Struve 2398 A
Star
Struve 2398 A — the brighter of a pair of red dwarfs (M3V) 11.5 light-years away in Draco. About a third of the Sun's mass, it and its slightly smaller companion circle each other on a wide, slow orbit lasting many centuries. Both are gently flaring stars. No planets are confirmed.
Open in 3D viewSee Struve 2398 A in the live, interactive 3D map
Key facts
Mutual orbit
~1,200 Earth years
Mass
6.64 × 10²⁹ kg
0.334 M☉
Radius
243,495 km
35% of the Sun's radius
Surface temperature
3,441 K (3,168 °C)
Luminosity
4.67 × 10²⁴ W
Spectral type
M3V (red dwarf)
Science
Physical
- Mass
- 6.64 × 10²⁹ kg · 0.334 M☉
- Radius
- 243,495 km · 35% of the Sun's radius
- Density
- 10,985 kg/m³ · 11× water
- Computed from mass and radius
- Spectral type
- M3V (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
- 26.8 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 third of the Sun's mass, radiating a little over 1% of the Sun's light. It flares gently and shares a large common proper motion with its companion.
Temperature
- Surface
- 3,441 K (3,168 °C)
Radiation & temperature
- Luminosity
- 4.67 × 10²⁴ W · 0.0122 L☉
- Surface temperature
- 3,441 K (3,168 °C)
- Peak wavelength
- 842 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
- Named for the astronomer F. G. W. von Struve and its number in his double-star catalogue (Σ, 'Struve', 2398). Also catalogued as GJ 725.
Recorded as a double star by Friedrich Georg Wilhelm von Struve at Dorpat Observatory around 1822 — the 2398th entry in his catalogue of visual binaries. The pair, also known as GJ 725, shares a large common proper motion.
Images
Images from open archives · credit shown per image