Issue |
A&A
Volume 506, Number 2, November I 2009
|
|
---|---|---|
Page(s) | 927 - 934 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/200912098 | |
Published online | 18 August 2009 |
A&A 506, 927-934 (2009)
Constraining the orbit of the possible
companion to
Pictoris
New deep imaging observations
A.-M. Lagrange1 - M. Kasper2 - A. Boccaletti3 - G. Chauvin1 - D. Gratadour3 - T. Fusco4 - D. Ehrenreich1 - D. Apai5 - D. Mouillet1 - D. Rouan3
1 - Laboratoire d'Astrophysique de l'Observatoire de Grenoble,
Université Joseph Fourier, CNRS (UMR 5571), BP 53, 38041
Grenoble, France,
2 - European Southern Observatory, Karl Schwarzschild Straße, 2, 85748
Garching bei München, Germany
3 - Laboratoire d'Études Spatiales et d'Instrumentation en
Astrophysique, Observatoire de Paris, CNRS (UMR 8109),
Université Pierre et Marie Curie, Université Paris-Diderot, 5 place
Jules Janssen, 92195 Meudon, France
4 - Office National d'Études et de Recherches Aérospatiales, 29 avenue
de la Division Leclerc, 92322 Châtillon, France
5 - Space Telescope Science Institute, 3700 San Martin Drive,
Baltimore, MD 21218, USA
Received 18 March 2009/ Accepted 9 June 2009
Abstract
Context. We recently reported on the detection of a
possible planetary mass companion to β Pictoris at a
projected separation of 8 AU from the star, using data taken
in November 2003 with NaCo, the adaptive-optics system installed on the
Very Large Telescope UT4. Even though no second epoch detection was
available, there are strong arguments to favor a gravitationally bound
companion rather than a background object. If confirmed and located at
a physical separation of 8 AU, this companion would be the
closest planet ever imaged, and above all, could have formed via
core-accretion. Its apparent magnitude would indicate a typical
temperature of 1500 K
and a mass of
8
.
Interestingly, a planet with such characteristics would explain the
main morphological and dynamical peculiarities of the
Pic
system.
Aims. Our goal was to re-observe Pic
five years later to again detect the companion or, in the case of a
non-detection, constrain its orbit.
Methods. Deep adaptive-optics L'-band
direct images of Pic
as well as
-band
Four Quadrant Phase Mask coronagraph images with were recorded with
NaCo.
Results. No point-like signal with the brightness of
the companion candidate (apparent magnitudes L'=
11.2 or )
was detected at projected distances down to
6.5 AU in the present
data from the star (by comparison, the same limit was reached at
5.5 AU
in the better quality November 2003 data). As expected, the non
detection does not allow us to rule out a background companion from an
observational point of view. We show that the non detection is
consistent with orbital motion. Using these data and previous
-band data
obtained in 2004, we place strong constraints on the possible orbits of
the companion.
Key words: instrumentation: adaptive
optics - stars: early-type - stars: planetary systems - stars:
individual: Pictoris
1 Introduction
The
Using L'-band high-angular resolution
imaging data obtained with the NAOS-CONICA adaptive optic system (NaCo)
on the Very Large Telescope UT4, we discovered a point-like source with
an apparent magnitude mag
at
(
8 AU)
north-east of
Pic,
well aligned with the dust disk. Even though no second epoch data were
available with enough sensitivity to detect the companion candidate
(cc), we were confident that this signal was not due to a background
object, as the associated probability was shown to be very low. We
therefore attributed the source to a probable bound
object. Given the star proper motion, a background object would now lie
angularly too close to the star to be detected again and a few more
years (see below) are necessary to rule out this possibility from an
observational point of view.
Very interestingly, if this cc is indeed at a physical
separation of 8 AU, it would explain most of the Pic
system's morphological and dynamical peculiarities: the disk inner
warp, its brightness asymmetries, as well as the observed falling
evaporating bodies (FEBs, Lagrange
et al. 2009). Recently, Lecavelier des Etangs &
Vidal-Madjar (2009) investigated whether the observed cc could also be
responsible for the photometric variability observed in November 1981 (Lecavelier des Etangs et al.
1995) and analysed in detail in a subsequent paper (Lecavelier des Etangs et al.
