Tau Ceti

Not to be confused with T Ceti. For the video game, see Tau Ceti (video game).

Tau Ceti, Latinized from τ Ceti, is a single star in the constellation Cetus that is spectrally similar to the Sun, although it has only about 78% of the Sun's mass. At a distance of just under 12 light-years (3.7 parsecs) from the Solar System, it is a relatively nearby star and the closest solitary G-class star. The star appears stable, with little stellar variation, and is metal-deficient (low in elements other than hydrogen and helium) relative to the Sun.

Tau Ceti

Location of τ Ceti (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Cetus
Pronunciation	/ˌtaʊ ˈsiːtaɪ/
Right ascension	01^h 44^m 04.083^s^[1]
Declination	−15° 56′ 14.93″^[1]
Apparent magnitude (V)	3.50±0.01^[2]
Characteristics
Evolutionary stage	Main sequence
Spectral type	G8V^[3]
U−B color index	+0.21^[4]
B−V color index	+0.72^[4]
Astrometry
Radial velocity (Rv)	−16.68±0.05^[5] km/s
Proper motion (μ)	RA: −1721.728 mas/yr^[1] Dec.: +854.963 mas/yr^[1]
Parallax (π)	273.8097 ± 0.1701 mas^[1]
Distance	11.912 ± 0.007 ly (3.652 ± 0.002 pc)
Absolute magnitude (MV)	5.69±0.01^[2]
Absolute bolometric magnitude (Mbol)	5.52±0.02^[2]
Details
Mass	0.783±0.012^[2] M☉
Radius	0.793±0.004^[2] R☉
Luminosity	0.488±0.010^[2] L☉
Luminosity (visual, LV)	0.45^[nb 1] L☉
Surface gravity (log g)	4.48±0.05^[6] cgs
Temperature	5,320±40^[6] K
Metallicity	28±3% Sun
Metallicity [Fe/H]	−0.55±0.05^[7] dex
Rotation	34 d,^[8] 46±4 d^[6]
Rotational velocity (v sin i)	0.1±0.1^[6] km/s
Age	8–10^[9] Gyr
Other designations
52 Cet, BD−16° 295, FK5 59, GJ 71, HD 10700, HIP 8102, HR 509, SAO 147986, LFT 159, LHS 146, LTT 935^[4]
Database references
SIMBAD	data
Exoplanet Archive	data
ARICNS	data

It can be seen with the unaided eye with an apparent magnitude of 3.5.^[2] As seen from Tau Ceti, the Sun would be in the northern hemisphere constellation Boötes with an apparent magnitude of about 2.6.^{[nb 2][10]}

Observations have detected more than ten times as much dust surrounding Tau Ceti as is present in the Solar System. Since December 2012, there has been evidence of at least four planets—all likely super-Earths—orbiting Tau Ceti, and two of these are potentially in the habitable zone.^[11][12][13] There is evidence of up to an additional four unconfirmed planets, one of which would be a Jovian planet between 3 and 20 AU from the star.^[14] Because of its debris disk, any planet orbiting Tau Ceti would face far more impact events than Earth. Note that those planetary candidates have been contested recently^[15] and recent discoveries about the stellar inclination cast doubt about the terrestrial nature of these worlds.^[6] Despite this hurdle to habitability, its solar analog (Sun-like) characteristics have led to widespread interest in the star. Given its stability, similarity and relative proximity to the Sun, Tau Ceti is consistently listed as a target for the search for extraterrestrial intelligence (SETI).^[16]

Name

The name "Tau Ceti" is the Bayer designation for this star, established in 1603 as part of German celestial cartographer Johann Bayer's Uranometria star catalogue: it is "number T" in Bayer's sequence of constellation Cetus. In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, written at Cairo about 1650, this star was designated Thālith al Naʽāmāt (ثالث النعامات - thālith al-naʽāmāt), which was translated into Latin as Tertia Struthionum, meaning the third of the ostriches.^[17] This star, along with η Cet (Deneb Algenubi), θ Cet (Thanih Al Naamat), ζ Cet (Baten Kaitos), and υ Cet, were Al Naʽāmāt (النعامات), the Hen Ostriches.^[18][19]

In Chinese astronomy, the "Square Celestial Granary" (Chinese: 天倉; pinyin: Tiān Cāng) refers to an asterism consisting of τ Ceti, ι Ceti, η Ceti, ζ Ceti, θ Ceti and 57 Ceti.^[20] Consequently, the Chinese name for τ Ceti itself is "the Fifth Star of Square Celestial Granary" (Chinese: 天倉五; pinyin: Tiān Cāng wǔ).^[21]

