Two planets discovered orbiting the star TOI-4468 including a hot Jupiter

Star system: TOI-4468 | Distance from the Sun: 1233 light years

A new planetary system has been identified orbiting the star TOI-4468, featuring a hot Jupiter and a nearby outer sub-Neptune. This system is unique because it includes a close outer companion to a hot Jupiter without any inner planets, a configuration not typically seen in the current census of known worlds. These findings provide new insights into how these massive, short-period planets form and evolve over time.

The research confirmed the presence of TOI-4468 b, a hot Jupiter with a mass of 0.54 Jupiter masses and a radius of 1.01 Jupiter radii, which completes an orbit every 2.77 days. The outer planet, TOI-4468 c, was validated as a sub-Neptune with a radius of 0.28 Jupiter radii and an orbital period of 7.01 days.

To characterize these planets, data were combined from the TESS space telescope and various ground-based observatories. Radial velocity measurements—a technique that detects the slight gravitational wobble of a star caused by orbiting planets—were gathered using the NEID spectrograph to confirm masses and orbital characteristics.

The system shows evidence of an additional potential outer giant planet with an orbital period of 624 days, though this signal remains unconfirmed. The current orbital geometry suggests that the system avoided early gravitational interactions that would have otherwise tipped or tilted the orbits of these planets. This lack of disturbance offers researchers a cleaner view of how hot Jupiters might settle into their tight, close-in orbits without the typical chaotic influence of inner companions.

Key findings
- Confirmed the hot Jupiter TOI-4468 b with a 2.77-day orbital period.
- Validated the outer sub-Neptune TOI-4468 c with a 7.01-day orbital period.
- Identified a potential, unconfirmed third outer giant planet with a 624-day orbit.
- Found no evidence of early resonance that usually affects the alignment of planetary systems.
- Demonstrated a unique system architecture where a hot Jupiter lacks an inner companion.

Scientific study

Discovery and Characterization of the TOI-4468 Planetary System: A Transiting Hot Jupiter With a Lone Nearby Outer Companion (external link)