma$ errors.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{H3242f14.eps} \end{figure}$	Figure 14: a) The distribution of the IRAS temperatures based on the 60 and 100 $\mu$ fluxes. b) The IRAS luminosities in solar units. c) The ratio between the FIR luminosity and the blue luminosity. The solid line is the interacting and merging galaxies and the dotted line is the comparison sample.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8cm,clip]{H3242f15.eps} \end{figure}$	Figure 15: NGC 1487 in B filter. The size of the field is $2.2\hbox {$^\prime $ }\times 2.2\hbox {$^\prime $ }$ . North is up, east is to the left. ESO/MPI 2.2-m telescope, La Silla.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8cm,clip]{H3242f16.eps} \end{figure}$	Figure 16: NGC 1487 in H filter. The size of the field is $2.2\hbox {$^\prime $ }\times 2.2\hbox {$^\prime $ }$ . North is up, east is to the left. ESO/MPI 2.2-m telescope, La Silla.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{H3242f17.eps} \end{figure}$	Figure 17: The correlation between the FIR luminosity and a few optical/near-IR parameters. The symbols are the same as in Fig. 6.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{H3242f18.eps} \end{figure}$	Figure 18: The correlation between the FIR temperature index f₆₀/f₁₀₀ and a few optical/near-IR parameters. The symbols are the same as in Fig. 6.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f19.eps} \end{figure}$	Figure 19: The correlation between absolute magnitude and FIR luminosity. The symbols are the same as in Fig. 6. The solid lines are the linear regression lines and the dotted line the symmetry line.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f20.eps} \end{figure}$	Figure 20: The Q1 parameter (Dahari & de Robertis 1988) versus various star formation parameters for our sample of interacting galaxies. Symbols as in Fig. 4. Increasing strength of interaction $\rightarrow$ higher Q1 value. No value of the parameter can be derived for most of the merger candidates (stars) which have been placed at Q1=3 for comparison.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{H3242f21.eps} \end{figure}$	Figure 21: The Q2 parameter (Dahari & de Robertis 1988) versus various star formation parameters for our sample of interacting galaxies. Symbols as in Fig. 4. Increasing strength of interaction $\rightarrow$ higher Q2 value. No value of the parameter can be derived for most of the merger candidates (stars) which have been placed at Q2=0 for comparison.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H3242f22.eps} \end{figure}$	Figure 22: The relation between total gas mass and FIR/B luminosity ratio for the sample galaxies.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{H3242f23.eps}\end{figure}$	Figure 23: The relation between total gas mass and FIR luminosity for the sample galaxies. Upper and lower limits are marked with arrows. The solid line shows the slope of the $\cal M$ (HI+H $_2) \propto$ $L_{\rm FIR}$ , arbitrarily shifted to fit the data.
Open with DEXTER