HATS-26 b
Astrophysical Synthesis & Habitability Characterization
HATS-26 b is a confirmed gas giant exoplanet orbiting the star HATS-26, located approximately 2811 light-years (861.84 parsecs) from the Solar System. First announced in 2016 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 0.7771% across the stellar disk), this world measures 19.616 Earth radii (1.75 Jupiter radii) and has a measured mass of 206.59 Earth masses (0.65 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.15 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.54 g⊕ (5.3 m/s²), and an escape velocity of 36.3 km/s.
In its orbital architecture around HATS-26, HATS-26 b completes one full revolution every 3.302 Earth days at a semi-major axis of 0.04735 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 156 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.245 carries the world between 0.0357 AU at periapsis and 0.059 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1918 K (+1645°C / +2993°F) and receiving 2,236.57 S⊕ (~3,043,974 W/m²), HATS-26 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-26 is classified as a warm F-type star of spectral type F with an effective photospheric temperature of 6,071 K, a radius of 2.04 R☉, a mass of 1.299 M☉, an estimated bolometric luminosity of 5.072 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.04 Gyr and a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, HATS-26 shines at apparent V-band magnitude 13.006 (faint and requiring research-grade or CCD telescopic photometry) 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: HATSouth · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HATS-26 |
| Spectral Type | F |
| Effective Temp (Teff) | 6,071 K |
| Stellar Radius | 2.0400 R☉ |
| Stellar Mass | 1.2990 M☉ |
| Bolometric Luminosity | 5.072 L☉ |
| Metallicity [Fe/H] | -0.020 dex |
| Stellar Age | 4.040 Gyr |
| Apparent Magnitude | V: 13.006 · G: 12.843 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.047350 AU |
| Orbital Period | 3.302 days |
| Mean Orbital Velocity | 156 km/s |
| Orbital Eccentricity (e) | 0.24500 |
| Orbital Inclination (i) | 86.2000° |
| Mean Bulk Density | 0.15 g/cm³ (36.3 km/s vesc) |
| Insolation Flux | 2236.5716 S⊕ (~3,043,974 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2811.000 LY (861.843 pc) |