HD 74156 b
HD 74156 b
confirmed planet • updated: 2023-06-14
HD 74156 b orbits the star HD 74156, located about 58 light-years away. Scientists first spotted it in 2003 using the radial velocity method, which tracks tiny changes in the star’s motion caused by the planet’s gravity.
This page summarizes data from multiple studies. When values differ between sources, we show the range. If a measurement is missing, it is not guessed or filled in — we only report what has been published.
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 very elliptical orbit — it swings close to its star and then far away again every 52 days. Its mass is estimated to be at least 1.7 times that of Jupiter, but because we only measure the minimum mass (called m sin i), the real mass could be higher if the orbit is tilted. The star it orbits is slightly more massive 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.
HD 74156 b was first reported in 2003 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 51.64 days, a semi-major axis near 0.280 AU. The orbit’s eccentricity is 0.64, which describes how stretched the orbit is.
A higher eccentricity can imply stronger past interactions or migration, and it can matter for long‑term stability in multi‑planet systems. 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 1.7 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 74156 b orbits HD 74156.
The system is about 187.9 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.