TOI-544 c
Astrophysical Synthesis & Habitability Characterization
TOI-544 c is a confirmed sub-neptune exoplanet orbiting the star TOI-544, located approximately 134.1 light-years (41.12 parsecs) from the Solar System. First announced in 2023 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 4.92 Earth radii (0.44 Jupiter radii) and has a measured mass of 21.5 Earth masses. Combining its mass and radius yields a mean bulk density of 1 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.89 g⊕ (8.73 m/s²), and an escape velocity of 23.4 km/s.
In its orbital architecture around TOI-544, TOI-544 c completes one full revolution every 50.089 Earth days. The planet follows a highly eccentric trajectory (e = 0.32), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 4.920 R⊕, TOI-544 c exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star TOI-544 is classified as a stellar host with an effective photospheric temperature of 4,169 K, a radius of 0.623 R☉, a mass of 0.631 M☉, an estimated bolometric luminosity of 0.105 L☉. Stellar evolution modeling indicates an estimated stellar age of 9 Gyr and a metallicity of [Fe/H] = -0.17 dex (metal-poor relative to the Sun). From Earth, TOI-544 shines at apparent V-band magnitude 10.777 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-544 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-544 c sharing its stellar neighborhood alongside TOI-544 b.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-544 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,169 K |
| Stellar Radius | 0.6230 R☉ |
| Stellar Mass | 0.6310 M☉ |
| Bolometric Luminosity | 0.105 L☉ |
| Metallicity [Fe/H] | -0.170 dex |
| Stellar Age | 9.000 Gyr |
| Apparent Magnitude | V: 10.777 · G: 10.414 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 50.089 days |
| Orbital Eccentricity (e) | 0.32000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1 g/cm³ (23.4 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 134.100 LY (41.117 pc) |