1997). In the latter paper, the complex photometric curve
observed was explained either by a planet located in a dust-free region
of the disk, or a cloud of dust passing in front of the star. In the
planet scenario, an object with a radius larger than 2 Jupiter radii,
located at less than 8 AU and surrounded by a void of material
within its Hill radius, could explain both the eclipse signal and the
observed higher brightness a few days around the eclipse. From their
dynamical analysis, Lecavelier des Etangs & Vidal-Madjar (2009)
conclude that the cc observed in 2003 could be responsible for the 1981
eclipse provided the semi-major axis of its orbit (circular case or
assuming a low eccentricity) is in the range 7.6-8.7 AU,
corresponding to periods in the range 15.9-19.5 years. Another
longer-period orbit, dynamically compatible with the existence of an
eclipse and the November 2003 data, was excluded on the basis that the
cc would have been detected earlier. We note that the corresponding
orbital radius, 17 AU, is also much larger than the one
predicted by the modeling of the photometric curve. As noted by these
authors and Lagrange et al. (2009), a cc on an orbit with a radius of
8 AU
would not be detectable end of 2008 nor in early 2009. Lecavelier des
Etangs & Vidal-Madjar (2009) furthermore predict that if the cc
is responsible for the 1981 eclipse, then it should reach its maximum
elongation between 2011 and 2015. Finally, we note that the data
available to Lecavelier des Etangs & Vidal-Madjar (2009) did
not allow them to disentangle two possible cases: a first case where
the cc would have been located before quadrature in 2003, and a second
case where the cc would have been located after quadrature in 2003.
Obviously, new deep imaging observations are needed to further
constrain the possible orbits of the cc. A major question is the true
(unprojected) separation of the cc from the star. Four Quadrant Phase
Mask (4QPM) coronagraph observations performed in 2004 did not reveal
any point-like source with an absolute magnitude
in the
band of
at a projected separation >8 AU (Boccaletti et al. 2009).
Using the COND and DUSTY models (Baraffe
et al. 2003; Chabrier
et al. 2000), we obtained a
color of 1.2 (COND) to 1.4 (DUSTY); hence a cc with
(i.e., an absolute magnitude
)
would have
to
,
respectively. If located beyond 8 AU, the cc seen in 2003
would then have been detected in these 4QPM data. This allows us to
conclude that its projected separation had decreased between 2003 and
2004.
In order to confirm the companionship and/or to further
constrain the cc orbit, we obtained discretionary time in January and
February 2009 to perform new high-contrast and high-spatial-resolution
observations of the Pic
system with NaCo (Rousset
et al. 2003; Lenzen
et al. 2003) in the L' band, thus
allowing a direct comparison between 2003 and 2009 data, as well as
with the 2004
-band
4QPM data
. The observations were
designed to detect the faint companion as close as possible to the
star. A positive detection would both confirm the companionship and
provide crucial constraints on the companion orbital parameters. A
non-detection would provide valuable constraints on the orbit of the
cc. We present these observations in Sect. 2, and we use these
new results to constrain the possible location of the cc in
Sect. 3.
2 Observations and data reduction procedures
2.1 L
-band
observations (February 2009)
2.1.1 Observing strategies
L'-band images of


For the second strategy (runs B1 and B2), Pic
and HR 2435 images were recorded at two different de-rotator
positions, to be able to use either
Pic or
HR 2435 to remove the star halo (see examples of the use of
the star itself observed at different rotator positions to remove the
PSF halo in Kasper et
al. 2007). The offset between the two rotator positions was
chosen to be 30
(run B1) or 180
(run B2). The latter was chosen such that the VLT aperture spiders
remain in the same orientation.
For all runs, the time elapsed between Pic and
HR 2435 observations was precisely calculated so that the
images for both stars were recorded at similar parallactic angles,
within 0.5
,
so as to remove as accurately as possible the PSF wings.
2.1.2 Instrumental set-up
The visible wavefront sensor was used with the



Non-saturated images were also recorded to obtain images of
the stellar point spread function (PSF) as well as a photometric
calibration. In such cases, we added the Long Neutral Density filter
(transmission 0.018)
in the CONICA optical path, and recorded images with DITs of 0.2s.
Twilight flat fields were recorded as well.
The log of the observations is reported in Table 1, as well as the
observing conditions. The observing conditions were noticeably not as
good as during the November 2003 run, with coherent energies (estimated
in the K band) of 40-50% for run A, and 25-30% for
runs B1 and B2, instead of 50-70% in 2003, and coherent times
between 2.8 and 6.2 ms, instead of 20 ms in the best
data sets in November 2003. The conditions during run B1 and even more
during run B2 were rather poor, resulting in an unstable and mediocre
adaptive optics (AO) correction.