Motion

The proper motion of a star is its rate of movement across the celestial sphere, determined by comparing its position relative to more distant background objects. Tau Ceti is considered to be a high-proper-motion star, although it only has an annual traverse of just under 2 arc seconds.^{[nb 3]} Thus it will require about 2000 years before the location of this star shifts by more than a degree. A high proper motion is an indicator of closeness to the Sun.^[22] Nearby stars can traverse an angle of arc across the sky more rapidly than the distant background stars and are good candidates for parallax studies. In the case of Tau Ceti, the parallax measurements indicate a distance of 11.9 ly. This makes it one of the closest star systems to the Sun and the next-closest spectral class-G star after Alpha Centauri A.^[23]

The radial velocity of a star is the component of its motion that is toward or away from the Sun. Unlike proper motion, a star's radial velocity cannot be directly observed, but can be determined by measuring its spectrum. Due to the Doppler shift, the absorption lines in the spectrum of a star will be shifted slightly toward the red (or longer wavelengths) if the star is moving away from the observer, or toward blue (or shorter wavelengths) when it moves toward the observer. In the case of Tau Ceti, the radial velocity is about −17 km/s, with the negative value indicating that it is moving toward the Sun.^[24] The star will make its closest approach to the Sun in about 43,000 years, when it comes to within 10.6 ly (3.25 pc).^[25]

The distance to Tau Ceti, along with its proper motion and radial velocity, together give the motion of the star through space. The space velocity relative to the Sun is 37.2 km/s.^[26] This result can then be used to compute an orbital path of Tau Ceti through the Milky Way. It has a mean galacto-centric distance of 9.7 kiloparsecs (32000 ly) and an orbital eccentricity of 0.22.^[27]

Physical properties

 

The Sun (left) is both larger and somewhat hotter than the less active Tau Ceti (right).

The Tau Ceti system is believed to have only one stellar component. A dim optical companion has been observed with magnitude 13.1. As of 2000, it was 137 arcseconds distant from the primary. It may be gravitationally bound, but it is considered more likely to be a line-of-sight coincidence.^[28][29][30]

Most of what is known about the physical properties of Tau Ceti and its system has been determined through spectroscopic measurements. By comparing the spectrum to computed models of stellar evolution, the age, mass, radius and luminosity of Tau Ceti can be estimated. However, using an astronomical interferometer, measurements of the radius of the star can be made directly to an accuracy of 0.5%.^[2] Through such means, the radius of Tau Ceti has been measured to be 79.3%±0.4% of the solar radius.^[2] This is about the size that is expected for a star with somewhat lower mass than the Sun.^[31]

Rotation

The rotation period for Tau Ceti was measured by periodic variations in the classic H and K absorption lines of singly ionized calcium (Ca II). These lines are closely associated with surface magnetic activity,^[32] so the period of variation measures the time required for the activity sites to complete a full rotation about the star. By this means the rotation period for Tau Ceti is estimated to be 34 d.^[8] Due to the Doppler effect, the rotation rate of a star affects the width of the absorption lines in the spectrum (light from the side of the star moving away from the observer will be shifted to a longer wavelength; light from the side moving towards the observer will be shifted toward a shorter wavelength). By analyzing the width of these lines, the rotational velocity of a star can be estimated. The projected rotation velocity for Tau Ceti is

v_eq · sin i ≈ 1 km/s,

where v_eq is the velocity at the equator, and i is the inclination angle of the rotation axis to the line of sight. For a typical G8 star, the rotation velocity is about 2.5 km/s. The relatively low rotational velocity measurements may indicate that Tau Ceti is being viewed from nearly the direction of its pole.^[33][34]

More recently, a 2023 study has estimated a rotation period of 46±4 d and a v_eq sin i of 0.1±0.1 km/s, corresponding to a pole-on inclination of 7°±7°.^[6]

Metallicity

The chemical composition of a star provides important clues to its evolutionary history, including the age at which it formed. The interstellar medium of dust and gas from which stars form is primarily composed of hydrogen and helium with trace amounts of heavier elements. As nearby stars continually evolve and die, they seed the interstellar medium with an increasing portion of heavier elements. Thus younger stars tend to have a higher portion of heavy elements in their atmospheres than do the older stars. These heavy elements are termed "metals" by astronomers, and the portion of heavy elements is the metallicity.^[35] The amount of metallicity in a star is given in terms of the ratio of iron (Fe), an easily observed heavy element, to hydrogen. A logarithm of the relative iron abundance is compared to the Sun. In the case of Tau Ceti, the atmospheric metallicity is

${\displaystyle \left[{\frac {\text{Fe}}{\text{H}}}\right]\approx -0.50}$  dex,

equivalent to about a third the solar abundance. Past measurements have varied from −0.13 to −0.60.^[36][37]

