Lalande 21185
One of the Closest Red Dwarfs with Planetary Candidates
Quick Reader
| Attribute | Details |
|---|---|
| Name | Lalande 21185 |
| Other Designations | BD+36°2147, Gliese 411, HD 95735 |
| Star Type | Red dwarf |
| Spectral Class | M2 V |
| Constellation | Ursa Major |
| Distance from Earth | ~8.31 light-years |
| Mass | ~0.40 M☉ |
| Radius | ~0.39 R☉ |
| Luminosity | ~0.02 L☉ |
| Temperature | ~3,500 K |
| Metallicity | Slightly metal-poor |
| Notable Features | Two confirmed planets (b and c), possible debris structures |
| Exoplanets | GJ 411 b, GJ 411 c |
| Best Viewing Months | January to April |
Introduction – A Quiet Red Dwarf in Our Galactic Backyard
Lalande 21185, also known as Gliese 411, is one of the Solar System’s closest stellar neighbors. Located just 8.31 light-years away in the constellation Ursa Major, it ranks among the top six nearest star systems.
Although faint and invisible to the naked eye, Lalande 21185 has drawn sustained scientific interest for over a century due to its:
High proper motion
Stability and relative quietness
Long lifespan as a red dwarf
Confirmed exoplanet system
Potential debris disk
It is one of the most thoroughly measured red dwarfs and a key object for studying low-mass stars and their planetary companions.
Physical Characteristics – A Typical but Extremely Stable Red Dwarf
Lalande 21185 is a classic M2 V red dwarf:
Cool, with a temperature around 3,500 K
Dim, shining at just 2% the luminosity of the Sun
Small, with less than half the Sun’s radius
Mass-rich interior characterized by full convection
Red dwarfs like Lalande 21185 are expected to live for trillions of years, far outlasting every other type of star.
Though small and faint, Lalande 21185 is unusually stable:
Low magnetic activity compared to more active M-dwarfs
Mild starspot cycles
Occasional but weak flares
Long-term brightness stability
This quietness increases its potential habitability—for any planets located in temperate zones.
The Lalande 21185 Planetary System – Small Worlds Around a Small Star
In the last decade, precision radial-velocity measurements have revealed two planets orbiting the star: GJ 411 b and GJ 411 c.
Planet GJ 411 b (Confirmed)
Minimum mass: ~2.6 Earth masses
Orbit: 0.079 AU
Period: 12.95 days
Type: Hot super-Earth
Located very close to the star, this planet is too hot for surface liquid water.
Planet GJ 411 c (Confirmed)
Minimum mass: ~8 Earth masses
Orbit: ~0.25 AU (approximate)
Period: ~55 days
Type: Warm super-Earth / mini-Neptune
This world is located closer to the habitable zone and may experience moderate temperatures depending on atmospheric composition.
Why These Planets Are Important
The Lalande 21185 system provides a valuable opportunity to study small planets around quiet red dwarfs.
Insights gained from these planets:
Red dwarfs commonly host multiple low-mass planets
Even relatively inactive M-dwarfs can support stable planetary systems
Formation of larger super-Earths is common around low-mass stars
Planets in compact orbits may migrate inward over time
Because Lalande 21185 is so nearby, future telescopes (JWST, ELT, LUVOIR-type missions) may attempt:
Atmospheric characterization
Direct imaging (especially for outer planet candidates)
Search for additional planets in wider orbits
Proper Motion – One of the Fastest-Moving Stars in the Sky
Lalande 21185 has a remarkably high proper motion:
Over 4.8 arcseconds per year
One of the highest among nearby stars
This motion indicates:
Proximity to the Sun
Rapid speed relative to our Solar System
Likely an older star belonging to the galactic thin disk population
Historic star catalogues have tracked its movement for more than 200 years.
Stellar Environment and Potential Debris Disk
There is tentative evidence of:
A cold debris disk
Excess emission in the infrared
Dust rings similar to a Kuiper Belt
Although these detections remain uncertain, the possibility of a debris structure adds depth to the planetary system, hinting at leftover planetesimals or collisions among icy bodies.
