ome Like it Hot:
idence for the Shrinking
bit of the 2.2-d Transiting
t Jupiter Exoplanet
D 189733b
m Santapaga, Edw Guinan, R-L. Ballouz,
G. Engle, L.E. DeWarf (Villanova Univ.)
ella Kafka (Carnegie Inst, Washington, D.C)
Scale Model for the HD189733 Star- Planet System Showing the
interaction of the planet and star’s Magnetic fields. As shown the
planet’s orbital motion (~152 km/s) pushes against the magnetic
field lines of the star causing the star to spin-up.
Art credit Nick Tripicino
The 8th mag K1.5 V star, HD 189733A shown in the field
of the nearby Dumbbell Nebula
A
a = 0.031 AU (8.75 RK)
[3% Distance Earth to Sun]
b
~220AU
(12.2 arcsec)
B
Model of the HD 189733 Star/ Planet System
A
b
HD 189733 b
HD 189733 A
K1.5V Star
M ~ 0.81 Mʘ
R ~ 0.76 Rʘ
Prot ~ 11.95 d
L ~ 0.26 Lʘ
M = 1.13 MJ; R = 1.14 RJ
Porb = 2.22 d; a = 0.031 AU
T = 844°C+; (~1550°F)
Atm.: H2O, CH4 , (H2O vapor),
methane, CO2, sodium
B
HD 18733 B (12” away from
A: 220 AU; P ~3200 yr)
M 5V Star/ age ~5-7 Billion yrs
R ~ 0.2 Rʘ ; L ~ 10-4 Lʘ
(Bakos et al. 2006)
Same Vr μα μδ as star A
HD 189733 – Selected Properties
Mass
Radius
HD 189733A HD 189733b HD 189733B
(K star)
(Planet)
(M star)
0.81 M
~1.15 MJ
~0.2 M
0.76 R
~1.26 RJ
~0.2 Ro
Rotational
Period
~11.95 d
(tidally locked
2.219 d)
Est: >80 d
-
2.219 d
~3200 yr
-
0.031 AU
~220 AU
Orbital
Period
Orbital
Radius
Age Determinations for the HD 189733 System
METHOD
Value
AGE
Rotation (dK star ) ~11.95 d ~0.6 Gyr
REFERENCE
Henry et al. (2007); This study
Ca II HK Emission S(HK) =
Ca II HK Emiss. (Moutou et al.
<0.8 Gyr
(dK star)
0.52
2007 AA, 473.
X-ray Activity (dK
XMM/ Pilletteri et al. (2010); Age
~10 Lxx ~0.7 Gyr
star )
from this study
Lithium Abundance A (Li) <
( dK star )
0.01
X-ray Activity ( M
star )
>4 Gyr:
Log Lx <
>4.5 Gyr
26.9
H-alpha emission (
EW ~0.0 > 5-6 Gyr
M star )
Melo, C., (2006), A&A, 460, Age
from Li-depletion
XMM-Newton from Pillitteri I.,(
2010); Age – this study
Spectra from S. Kafka
(Carnegie Cray Telescope)
A
b
HD 189733 A
HD 189733 b
K1.5V Star
M ~ 0.81 Mʘ
R ~ 0.76 Rʘ
Prot ~ 11.95 d
L ~ 0.26 Lʘ
M = 1.13 MJ; R = 1.14 RJ
Porb = 2.22 d; a = 0.031 AU
T = 844°C+; (~1550°F)
Atm.: H2O, CH4 , (H2O vapor),
methane, CO2, sodium
B
HD 18733 B
M 5V Star
R ~ 0.2 Rʘ ; L ~ 10-4 Lʘ
(Bakos et al. 2006)
Same Vr μα μδ as star A
A
a = 0.031 AU (8.75 RK)
[3% Distance Earth to Sun]
b
~220AU
B
Io – Jupiter - A possible Analog for
understanding the HD 189733Ab
magnetically Interacting Planet-Star System
HD189733 A & Ab
HD 189733 A has signifcant
chromospheric & coronal X-ray
emissions. Also the star has
starspots covering ~3% of
star’s surface that produce
brightness variations of up to
2%. The star’s rotation period
(11.95 days) and its resulting
magnetic dynamo-generated
emissions are similar to dK0-5
stars in the Hyades cluster (age
~ 650 Myr). But the age
indicators of the dM5
companion indicate a much
older age (>5-6 Gyr).
Artwork from Tinetti: ESA/NASA
The final fate of
HD189733b
as it reaches its Roche critical
surface. This occurs at an
orbital period of ~ 6 hr and at an
orbital distance of ~2 stellar radii
(i.e. at a = 0.007 AU).