CI Tauri is a young star, about 2 million years old, located approximately 523 light-years (160 parsecs) away in the constellation Taurus. It is still accreting material from a debris disk at an unsteady pace, possibly modulated by the eccentric[8] orbital motion of an inner planet.[9] The spectral signatures of compounds of sulfur were detected from the disk.[10]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Taurus |
| Right ascension | 04h 33m 52.01440s[1] |
| Declination | +22° 50′ 30.0941″[1] |
| Apparent magnitude (V) | 13.8[2] |
| Characteristics | |
| Evolutionary stage | T Tauri star |
| Spectral type | K4IVe[2] |
| Variable type | Orion variable |
| Astrometry | |
| Radial velocity (Rv) | +16.2[2] km/s |
| Proper motion (μ) | RA: +8.942 mas/yr[1] Dec.: –17.079 mas/yr[1] |
| Parallax (π) | 6.2376 ± 0.0205 mas[1] |
| Distance | 523 ± 2 ly (160.3 ± 0.5 pc) |
| Details | |
| Mass | 0.90±0.02[3] M☉ |
| Radius | 1.679[4] R☉ |
| Rotation | 6.6 d[5] or 9 d[6] |
| Age | 2-3[3] Myr |
| Other designations | |
CI Tau, 2MASS J04335200+2250301, EPIC 247584113[2] | |
| Database references | |
| SIMBAD | data |
The magnetic field on the surface of CI Tauri, equal to 0.22 T, is close to average for T Tauri stars.[11]
Planetary system
editCI Tauri hosts a protoplanetary disk, and evidence for planets has been found via both radial velocity and disk morphology.[12][6]
Radial velocity
editCI Tauri displays several periodic radial velocity variations, including periods of 6.6 days, 9 days, and 25 days.[6] The 9-day period was proposed to be due to a candidate massive planet on an eccentric orbit, CI Tauri b, in 2016.[13] The discovery of CI Tauri b was notable because it is a hot Jupiter, which are supposed to take a minimum of 10 million years to form, and are often thought to be too close to their parent stars to have formed there.[14][15]
The existence of this planet has been debated; in 2019, a detection of carbon monoxide attributed to the planet's atmosphere was announced, seemingly confirming it.[3] However, a 2020 study found that the star rotates with a period of 9 days, and suggested that the radial velocity variations may be caused by the star's rotation rather than a planet. The carbon monoxide detection was attributed to magnetic interaction of the star with the circumstellar disk.[16] Other studies have attributed the 6.6-day period to the stellar rotation and the 9-day period to the candidate planet.[9][5]
A 2024 study found evidence for a planetary origin of the 25-day radial velocity signal, while considering the 9-day signal to correspond to the stellar rotation and be caused by a starspot.[6] This 25-day candidate planet would orbit CI Tauri at a distance of 0.17 AU in a highly-eccentric orbit (e = 0.58). The mass of this planet is estimated to be 3.6±0.3 MJ.[6] While this is treated as a strong candidate and left undesignated by its discovery paper, the NASA Exoplanet Archive lists it as a confirmed planet with the designation CI Tauri c.[4]
Disk morphology
editIn 2018 the possible detection of three more planets, inferred by gaps in the protoplanetary disk surrounding the star, was announced. Using the Atacama Large Millimeter Array (ALMA) to look for 'siblings' of CI Tauri b, a team of researchers detected three distinct gaps in the protoplanetary disk which their theoretical modelling suggests are caused by three other planets. The two outer planets are believed to be about the mass of Saturn, while the inner planet's mass is around the same as Jupiter.[15] Two of the new planets are similarly located to those inferred in the HL Tauri protoplanetary disk.[12]
Another 2018 study also found evidence for the outermost of these planets at around 100 AU, estimating a mass of 0.25-0.8 times that of Jupiter.[17] If this discovery is confirmed this would be the most massive collection of exoplanets ever detected at this age with its four planets spanning a factor of a thousand in orbital radius.[12]
The gaps are visible in wideband photography, but not in the gas spectral lines. These "gaps" may be lower-temperature shadows of dust in the inner disk cast on outer parts rather than true gaps carved by planets.[18]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (false positive[4]) | 11.6+2.9 −2.7 MJ |
— | 8.9891±0.0202 | 0.25±0.16 | 50.5+6.3 −8.5° |
— |
| c | 3.6±0.3 MJ | 0.17±0.08 | 25.2+1.7 −1.8 |
0.58+0.05 −0.06 |
— | — |
| (unconfirmed) | ~0.75 MJ | ~14 | — | — | — | — |
| (unconfirmed) | ~0.15 MJ | ~43 | — | — | — | — |
| (unconfirmed) | ~0.4 MJ | ~108 | — | — | — | — |
| debris disk[10] | 200–600 AU | 50.3° | — | |||
References
edit- ^ a b c d 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.
- ^ a b c d "V* CI Tau -- T Tau-type Star". SIMBAD. Retrieved 19 October 2018.
- ^ a b c d Flagg, Laura; Johns-Krull, Christopher M.; Nofi, Larissa; Llama, Joe; Prato, Lisa A.; Sullivan, Kendall; Jaffe, D. T.; Mace, Gregory (2019). "CO Detected in CI Tau b: Hot Start Implied by Planet Mass and MK". The Astrophysical Journal. 878 (2): L37. arXiv:1906.02860. Bibcode:2019ApJ...878L..37F. doi:10.3847/2041-8213/ab276d. S2CID 174801528.
- ^ a b c "CI Tau". NASA Exoplanet Archive. Retrieved 29 March 2024.
