HD 1461 c
Astrophysical Synthesis & Habitability Characterization
HD 1461 c is a confirmed sub-neptune exoplanet orbiting the star HD 1461, located approximately 76.5 light-years (23.45 parsecs) from the Solar System. First announced in 2015 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.23 Earth radii and has a measured mass of 5.59 Earth masses. Combining its mass and radius yields a mean bulk density of 2.78 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.7 km/s.
In its orbital architecture around HD 1461, HD 1461 c completes one full revolution every 13.505 Earth days at a semi-major axis of 0.1117 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 90 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.305, swinging from 0.0776 AU at periapsis out to 0.1458 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 893 K (+620°C / +1148°F) and receiving 99.84 S⊕ (~135,877 W/m²), HD 1461 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 1461 is classified as a solar-type yellow star of spectral type G0 V with an effective photospheric temperature of 5,765 K, a radius of 1.1523 R☉, a mass of 1.02 M☉, an estimated bolometric luminosity of 1.316 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.12 Gyr and a metallicity of [Fe/H] = 0.19 dex (metal-rich relative to the Sun). From Earth, HD 1461 shines at apparent V-band magnitude 6.479 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 1461 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 1461 c sharing its stellar neighborhood alongside HD 1461 b.
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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 1461 |
| Spectral Type | G0 V |
| Effective Temp (Teff) | 5,765 K |
| Stellar Radius | 1.1523 R☉ |
| Stellar Mass | 1.0200 M☉ |
| Bolometric Luminosity | 1.316 L☉ |
| Metallicity [Fe/H] | 0.190 dex |
| Stellar Age | 7.120 Gyr |
| Apparent Magnitude | V: 6.479 · G: 6.295 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.111700 AU |
| Orbital Period | 13.505 days |
| Mean Orbital Velocity | 90 km/s |
| Orbital Eccentricity (e) | 0.30500 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.78 g/cm³ (17.7 km/s vesc) |
| Insolation Flux | 99.8365 S⊕ (~135,877 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 76.500 LY (23.453 pc) |