Are Planets in Unresolved Candidates of Debris Disks Stars

1
Are Planets in Unresolved Candidates of Debris
Disks Stars?
R. de la Reza (1), C. Chavero (1), C.A.O. Torres
(2) E. Jilinski (1) (1) Observatorio
Nacional - Rio de Janeiro (2) Laboratorio
Nacional de Astrofísica
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Properties
Debris disks (DD) are evolved disks presenting
the following properties 1) in general
absence or few gas content 2) structural
pattern dominated by new generation dust produced
by strong collisions of planetesimals 3)
in general disks are assymmetrical 4) presence
of warps and local perturbations of the dust
5) longlife structures 6) difficult to be
detected, only approximatley 12 are resolved
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Questions
1) are there planets hidden in their disks ? At
present only one planet have been clearly
detected around a resolved disk in Epsilon
Eridani (Greaves et al. 2005) 2) are these
disks failed planetary disks ? 3) are these
disks left over debris of incomplete planetary
formation ? 4) are hidden planets producing the
observed warps and assymmetries, gaps or rings
? 5) why they are longlived structures ? what
maintain their dynamical stability ? is that
due to a special configuration of dust maintained
in resonances and what is the role of eventual
planets ? 6) when DD evolution begins ? 8 Myr
following de la Reza et al. 2005
COROT can in principle detect for the first time
the passage of dust structures or planets in
unresolved Debris Disks candidates.
Motivation
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• Epsilon Eridani

The only example of a DD star with a planet close
to the star detected by radial velocity surveys.
Distance 3.2 pc SpT K2V M0.8 Msun Planet 1
Eps Eri b a 3.3 AU Mp 0.86 M Jup Method
RV Planet 2 Eps Eri c -Unconfirmed a 40AU Mp
0.1 MJup Method Dust ring morphology
850 microns.
450 microns.
Planet 2 is sheppering the ring?
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The ß Pic star with an edge-on disk. This is an
example of a convenient geometry for COROT
observations.
ß Pic
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Unique emission absortion event detected on Nov
10th 1981 by ground based photometric observations
(Lecavelier et al. 1997)
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1
First interpretation of the 1981 event a planet
into the disk.
(Lecavelier et al. 1997)
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2
Two other geometrical interpretations 2-a
spherical cloud 3- a cometary cloud falling into
the star.
3
(Lamers et al. 1997)
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The most successful model (3) a large
comet or a fragmented falling comet.
(Lamers et al. 1997)
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Result of a radial velocity survey of the ß Pict
star
(Galland et al. 2005)
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Search for DD candidates stars for COROT
Distribution of resolved DD stars in an IRAS
Color-Color diagram

• B BD31643
• A 1-HR4796
• 2 - Bpic
• 3 - AB Aur
• 4 - HD32297
• 5 - Fomahault
• 6 - Vega
• F AeBe- HD141569
• G 1- HD107146
• 2 - Tau Cet
• K Epsilon Eridani
• M Au Mic

60 - 25
25 - 12
12
Unresolved DD candidate stars with high IRAS
quality
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Conclusions
Up to the present only one planet has been
discovered in a resolved Debris Disk star
(Epsilon Eridani). CoRoT can in principle
discover some new cases and give an important
insight on studies of the evolution of Debris
Disks and on planetary formation. The only
problem is the difficulty to find targets for
11IRASare in general M giants stars We are now
looking for hot B/A/F stars with IR excesses.
References De la Reza et al., submitted to the
AJ Galland et al., 2005 AA, 443,337 Lamers et
al.., 1997, AA 328, 321 Lecavelier des Etangs,
1997, AA, 328, 311