Temperature
3722 K
3611 to 3889
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Stellar HostProfile
GJ 3998
M1 • 18.15 pc
Records
6
literature rows
Planets
3
system count
References
7
distinct source labels
TIC: TIC 459558974HIP: HIP 84460
Approximate color
from effective temperature
Canonical Summary
Adopted host values from one source row
Values come from the row with the most populated summary measurements. Missing values stay missing. Ranges and counts describe all source rows.
Stellar source: Affer et al. 2016 • System source: TICv8
Mass
0.50 Msun
0.45 to 0.52
Radius
0.49 Rsun
0.49 to 0.54
Luminosity
-1.39 log(Lsun)
-1.40 to -1.36
Distance
18.15 pc
single adopted value
Spectral Type
M1
Multiple classifications reported
Planets
3
Stable across source rows
Scale Comparison
Radius against the Sun
Current adopted radius: 0.49 R☉ (circles scaled linearly by radius)
Sun
1.0 R☉ baseline
GJ 3998
0.49 R☉
System Layout
Known planets
3 planets linked to this host
GJ 3998 and Its Three Known Planets
GJ 3998 is an M1 red dwarf located 59.2 light-years away, and three planets have been found around it. The star has a mass of 0.5 solar masses and a radius of 0.49 solar radii, both smaller than the Sun's, and its temperature of 3720 K is cooler than the Sun's.
All three planets were detected by the radial velocity method, which measures the wobble a planet's gravity induces in its star's motion; repeated wobbles reveal the planet and its orbital period. GJ 3998 b was announced in 2016 with a minimum mass of 2.5 Earth masses, larger than Earth's, and an orbital period of 2.65 days, the shortest year among the listed planets. GJ 3998 c, also announced in 2016, has a minimum mass of 6.82 Earth masses and a period of 13.7 days, the second-shortest year among the listed planets. GJ 3998 d, announced in 2025, has a minimum mass of 6.07 Earth masses and an orbital period of 41.8 days, the longest year among the listed planets.
A minimum mass is a lower bound on a planet's true mass. Among the listed planets, GJ 3998 b has the smallest minimum mass at 2.5 Earth masses, GJ 3998 d has the second-smallest at 6.07 Earth masses, and GJ 3998 c has the largest at 6.82 Earth masses.
Provenance
Underlying measurements and references
Evidence Summary
Rows
6
Stellar refs
6
System refs
1
Distancestable
Parallaxstable
Temperaturedisputed
Massdisputed
Radiusdisputed
Agestable
Luminositydisputed
Surface Gravitydisputed
Metallicitydisputed
Spectral Typedisputed
| ST TEFF | ST MASS | ST RAD | ST AGE | ST LUM | ST SPECTYPE | SY DIST | Stellar Ref | System Ref |
|---|---|---|---|---|---|---|---|---|
| — | — | — | — | — | M1 | 18.15 | Hawley et al. 1996 | TICv8 |
| 3667 | 0.52 | 0.52 | — | -1.36 | — | 18.15 | TICv8 | TICv8 |
| 3722 | 0.50 | 0.49 | — | -1.39 | M1 | 18.15 | Affer et al. 2016 | TICv8 |
| 3611 | 0.45 | 0.54 | — | -1.40 | M2.5 | 18.15 | Turnbull 2015 | TICv8 |
| 3726 | 0.52 | 0.50 | 8.38 | -1.36 | — | 18.15 | Stefanov et al. 2025 | TICv8 |
| 3889 | — | — | — | — | — | 18.15 | Gaia DR2 | TICv8 |