Habitability Potential
While the known planets orbit too close to be habitable, Lalande 21185’s habitable zone lies between roughly:
0.15 AU to 0.30 AU
This region remains open for the possibility of additional planets that current instruments cannot detect yet.
If a temperate terrestrial world exists, its conditions would depend on:
Magnetic shielding
Atmospheric retention
Stellar wind intensities
Stability of the star’s mild activity cycle
Lalande 21185’s quietness improves the chances for habitability compared to more active M-dwarfs like Proxima Centauri.
A Closer Look at the Star’s Interior and Magnetic Behavior
Although Lalande 21185 is a red dwarf, it stands out for being less active than most of its spectral class.
Many M-dwarfs produce intense flares, strong magnetic storms, and violent stellar winds—but Lalande 21185 is unusually calm.
Interior Properties
Red dwarfs are fully convective, meaning:
Energy circulates throughout the entire star
Magnetic fields behave differently than in Sun-like stars
Fusion of hydrogen occurs efficiently at lower temperatures
Because of this, red dwarfs can remain stable for trillions of years, long after the Sun becomes a white dwarf.
Magnetic Activity Level
Lalande 21185 shows:
Mild chromospheric activity
Occasional weak flares
Long-term stability
No major magnetic cycles detectable yet
This low activity enhances the potential for planetary habitability, as strong flares can strip atmospheres from nearby planets.
Orbital Architecture – A Compact, Dynamically Stable System
The planets around Lalande 21185 orbit close to the star, similar to systems like TRAPPIST-1 and Proxima Centauri.
Known Planets
GJ 411 b
A hot super-Earth orbiting very close at 0.079 AU
Too hot for habitability
One of the closest known exoplanets to the Solar System
GJ 411 c
A warm super-Earth or mini-Neptune
Orbits around ~0.25 AU
Near the inner edge of the habitable zone
Possible Additional Planets
Models of the star’s radial velocity data suggest:
A potential third planet in a wider orbit
A possible long-period companion shaping any outer debris disk
More planets may exist below detection thresholds
Future observations may confirm one or more new candidates.
Dynamical History – How Did These Planets Form?
Because Lalande 21185 is slightly metal-poor, the formation of super-Earths around it challenges earlier assumptions that high metallicity is required for planet formation.
Likely formation processes:
Rapid accumulation of dust close to the star
Migration of planets inward from cooler regions
Possible scattering interactions early in system evolution
Survival of small-mass planets despite low metallicity
This system helps refine models of planetary formation around low-mass stars.
Galactic Motion – A High-Speed Traveler
Lalande 21185’s significant proper motion is a clue to its history within the Milky Way.
Its motion suggests:
It is part of the galactic thin disk population
It may have undergone past gravitational interactions
It travels faster than most nearby stars
It is on a stable orbit around the galactic center
Its rapid movement across the sky will eventually bring it even closer to the Solar System in the distant future.
Long-Term Stellar Evolution
As a low-mass red dwarf, Lalande 21185 will experience:
Trillions of years of hydrogen fusion
Slow brightening over time
Eventual transformation into a helium white dwarf
A long-lasting evolutionary path far outliving the Sun
Red dwarfs burn their fuel so efficiently that they never become giants like the Sun. Instead, they fade slowly over cosmic timescales.
Comparison With Other Nearby Red Dwarfs
| Star | Distance | Spectral Type | Activity Level | Known Planets |
|---|---|---|---|---|
| Proxima Centauri | 4.24 ly | M5.5 V | Highly active | 3 |
| Barnard’s Star | 5.96 ly | M4 V | Mildly active | 1? (uncertain) |
| Lalande 21185 | 8.31 ly | M2 V | Very quiet | 2 |
| Wolf 359 | 7.78 ly | M6 V | Very active | 0 |
| Ross 128 | 11.0 ly | M4 V | Very quiet | 1 |
Lalande 21185 stands out as one of the most stable and least active among nearby M-dwarfs.
