HAT-P-70 b
Astrophysical Synthesis & Habitability Characterization
HAT-P-70 b is a confirmed gas giant exoplanet orbiting the star HAT-P-70, located approximately 1078.7 light-years (330.74 parsecs) from the Solar System. First announced in 2019 by HATNet using the Transit detection technique (producing an estimated primary transit depth of 1.0697% across the stellar disk), this world measures 20.961 Earth radii (1.87 Jupiter radii) and has a measured mass of 2154.887 Earth masses (6.78 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.29 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.9 g⊕ (48.05 m/s²), and an escape velocity of 113.4 km/s.
In its orbital architecture around HAT-P-70, HAT-P-70 b completes one full revolution every 2.744 Earth days at a semi-major axis of 0.04739 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 187.9 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 2562 K (+2289°C / +4152°F) and receiving 5,405.60 S⊕ (~7,357,022 W/m²), HAT-P-70 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HAT-P-70 is classified as a stellar host with an effective photospheric temperature of 8,450 K, a radius of 1.858 R☉, a mass of 1.89 M☉, an estimated bolometric luminosity of 15.791 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.6 Gyr and a metallicity of [Fe/H] = -0.059 dex (near-solar heavy-element abundance). From Earth, HAT-P-70 shines at apparent V-band magnitude 9.47 (accessible to binoculars and small amateur telescopes) in the Northern 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: HATNet · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HAT-P-70 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 8,450 K |
| Stellar Radius | 1.8580 R☉ |
| Stellar Mass | 1.8900 M☉ |
| Bolometric Luminosity | 15.791 L☉ |
| Metallicity [Fe/H] | -0.059 dex |
| Stellar Age | 0.600 Gyr |
| Apparent Magnitude | V: 9.470 · G: 9.452 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.047390 AU |
| Orbital Period | 2.744 days |
| Mean Orbital Velocity | 187.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 96.5000° |
| Mean Bulk Density | 1.29 g/cm³ (113.4 km/s vesc) |
| Insolation Flux | 5405.6000 S⊕ (~7,357,022 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1078.700 LY (330.739 pc) |