HD 137496 b
Astrophysical Synthesis & Habitability Characterization
HD 137496 b is a confirmed super-earth exoplanet orbiting the star HD 137496, located approximately 506.6 light-years (155.32 parsecs) from the Solar System. First announced in 2021 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0057% across the stellar disk), this world measures 1.31 Earth radii and has a measured mass of 4.04 Earth masses. Combining its mass and radius yields a mean bulk density of 9.91 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 2.35 g⊕ (23.05 m/s²), and an escape velocity of 19.6 km/s.
In its orbital architecture around HD 137496, HD 137496 b completes one full revolution every 1.621 Earth days at a semi-major axis of 0.02732 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 183.3 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 2130 K (+1857°C / +3375°F) and receiving 3,114.34 S⊕ (~4,238,612 W/m²), HD 137496 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 137496 is classified as a solar-type yellow star of spectral type G with an effective photospheric temperature of 5,799 K, a radius of 1.59 R☉, a mass of 1.04 M☉, an estimated bolometric luminosity of 2.565 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.3 Gyr and a metallicity of [Fe/H] = -0.03 dex (near-solar heavy-element abundance). From Earth, HD 137496 shines at apparent V-band magnitude 9.899 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 137496 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 137496 b sharing its stellar neighborhood alongside HD 137496 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: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 137496 |
| Spectral Type | G |
| Effective Temp (Teff) | 5,799 K |
| Stellar Radius | 1.5900 R☉ |
| Stellar Mass | 1.0400 M☉ |
| Bolometric Luminosity | 2.565 L☉ |
| Metallicity [Fe/H] | -0.030 dex |
| Stellar Age | 8.300 Gyr |
| Apparent Magnitude | V: 9.899 · G: 9.772 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.027320 AU |
| Orbital Period | 1.621 days |
| Mean Orbital Velocity | 183.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 85.8000° |
| Mean Bulk Density | 9.91 g/cm³ (19.6 km/s vesc) |
| Insolation Flux | 3114.3366 S⊕ (~4,238,612 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 506.600 LY (155.317 pc) |