CI Tauri

CI Tauri is a young star, about 2 million years old, located approximately 500 light years away in the constellation Taurus. It is still accreting material from a debris disk at an unsteady pace, possibly modulated by the eccentric[4] orbital motion of the inner planet.[5] The spectral signatures of compounds of sulfur were detected from the disk.[6]

CI Tauri

Atacama Large Millimeter Array image of CI Tauri, showing three gaps in the disk
Observation data
Epoch J2000      Equinox J2000
Constellation Taurus
Right ascension 04h 33m 52.01444s[1]
Declination +22° 50′ 30.0937″[1]
Apparent magnitude (V) 13.8[1]
Characteristics
Evolutionary stage T Tauri star
Spectral type K4IVe [1]
Variable type Orion variable
Astrometry
Radial velocity (Rv)+16.2[1] km/s
Proper motion (μ) RA: +8.904[1] mas/yr
Dec.: –17.067[1] mas/yr
Parallax (π)6.3008 ± 0.473 mas[1]
Distance520 ± 40 ly
(160 ± 10 pc)
Details
Mass0.80 ± 0.02[2] M☉
Age.0020[2] Gyr
Other designations
CI Tau, 2MASS J04335200+2250301, EPIC 247584113[1]
Database references
SIMBADdata
A broad-band optical light curve for CI Tauri, adapted from Roggero et al. (2021)[3]

The magnetic field on the surface of CI Tauri, equal to 0.22 T, is close to average for T Tauri stars.[7]

Planetary system

In 2016 a planet, CI Tauri b, was discovered orbiting CI Tauri on a very tight yet eccentric 9-day orbit.[8][2]

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.[9][10]

The spectral signature of carbon monoxide attributed to the atmosphere of CI Tauri b was detected in 2019.[11]

The CI Tauri planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 11.6+2.9
−2.7 MJ		 — 8.9891±0.0202 0.25±0.16 — —
c[12] (unconfirmed) 0.525±0.275 MJ 104.5±1.6 — — — —
d (Unconfirmed) — — — — — —
e (Unconfirmed) — — — — — —
debris disk[6] 200–600 AU 50.3° —

Additional planets suspected

In 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 CI Tauri b.[10] Two of the new planets are similarly located to those inferred in the HL Tauri protoplanetary disk.[13]

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.[13]

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.[14]

References
  1. "V* CI Tau -- T Tau-type Star". SIMBAD. Retrieved 19 October 2018.
  2. "CI Tau". Open Exoplanet Catalogue. Retrieved 20 October 2018.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. 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
  9. "Astronomers find giant planet around very young star CI Tauri". Astronomy Now. Retrieved 20 October 2018.
  10. "Giant planets around young star raise questions about how planets form". University of Cambridge. 2018-10-15. Retrieved 20 October 2018.
  11. 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.
  12. 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.
  13. 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: L6. arXiv:1809.08147. doi:10.3847/2041-8213/aae36b. S2CID 119042020.
  14. 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.
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