MASCARA-1 b
Astrophysical Synthesis & Habitability Characterization
MASCARA-1 b is a confirmed gas giant exoplanet orbiting the star MASCARA-1, located approximately 594.5 light-years (182.27 parsecs) from the Solar System. First announced in 2017 by Multiple Observatories using the Transit detection technique (producing an estimated primary transit depth of 0.6213% across the stellar disk), this world measures 17.901 Earth radii (1.6 Jupiter radii) and has a measured mass of 1175.971 Earth masses (3.7 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.13 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.67 g⊕ (35.99 m/s²), and an escape velocity of 90.7 km/s.
In its orbital architecture around MASCARA-1, MASCARA-1 b completes one full revolution every 2.149 Earth days at a semi-major axis of 0.040352 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 204.3 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.00034 (ranging from 0.0403 AU at periapsis to 0.0404 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 2594 K (+2321°C / +4210°F) and receiving 38,711.50 S⊕ (~52,686,352 W/m²), MASCARA-1 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star MASCARA-1 is classified as a luminous A-type star of spectral type A8 with an effective photospheric temperature of 7,490 K, a radius of 2.082 R☉, a mass of 1.9 M☉, an estimated bolometric luminosity of 12.24 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.8 Gyr and a metallicity of [Fe/H] = 0.15 dex (metal-rich relative to the Sun). From Earth, MASCARA-1 shines at apparent V-band magnitude 8.28 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | MASCARA-1 |
| Spectral Type | A8 |
| Effective Temp (Teff) | 7,490 K |
| Stellar Radius | 2.0820 R☉ |
| Stellar Mass | 1.9000 M☉ |
| Bolometric Luminosity | 12.24 L☉ |
| Metallicity [Fe/H] | 0.150 dex |
| Stellar Age | 0.800 Gyr |
| Apparent Magnitude | V: 8.280 · G: 8.242 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.040352 AU |
| Orbital Period | 2.149 days |
| Mean Orbital Velocity | 204.3 km/s |
| Orbital Eccentricity (e) | 0.00034 |
| Orbital Inclination (i) | 88.4500° |
| Mean Bulk Density | 1.13 g/cm³ (90.7 km/s vesc) |
| Insolation Flux | 38711.5000 S⊕ (~52,686,352 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 594.500 LY (182.273 pc) |