HD 202772 A b
Astrophysical Synthesis & Habitability Characterization
HD 202772 A b is a confirmed gas giant exoplanet orbiting the star HD 202772 A, located approximately 526.7 light-years (161.5 parsecs) from the Solar System. First announced in 2019 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.4286% across the stellar disk), this world measures 18.237 Earth radii (1.63 Jupiter radii) and has a measured mass of 323.549 Earth masses (1.02 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.29 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 47.1 km/s.
In its orbital architecture around HD 202772 A, HD 202772 A b completes one full revolution every 3.309 Earth days at a semi-major axis of 0.05208 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 171.2 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.03 (ranging from 0.0505 AU at periapsis to 0.0536 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 2181 K (+1908°C / +3466°F) and receiving 3,770.00 S⊕ (~5,130,970 W/m²), HD 202772 A b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 202772 A is classified as a stellar host with an effective photospheric temperature of 6,442 K, a radius of 2.554 R☉, a mass of 1.721 M☉, an estimated bolometric luminosity of 10.079 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.63 Gyr and a metallicity of [Fe/H] = 0.232 dex (metal-rich relative to the Sun). From Earth, HD 202772 A shines at apparent V-band magnitude 8.324 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere.
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 | HD 202772 A |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,442 K |
| Stellar Radius | 2.5540 R☉ |
| Stellar Mass | 1.7210 M☉ |
| Bolometric Luminosity | 10.079 L☉ |
| Metallicity [Fe/H] | 0.232 dex |
| Stellar Age | 1.630 Gyr |
| Apparent Magnitude | V: 8.324 · G: 8.227 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.052080 AU |
| Orbital Period | 3.309 days |
| Mean Orbital Velocity | 171.2 km/s |
| Orbital Eccentricity (e) | 0.03000 |
| Orbital Inclination (i) | 84.9000° |
| Mean Bulk Density | 0.29 g/cm³ (47.1 km/s vesc) |
| Insolation Flux | 3770.0000 S⊕ (~5,130,970 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 526.700 LY (161.498 pc) |