CD Ceti
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Cetus |
| Right ascension | 03h 13m 22.92s |
| Declination | +04° 46′ 29.3″ |
| Apparent magnitude (V) | +13.81 to 13.87 |
| Characteristics | |
| Spectral type | M5.0V |
| Variable type | BY Dra |
| Astrometry | |
| Radial velocity (Rv) | +28.16±0.46 km/s |
| Proper motion (μ) | RA: +1741.875 mas/yr Dec.: +86.494 mas/yr |
| Parallax (π) | 116.2678±0.0427 mas |
| Distance | 28.05 ± 0.01 ly (8.601 ± 0.003 pc) |
| Details | |
| Mass | 0.161±0.010 M☉ |
| Radius | 0.175±0.006 R☉ |
| Luminosity | 0.002934(53) L☉ |
| Surface gravity (log g) | 4.93±0.04 cgs |
| Temperature | 3,130±51 K |
| Metallicity [Fe/H] | +0.13±0.16 dex |
| Rotation | 126.2 days |
| Rotational velocity (v sin i) | ≤2.0 km/s |
| Age | 1–5 Gyr |
| Other designations | |
| CD Cet, GJ 1057, G 77-31, LHS 168, NLTT 10256 | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
CD Ceti (CD Cet) is a star located in the constellation of Cetus. With an apparent magnitude of +13.8, it is not visible to the naked eye. Based on its parallax, it is located 8.6 parsecs (28 light-years) from the Solar System.
Characteristics
CD Ceti is a faint red dwarf of spectral type M5.0V. Similar to GJ 1156 or the well-known Proxima Centauri - the nearest star to the Solar System - it has an effective temperature of 3,240 K.
Small in size, its radius is 18% of the solar radius, and it rotates with a projected rotational velocity of less than 3 km/s.
Its rotation period is approximately 126.2 days, as determined from MEarth photometry. Its weak stellar magnetic field, below 2 kG, is associated with its slow rotation. It has a mass equal to 15.5-16% of the solar mass.
CD Ceti is a relatively quiet star, with a low chromospheric activity level and no detected Hα emission. High-resolution imaging searches found no stellar or substellar companions, confirming that CD Ceti is a single star.
CD Ceti is classified as a BY Draconis variable. These variables - among which DK Ceti and EX Ceti are found in the same constellation - show variations in luminosity due to spots on their surface or other types of chromospheric activity. The brightness variation of CD Ceti is 0.06 magnitudes, with no known period.
Planetary system
In 2020, the CARMENES spectrograph detected a super-Earth companion, CD Cet b, orbiting the star. The planet has a minimum mass of approximately 4.0 ± 0.4 M⊕ and completes one orbit every 2.29 days. The signal was detected independently in both the visible and near-infrared channels of CARMENES and subsequently confirmed with the ESPRESSO spectrograph at the Very Large Telescope. No transit was detected in TESS photometry, indicating that the planet does not transit its host star as seen from Earth. Depending on its Bond albedo, the planet's equilibrium temperature is estimated to range from approximately 325 to 464 K.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | ≥3.95+0.42 −0.43 M🜨 |
0.0185±0.0013 | 2.29070±0.00012 | — | — | — |
References
- 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.
- 1 2 Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085.
- 1 2 3 4 5 6 7 8 9 10 11 12 13 Bauer, F. F.; Zechmeister, M.; Kaminski, A.; et al. (2020). "The CARMENES search for exoplanets around M dwarfs. Measuring precise radial velocities in the near infrared: The example of the super-Earth CD Cet b". Astronomy & Astrophysics. 640: A50. arXiv:2006.01684. doi:10.1051/0004-6361/202038031.
- ↑ "CD Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-03-27.
- 1 2 Reiners, A.; Basri, G. (2007). "The First Direct Measurements of Surface Magnetic Fields on Very Low Mass Stars". The Astrophysical Journal. 656 (2): 1121–1135. arXiv:astro-ph/0610365. Bibcode:2007ApJ...656.1121R. doi:10.1086/510304.
- 1 2 Reiners, A.; Basri, G.; Browning, M. (2009). "Evidence for Magnetic Flux Saturation in Rapidly Rotating M Stars". The Astrophysical Journal. 692 (1): 538–545. arXiv:0810.5139. doi:10.1088/0004-637X/692/1/538.
- ↑ Jenkins, J. S.; Ramsey, L. W.; Jones, H. R. A.; Pavlenko, Y.; Gallardo, J.; Barnes, J. R.; Pinfield, D. J. (2009). "Rotational Velocities for M Dwarfs". The Astrophysical Journal. 704 (2): 975–988. arXiv:0908.4092. doi:10.1088/0004-637X/704/2/975.
- ↑ "CD Ceti". General Catalogue of Variable Stars.
