BD+42 2315 b
Astrophysical Synthesis & Habitability Characterization
BD+42 2315 b is a confirmed gas giant exoplanet orbiting the star BD+42 2315, located approximately 1991.9 light-years (610.72 parsecs) from the Solar System. First announced in 2023 by McDonald Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 14.2 Earth radii (1.27 Jupiter radii) and has a measured mass of 174.806 Earth masses (0.55 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.34 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.87 g⊕ (8.53 m/s²), and an escape velocity of 39.2 km/s.
In its orbital architecture around BD+42 2315, BD+42 2315 b completes one full revolution every 123.05 Earth days at a semi-major axis of 0.54 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 47.7 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.73, swinging from 0.1458 AU at periapsis out to 0.9342 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1248 K (+975°C / +1787°F) and receiving 335.13 S⊕ (~456,111 W/m²), BD+42 2315 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star BD+42 2315 is classified as a stellar host with an effective photospheric temperature of 4,500 K, a radius of 17.85 R☉, a mass of 1.38 M☉, an estimated bolometric luminosity of 117.224 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.2 dex (metal-poor relative to the Sun). From Earth, BD+42 2315 shines at apparent V-band magnitude 9.723 (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: McDonald Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | BD+42 2315 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,500 K |
| Stellar Radius | 17.8500 R☉ |
| Stellar Mass | 1.3800 M☉ |
| Bolometric Luminosity | 117.224 L☉ |
| Metallicity [Fe/H] | -0.200 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.723 · G: 9.430 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.540000 AU |
| Orbital Period | 123.05 days |
| Mean Orbital Velocity | 47.7 km/s |
| Orbital Eccentricity (e) | 0.73000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.34 g/cm³ (39.2 km/s vesc) |
| Insolation Flux | 335.1294 S⊕ (~456,111 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1991.900 LY (610.715 pc) |