Table 1:
Observing log of the Pic
saturated images, and corresponding atmospheric conditions.
2.1.3 Data processing
The data were reduced using different methods. The first two methods are described in Lagrange et al. (2009). A third method, which makes use of the different rotator positions in order to remove the

2.2
-band
observations (January 2009)
2.2.1 Observing strategy and instrumental set-up
As the brightness ratio of the cc in









For these -band
observations, the visible wavefront sensor again was used with the
lenslet array, together with the visible dichroic. We used the CONICA
S13 camera, which provides a pixel scale of 13.25 mas. The DCS
detector mode and readout modes were respectively set to
``HighDynamic'' and ``Double''.
2.2.2 Data processing
After standard flat-field correction and bad pixel removal, the 400 images (
- Method 1: images are de-rotated and co-added, resulting in
2 images, one for the target star and one for the reference star. The
speckle background is averaged by a factor equal to the number of
rotator angles (
). An optimal subtraction is performed between the star and the reference.
- Method 2: image at rotator position i+1
is subtracted from image at position i. The
resulting subtraction is de-rotated and co-added to the previous one.
The same procedure is repeated on the reference star images. Finally,
the reference image is subtracted from the target image. The speckle
background here is averaged by a factor
.
- Method 3: the target star image is subtracted from the
reference star image for each rotator angle. As in method 2, this image
at position i+1 is subtracted to image at position i.
The final image is obtained after de-rotating and co-adding each of
these subtractions. Again, the speckle are averaged by a factor
.
- Method 4: the last method is closer to that of Marois et
al. (2006). A median map is estimated on each pixel for the target set
of images as for the reference star. This median map is subtracted from
each rotator position. Then, the images are derotated and co-added. As
for method 1, the background is averaged by a factor
.


![]() |
Figure 1:
Top: residual L' image
after subtracting |
Open with DEXTER |
3 Results
3.1 Detection limits
We show in Fig. 1
the subtracted image corresponding to run A data, as well as the
corresponding
detection limit obtained when using HR 2435 to remove the PSF halo. The
detection limits were computed by measuring for each pixel the noise
within a
-pixel box
centered on a given pixel, and determining the corresponding
limits, using the non-saturated images to obtain a photometric scaling
factor, taking into account the instrumental set up used to record the
non-saturated and saturated images.
No companion with ML'
= 9.8, corresponding to the absolute magnitude of the cc detected in
November 2003 (if bound) is detected on the data down to a separation -13 pixels,
i.e., about 6.5 AU. Comparatively,
detection limits of ML'
= 9.8 were achieved down to r =
10-11 pixels (i.e., about 5.5 AU) in the best set
(set A) of the better quality November 2003 data. Taking into account
the error bars associated with the measured magnitude
(0.3 mag) does not significantly change these results (the
slope
pixels mag-1
at
).
Much less homogeneous results were obtained with run B1 data.
Again using HR 2435 to remove the PSF halo, a
detection limits of ML'
= 9.8 is achieved down to r=12-17 pixels,
depending on the position angle. This is coherent with the lower
quality of the data compared to run A data. Using
Pic
as a comparison did not improve the results. Finally, run B2 data did
not allow us to properly remove the PSF halo, as the image quality had
changed signficantly between the recording of
Pic and
HR 2435 images. So, no attempt was made to derive detection
limits.
![]() |
Figure 2:
Top: residual |
Open with DEXTER |
Similarly, we show in Fig. 2 the
results obtained in the
band. No companion is detected in the present data, which reach a
typical limit of
at a separation of 0
4
(8 AU). An absolute magnitude
of 11.3, corresponding to the one expected from the cc if bound (see
above) is reached further than 40-44 pixels, i.e., at about
10 AU. Hence, the present
data do not allow us to test the presence of the cc at 0
4
(or less). For comparison, the computation of the
detection limit in the November 2004 4QPM data show that a cc with
would have been detected down to about 6.5-7 AU.
4 Constraints on the physical position of the companion candidate
4.1 Constraints from available deep images
First, we recall that as expected, the non-detection of the cc in February 2009 does not bring new constraints to the background object scenario. This can be seen in Fig. 3 where we have plotted the position of the cc between 2003 and 2013, taking into account the stellar proper motion. Note that we assume, as is usually done, that the cc has no proper motion). Should the object be a physical companion, our new non-detection would place strong constraints on its possible orbits; in the following we discuss this scenario.
