HD 260655 b
Astrophysical Synthesis & Habitability Characterization
HD 260655 b is a confirmed terrestrial exoplanet orbiting the star HD 260655, located approximately 32.6 light-years (10.01 parsecs) from the Solar System. First announced in 2022 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0671% across the stellar disk), this world measures 1.24 Earth radii and has a measured mass of 2.14 Earth masses. Combining its mass and radius yields a mean bulk density of 6.19 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.39 g⊕ (13.63 m/s²), and an escape velocity of 14.7 km/s.
In its orbital architecture around HD 260655, HD 260655 b completes one full revolution every 2.77 Earth days at a semi-major axis of 0.02933 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 115.2 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.039 (ranging from 0.0282 AU at periapsis to 0.0305 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 709 K (+436°C / +817°F) and receiving 42.20 S⊕ (~57,434 W/m²), HD 260655 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 260655 is classified as a low-mass red dwarf of spectral type M0 V with an effective photospheric temperature of 3,803 K, a radius of 0.439 R☉, a mass of 0.439 M☉, an estimated bolometric luminosity of 0.036 L☉. Stellar evolution modeling indicates an estimated stellar age of 5 Gyr and a metallicity of [Fe/H] = -0.43 dex (metal-poor relative to the Sun). From Earth, HD 260655 shines at apparent V-band magnitude 9.63 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 260655 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 260655 b sharing its stellar neighborhood alongside HD 260655 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: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 260655 |
| Spectral Type | M0 V |
| Effective Temp (Teff) | 3,803 K |
| Stellar Radius | 0.4390 R☉ |
| Stellar Mass | 0.4390 M☉ |
| Bolometric Luminosity | 0.036 L☉ |
| Metallicity [Fe/H] | -0.430 dex |
| Stellar Age | 5.000 Gyr |
| Apparent Magnitude | V: 9.630 · G: 8.876 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.029330 AU |
| Orbital Period | 2.77 days |
| Mean Orbital Velocity | 115.2 km/s |
| Orbital Eccentricity (e) | 0.03900 |
| Orbital Inclination (i) | 87.3500° |
| Mean Bulk Density | 6.19 g/cm³ (14.7 km/s vesc) |
| Insolation Flux | 42.2000 S⊕ (~57,434 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 32.600 LY (10.006 pc) |