Importance for Exoplanet Research
Because of its proximity and stability, Lalande 21185 is an ideal target for:
High-precision radial velocity surveys
Atmospheric studies of super-Earths
Future direct imaging missions
Searches for additional planets in the habitable zone
Understanding quiet M-dwarf systems
The planets around such stars may be prime candidates for eventual biosignature detection.
Habitability Potential – Could Life Exist Around Lalande 21185?
Although the two known planets orbit inside the inner, hotter regions of the system, Lalande 21185’s habitable zone lies farther out:
Approximate habitable zone range: 0.15 AU – 0.30 AU
No confirmed planets have yet been detected in this zone, but it remains dynamically stable and observationally accessible.
What would a habitable planet need to survive here?
A strong magnetic field
To protect against stellar wind and flares, even though Lalande 21185 is relatively quiet.A thick or moderate atmosphere
Necessary for temperature regulation and surface stability.Tidal locking considerations
A planet in such a close orbit would likely be tidally locked, with one hemisphere always facing the star.
This does not make habitability impossible—terminator regions or thick atmospheres can distribute heat.Low flare risk
Lalande 21185’s mild activity makes habitability more plausible than in highly active red dwarf systems like Proxima Centauri.
Because this star is so stable, many astronomers consider it one of the most promising nearby stars for finding a truly habitable world if more planets are discovered.
Debris Disk Indicators – A Clue to Early Planetary Architecture
While not definitively confirmed, there are hints that Lalande 21185 hosts a cold debris disk similar to our Kuiper Belt.
Evidence includes:
Infrared excess detected at long wavelengths
Possible dust ring beyond the orbit of the known planets
Dynamical modeling suggesting outer bodies may still be present
If real, such a disk would indicate:
Leftover planetesimals
A more complex planetary system
Potential outer planets shepherding the debris
Confirming this disk would significantly enhance our understanding of the system’s structure and evolution.
The Future of Exploration – Telescopes Aimed at Gliese 411
Lalande 21185 is a prime target for current and upcoming observatories:
James Webb Space Telescope (JWST)
Could detect atmospheric signatures of GJ 411 c
Could search for additional planets in wider orbits
Could probe the presence of dust rings
Extremely Large Telescope (ELT)
Potential for high-contrast direct imaging
Surface mapping of planetary atmospheres in the near future
Roman Space Telescope
May reveal debris disk structures
May detect long-period planets previously missed
Because the system is so close, even small enhancements in detection techniques dramatically increase our ability to characterize it.
Frequently Asked Questions (FAQ)
Why is Lalande 21185 so faint if it is nearby?
Red dwarfs emit very little visible light, even when they are close. Most of their radiation is in the infrared.
Is it more stable than Proxima Centauri?
Yes. Lalande 21185 is significantly less active and emits weaker, less frequent flares.
Could an Earth-like planet exist there?
Yes, in theory. The habitable zone is stable and does not currently contain any known planets, but future observations may find one.
How old is Lalande 21185?
Likely several billion years old, but exact estimates vary due to red dwarfs’ slow evolution.
Is it moving toward or away from us?
It has a high proper motion but is not on a collision course with the Solar System. It will slowly drift across our sky over millennia.
Comparative Context Among Nearby Stars
| Star | Activity Level | Habitable Zone Planets | Red Dwarf Stability |
|---|---|---|---|
| Proxima Centauri | High | 2 (but flare-heavy) | Low |
| Barnard’s Star | Mild | 1 possible | Medium |
| Lalande 21185 | Low | None known (zone empty) | High |
| Ross 128 | Low | 1 | High |
Lalande 21185 stands out as one of the quietest and most stable nearby M-dwarfs—ideal for long-term habitability.
Final Thoughts
Lalande 21185 is a remarkable system because of its:
Proximity to the Solar System
Exceptional stellar stability
Confirmed super-Earth planets
Possible outer debris structures
Potential for undiscovered planets within the habitable zone
As technology improves, Lalande 21185 may become one of the first nearby stars where scientists can directly analyze the atmospheres of small exoplanets—potentially even searching for habitability markers.
Its closeness ensures that it will remain a cornerstone of exoplanet research and a major target for observing programs throughout the coming decades.
