17 Sco b
Astrophysical Synthesis & Habitability Characterization
17 Sco b is a confirmed gas giant exoplanet orbiting the star 17 Sco, located approximately 407.5 light-years (124.95 parsecs) from the Solar System. First announced in 2020 by Lick Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.9 Earth radii (1.15 Jupiter radii) and has a measured mass of 1373.019 Earth masses (4.32 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.53 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 8.25 g⊕ (80.9 m/s²), and an escape velocity of 115.4 km/s.
In its orbital architecture around 17 Sco, 17 Sco b completes one full revolution every 578.38 Earth days (1.58Julian years) at a semi-major axis of 1.45 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 27.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.06 carries the world between 1.363 AU at periapsis and 1.537 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 848 K (+575°C / +1067°F) and receiving 85.43 S⊕ (~116,272 W/m²), 17 Sco b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star 17 Sco is classified as an orange K-type star of spectral type K3 III with an effective photospheric temperature of 4,157 K, a radius of 25.92 R☉, a mass of 1.22 M☉, an estimated bolometric luminosity of 180.003 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.13 Gyr and a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, 17 Sco shines at apparent V-band magnitude 5.226 (visible to the unaided human eye under dark skies) 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: Lick Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | 17 Sco |
| Spectral Type | K3 III |
| Effective Temp (Teff) | 4,157 K |
| Stellar Radius | 25.9200 R☉ |
| Stellar Mass | 1.2200 M☉ |
| Bolometric Luminosity | 180.003 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | 5.130 Gyr |
| Apparent Magnitude | V: 5.226 · G: 4.754 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.450000 AU |
| Orbital Period | 578.38 days |
| Mean Orbital Velocity | 27.3 km/s |
| Orbital Eccentricity (e) | 0.06000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 3.53 g/cm³ (115.4 km/s vesc) |
| Insolation Flux | 85.4316 S⊕ (~116,272 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 407.500 LY (124.953 pc) |