HD 148797 b
Astrophysical Synthesis & Habitability Characterization
HD 148797 b is a confirmed gas giant exoplanet orbiting the star HD 148797, located approximately 562.2 light-years (172.37 parsecs) from the Solar System. First announced in 2026 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.239% across the stellar disk), this world measures 8.25 Earth radii (0.74 Jupiter radii) and has a measured mass of 39.3 Earth masses (0.12 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.39 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.58 g⊕ (5.69 m/s²), and an escape velocity of 24.4 km/s.
In its orbital architecture around HD 148797, HD 148797 b completes one full revolution every 42.099 Earth days at a semi-major axis of 0.2568 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 66.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.153 carries the world between 0.2175 AU at periapsis and 0.2961 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 762 K (+489°C / +912°F) and receiving 57.93 S⊕ (~78,837 W/m²), HD 148797 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 148797 is classified as a warm F-type star of spectral type F6 with an effective photospheric temperature of 6,441 K, a radius of 1.547 R☉, a mass of 1.272 M☉, an estimated bolometric luminosity of 3.696 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.94 Gyr and a metallicity of [Fe/H] = -0.093 dex (near-solar heavy-element abundance). From Earth, HD 148797 shines at apparent V-band magnitude 9.569 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 148797 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 148797 b sharing its stellar neighborhood alongside HD 148797 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 | HD 148797 |
| Spectral Type | F6 |
| Effective Temp (Teff) | 6,441 K |
| Stellar Radius | 1.5470 R☉ |
| Stellar Mass | 1.2720 M☉ |
| Bolometric Luminosity | 3.696 L☉ |
| Metallicity [Fe/H] | -0.093 dex |
| Stellar Age | 2.940 Gyr |
| Apparent Magnitude | V: 9.569 · G: 9.433 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.256800 AU |
| Orbital Period | 42.099 days |
| Mean Orbital Velocity | 66.4 km/s |
| Orbital Eccentricity (e) | 0.15300 |
| Orbital Inclination (i) | 88.6500° |
| Mean Bulk Density | 0.39 g/cm³ (24.4 km/s vesc) |
| Insolation Flux | 57.9260 S⊕ (~78,837 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 562.200 LY (172.374 pc) |