Astronomy:Ross 318 b
| Discovery[1] | |
|---|---|
| Discovered by |
|
| Discovery date | May 2026 |
| Radial velocity | |
| Designations | |
| |
| Orbital characteristics[1] | |
| 0.159±0.002 astronomical unit|AU | |
| Eccentricity | 0 (fixed) |
| Orbital period | 39.6299±0.29 d |
| Inclination | < 88.5° |
| Semi-amplitude | 2.11±0.21 m/s |
| Star | Ross 318 |
| Physical characteristics | |
| Mean radius | ~1.74 R⊕ (predicted) |
| Mass | ≥6.21±0.62 M🜨 |
| Physics | Teq: 237 K (−36 °C) (for albedo 0.1) |
Ross 318 b is an exoplanet candidate orbiting within the habitable zone of the red dwarf star Ross 318 (also designated Gliese 48 or TIC 379084450). Located approximately 28 light-years (8.6 parsecs) from Earth, this temperate world is classified as a Super-Earth.[2] The planet candidate was identified through a long-term analysis of radial velocity data, showing a stable signal over a 15-year baseline.[1]
Ross 318 b orbits its parent star at a distance of about 0.159 AU (23,800,000 km; 14,800,000 mi) with an orbital period of approximately 39.6 Earth days.[2] While it has not been observed to transit its star, its minimum mass is 6.21 M🜨, and theoretical models suggest a radius of about 1.74 R⊕, indicating a likely rocky composition.[1] Receiving about 58% of the stellar flux that Earth receives from the Sun, it is considered a candidate for future atmospheric study.[2]
Discovery
The discovery of Ross 318 b was announced in a May 2026 preprint submitted for peer review.[1] The detection utilized a systematic re-analysis of radial velocity (RV) measurements from the CARMENES and HIRES spectrographs. The signal's validity was evaluated by its temporal coherence over 15 years and its achromatic nature across visible and near-infrared wavelengths.[1]
Photometric data from the TESS (Sectors 18, 19, 24, and 25) was used to search for transits. Although no transit events were detected, these observations allowed researchers to constrain the orbital inclination and rule out the presence of larger transiting companions in the inner system.[1]
Physical properties
Ross 318 b orbits a relatively quiet M-dwarf star. The planet's orbit is assumed to be circular ($e=0$) for the current dynamical model.[2] With a minimum mass of 6.21±0.62 M🜨, it sits at the transition between terrestrial worlds and mini-Neptunes. However, its position in the mass-radius diagram suggests a predominantly rocky structure.[1]
The planet is located within the "conservative" habitable zone of Ross 318. Its equilibrium temperature is estimated at 237 K (−36 °C; −33 °F) (assuming an albedo of 0.1).[2] Because Ross 318 is an M-dwarf, the planet is likely tidally locked, meaning one side permanently faces the star. Despite this, the presence of an atmosphere could potentially redistribute heat, allowing for temperate surface conditions.[1]
Host star
Ross 318 is an M3.5V red dwarf with a mass approximately 34% that of the Sun. The star exhibits magnetic activity with a rotation period of approximately 51.5 days. This rotation period was a critical factor in the analysis, as the 39.6-day planetary signal had to be distinguished from the star's natural activity cycles.[1]
See also
- List of potentially habitable exoplanets
- Ross 128 b
- Gliese 581 c
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Conzo, G.; Moriconi, M.; Corrêa, S. A. (2026-05-11). "Detection and Characterization of the Temperate Super-Earth Ross 318 b". Open European Journal on Variable Stars (submitted). https://arxiv.org/abs/2605.11123. Retrieved 18 May 2026.
- ↑ 2.0 2.1 2.2 2.3 2.4 "Planet Ross 318 b". https://exoplanet.eu/catalog/ross_318_b--12304/.
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