pi Men d
pi Men d is a Neptune-like planet orbiting HD 39091 in the constellation Mensa. It lies about 60 light-years from Earth and was discovered in 2022 using the radial velocity method.
Is pi Men d in the Habitable Zone?
The position of pi Men d relative to the habitable zone of HD 39091 cannot be precisely determined from the available orbital data.
Habitable zone of HD 39091: 0.934–2.188 AU (conservative: 1.183–2.074 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Orbit and Year Length
A year on pi Men d — one full orbit around HD 39091 — lasts 124.6 Earth days, between the years of Mercury (88 days) and Earth (365 days). Its orbit is mildly elliptical (eccentricity 0.22).
How Was pi Men d Discovered?
pi Men d was discovered in 2022 using the radial velocity method, with observations from La Silla Observatory.
The radial velocity method measures the subtle wobble of a star caused by the gravitational pull of an orbiting planet, visible as periodic shifts in the star's light spectrum. The size of the wobble reveals the planet's minimum mass.
How Far Away Is pi Men d?
pi Men d is 59.6 light-years (18.3 parsecs) from Earth. Light arriving here tonight left the planet around the year 1967. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,048,960 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. pi Men d scores 0.34, ranking #837 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 39091
HD 39091
- Surface temperature
- 5,998 K (Sun: 5,772 K)
- Mass
- 1.07 M☉
- Radius
- 1.17 R☉
- Age
- 3.9 billion years (Sun: 4.6)
The HD 39091 Planetary System
pi Men d is one of 3 known planets in the HD 39091 system. Its siblings:
- HD 39091 b
- pi Men c (Mini Neptune)
pi Men d — Complete Data
| Mass (best estimate) | 13.38 Earth masses |
|---|---|
| Orbital period | 124.64 days |
| Eccentricity | 0.220 |
| Earth Similarity Index | 0.34 |
| Distance from Earth | 59.6 light-years (18.3 parsecs) |
| Constellation | Mensa |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2022-05-03. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About pi Men d
Is pi Men d habitable?
pi Men d is not known to orbit within the habitable zone of HD 39091, and as a Neptune-like planet it is an unlikely candidate for life as we know it.
How far away is pi Men d?
pi Men d is about 60 light-years from Earth in the constellation Mensa. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,048,960 years to get there.
How long is a year on pi Men d?
One orbit around HD 39091 takes 124.6 Earth days.
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