HIP 41378 b
HIP 41378 b
confirmed planet • updated: 2019-06-03
HIP 41378 b orbits the star HIP 41378, located about 106 light-years away. Scientists found it using the transit method, which detects 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.
The planet orbits its star every 15.6 days. Based on transit data, its size is estimated to be between 2.4 and 2.9 times Earth’s radius — likely a mini-Neptune or sub-Saturn. Its mass is not measured, so we don’t know if it’s rocky, gassy, or something in between. The star is slightly hotter and larger 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.
HIP 41378 b was first reported in 2016 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 15.57 days.
Eccentricity is not provided here; many catalogs omit it when the solution is underconstrained. Because this is a multi‑planet system, stability is ultimately tested with dynamical (N‑body) fits; catalogs can update as models improve.
A measured mass is not available in this row, which limits what we can infer about composition.
Radius is not listed, so density and surface gravity cannot be derived from this row alone.
Why “m·sin i” shows up on RV planets
HIP 41378 b orbits HIP 41378.
A temperature near 6226 K places it on the hotter side of the main sequence. The system is about 346.7 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.
In this case the most noticeable gaps are: radius, catalog equilibrium temperature, semi‑major axis, eccentricity, mass. 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.