- ^ a b Biddle, Lauren I.; Llama, Joe; et al. (January 2021). "Amplitude Modulation of Short-timescale Hot Spot Variability". The Astrophysical Journal. 906 (2): 113. arXiv:2011.05388. Bibcode:2021ApJ...906..113B. doi:10.3847/1538-4357/abc889.
- ^ a b c d e f Manick, R.; Sousa, A. P.; et al. (March 2024), "Long period modulation of the classical T Tauri star CI Tau: evidence for an eccentric close-in massive planet at 0.17 au", Astronomy & Astrophysics, 686, arXiv:2403.03706, Bibcode:2024A&A...686A.249M, doi:10.1051/0004-6361/202348258
- ^ Roggero, Noemi; Bouvier, Jérôme; Rebull, Luisa M.; Cody, Ann Marie (July 2021). "The dipper population of Taurus seen with K2". Astronomy and Astrophysics. 651: A44. arXiv:2106.02064. Bibcode:2021A&A...651A..44R. doi:10.1051/0004-6361/202140646. S2CID 235352553. Retrieved 28 March 2022.
- ^ Lai, Dong; Teyssandier, Jean (2020). "Pulsed Disc Accretion Driven by Hot Jupiters". Monthly Notices of the Royal Astronomical Society. 495 (4): 3920–3928. arXiv:1911.08492. Bibcode:2020MNRAS.495.3920T. doi:10.1093/mnras/staa1363. S2CID 208175992.
- ^ a b Biddle, Lauren I.; Johns-Krull, Christopher M.; Llama, Joe; Prato, Lisa A.; Skiff, Brian A. (2018). "K2 reveals pulsed accretion driven by the 2 Myr old hot Jupiter CI Tau b". The Astrophysical Journal. 853 (2): L34. arXiv:1801.06234. Bibcode:2018ApJ...853L..34B. doi:10.3847/2041-8213/aaa897. S2CID 111379078.
- ^ a b Le Gal, Romane; Öberg, Karin I.; Loomis, Ryan A.; Pegues, Jamila; Bergner, Jennifer B. (2019). "Sulfur chemistry in protoplanetary disks: CS and H2CS". The Astrophysical Journal. 876 (1): 72. arXiv:1903.11105. Bibcode:2019ApJ...876...72L. doi:10.3847/1538-4357/ab1416. S2CID 85528537.
- ^ Sokal, Kimberly R.; Johns-Krull, Christopher M.; Mace, Gregory N.; Nofi, Larissa; Prato, Lisa A.; Lee, Jae-Joon; Jaffe, Daniel T. (2020). "The Mean Magnetic Field Strength of CI Tau". The Astrophysical Journal. 888 (2): 116. arXiv:1911.00784. Bibcode:2020ApJ...888..116S. doi:10.3847/1538-4357/ab59d8. S2CID 207870483.
- ^ a b c d Clarke, Cathie J; Tazzari, Marco; Juhasz, Attila; Rosotti, Giovanni; Booth, Richard; Facchini, Stefano; Ilee, John D; Johns-Krull, Christopher M; Kama, Mihkel; Meru, Farzana; Prato, Lisa A. (2018). "High resolution millimetre imaging of the CI Tau protoplanetary disc - a massive ensemble of protoplanets from 0.1 - 100 au". The Astrophysical Journal. 866 (1): L6. arXiv:1809.08147. Bibcode:2018ApJ...866L...6C. doi:10.3847/2041-8213/aae36b. S2CID 119042020.
- ^ Johns-Krull, Christopher M.; McLane, Jacob N.; Prato, L.; Crockett, Christopher J.; Jaffe, Daniel T.; Hartigan, Patrick M.; Beichman, Charles A.; Mahmud, Naved I.; Chen, Wei; Skiff, B. A.; Wilson Cauley, P.; Jones, Joshua A.; Mace, G. N. (2016), "A Candidate Young Massive Planet in Orbit around the Classical T Tauri Star CI Tau", The Astrophysical Journal, 826 (2): 206, arXiv:1605.07917, Bibcode:2016ApJ...826..206J, doi:10.3847/0004-637X/826/2/206, S2CID 19060087
- ^ "Astronomers find giant planet around very young star CI Tauri". Astronomy Now. Retrieved 20 October 2018.
- ^ a b "Giant planets around young star raise questions about how planets form". University of Cambridge. 2018-10-15. Retrieved 20 October 2018.
- ^ Donati, J.-F.; Bouvier, J.; et al. (February 2020). "The magnetic field and accretion regime of CI Tau". Monthly Notices of the Royal Astronomical Society. 491 (4): 5660–5670. arXiv:1911.12818. Bibcode:2020MNRAS.491.5660D. doi:10.1093/mnras/stz3368.
- ^ Konishi, Mihoko; Hashimoto, Jun; Hori, Yasunori (2018). "Probing Signatures of a Distant Planet around the Young T-Tauri Star CI Tau Hosting a Possible Hot Jupiter". The Astrophysical Journal. 859 (2): L28. arXiv:1805.07498. Bibcode:2018ApJ...859L..28K. doi:10.3847/2041-8213/aac6d2. S2CID 119208569.
- ^ Rosotti, Giovanni P.; Ilee, John D.; Facchini, Stefano; Tazzari, Marco; Booth, Richard A.; Clarke, Cathie; Kama, Mihkel (2020). "High resolution observations of molecular emission lines toward the CI Tau proto-planetary disc: planet-carved gaps or shadowing?". Monthly Notices of the Royal Astronomical Society. 501 (3): 3427. arXiv:2012.07848. Bibcode:2021MNRAS.501.3427R. doi:10.1093/mnras/staa3869. S2CID 229180958.