K2-3 c
confirmed planet • updated: 2023-07-10
K2-3 c circles the star K2-3, a small, dim red star about 44 light-years away. Scientists spotted it using the transit method, which detects tiny dips in starlight when a planet crosses in front of its star.
This page summarizes a catalog entry. If a measurement is missing, it is not shown or guessed. Some values can differ slightly between studies; when that happens, we describe the range rather than picking a favorite 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.
K2-3 c is about 1.6 times Earth’s size and has a mass roughly 2.7 times Earth’s — suggesting it’s a rocky or rocky-with-water world. It orbits its star every 24.6 days at a distance that gives it about 3 times Earth’s sunlight. Its orbit is nearly circular. The star is cooler and smaller than our Sun, so the planet’s temperature is estimated at around 372 Kelvin (about 210°F or 99°C).
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.
K2-3 c was first reported in 2015 using the Transit method. The discovery is linked to observations from K2.
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 24.65 days, a semi-major axis near 0.136 AU.
The orbit’s eccentricity is 0.05, which describes how stretched the orbit is. Because this is a multi‑planet system, stability is ultimately tested with dynamical (N‑body) fits; catalogs can update as models improve.
The archive reports a mass scale of 0.0 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
K2-3 c orbits K2-3. The star is classified as M V, which is a shorthand for temperature and color.
A temperature near 3844 K places it on the cool side of the main sequence. The system is about 143.7 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. 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.