CI Tauri

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CI Tauri
CL Tauri.jpg
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 52.01440s [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
A broad-band optical light curve for CI Tauri, adapted from Roggero et al. (2021) CITauLightCurve.png
A broad-band optical light curve for CI Tauri, adapted from Roggero et al. (2021)

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]

Contents

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

CI Tauri hosts a protoplanetary disk, and evidence for planets has been found via both radial velocity and disk morphology. [12] [6]

Radial velocity

CI 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

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 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]

The CI Tauri planetary system [3] [6] [12] : 5 
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±0.02020.25±0.1650.5+6.3
−8.5 ° 		—
c3.6±0.3  MJ 0.17±0.0825.2+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° —

Related Research Articles

<span class="mw-page-title-main">Protoplanetary disk</span> Gas and dust surrounding a newly formed star

A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may also be considered an accretion disk for the star itself, because gases or other material may be falling from the inner edge of the disk onto the surface of the star. This process should not be confused with the accretion process thought to build up the planets themselves. Externally illuminated photo-evaporating protoplanetary disks are called proplyds.

<span class="mw-page-title-main">Protoplanet</span> Large planetary embryo

A protoplanet is a large planetary embryo that originated within a protoplanetary disk and has undergone internal melting to produce a differentiated interior. Protoplanets are thought to form out of kilometer-sized planetesimals that gravitationally perturb each other's orbits and collide, gradually coalescing into the dominant planets.

<span class="mw-page-title-main">Rogue planet</span> Planetary object without a planetary system

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<span class="mw-page-title-main">TW Hydrae</span> T Tauri star in the constellation Hydra

TW Hydrae is a T Tauri star approximately 196 light-years away in the constellation of Hydra. TW Hydrae is about 80% of the mass of the Sun, but is only about 5-10 million years old. The star appears to be accreting from a face-on protoplanetary disk of dust and gas, which has been resolved in images from the ALMA observatory. TW Hydrae is accompanied by about twenty other low-mass stars with similar ages and spatial motions, comprising the "TW Hydrae association" or TWA, one of the closest regions of recent "fossil" star-formation to the Sun.

TW Hydrae b is a likely extrasolar planet orbiting the young T Tauri star TW Hydrae approximately 176 light-years (54 parsecs, or nearly 1.665×1016 km) away in the constellation of Hydra. It is likely a Neptune-like planet orbiting at a distance of nearly 22 AU from its star.

<span class="mw-page-title-main">Taurus molecular cloud</span> Interstellar molecular cloud in the constellations Taurus and Auriga

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<span class="mw-page-title-main">LkCa 15</span> Star system in the constellation Taurus

LkCa 15 is a T Tauri star in the Taurus Molecular Cloud. These types of stars are relatively young pre-main-sequence stars that show irregular variations in brightness. It has a mass that is about 97% of the Sun, an effective temperature of 4370 K, and is slightly cooler than the Sun. Its apparent magnitude is 11.91, meaning it is not visible to the naked eye.

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<span class="mw-page-title-main">GW Orionis</span> Star in the constellation Orion

GW Orionis is a T Tauri type pre-main sequence hierarchical triple star system. It is associated with the Lambda Orionis star-forming region and has an extended circumtrinary protoplanetary disk.

<span class="mw-page-title-main">PDS 70</span> T Tauri-type star in the constellation Centaurus

PDS 70 is a very young T Tauri star in the constellation Centaurus. Located 370 light-years from Earth, it has a mass of 0.76 M☉ and is approximately 5.4 million years old. The star has a protoplanetary disk containing two nascent exoplanets, named PDS 70b and PDS 70c, which have been directly imaged by the European Southern Observatory's Very Large Telescope. PDS 70b was the first confirmed protoplanet to be directly imaged.

Catherine Jane Clarke is a Professor of Theoretical Astrophysics at the University of Cambridge and a fellow of Clare College, Cambridge. In 2017 she became the first woman to be awarded the Eddington Medal by the Royal Astronomical Society. In 2022 she became the first female director of the Institute of Astronomy, Cambridge.

<span class="mw-page-title-main">Circumplanetary disk</span> Accumulation of matter around a planet

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<span class="mw-page-title-main">V1298 Tauri</span> Star in the constellation Taurus

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<span class="mw-page-title-main">GI Tauri and GK Tauri</span> Binary star system in the constellation of Taurus

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<span class="mw-page-title-main">CQ Tauri</span> Star in the constellation Taurus

CQ Tauri is a young variable star in the equatorial constellation of Taurus. It is too faint to be visible to the naked eye with an apparent visual magnitude that ranges from 8.7 to 12.25. The distance to this star is approximately 487 light years based on parallax measurements, and it is drifting further away with a radial velocity of ~23 km/s. It appears to be part of the T-association Tau 4. CQ Tauri lies close enough to the ecliptic to undergo lunar occultations.

<span class="mw-page-title-main">IM Lupi</span> Pre-main-sequence star in the constellation Lupus

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References

  1. 1 2 3 4 5 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.
  2. 1 2 3 4 "V* CI Tau -- T Tau-type Star". SIMBAD. Retrieved 19 October 2018.
  3. 1 2 3 4 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.
  4. 1 2 3 "CI Tau". NASA Exoplanet Archive . Retrieved 29 March 2024.
  5. 1 2 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 .
  6. 1 2 3 4 5 6 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 , arXiv: 2403.03706
  7. ↑ 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.
  8. ↑ 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.
  9. 1 2 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.
  10. 1 2 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.
  11. ↑ 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.
  12. 1 2 3 4 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.
  13. ↑ 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
  14. ↑ "Astronomers find giant planet around very young star CI Tauri". Astronomy Now. Retrieved 20 October 2018.
  15. 1 2 "Giant planets around young star raise questions about how planets form". University of Cambridge. 2018-10-15. Retrieved 20 October 2018.
  16. ↑ 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.
  17. ↑ 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.
  18. ↑ 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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