Astronomy:GJ 3998
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[2] mas/yr Dec.: -347.456[2] mas/yr |
| Parallax (π) | 55.0169 ± 0.0287[2] mas |
| 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 | |
| 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]
| 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±0.001 | 2.65033+0.00022 −0.00019 |
0 | — | — |
| c | ≥6.82+0.78 −0.75 M⊕ |
0.090±0.003 | 13.727+0.003 −0.004 |
0 | — | — |
| d | ≥6.07+1.00 −0.96 M⊕ |
0.189±0.006 | 41.78±0.05 | 0 | — | — |
References
- ↑ "Finding the constellation which contains given sky coordinates". 2 August 2008. http://djm.cc/constellation.html.
- ↑ 2.0 2.1 2.2 2.3 2.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 3.3 3.4 Koen, C. 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. doi:10.1111/j.1365-2966.2009.16182.x. Bibcode: 2010MNRAS.403.1949K.
- ↑ 4.0 4.1 "GJ 3998". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=GJ+3998.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Stefanov, A. K. 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. doi:10.1051/0004-6361/202452630. Bibcode: 2025A&A...695A..62S.
- ↑ 6.0 6.1 6.2 Affer, L. 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. doi:10.1051/0004-6361/201628690. Bibcode: 2016A&A...593A.117A.
- ↑ "IAC discovers a super-Earth in the habitable zone of a nearby red dwarf". Instituto de Astrofísica de Canarias. 11 March 2025. https://www.iac.es/en/outreach/news/iac-discovers-super-earth-habitable-zone-nearby-red-dwarf.
- ↑ Suárez Mascareño, A. 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. doi:10.1051/0004-6361/201732143. Bibcode: 2018A&A...612A..89S.
- ↑ Dodson-Robinson, Sarah E. et al. (April 2022). "Magnitude-squared Coherence: A Powerful Tool for Disentangling Doppler Planet Discoveries from Stellar Activity". The Astronomical Journal 163 (4): 169. doi:10.3847/1538-3881/ac52ed. Bibcode: 2022AJ....163..169D.
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