MASCARA-4 b
Astrophysical Synthesis & Habitability Characterization
MASCARA-4 b is a confirmed gas giant exoplanet orbiting the star MASCARA-4, located approximately 556.7 light-years (170.7 parsecs) from the Solar System. First announced in 2020 by Multiple Observatories using the Transit detection technique (producing an estimated primary transit depth of 0.7565% across the stellar disk), this world measures 16.982 Earth radii (1.52 Jupiter radii) and has a measured mass of 532.363 Earth masses (1.67 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.6 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.85 g⊕ (18.14 m/s²), and an escape velocity of 62.6 km/s.
In its orbital architecture around MASCARA-4, MASCARA-4 b completes one full revolution every 2.824 Earth days at a semi-major axis of 0.0474 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 182.6 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 2250 K (+1977°C / +3591°F) and receiving 4,913.69 S⊕ (~6,687,532 W/m²), MASCARA-4 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star MASCARA-4 is classified as a luminous A-type star of spectral type A7 V with an effective photospheric temperature of 7,800 K, a radius of 1.79 R☉, a mass of 1.75 M☉, an estimated bolometric luminosity of 10.641 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.8 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, MASCARA-4 shines at apparent V-band magnitude 8.191 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | MASCARA-4 |
| Spectral Type | A7 V |
| Effective Temp (Teff) | 7,800 K |
| Stellar Radius | 1.7900 R☉ |
| Stellar Mass | 1.7500 M☉ |
| Bolometric Luminosity | 10.641 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 0.800 Gyr |
| Apparent Magnitude | V: 8.191 · G: 8.174 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.047400 AU |
| Orbital Period | 2.824 days |
| Mean Orbital Velocity | 182.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.8900° |
| Mean Bulk Density | 0.6 g/cm³ (62.6 km/s vesc) |
| Insolation Flux | 4913.6900 S⊕ (~6,687,532 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 556.700 LY (170.696 pc) |