All Figures

$\begin{figure} \par\includegraphics[width=5.9cm,clip]{7575f1.eps}\end{figure}$ Figure 1: Mars-orbit-plane view of the positions of particles ejected from 79P/du Toit-Hartley in 1814 and propagated forward in time to 26 April, 2003. The asterisks mark the position of Mars and Jupiter along their orbits in 2003. The observed strands and kinks were created as a result of close approaches to Jupiter. X and Y are cartesian coordinates in the Martian orbit plane.
Open with DEXTER

In the text

$\begin{figure} \par\mbox{\includegraphics[width=4.9cm,clip]{7575f2a.eps}\hspace*{1cm} \includegraphics[width=6.1cm,clip]{7575f2b.eps} } \end{figure}$ Figure 2: Passages of 79P particles through the vicinity of Mars in 1999 ( left panel) and 2000 ( right panel). In the first instance we observe at least three distinct strands crossing the Martian orbit when the stream is on the outbound leg of its orbit with a daytime radiant. The first two contain the bulk of the meteoroid flux in this instance and occur within $\sim$ 3 days of each other. The passage of the third strand, of significantly lower flux and duration than the other two, occurs almost a month later. In the 2000 case, we observe a single event occuring on the inbound leg of the stream's orbit resulting in a nighttime radiant. The profile of this structure as projected on the Martian orbit is broad, resulting in an outburst duration of 72 h. No MGS data was available at those instances. See also Table 3.
Open with DEXTER

In the text

$\begin{figure} \par\mbox{\includegraphics[width=5.5cm,clip]{7575f3a.eps}\hspace*{1cm} \includegraphics[width=5.5cm,clip]{7575f3b.eps} } \end{figure}$ Figure 3: As Fig. 2 for the years 2003 and 2005, At both of these epochs, MGS was monitoring the Martian ionosphere. The structure on the left panel was relatively short in duration and coincided with a close approach of the comet to Mars in late April 2003. The 2005 passage on the right panel shows a structure that is broader and more compact, with a division in intensity at the orbit of Mars. This should result in a longer, potentially stronger outburst. See Table 3 for details.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7575f4.eps}\end{figure}$ Figure 4: Twelve ionospheric profiles collected during 21 MGS orbits between $L_{\rm S}=174.25^{\circ }$ and $L_{\rm S}=175.16^{\circ }$ at an areographic latitude of $74^{\circ }$ and a local solar time (LTST) of 13:45. The two middle cases at 10:58 UT and 12:56 UT on Apr. 26 show structures at altitudes below 95 km not seen in the other profiles. Increased meteor activity was predicted in this work to occur between 07:00 UT and 10:00 UT during an MGS five-orbit period when no measurements of ionospheric electron density were carried out. The electron density values within each profile have been normalized and stretched for clarity. For all profiles, the lowest-altitude value (<10¹⁰ ${\rm e}^{-}{\rm m}^{-3}$ ) corresponds to x=k, $k=1, \ldots, 12$ while the peak value (between 0.85 and 1.1 $\times$ 10¹¹ ${\rm e}^{-}{\rm m}^{-3}$ ) near 140 km is always at x=k+4. Typical measurement uncertainties (3 $\times$ 10⁹ ${\rm e}^{-}{\rm m}^{-3}$ ) correspond to half the distance between minor tick marks for the low-altitude data points. See also Fig. 7.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[height=5.95cm,width=8cm,clip]{7575f5a.eps}\h... ....5cm} \includegraphics[height=5.95cm,width=7.85cm,clip]{7575f5b.eps}\end{figure}$ Figure 5: Distribution of structures identified by the CVW criterion within the period between $L_{\rm S}=169.7^{\circ }$ and $L_{\rm S}=179.7^{\circ }$ in 2003 in terms of areographic longitude ( left panel) and altitude ( right panel). The size of the diamonds is proportional to the strength j of each structure with dots corresponding to ionospheric profiles where no structures were detected. The vertical dashed line indicates the midtime of the meteor outburst predicted in this work. In the left panel, gaps indicate orbits when no measurements were made while the area between the two horizontal lines corresponds to the sub-radiant hemisphere of the planet at the outburst midtime. Where more than one structure is present per profile, only the structure of highest j is plotted in the left panel whereas all structures are shown in the right panel. Note that the locations of the claimed layers detected on consecutive MGS orbits (the two large diamonds just below of centre of each figure) lie at the centre of the sub-radiant hemisphere in the left panel and at relatively low altitudes in the right panel as do other structures with high j.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[height=5.95cm,width=8cm,clip]{7575f6a.eps}\h... ...aphics[height=5.95cm,width=7.85cm,clip]{7575f6b.eps}\hspace*{0.3cm} \end{figure}$ Figure 6: As Fig. 5 but for the outburst predicted in 2005. The period covered here is between $L_{\rm S}=169.0^{\circ }$ and $L_{\rm S}=179.0^{\circ }$ . The sub-radiant hemisphere corresponds to the area outside the two horizontal lines in the left panel. No significant structures are observed near or immediately following the predicted time of the outburst. Note that, as in the 2003 case, the strongest structures lie at low altitudes, within a band between 83 and 92 km.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7575f7.eps}\end{figure}$ Figure 7: Two ionospheric electron density profiles collected during consecutive MGS orbits at 10:58 UT and 12:56 UT on 26 Apr., 2003. The continuous, dashed and dotted vertical lines indicate electron density values of 0, 5.0 $\times$ 10⁹ and 10¹⁰ ${\rm e}^{-}{\rm m}^{-3}$ respectively for each profile. The two dashed curves on either side of the profiles represent the nominal measurement uncertainties.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=5.9cm,clip]{7575f1.eps}\end{figure}$	Figure 1: Mars-orbit-plane view of the positions of particles ejected from 79P/du Toit-Hartley in 1814 and propagated forward in time to 26 April, 2003. The asterisks mark the position of Mars and Jupiter along their orbits in 2003. The observed strands and kinks were created as a result of close approaches to Jupiter. X and Y are cartesian coordinates in the Martian orbit plane.
Open with DEXTER