Warm Jupiter HD 715 b orbits a massive subgiant star

A new warm Jupiter named HD 715 b has been confirmed orbiting the bright subgiant star HD 715. Identified initially through a single transit event captured by the TESS mission, follow-up observations have revealed the planet's orbital characteristics. This system is particularly notable because the host star is among the most massive known to harbor a transiting warm Jupiter, providing new data on orbital diversity.

Star system: HD 715 | Distance from the Sun: 543 light years

The planet HD 715 b has been confirmed as a warm Jupiter orbiting the bright subgiant star HD 715, also known as TOI-6893. Warm Jupiters are gas giant planets that orbit their host stars very close. The planet was first detected when it passed in front of its host star, an event known as a transit that causes a slight dip in the star's brightness. HD 715 is a massive subgiant star, with a mass approximately 1.6 times that of our Sun, making it one of the largest stars currently known to host such a planet.

To confirm the planet's existence and determine its properties, researchers performed radial velocity measurements over two seasons. This technique monitors the tiny "wobble" of a star caused by the gravitational pull of an orbiting planet, which allows for the calculation of the planet's mass. By combining these measurements with the initial transit data, the team determined the planet's orbital period to be approximately 56.4 days. The planet has a mass of 0.635 times that of Jupiter and a radius 1.07 times that of Jupiter, placing it well within the expected range for gas giants of this class.

Additional findings reveal that HD 715 b has an orbital eccentricity of 0.21, meaning its path around the star is moderately oval rather than circular. This value is lower than the eccentricities observed in many similar planets orbiting other evolved stars, suggesting that planetary systems around massive stars exhibit a wider variety of orbital shapes than previously assumed. Although the current timing data for the transits includes some uncertainty, future observations are expected to better pin down the planet's orbital path.

Key findings
HD 715 b is a warm Jupiter with an orbital period of approximately 56.4 days.
The host star HD 715 has a mass of 1.6 times the mass of the Sun.
The planet possesses a mass of 0.635 Jupiter masses and a radius of 1.07 Jupiter radii.
The planet's orbital eccentricity of 0.21 indicates a diverse range of orbital shapes among warm Jupiters.

Scientific study

HD 715 b, a Warm Jupiter Orbiting a Massive Subgiant Discovered from a Single TESS Transit (external link)