Some Like it Hot:

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Some Like it Hot Evidence for the Shrinking
Orbit of the 2.2-d Transiting Hot Jupiter
Exoplanet HD 189733b
Tom Santapaga, Edw Guinan, R-L. Ballouz, S.G.
Engle, L.E. DeWarf (Villanova Univ.) Stella Kafka
(Carnegie Inst, Washington, D.C)
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Scale Model for the HD189733 Star- Planet System
Showing the interaction of the planet and stars
Magnetic fields. As shown the planets orbital
motion (152 km/s) pushes against the magnetic
field lines of the star causing the star to
spin-up.
Art credit Nick Tripicino
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The 8th mag K1.5 V star, HD 189733A shown in the
field of the nearby Dumbbell Nebula
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a 0.031 AU (8.75 RK) 3 Distance Earth to
Sun
A
b
220AU (12.2 arcsec)
B
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Model of the HD 189733 Star/ Planet System
A
b
HD 189733 b M 1.13 MJ R 1.14 RJ Porb 2.22
d a 0.031 AU T 844C (1550F) Atm. H2O,
CH4 , (H2O vapor), methane, CO2, sodium
HD 189733 A K1.5V Star M 0.81 M? R 0.76
R? Prot 11.95 d L 0.26 L?
B
HD 18733 B (12 away from A 220 AU P 3200
yr) M 5V Star/ age 5-7 Billion yrs R 0.2 R?
L 10-4 L? (Bakos et al. 2006) Same Vr µa µd as
star A
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HD 189733 Selected Properties HD 189733 Selected Properties HD 189733 Selected Properties HD 189733 Selected Properties
HD 189733A (K star) HD 189733b (Planet) HD 189733B (M star)
Mass 0.81 M? 1.15 MJ 0.2 M?
Radius 0.76 R? 1.26 RJ 0.2 Ro
Rotational Period 11.95 d (tidally locked 2.219 d) Est gt80 d
Orbital Period - 2.219 d 3200 yr
Orbital Radius - 0.031 AU 220 AU
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Age Determinations for the HD 189733 System Age Determinations for the HD 189733 System Age Determinations for the HD 189733 System Age Determinations for the HD 189733 System
METHOD Value AGE REFERENCE
Rotation (dK star ) 11.95 d 0.6 Gyr Henry et al. (2007) This study
Ca II HK Emission (dK star) S(HK) 0.52 lt0.8 Gyr Ca II HK Emiss. (Moutou et al. 2007 AA, 473.
X-ray Activity (dK star ) 10 Lxx? 0.7 Gyr XMM/ Pilletteri et al. (2010) Age from this study
Lithium Abundance ( dK star ) A (Li) lt 0.01 gt4 Gyr Melo, C., (2006), AA, 460, Age from Li-depletion
X-ray Activity ( M star ) Log Lx lt 26.9 gt4.5 Gyr XMM-Newton from Pillitteri I.,( 2010) Age this study
H-alpha emission ( M star ) EW 0.0 gt 5-6 Gyr Spectra from S. Kafka (Carnegie Cray Telescope)
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A
b
HD 189733 b M 1.13 MJ R 1.14 RJ Porb 2.22
d a 0.031 AU T 844C (1550F) Atm. H2O,
CH4 , (H2O vapor), methane, CO2, sodium
HD 189733 A K1.5V Star M 0.81 M? R 0.76
R? Prot 11.95 d L 0.26 L?
B
HD 18733 B M 5V Star R 0.2 R? L 10-4
L? (Bakos et al. 2006) Same Vr µa µd as star A
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a 0.031 AU (8.75 RK) 3 Distance Earth to
Sun
A
b
220AU
B
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Io Jupiter - A possible Analog for
understanding the HD 189733Ab magnetically
Interacting Planet-Star System
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HD189733 A Ab
HD 189733 A has signifcant chromospheric
coronal X-ray emissions. Also the star has
starspots covering 3 of stars surface that
produce brightness variations of up to 2. The
stars 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 (gt5-6
Gyr). Artwork from Tinetti ESA/NASA
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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).