![]() |
Figure 3:
Expected position of the source detected in November 2003 (black dot),
assuming it was a background (BKG) object, taking the parallactic and
stellar proper motions into account, for the 10 following years (thin
curved line). Note that we assume, as is usually done, that the cc has
no proper motion. The |
Open with DEXTER |
We will assume that the ML'
= 9.8 cc orbits within the plane of the debris disk itself; the orbit
is then seen edge-on as well; we furthermore assume that its orbit is
prograde relative to the disk (see, e.g., Olofsson et al. 2001),
and circular. Assuming a circular orbit is justified by the fact that
the models proposed so far to explain the Pic disk
peculiarities (disk asymmetries, FEBs) require planets on circular or
low eccentric orbits (i.e.,
0.1;
see the review in Lecavelier des Etangs & Vidal-Madjar 2009),
and as shown by the same authors, assuming such a low eccentricity does
not significantly change the dynamical results. Besides, the relevant
parameters adopted for the star itself are its mass,
,
and its distance
pc
(Crifo et al. 1997).
In Fig. 4,
we show the various regions of the Pic disk that were
explored in November 2003 and/or in 2009. With only a single epoch of
observation, an important part of the star's immediate surroundings is
not explored. The new observations, in contrast, allow us to
significantly increase the explored surroundings. We see, in
particular, that the full 8-10 AU annulus around the star has
now been fully explored, i.e., a companion with a mass higher than a
few Jovian masses with a separation in the 8-10 AU range would
have been detected either in 2003 or 2009 (circular orbit assumed). In
other words, we can now exclude the presence of a massive cc at these
separations, apart from the one detected in 2003.
![]() |
Figure 4:
Coverage map of the |
Open with DEXTER |
We now constrain the physical position of the cc knowing that its
projected separation was 8 AU in November 2003 and is less
than 6.5 AU in February 2009. In Fig. 5, we plot its
projected separation in February 2009, assuming its projected
separation was 8 AU on November 2003, as a function of its
orbital radius. We note that the impact of the error associated with
the star mass is negligible (3%).
We can see that:
- initial configurations where the cc orbited before quadrature (i.e., before the maximum elongation, see Fig. 7 for an illustration) in 2003 are ruled out except for separations between 8 and 9.75 AU. Larger separations are excluded. We note that to rule out a cc before quadrature and with a separation between 8 and 9.5 AU with the L' data, we will need to wait until 2012-2013;
- initial configurations where the cc orbited in 2003 after
quadrature lead to current positions too close to the star to be
detectable in February 2009. However, we note that for orbits with
radii between 8 and 10 AU, the projected separation is about
4 AU (
8 pixels), so not far from the detection limits in the case of very good atmospheric conditions.



![]() |
Figure 5:
Projected separations of the cc in 2009 (dashed curve) and 2004 (solid
curve), as a function of its orbital radius, assuming its projected
separation was 8 AU in 2003. Top: orbital
radii up to 1000 AU are considered. Bottom:
zoom of the same plot, with orbital radii up to 100 AU. The
horizontal dotted lines indicate separations corresponding to the
computed 6 sigma detection limits of an ML'9.8
source in November 2003 (5.5 AU), and to an ML'9.8
source in February 2009 (6.5 AU) or a |
Open with DEXTER |
We conclude then that the 2004 data definitely rule out any cc that
would have been before quadrature in 2003, as well as a cc after
quadrature in 2003, with an orbital radius larger than 100 AU.
The data do not allow us to derive conclusions for cc orbital radii in
the range 8 to 30-100 AU. The conclusions derived from the
4QPM data rely on
color estimations. Knowing the actual
magnitude of the cc would therefore be very important.
