Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[angle=-90,width=8.65cm,clip]{0857fig1.ps}\end{figure}$ Figure 1: Time series fields in the Pleiades: the image shows our two fields (field A - solid lines, field B - dashed lines) plotted over a DSS image. The squares mark our targets, which are Pleiades members from the survey of Pinfield et al. (2000).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.85cm,clip]{0857fig2.ps}\vspace*{3mm} \includegraphics[angle=-90,width=7.85cm,clip]{0857fig3.ps}\end{figure}$ Figure 2: Observing data distribution for the time series campaign in field A ( upper panel) and field B ( lower panel). Plotted is the non-integer fraction of the observing time against the observing time.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.1cm,clip]{0857fig4.ps}\end{figure}$ Figure 3: Lightcurve rms vs. magnitude for all targets: the solid line shows our photometric precision, determined by fitting the rms of all stars in our fields with a low degree polynomial. The VLM Pleiades members are shown as dots, and all variable objects among them are marked with a cross. The four objects, which are variable but without periodicity are additonally marked with a square. One object with significant periodic variability, but without variability detection in the generic test, is marked with a triangle (object BPL150, see Sect. 3.2). The magnitudes on the x-axis are instrumental, though the deviations from the I-band magnitudes given by Pinfield et al. (2000) are $\le$ 0.3 mag.
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In the text

$\begin{figure} \par\includegraphics[height=5.45cm,width=4cm,angle=-90,clip]{0857... ...includegraphics[height=5.45cm,width=4cm,angle=-90,clip]{0857pp09.ps}\end{figure}$ Figure 4: Phased lightcurves for the detected periodicities. No. and period from Table 1 are indicated.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.1cm,clip]{0857fig5.ps}\vspace*{2mm} \includegraphics[angle=-90,width=8.1cm,clip]{0857fig6.ps}\end{figure}$ Figure 5: Phased lightcurves for part of the time series of objects 115 ( upper panel, only datapoints after 10 Oct. UT12:00) and 150 ( lower panel, only datapoints before 6 Oct. UT12:00).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.1cm,clip]{0857fig7.ps}\vspace*{4mm} \includegraphics[angle=-90,width=8.1cm,clip]{0857fig8.ps}\end{figure}$ Figure 6: Sensitivity of the period search: the absolute difference between detected period and true period vs. true period for field A ( upper panel) and field B ( lower panel). The signal-to-noise ratio of the periodicity is 2.5; the dotted line corresponds to a period error of 10%.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0857fig9.ps}\end{figure}$ Figure 7: Photometric amplitude vs. mass for stars from the Open Cluster Database (triangles) and our targets (crosses). The detection limit for the solar-mass stars is 0.02 mag, explaining the lack of stars with very low amplitude in this sample.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0857fig10.ps}\end{figure}$ Figure 8: Rotation periods vs. mass: our VLM rotation periods are shown as crosses. Triangles mark the periods for more massive stars from the Open Cluster Database (see Sect. 1 for complete references). The two squares show the periods from Terndrup et al. (1999). The solid line marks a rough lower envelope to the observed $v\sin i$ values of Terndrup et al. (2000).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0857fig11.ps}\end{figure}$ Figure 9: Period-mass relation in the VLM regime: crosses are the nine periods determined in this work. The dashed line is a linear fit to their period-mass relation. The two squares indicate the two periods of Terndrup et al. (1999).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.9cm,clip]{0857fig12.ps}\vspace*{4mm} \includegraphics[angle=-90,width=7.9cm,clip]{0857fig13.ps}\end{figure}$ Figure 10: Rotational evolution of VLM objects: the upper panel shows the evolution of the rotation period for model A (no braking, dotted lined), model B (Skumanich braking, dash-dotted lines), and model C (exponential braking, dashed lines). In the lower panel, we compare model C (dashed lines) with model D (exponential braking with disk-locking, solid lines).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0857fig14.ps}\vspace*{4mm} \includegraphics[angle=-90,width=8cm,clip]{0857fig15.ps}\end{figure}$ Figure A.1: String length ( upper panel) and entropy ( lower panel) vs. period for the lightcurve of BPL129 (see text for explanation).

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.65cm,clip]{0857fig1.ps}\end{figure}$	Figure 1: Time series fields in the Pleiades: the image shows our two fields (field A - solid lines, field B - dashed lines) plotted over a DSS image. The squares mark our targets, which are Pleiades members from the survey of Pinfield et al. (2000).
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$\begin{figure} \par\includegraphics[angle=-90,width=7.85cm,clip]{0857fig2.ps}\vspace*{3mm} \includegraphics[angle=-90,width=7.85cm,clip]{0857fig3.ps}\end{figure}$	Figure 2: Observing data distribution for the time series campaign in field A ( upper panel) and field B ( lower panel). Plotted is the non-integer fraction of the observing time against the observing time.
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$\begin{figure} \par\includegraphics[height=5.45cm,width=4cm,angle=-90,clip]{0857... ...includegraphics[height=5.45cm,width=4cm,angle=-90,clip]{0857pp09.ps}\end{figure}$	Figure 4: Phased lightcurves for the detected periodicities. No. and period from Table 1 are indicated.
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$\begin{figure} \par\includegraphics[angle=-90,width=8.1cm,clip]{0857fig5.ps}\vspace*{2mm} \includegraphics[angle=-90,width=8.1cm,clip]{0857fig6.ps}\end{figure}$	Figure 5: Phased lightcurves for part of the time series of objects 115 ( upper panel, only datapoints after 10 Oct. UT12:00) and 150 ( lower panel, only datapoints before 6 Oct. UT12:00).
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$\begin{figure} \par\includegraphics[angle=-90,width=8.1cm,clip]{0857fig7.ps}\vspace*{4mm} \includegraphics[angle=-90,width=8.1cm,clip]{0857fig8.ps}\end{figure}$	Figure 6: Sensitivity of the period search: the absolute difference between detected period and true period vs. true period for field A ( upper panel) and field B ( lower panel). The signal-to-noise ratio of the periodicity is 2.5; the dotted line corresponds to a period error of 10%.
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$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0857fig9.ps}\end{figure}$	Figure 7: Photometric amplitude vs. mass for stars from the Open Cluster Database (triangles) and our targets (crosses). The detection limit for the solar-mass stars is 0.02 mag, explaining the lack of stars with very low amplitude in this sample.
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$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0857fig10.ps}\end{figure}$	Figure 8: Rotation periods vs. mass: our VLM rotation periods are shown as crosses. Triangles mark the periods for more massive stars from the Open Cluster Database (see Sect. 1 for complete references). The two squares show the periods from Terndrup et al. (1999). The solid line marks a rough lower envelope to the observed $v\sin i$ values of Terndrup et al. (2000).
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$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0857fig11.ps}\end{figure}$	Figure 9: Period-mass relation in the VLM regime: crosses are the nine periods determined in this work. The dashed line is a linear fit to their period-mass relation. The two squares indicate the two periods of Terndrup et al. (1999).
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$\begin{figure} \par\includegraphics[angle=-90,width=7.9cm,clip]{0857fig12.ps}\vspace*{4mm} \includegraphics[angle=-90,width=7.9cm,clip]{0857fig13.ps}\end{figure}$	Figure 10: Rotational evolution of VLM objects: the upper panel shows the evolution of the rotation period for model A (no braking, dotted lined), model B (Skumanich braking, dash-dotted lines), and model C (exponential braking, dashed lines). In the lower panel, we compare model C (dashed lines) with model D (exponential braking with disk-locking, solid lines).
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