Kepler-1229b

Lore & Background

Kepler-1229b was discovered by NASA's Kepler spacecraft during its final observing campaign before two of its reaction wheels failed. The spacecraft's photometer detected periodic dimming of the star Kepler-1229, indicating a transiting planet. Radial velocity observations later confirmed that a planetary body was responsible for the dips in the star's light curve. The planet was announced in a catalog released by NASA on May 12, 2016.

The planet is 2.7 times the mass of Earth and has a radius 1.4 times that of Earth, placing it in the super-Earth category—larger than Earth but smaller than Neptune or Uranus. Its equilibrium temperature is 213 K. The host star, Kepler-1229, is an M-type red dwarf with about half the mass and radius of the Sun, a temperature of 3724 K, and an age of 3.72 billion years. The star's apparent magnitude is 15.474, making it too dim to be seen with the naked eye.

Kepler-1229b orbits its star every 86.829 days at a distance comparable to Mercury's orbit around the Sun. The star has only about 4% of the Sun's luminosity. Because red dwarfs can live 50–60 billion years, the system offers a long-term stable environment for potential habitability.

Reader's Guide

Kepler-1229b is notable as one of nine exoplanets announced in 2016 to orbit within the habitable zone of their parent stars—the region where liquid water could exist on a planetary surface under suitable atmospheric conditions. Its radius of 1.4 Earth radii suggests a likely rocky composition, and its position in the habitable zone of a long-lived red dwarf makes it a candidate for future study of potentially habitable worlds.

However, at nearly 870 light years distant, Kepler-1229b is too remote for current or next-generation telescopes to determine its mass directly or to analyze its atmosphere. The Kepler spacecraft focused on a small region of the sky, but upcoming space telescopes such as TESS and CHEOPS will survey nearby stars across the entire sky. Planets around nearby stars can then be examined by the James Webb Space Telescope and future large ground-based observatories to study atmospheres, determine masses, and infer compositions. Additionally, the Square Kilometer Array could significantly improve radio observations of such systems.

Kepler-1229b's legacy lies in demonstrating the prevalence of potentially habitable super-Earths around red dwarfs and in setting the stage for future characterization efforts. It is often compared to Kepler-62f, a similar exoplanet with comparable radius and stellar flux.

Did You Know?

• Kepler-1229b has an equilibrium temperature of 213 K.
• Its host star, Kepler-1229, is about 3.72 billion years old, younger than the Sun's 4.6 billion years.
• The planet orbits its star every 86.829 days at a distance similar to Mercury's orbit.
• Kepler-1229b was confirmed via radial velocity observations after initial detection by the transit method.