4.2 Can the companion candidate still be responsible for the 1981 photometric eclipse?
Lecavelier des Etangs & Vidal-Madjar (2009) proposed that in order to be responsible for the 1981 eclipse, the cc observed in 2003 should have a physical separation in the range 7.6-8.7 AU (see Sect. 1). As underlined, they could not at that time disentangle a cc that was before or after quadrature in 2003. There was thus a degeneracy in the solutions.We now test whether the constraints brought by the 2004
and 2009 L' images still allow the cc to be the
transiting planet of 1981. The 2004 data now excludes any cc that would
have been before quadrature in 2003. This removes the degeneracy for
the possible locations of the cc in November 2003. Assuming that the cc
was at a projected separation of 8 AU in November 2003, and
was after quadrature, we plot in Fig. 6 the positions
of the cc in 1981. Three possible orbital radii are compatible, with a
projected separation of 0 AU in 1981: 8.1, 10.5 and 17 AU. The
radii at 10.5 AU corresponds to an anti-transit solution
(where the cc is aligned with the star and the observer, but is located
exactly behind the star), so are not acceptable. The 8.1 and
17 AU orbital radii correspond to transit positions in 1981
and therefore are dynamically acceptable.
![]() |
Figure 6: Top: projected separation of the cc in 2004 (dashed curve) and 1981 (solid line curve), as a function of its orbital radius, assuming its projected separation was 8 AU in 2003. Bottom: projected separation of the cc in 2009 (dashed curve) and in 1981 (solid line curve), as a function of its radius, assuming its projected separation was 8 AU in 2003. In both cases, we took into account the fact that the cc was located after quadrature in November 2003. Horizontal lines: same conventions as in Fig. 5. Circular orbits are assumed and the cc is assumed to rotate prograde with respect to the circumstellar disk. |
Open with DEXTER |
An alternative (but equivalent) approach, as adopted by Lecavelier des Etangs & Vidal-Madjar (2009) is to consider the projected separation of the cc in 2003 and 2009, assuming that it was transiting in 1981. In that case, we compute the projected separation assuming that at a time t=0, the cc is transiting, where as in the previous approach, we assumed that at t=0, the cc had a projected separation of 8 AU. The results are shown in Fig. 7. We see that the projected separation of the cc in 2003 is compatible with the detected (projected) position at 8 AU for a semi-major axis of 8.1, 8.5, and 17.1 AU. The orbits with a semi-major axis of 8.1 and 8.5 AU correspond to positions before and after quadrature, respectively. The before-quadrature scenario is excluded by the 2004 4QPM images (see Fig. 4, right panel). We furthermore see that with the 8.1, and 17.1 AU solutions, the projected separation of the cc in February 2009 is much smaller than 6.5 AU (unhatched region in the top panel of Fig. 7). We conclude then that both possible semi-major axe of 8.5 and 17.1 AU are compatible with the cc being responsible for the 1981 eclipse, and being at a projected separation of 8 AU after quadrature in November 2003, and being undetected in February 2009.
![]() |
Figure 7:
Top: projected separation of the cc in 2003
(dash-dotted curve) and 2009 (solid curve) as a function of its orbital
radius, assuming it was transiting |
Open with DEXTER |
![]() |
Figure 8:
Projected separation of the cc in forthcoming years as a function of
its orbital radius, assuming its projected separation was 8 AU
in 2003. Left: we assume, as suggested by the |
Open with DEXTER |
We note that a cc with an orbital radius of 8.1 AU was at the
limit of the detectable zone in 2004 in the 4 QPM images, but as seen
earlier, it is not possible from these data to definitively draw any
firm conclusions on the detectability of a cc with a 30 AU
in 2004. We therefore regard the 8.1 AU solution as a possible
one.
A cc with an orbital radius of 17.1 AU was much too close to
the star to be detected in 2004 or 2009. Lecavelier des Etangs
Vidal-Madjar (2009) proposed that a planet orbiting at 17.1 AU
could have been detected when it was near quadrature between 1993 and
1998, and thus excluded this solution. This is in fact not so clear, as
the visible magnitude of the cc is estimated to be V
= 21, below the detection limits of the 1997 HST/STIS observations that
probed the surroundings of
Pic
as close as 15 AU for companions with V
< 17 (Heap et al. 2000; Lagrange et al. 2009).
4.3 Expected separations of the cc in forthcoming years
Given the constraints brought by the L' and 4QPM images, we plot in Fig. 8 the projected separation of the cc in the forthcoming years, assuming a circular orbit. We see that if its actual orbital radius is low (between 8 and 12-15 AU), the cc should be detectable again end of 2009, under good atmospheric conditions. If we take into account only the constraints provided by L'-band data, we cannot exclude a cc before quadrature with an orbital radius smaller than 9.5 AU; in that case (see also Fig. 8), the cc would be detectable again only after 2012.5 Summary and future prospects
New L'-band data were obtained in February 2009 and did not reveal the presence of the cc detected in 2003 down to 6.5 AU. We show that the non detection does not allow us to rule out a background companion. The L'-band data allow us to exclude initial positions for the cc before quadrature and with radii larger than 9.75 AU (circular orbits assumed). However, they do not constrain the possible orbits of a cc located after quadrature in 2003. 4QPM data obtained in January 2009 did not have the sensitivity to detect the cc in the
Assuming a
color of 1.2-1.5, a similar analysis made on the 2004 4QPM data allowed
to exclude us all initial configurations where the cc was located
before quadrature. Moreover,they restrict the possible orbital radius
of the cc to less than a maximum radius of
30-100 AU from the
star. Nevertheless, the conclusions derived from the 4QPM data rely on
color estimations.
