Gliese 849 (also designated HIP 108752 and LHS 381) is a red dwarf star of spectral type M3.5V located in the constellation Pegasus. It lies at a distance of approximately 29.4 light‑years (9.0 parsecs) from the Sun, as measured by parallax data from the Gaia mission.
Stellar characteristics
- Apparent magnitude (V): 10.42, making it invisible to the unaided eye.
- Absolute magnitude (V): 10.29.
- Mass: About 0.36 M☉ (36 % of the Sun’s mass).
- Radius: Approximately 0.39 R☉.
- Luminosity: Roughly 2 % of the solar bolometric luminosity.
- Effective temperature: ~3,500 K.
- Metallicity: Slightly above solar ([Fe/H] ≈ +0.12).
- Rotational period: Estimated near 40 days, consistent with its low activity level.
Kinematics
- Radial velocity: +18.5 km s⁻¹ (receding).
- Proper motion: 1,124 mas yr⁻¹ in right ascension and –291 mas yr⁻¹ in declination, indicating relatively high space motion relative to the Sun.
Planetary system In 2006, radial‑velocity observations by the High Accuracy Radial velocity Planet Searcher (HARPS) revealed a Jovian‑mass exoplanet orbiting Gliese 849:
- Gliese 849 b
- Minimum mass (M sin i): ≈ 0.82 M_Jup.
- Orbital period: 5.2 years (≈ 1,913 days).
- Semi‑major axis: ~2.35 AU.
- Eccentricity: ≈ 0.06, indicating a nearly circular orbit.
The planet’s long period places it among the few known giant planets orbiting low‑mass M dwarfs, providing valuable constraints for theories of planet formation around such stars.
Discovery and naming Gliese 849 appears in the Gliese Catalogue of Nearby Stars, which lists stars within 25 pc of the Sun. Its designation follows the catalog number assigned by Wilhelm Gliese. The planetary companion was independently confirmed by subsequent Doppler‑spectroscopy campaigns and remains listed in the NASA Exoplanet Archive.
Observational notes Due to its proximity and relatively bright infrared magnitude (K ≈ 5.9), Gliese 849 is a frequent target for high‑resolution spectroscopy and astrometric monitoring. Ongoing surveys aim to detect additional, lower‑mass companions that may reside closer to the host star.
