TOI-544 b
Astrophysical Synthesis & Habitability Characterization
TOI-544 b 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 2022 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0882% across the stellar disk), this world measures 2.018 Earth radii and has a measured mass of 2.89 Earth masses. Combining its mass and radius yields a mean bulk density of 1.94 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.71 g⊕ (6.96 m/s²), and an escape velocity of 13.4 km/s.
In its orbital architecture around TOI-544, TOI-544 b completes one full revolution every 1.548 Earth days at a semi-major axis of 0.0225 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 158.1 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 999 K (+726°C / +1339°F) and receiving 240.20 S⊕ (~326,905 W/m²), TOI-544 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
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 b sharing its stellar neighborhood alongside TOI-544 c.
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: Transiting Exoplanet Survey Satellite (TESS) · 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) | 0.022500 AU |
| Orbital Period | 1.548 days |
| Mean Orbital Velocity | 158.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.94 g/cm³ (13.4 km/s vesc) |
| Insolation Flux | 240.1950 S⊕ (~326,905 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 134.100 LY (41.117 pc) |