Unveiling the Mysteries of Hot Jupiters: WASP-132 Defies Planetary System Norms

Hot Jupiters, once believed to orbit their stars alone, were thought to consume or eject nearby planets during their inward migration. However, recent findings have challenged this notion. A study from the University of Geneva (UNIGE), in collaboration with NCCR PlanetS, the Universities of Bern (UNIBE) and Zurich (UZH), and international institutions, uncovers a fascinating planetary system, WASP-132, which includes a Hot Jupiter, an inner Super-Earth, and a distant icy giant.

Published in Astronomy & Astrophysics, the study redefines our understanding of Hot Jupiter migration and highlights the surprising diversity of planetary systems.

Rethinking Hot Jupiter Formation

Hot Jupiters, massive planets close to their stars, are unlikely to form in their observed locations due to insufficient nearby gas and dust. Instead, they likely originate farther out and migrate inward. Previously, astronomers thought this migration disrupted or eliminated neighboring planets, leaving Hot Jupiters isolated. However, the discovery of WASP-132 proves otherwise, suggesting a more stable migration process that preserves complex planetary arrangements.

WASP-132 System

WASP-132 system defies expectations with its unique configuration:

• Hot Jupiter: Orbits its star in just over seven days with a mass of 0.41 Jupiter masses.
• Super-Earth: A rocky planet six times Earth’s mass, completing its orbit in a single day.
• Outer Giant: Five times Jupiter’s mass, orbiting over five years.
• Distant Companion: Likely a brown dwarf, orbiting at a far greater distance.

“This system is a remarkable laboratory for studying planetary formation and evolution,” said François Bouchy, associate professor at UNIGE and co-author of the study.

A Decade of Observations

The story of WASP-132 began in 2006 with the Wide-Angle Search for Planets (WASP) program. By 2012, over 23,000 photometric measurements identified the Hot Jupiter candidate, later confirmed by the Swiss Euler telescope in 2016. In 2021, NASA’s TESS space telescope detected the inner Super-Earth, and by 2022, the HARPS spectrograph determined its mass and density, revealing a rocky composition similar to Earth’s.

Implications for Planetary Science

The discovery of both an inner Super-Earth and an outer giant planet challenges existing migration theories. A more stable migration path in a protoplanetary disk likely preserved the orbits of the neighboring planets, offering new insights into the dynamics of planetary systems.

Precise mass and radius measurements have also revealed details about the planets’ internal compositions. WASP-132b contains heavy elements equivalent to 17 Earth masses, consistent with gas giant formation models. The Super-Earth, rich in metals and silicates, mirrors Earth’s density.

“The combination of a Hot Jupiter, an inner Super-Earth, and an outer giant planet provides vital constraints on planet formation and migration theories,” said Ravit Helled, professor at UZH and study co-author.

The discovery of WASP-132 underscores the complexity of planetary systems, emphasizing the importance of long-term, high-precision observations in unraveling their mysteries.

Read Original Article: Scitechdaily

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