Beforewestart - PowerPoint PPT Presentation

Before
we
start
  Brief
introduc-on
of
the
plans
and
ideas
for
the
planetary
group
 (Links
with
Chilean
Universi-es
JC/One
Day
WS;
Planetary
Systems
 II)
  Visitors
encouraged
  Members
to
provide
cross‐training
to
PAO
members
(PAO
is
a
place
 to
talk
about
science!
Planets
is
a
key
driver
for
the
future
of
ESO,
 we
should
to
grow
exper-se
and
interest
on
the
field)
  Frequency
of
the
mee-ngs
–
Every
two
weeks
seems
a
good
 number


Spin‐orbit
angle
measurements
for
six
  
 southern
transiting
planets
 Amaury
Triaud
et
al
 http://www.superwasp.org/documents/triaud2010_rossiter.pdf 


“This
is
a
real
bomb
we
are
dropping
into
the
field
of
exoplanets,” 
says
Amaury
Triaud,
a
 PhD
student
at
the
Geneva
Observatory
who,
with
Andrew
Cameron
and
Didier
Queloz,
 leads
a
major
part
of
the
observa-onal
campaign.
 WHY???


Rossiter‐McLaughlin
effect
  We
all
know
how
a
photometric
transit
looks
like
 How
about
the
spectroscopic
transit?


Radial
velocity


The
transi/ng
object
blocks
the
stellar
disk
producing
a
shi:
in
 the
RV
 The
amplitude
of
this
effect
is
related
to
the
geometry
and
to
 the
rota/onal
velocity


Ohta
et
al.
(2005)


Ohta
et
al.
(2005)


Gaudi
&
Winn
2006,
ApJ
 λ 
(or
 β in
Triaud’s
paper)
is
the
projected
spin
orbit
misalignment
angle.
 
 Thus:
 • for
 β =0
the
planetary
orbit
is
perpendicular
to
the
stellar
rota/on
axis;
 • For
 β =90
the
orbit
is
along
the
rota/on
axis
 • For
 β >90
the
orbital
mo/on
is
retrograde


Measurements
 Amaury
Triaud
et
al
 Global
fiang
of
  photometric
transit,
RV
 curve
and
spectroscopic
 transit

 6
transi-ng
planets
found
  by
WASP
were
studied
in
 the
paper
 3
of
them
have
 β 
>
90 
  (retrograde
orbits)
 3
others
have
 β 
~
0
  WASP‐5b;
 β 
~
0
 WASP‐15b;
 β 
=
139


The
real
misalignment
 Amaury
Triaud
et
al
 They
measured
the
sky‐  projected
spin‐orbit
angle
 The
real
angle
 ψ is
es-mated
  using
the
argument
that
the
 spin
axis
is
isotropically
 distributed
 cos
 ψ 
=
cos
I
cosi
+
sin
I
cos
 β  I
is
the
inclina-on
of
the
  stellar
spin
axis
and
I
the
 inclina-on
of
the
planet’s
 orbital
axis.



Discussion
 Amaury
Triaud
et
al
  26
RM
effects
have
 been
observed
so
far
  14
have
 β 
<
22
and
 are
considered
 aligned
  They
find
that
there
is
 a
82%
probability
that
 ψ 
is
>22deg
(Solar
 System
case)


Kozai
Mechanism
  In
a
presence
of
a
3 rd 
distant
body,
if
the
orbital
 plane
of
the
inner
binary
is
not
aligned
with
the
 outer
orbit,
the
e_in
and
the
inclina-on
between
 the
two
orbits
will
oscillate
in
cycles.
  KC+Tidal
fric-on
the
e_in
becomes
large
so
that
in
 the
periastron
passage
-des
take
over
for
a
while
 working
towards
a
circular
orbit.


Theoretical
prediction
 The
predic-on
for
the
misalignment
spin‐planetary
orbit

 For
systems
with
a
third
companion.
(Fabrycky
and
Tremaine
2007)


It
matches
beau-fully
the
observa-ons!


Conclusions
  RM
measurements
obtained
with
high
accuracy
RV
data
 suggest
that
>80%
of
the
hot‐jupiters
are
misaligned
 with
angles
some-mes
>
90%
  Forma-on
of
hot‐jupiters
via
migra-on
requires
 interac-ons
with
the
disc
and
therefore
coplanarity
  Kozai
mechanism
would
cause
the
inner
orbit
to
oscillate
 (e_in,
inclina-on)
and
reduce
the
orbital
period.

  The
predicted
distribu-on
of
spin‐orbit
angle
is
very
 similar
to
the
one
drawn
from
sta-s-cal
arguments
 transforming
the
 β 
distribu-on.