HD 109246 b
confirmed planet • updated: 2018-09-04
HD 109246 b circles the star HD 109246, located about 68 light-years away. Scientists detected it using the radial velocity method, which tracks how the star moves slightly due to the planet’s gravity.
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 has a minimum mass about 273 times Earth’s (or 0.86 times Jupiter’s) and orbits very close to its star — just 0.33 times Earth’s distance from the Sun. Its orbit is slightly oval-shaped (eccentricity 0.12). Because radial velocity gives a minimum mass (m sin i), the true mass could be higher if the orbit is tilted relative to us.
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 109246 b was first reported in 2010 using the Radial Velocity method. The discovery is linked to observations from Haute-Provence 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 68.27 days, a semi-major axis near 0.330 AU.
The orbit’s eccentricity is 0.12, which describes how stretched the orbit is.
The archive reports a mass scale of 0.9 MJ.
For radial‑velocity work this is commonly m·sin i (a minimum mass) because the orbital tilt is unknown. A rough radius estimate is shown for UI completeness, but it should not be treated as a measurement.
Why “m·sin i” shows up on RV planets
HD 109246 b orbits HD 109246.
A temperature near 5844 K places it on the sun-like side of the main sequence. The system is about 221.2 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. 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.