Finally, we have shown that if its actual orbital radius is small (between 8 and 12-15 AU), the cc could be detectable at L' as soon as end of 2009 under very good atmospheric conditions if after quadrature, and after 2012 if before quadrature.
AcknowledgementsWe would like to thank ESO staff, in particular Lowell Tacconi for his very efficient support during phase II preparation, Paranal staff for the SM observations, and Christophe Dumas for his help. We thank Z. Haiman for pointing out precious information on galaxies/QSO contamination. We acknowledge financial support from the French Programme National de Planétologie (PNP, INSU), as well as from the French Agence Nationale pour la Recherche (ANR; project NT05-4_44463). These results have made use of the SIMBAD database, operated at CDS, Strasbourg, France.
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Footnotes
- ... observations
- Based on observations collected at the European Southern Observatory, Chile, ESO; runs 282.C5037(A), 282.C5037(B) and 282.C5037(D).
- ... magnitude
- In the following, absolute magnitudes in a photometric band i are noted Mi and calculated assuming a distance of 19.3 pc. The notation i will simply refer to the apparent magnitude in this band.
- ... data
- Note that we additionally acquired images of
Pic using the new Sparse Aperture Masking mode offered on NaCo in November 2008. However, the experimental observing template we tested as well as the SAM capabilites do not provide constraints on the cc. They are consequently not considered here.
All Tables
Table 1:
Observing log of the Pic
saturated images, and corresponding atmospheric conditions.
All Figures
![]() |
Figure 1:
Top: residual L' image
after subtracting |
Open with DEXTER | |
In the text |
![]() |
Figure 2:
Top: residual |
Open with DEXTER | |
In the text |
![]() |
Figure 3:
Expected position of the source detected in November 2003 (black dot),
assuming it was a background (BKG) object, taking the parallactic and
stellar proper motions into account, for the 10 following years (thin
curved line). Note that we assume, as is usually done, that the cc has
no proper motion. The |
Open with DEXTER | |
In the text |
![]() |
Figure 4:
Coverage map of the |
Open with DEXTER | |
In the text |
![]() |
Figure 5:
Projected separations of the cc in 2009 (dashed curve) and 2004 (solid
curve), as a function of its orbital radius, assuming its projected
separation was 8 AU in 2003. Top: orbital
radii up to 1000 AU are considered. Bottom:
zoom of the same plot, with orbital radii up to 100 AU. The
horizontal dotted lines indicate separations corresponding to the
computed 6 sigma detection limits of an ML'9.8
source in November 2003 (5.5 AU), and to an ML'9.8
source in February 2009 (6.5 AU) or a |
Open with DEXTER | |
In the text |
![]() |
Figure 6: Top: projected separation of the cc in 2004 (dashed curve) and 1981 (solid line curve), as a function of its orbital radius, assuming its projected separation was 8 AU in 2003. Bottom: projected separation of the cc in 2009 (dashed curve) and in 1981 (solid line curve), as a function of its radius, assuming its projected separation was 8 AU in 2003. In both cases, we took into account the fact that the cc was located after quadrature in November 2003. Horizontal lines: same conventions as in Fig. 5. Circular orbits are assumed and the cc is assumed to rotate prograde with respect to the circumstellar disk. |
Open with DEXTER | |
In the text |
![]() |
Figure 7:
Top: projected separation of the cc in 2003
(dash-dotted curve) and 2009 (solid curve) as a function of its orbital
radius, assuming it was transiting |
Open with DEXTER | |
In the text |
![]() |
Figure 8:
Projected separation of the cc in forthcoming years as a function of
its orbital radius, assuming its projected separation was 8 AU
in 2003. Left: we assume, as suggested by the |
Open with DEXTER | |
In the text |
Copyright ESO 2009
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