HIP 21152 b
HIP 21152 b
confirmed planet • updated: 2022-12-05
HIP 21152 b was spotted using direct imaging — meaning astronomers took a picture of it next to its star. It orbits far out, taking about 22,000 Earth days (roughly 60 years) to complete one trip.
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 object has a mass about 24 times that of Jupiter — so large it may be a brown dwarf (a failed star). Its orbit is very wide, about 17 times farther from its star than Earth is from the Sun, and it’s very elliptical (not circular). The planet’s temperature is estimated at around 1300 Kelvin (about 1000°C), likely from leftover heat since formation.
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.
HIP 21152 b was first reported in 2022 using the Imaging method. The discovery is linked to observations from Multiple Observatories.
Direct imaging tries to separate faint planetary light from the glare of the host star. It works best for young, warm planets far from their stars.
The catalog lists an orbital period of about 22000.00 days, a semi-major axis near 17.000 AU.
The orbit’s eccentricity is 0.36, which describes how stretched the orbit is.
The archive reports a mass scale of 24.0 MJ.
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
HIP 21152 b orbits HIP 21152. The star is classified as F5 V, which is a shorthand for temperature and color.
A temperature near 6655 K places it on the hotter side of the main sequence. The system is about 141.6 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. 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.