Struve 2398 B
Star
Struve 2398 B — the fainter red dwarf (M3.5V) of the Struve 2398 pair, about a quarter of the Sun's mass. It orbits its companion over many centuries and, like it, produces occasional flares. No planets are confirmed.
Open in 3D viewSee Struve 2398 B in the live, interactive 3D map
Key facts
Mutual orbit
~1,200 Earth years
Mass
4.93 × 10²⁹ kg
0.248 M☉
Radius
215,667 km
31% of the Sun's radius
Surface temperature
3,345 K (3,072 °C)
Luminosity
3.02 × 10²⁴ W
Spectral type
M3.5V (red dwarf)
Science
Physical
- Mass
- 4.93 × 10²⁹ kg · 0.248 M☉
- Radius
- 215,667 km · 31% of the Sun's radius
- Density
- 11,739 kg/m³ · 12× water
- Computed from mass and radius
- Spectral type
- M3.5V (red dwarf)
Motion through space
- Note
- The motion of the pair's common centre of mass, computed as the mass-weighted mean of its stars' catalogued motions.
- Proper motion
- 2.27 arcseconds per year · its drift across our sky
- SIMBAD — 2020yCat.1350....0G
- Radial velocity
- +0.2 km/s · moving away from the Sun
- SIMBAD — 2020yCat.1350....0G
- Speed across our line of sight
- 37.9 km/s
- Computed from proper motion and parallax
- Speed through space, relative to the Sun
- 37.9 km/s
- Computed from proper motion, parallax and radial velocity
Orbit (around the system barycenter)
- Semi-major axis
- 36.2 AU
- From the 2025 visual-binary orbit (Izmailov & Khovritchev; P ≈ 1166 yr, a ≈ 63 AU, e ≈ 0.44 — long and still poorly constrained; 2025 estimates span ~870–1170 yr)
- Eccentricity
- 0.44
- From the 2025 visual-binary orbit (Izmailov & Khovritchev; P ≈ 1166 yr, a ≈ 63 AU, e ≈ 0.44 — long and still poorly constrained; 2025 estimates span ~870–1170 yr)
- Orbital period
- 1166.00 years
- From the 2025 visual-binary orbit (Izmailov & Khovritchev; P ≈ 1166 yr, a ≈ 63 AU, e ≈ 0.44 — long and still poorly constrained; 2025 estimates span ~870–1170 yr)
Composition
- By mass
- A red dwarf about a quarter of the Sun's mass — cooler and fainter than its companion. It too produces occasional flares.
Temperature
- Surface
- 3,345 K (3,072 °C)
Radiation & temperature
- Luminosity
- 3.02 × 10²⁴ W · 0.0079 L☉
- Surface temperature
- 3,345 K (3,072 °C)
- Peak wavelength
- 866 nm · near-infrared (mostly invisible to the eye)
- Computed (Wien's law) from the surface temperature
Discovery & history
- Discovered
- 1822
- By
- F. G. W. von Struve
- Method
- Telescope
- Name
- 'Struve 2398 B' is the fainter component of the double star Σ 2398 (GJ 725).
Catalogued with its companion by F. G. W. von Struve around 1822. The two stars' shared motion across the sky marks them as a genuine bound pair.
Images
Images from open archives · credit shown per image