HIP 29442 c
HIP 29442 c
confirmed planet • updated: 2024-09-13
HIP 29442 c orbits the star HD 42813, located about 68 light-years away. Scientists detected it by measuring tiny wobbles in the star’s motion, a technique called radial velocity.
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.
This planet orbits its star in just over 3.5 days, very close in — about 4.5% of Earth’s distance from the Sun. It’s about 1.55 times Earth’s size and 4.5 times Earth’s mass, making it a super-Earth or mini-Neptune. Its surface temperature is estimated at around 1123 Kelvin (about 850°C), which is very hot. We don’t know if its orbit is circular or stretched out, because that measurement isn’t available.
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 29442 c was first reported in 2023 using the Radial Velocity method. The discovery is linked to observations from Paranal Observatory.
Radial-velocity detections come from subtle shifts in the star’s spectrum as it wobbles under the planet’s gravity. The first mass value is often a minimum (m·sin i) unless the orbit’s tilt is known.
The catalog lists an orbital period of about 3.54 days, a semi-major axis near 0.045 AU.
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.
The archive reports a mass scale of 0.0 MJ.
For radial‑velocity work this is commonly m·sin i (a minimum mass) because the orbital tilt is unknown. 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
HIP 29442 c orbits HD 42813.
A temperature near 5289 K places it on the sun-like side of the main sequence. The system is about 222.4 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: eccentricity. 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.