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


How
about
the
spectroscopic
transit?


 We
all
know
how
a
photometric
transit
looks
like


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)


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


λ
(or
β in
Triaud’s
paper)
is
the
projected
spin
orbit
misalignment
angle.



Gaudi
&
Winn
2006,
ApJ


Measurements




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‐15b;
β
=
139
 WASP‐5b;
β
~
0
 Amaury
Triaud
et
al


The
real
misalignment




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


• rbital
axis.



Amaury
Triaud
et
al


Discussion


 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)


Amaury
Triaud
et
al


Kozai
Mechanism


 In
a
presence
of
a
3rd
distant
body,
if
the
orbital


plane
of
the
inner
binary
is
not
aligned
with
the


• uter
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.