HD 75289 b
HD 75289 b
confirmed planet • updated: 2018-09-04
HD 75289 b circles the star HD 75289, which is slightly larger and hotter than our Sun. Scientists found it in 1999 by measuring how the star wobbles — a method called radial velocity.
This page summarizes what’s in the catalog. If a number is missing, we don’t guess or fill it in. Some values vary between studies — when that happens, we show the full range so you know what’s uncertain.
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, meaning it’s very close. Its minimum mass is about half that of Jupiter (or 156 Earth masses), but the true mass could be higher if the orbit is tilted. The orbit is nearly circular. The star is about 29 light-years away and slightly more massive and metal-rich 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 75289 b was first reported in 1999 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 3.51 days, a semi-major axis near 0.050 AU.
The orbit’s eccentricity is 0.03, which describes how stretched the orbit is.
The archive reports a mass scale of 0.5 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 75289 b orbits HD 75289.
A temperature near 6117 K places it on the hotter side of the main sequence. The system is about 95.0 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.