HD 221416 b
HD 221416 b
confirmed planet • updated: 2019-04-16
HD 221416 b was found when it passed in front of its star, causing a tiny dip in brightness — a method called transit. It’s a big, puffy planet orbiting close to a Sun-like star.
This page summarizes what’s been measured and published. If a value is missing, it’s not shown or guessed. Some numbers vary slightly between studies — when that happens, we describe the range instead of picking one without evidence.
Scientific context
Scientific context: This profile layers interpretation on top of archival measurements. Modeled bands appear where direct detections (like spectra or transits) are not listed.
What we can’t claim: surface conditions, biology, or breathable atmosphere without direct spectra.
This planet is about 60 times more massive than Earth and nearly 9 times wider. It orbits its star every 14 days at a distance of about 0.12 times Earth’s distance from the Sun. Its orbit is slightly oval-shaped. The star it orbits is slightly larger and cooler than our Sun.
Glossary (plain English)
- AU: the average Earth–Sun distance.
- Semi-major axis: the planet’s average distance from its star.
- Eccentricity: how oval the orbit is (0 = circle).
- Radial velocity: finding a planet by measuring a star’s tiny “wobble.”
- m·sin i: a minimum mass estimate; the true mass can be higher if the orbit is tilted.
- Equilibrium temperature: a rough estimate from starlight alone, not a surface reading.
HD 221416 b was first reported in 2019 using the Transit method. The discovery is linked to observations from Transiting Exoplanet Survey Satellite (TESS).
In transit work, astronomers watch for tiny, repeating dips in a star’s light as the planet passes in front of it. Follow-up observations help rule out false positives and refine the orbit.
The catalog lists an orbital period of about 14.28 days, a semi-major axis near 0.123 AU.
The orbit’s eccentricity is 0.12, which describes how stretched the orbit is.
The archive reports a mass scale of 0.2 MJ.
A catalog radius is also listed, which (together with mass) helps constrain density and interior structure.
Why “m·sin i” shows up on RV planets
HD 221416 b orbits HD 221416.
A temperature near 5080 K places it on the sun-like side of the main sequence. The system is about 311.6 light‑years away.
Several key parameters are not present in this single catalog row. Missing fields don’t mean the science is unknown—only that this particular snapshot doesn’t carry the values.
In this case the most noticeable gaps are: catalog equilibrium temperature. As new observations arrive, archives often refresh these entries (and sometimes revise earlier numbers).
Scientists keep revisiting systems like this because each new instrument pass can tighten uncertainties: better timing improves the orbit, better spectra improves the star, and better follow‑up can confirm or refute competing solutions. Even when a planet is well‑established, refined stellar properties can shift the inferred planet size, temperature, and habitability context. Transit systems are especially valuable because they can be re‑observed for decades to detect subtle changes in timing or additional planets.