K2-3 b
confirmed planet • updated: 2023-07-10
K2-3 b circles the star K2-3, a dim red dwarf. Scientists spotted it when the planet crossed in front of its star, causing a tiny, regular dip in brightness — a sign of a transit.
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 b is a super-Earth or mini-Neptune, with a radius about twice Earth’s and a mass about five times Earth’s. It orbits very close to its star — every 10 days — and receives about 10 times more starlight than Earth does. Its orbit is slightly oval-shaped, not perfectly circular. The planet’s temperature is estimated at around 500 Kelvin (about 228°C or 442°F), but this depends on how much light it reflects and how its atmosphere traps heat — details we don’t yet know.
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 b 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 10.05 days, a semi-major axis near 0.075 AU.
The orbit’s eccentricity is 0.11, 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 b 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.