Earth 2.0 could sharpen orbital decay measurements for WASP-12 b and hot Jupiters

WASP-12 b is currently the only hot Jupiter with conclusive evidence that its orbit is shrinking. Simulations suggest the planned Earth 2.0 mission could make orbital-decay measurements 7.2 times more precise by combining new observations with data from Kepler and TESS. Under an assumed level of tidal friction inside the stars, the mission could also detect decay in three additional systems.

Star system: WASP 12 | Distance from the Sun: 1347 light years

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Earth 2.0 could sharpen orbital decay measurements for WASP-12 b and hot Jupiters

Star system: WASP 12 | Distance from the Sun: 1347 light years

WASP-12 b is currently the only hot Jupiter with conclusive observational evidence that its orbit is shrinking. Hot Jupiters are gas giant planets that orbit very close to their stars. Measuring orbital decay in more of these systems would help show how strongly tidal forces transfer energy between a planet and its star.

Earth 2.0 is planned to revisit the original Kepler field and provide precise measurements of when planets cross in front of their stars. These events are called transits. Changes in transit timing over many years can reveal whether a planet’s orbit is gradually changing. The analysis combines simulated observations spanning four years with archived data from Kepler and TESS, extending the overall observing baseline to about 24 years, from 2009 to 2033.

The projected measurements improve precision for orbital-decay measurements by a factor of 7.2. If the stars’ tidal response matches the value inferred from earlier observations, Earth 2.0 is expected to detect orbital decay in three additional hot-Jupiter systems. A larger set of measured systems would help constrain stellar tidal quality factors, which describe how efficiently a star dissipates energy from tidal interactions. The predictions depend on the assumed value of this factor.

Key findings
WASP-12 b is the only hot Jupiter with conclusive evidence of orbital decay to date.
Earth 2.0 is expected to extend the observing baseline for the original Kepler field to about 24 years.
Combining simulated Earth 2.0 observations with Kepler and TESS data could improve measurement precision by a factor of 7.2.
Assuming a previously inferred stellar tidal quality factor, the mission is expected to detect orbital decay in three additional hot-Jupiter systems.

Scientific study

Prospects for detecting hot-Jupiter tidal decay through transit timing with the mission Earth 2.0