◀ D:\SPACE · ALL WORLDS

D:\SPACE\GJ_273_B>

SELECTED WORLD

GJ 273 b

GJ 273 · M3.5 host star · cool red dwarf

[ GJ_273_B.IMG ]
VIEW 1 · ON THE SURFACE
1 / 2
Artist’s impression of GJ 273 b: VIEW 1 · ON THE SURFACE
VIEW 1 · ON THE SURFACE · Artist’s impression. No surface has been seen.
USE ◀ ▶ TO SEE THE OTHER VIEWS · OR SWIPE
12.4 light-years from Earth
[ FACTS.DAT ]
Right ascension / declination111.852° / 5.226°J2000 / ICRS
Gravity1.27 × Earthmodelled estimate
Year18.6 days
From its star0.0911 AUabout 13.6 million km
Stars in the system1 star2 known planets in system
Stars this world orbits1 starOrbits GJ 273
Day and nightLikely synchronous spinProbably spins once per orbit, keeping one hemisphere in permanent day and the other in permanent night. Heuristic: likely at ≤0.25 AU, uncertain to 0.50 AU, probably not beyond; rotation is not directly measured.
[ TEMP.EST ]MODELLED, NOT MEASURED
Host star≈3,400 Ktypical M3.5 · 0.30 Sun radii
No atmosphere272 K · -1°C30% reflective · heat shared
Earth-like air305 K · 32°CBaseline plus 33°C

Star temperature and orbital distance set incoming energy, but stellar size is also required. This calculation uses a typical radius for the listed spectral type, 30% reflectivity and even heat redistribution. It is not a ground-temperature forecast: air, clouds, oceans and surface reflectivity could move the result by tens to hundreds of degrees. A likely synchronous spin also means the permanent day and night sides would not share one ground temperature.

[ STARLIGHT.SPC ]VISIBLE LIGHT ONLY

The marker above the bar is a typical temperature for this star’s class. The line below is Earth’s Sun.

red-orange

GJ 273 is class M3.5. Its visible daylight would be dim and strongly red-orange; most of its energy is infrared.

Representative lit-side geometry only. On a locked world, the star’s real elevation would depend on where you stand.

[ GROUND.TXT ]STILL INFERENCE

Most plausible case. Luyten’s Star is 12.4 light-years away. Planet b receives about Earth’s amount of light, around a 0.29-solar-radius star that spans about 1.7°. Eccentricity 0.10 nudges the flux through the year. Earth-like energy under a fixed red star: dark rock, ice at the night side, and a possible slush eyeball under the star rather than a global ocean.

Dry case. A red desert with dunes and no day-side ice. The Earth-like flux makes this warmer than Teegarden c or GJ 1002 c, so a dry day side stays warm.

Thick-air case. Clouds could cover the ground without requiring a steam sky. A modest atmosphere is enough to move heat toward the night side at this flux.

Walking. About 27% heavier than Earth, modelled. GJ 273 c is only about a fifth of the Moon’s width. The light is red and infrared-heavy, at roughly Earth’s total energy.

Based on: Astudillo-Defru et al. 2017; Luyten’s Star, 12.4 ly from parallax; Teff 3382 K, R 0.29 Rsun, S 1.06, e 0.10, a 0.091 AU

[ ORBIT.SYS ]2 KNOWN · ALL SHOWN
100% · Above 30°

GJ 273 b circles GJ 273. Also shown: GJ 273 c, each on its NASA-catalogued orbit. Use Higher and Lower to move your viewpoint above, through and below the orbital plane, and − / + to zoom. Orbit shapes and spacing are schematic.

[ SOURCES.TXT ]

Positions, distances, and system parameters come from the NASA Exoplanet Archive composite table, queried 25 Sep 2026. GJ 273 b uses the parallax in that row, 12.4 light-years. The 45 worlds follow Bohl, Lawrence, Lowry, and Kaltenegger.