HD 28109 c
HD 28109 c
confirmed planet • updated: 2022-06-08
HD 28109 c circles the star HD 28109, which is slightly hotter and larger than our Sun. Scientists found it using the transit method — watching for tiny dips in starlight as the planet passes in front.
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 is about 4 times wider than Earth and has a mass roughly 8 times Earth’s. It orbits at a distance where it receives more sunlight than Earth, making it fairly warm — around 585 Kelvin (about 593°F or 312°C). Its orbit is slightly oval-shaped, but the exact shape isn’t fully measured. The planet was found using data from TESS and confirmed in 2022.
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 28109 c was first reported in 2022 using the Transit method. The discovery is linked to observations from Transiting Exoplanet Survey Satellite (TESS).
In transit work, astronomers watch for tiny, repeating dips in a star’s light as the planet passes in front of it. Follow-up observations help rule out false positives and refine the orbit.
The catalog lists an orbital period of about 56.01 days, a semi-major axis near 0.308 AU.
The orbit’s eccentricity is 0.12, 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.
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
HD 28109 c orbits HD 28109. The star is classified as F8/G0 V, which is a shorthand for temperature and color.
A temperature near 6120 K places it on the hotter side of the main sequence. The system is about 455.3 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. 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. Transit systems are especially valuable because they can be re‑observed for decades to detect subtle changes in timing or additional planets.