HD 40307 f
HD 40307 f
confirmed planet • updated: 2014-05-14
HD 40307 f orbits the star HD 40307, a slightly cooler and smaller star than our Sun. Scientists found it using the radial velocity method at La Silla Observatory in 2013.
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 of about 5 Earth masses and orbits its star every 52 days. Because radial velocity gives a minimum mass (often written as m sin i), the true mass could be higher if the orbit is tilted relative to our view. The star is a K-type dwarf, cooler and smaller than the Sun, with a metal content slightly lower than average.
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 40307 f was first reported in 2013 using the Radial Velocity method. The discovery is linked to observations from La Silla 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 51.76 days, a semi-major axis near 0.247 AU.
The orbit’s eccentricity is 0.02, 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.
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 40307 f orbits HD 40307. The star is classified as K2.5 V, which is a shorthand for temperature and color.
A temperature near 4956 K places it on the sun-like side of the main sequence. The system is about 42.2 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.