GJ 3998

Last updated
GJ 3998
Observation data
Epoch J2000        Equinox J2000
Constellation Ophiuchus [1]
Right ascension 17h 16m 00.63687s [2]
Declination +11° 03′ 27.6158″ [2]
Apparent magnitude  (V)10.83 [3]
Characteristics
Evolutionary stage main sequence
Spectral type M1V [4]
Apparent magnitude  (J)7.634±0.021 [5]
Apparent magnitude  (H)7.020±0.029 [5]
Apparent magnitude  (K)6.816±0.016 [5]
U−B color index 1.183 [3]
B−V color index 1.510 [3]
V−R color index 0.970 [3]
Astrometry
Radial velocity (Rv)−45.62±0.14 [2] km/s
Proper motion (μ)RA: -137.435 mas/yr [2]
Dec.: -347.456 mas/yr [2]
Parallax (π)55.0169±0.0287  mas [2]
Distance 59.28 ± 0.03  ly
(18.176 ± 0.009  pc)
Absolute magnitude  (MV)9.58 [3]
Details [5]
Mass 0.52±0.05  M☉
Radius 0.50±0.05  R☉
Luminosity 0.041±0.008 [6]   L☉
Surface gravity (log g)4.75±0.04  cgs
Temperature 3726±68  K
Metallicity [Fe/H]−0.13±0.09  dex
Rotation 30.2±0.3  d
Rotational velocity (v sin i)0.93±0.55 [6]  km/s
Age 8.38±4.06  Gyr
Other designations
BD+11 3149, GJ 3998, HIP 84460, G 139-23, L 1205-67, LTT 15111, TYC 982-121-1 [4]
Database references
SIMBAD data
Exoplanet Archive data

GJ 3998 is a red dwarf star located 59.3 light-years (18.2 parsecs ) away in the constellation Ophiuchus. It has about half the mass and radius of the Sun, and only 4% of its luminosity. Its rotation period is 30 days. [5]

GJ 3998 hosts a system of three known planets, all super-Earth-mass planets detected by the radial velocity method. The outermost planet, with a minimum mass about six times the mass of Earth, orbits within the optimistic habitable zone. [5] [7] The star rotates with an inclination of >30° to the plane of the sky; if the planetary orbits are coplanar with the star, their true masses are at most twice their minimum masses. [8]

The two inner planets were found in 2016, [6] but were questioned by a 2022 study, which argued that the radial velocity signals may instead be due to intrinsic stellar activity. [9] The third planet was found by a 2025 follow-up study by the original discovery team, who did a series of tests on stellar activity signals that they believe validate all three planets. [5]

The GJ 3998 planetary system [5]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b≥2.50+0.30
−0.29  M🜨 		0.030±0.0012.65033+0.00022
−0.00019		0——
c≥6.82+0.78
−0.75  M🜨 		0.090±0.00313.727+0.003
−0.004		0——
d≥6.07+1.00
−0.96  M🜨 		0.189±0.00641.78±0.050——

References

  1. ↑ "Finding the constellation which contains given sky coordinates". djm.cc. 2 August 2008.
  2. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 4 5 Koen, C.; Kilkenny, D.; et al. (April 2010). "UBV(RI)C JHK observations of Hipparcos-selected nearby stars". Monthly Notices of the Royal Astronomical Society . 403 (4): 1949–1968. Bibcode:2010MNRAS.403.1949K. doi: 10.1111/j.1365-2966.2009.16182.x .
  4. 1 2 "GJ 3998". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 13 March 2025.
  5. 1 2 3 4 5 6 7 8 Stefanov, A. K.; Suárez Mascareño, A.; et al. (March 2025). "HADES RV Programme with HARPS-N at TNG: XVI. A super-Earth in the habitable zone of the GJ 3998 multi-planet system". Astronomy & Astrophysics . 695: A62. arXiv: 2503.08405 . Bibcode:2025A&A...695A..62S. doi: 10.1051/0004-6361/202452630 .
  6. 1 2 3 Affer, L.; Micela, G.; et al. (October 2016). "HADES RV program with HARPS-N at the TNG GJ 3998: An early M-dwarf hosting a system of super-Earths". Astronomy & Astrophysics . 593: A117. arXiv: 1607.03632 . Bibcode:2016A&A...593A.117A. doi: 10.1051/0004-6361/201628690 .
  7. ↑ "IAC discovers a super-Earth in the habitable zone of a nearby red dwarf". Instituto de Astrofísica de Canarias. 11 March 2025. Retrieved 17 March 2025.
  8. ↑ Suárez Mascareño, A.; Rebolo, R.; et al. (April 2018). "HADES RV programme with HARPS-N at TNG. VII. Rotation and activity of M-dwarfs from time-series high-resolution spectroscopy of chromospheric indicators". Astronomy & Astrophysics . 612: A89. arXiv: 1712.07375 . Bibcode:2018A&A...612A..89S. doi: 10.1051/0004-6361/201732143 .
  9. ↑ Dodson-Robinson, Sarah E.; Delgado, Victor Ramirez; et al. (April 2022). "Magnitude-squared Coherence: A Powerful Tool for Disentangling Doppler Planet Discoveries from Stellar Activity". The Astronomical Journal . 163 (4): 169. arXiv: 2201.13342 . Bibcode:2022AJ....163..169D. doi: 10.3847/1538-3881/ac52ed .
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