This lower abundance of iron indicates that Tau Ceti is almost certainly older than the Sun. Its age had previously been estimated to be 5.8 Gyr, but is now thought to be around 9 Gyr.^[9] This compares with 4.57 Gyr for the Sun. However, age estimates for Tau Ceti can range from 4.4 to 12 Gyr, depending on the model adopted.^[31]

Besides rotation, another factor that can widen the absorption features in the spectrum of a star is pressure broadening. The presence of nearby particles affects the radiation emitted by an individual particle. So the line width is dependent on the surface pressure of the star, which in turn is determined by the temperature and surface gravity. This technique was used to determine the surface gravity of Tau Ceti. The log g, or logarithm of the star's surface gravity, is about 4.4, very close to the log g = 4.44 for the Sun.^[36]

Luminosity and variability

The luminosity of Tau Ceti is equal to only 55% of the Sun's luminosity.^[27] A terrestrial planet would need to orbit this star at a distance of about 0.7 AU to match the solar insolation level of Earth. This is approximately the same as the average distance between Venus and the Sun.

The chromosphere of Tau Ceti—the portion of a star's atmosphere just above the light-emitting photosphere—currently displays little or no magnetic activity, indicating a stable star.^[38] One 9-year study of temperature, granulation, and the chromosphere showed no systematic variations; Ca II emissions around the H and K infrared bands show a possible 11-year cycle, but this is weak relative to the Sun.^[33] Alternatively it has been suggested that the star could be in a low-activity state analogous to a Maunder Minimum—a historical period, associated with the Little Ice Age in Europe, when sunspots became exceedingly rare on the Sun's surface.^[39][40] Spectral line profiles of Tau Ceti are extremely narrow, indicating low turbulence and observed rotation.^[41] The star's asteroseismological oscillations have an amplitude about half that of the Sun and a lower mode lifetime.^[2]

Planetary system

The Tau Ceti planetary system^{[7][14][42][43][44]}

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b (unconfirmed)	≥2.0 ± 0.8 M🜨	0.105+0.005 −0.006	13.965+0.017 −0.024	0.16 ± 0.22	—	—
g (unconfirmed)	≥1.75+0.25 −0.40 M🜨	0.133+0.001 −0.002	20.00+0.02 −0.01	0.06 ± 0.13	—	—
c (unconfirmed)	≥3.1+1.4 −1.1 M🜨	0.195+0.009 −0.011	35.362+0.088 −0.106	0.03 ± 0.28	—	—
h (unconfirmed)	≥1.83+0.68 −0.26 M🜨	0.243 ± 0.003	49.41+0.08 −0.10	0.23+0.16 −0.15	—	—
d (unconfirmed)	≥3.6 ± 1.7 M🜨	0.374+0.017 −0.020	94.11+0.70 −0.63	0.08 ± 0.26	—	—
e (unconfirmed)	≥3.93+0.83 −0.64 M🜨	0.538 ± 0.006	162.87+1.08 −0.46	0.18+0.18 −0.14	—	—
f (unconfirmed)	≥3.93+1.05 −1.37 M🜨	1.334+0.017 −0.044	636.13+11.70 −47.69	0.16+0.07 −0.16	—	—
i (unconfirmed)	≤5 MJ	3–20	—	—	—	—
Debris disk	6.2+9.8 −4.6–52+3 −8 AU				35±10°	—

Principal factors driving research interest in Tau Ceti are its proximity, its Sun-like characteristics, and the implications for possible life on its planets. For categorization purposes, Hall and Lockwood report that "the terms 'solarlike star', 'solar analog', and 'solar twin' [are] progressively restrictive descriptions".^[45] Tau Ceti fits the second category, given its similar mass and low variability, but relative lack of metals. The similarities have inspired popular culture references for decades, as well as scientific examination. In 1988, radial-velocity observations ruled out any periodical variations attributable to massive planets around Tau Ceti inside of Jupiter-like distances.^[46][47] Ever more precise measurements continue to rule out such planets, at least until December 2012.^[47] The velocity precision reached is about 11 m/s measured over a 5-year time span.^[48] This result excludes hot Jupiters and probably excludes any planets with minimal mass greater than or equal to Jupiter's mass and with orbital periods less than 15 years.^[49] In addition, a survey of nearby stars by the Hubble Space Telescope's Wide Field and Planetary Camera was completed in 1999, including a search for faint companions to Tau Ceti; none were discovered to limits of the telescope's resolving power.^[50]

However, these searches only excluded larger brown dwarf bodies and closer orbiting giant planets, so smaller, Earth-like planets in orbit around the star, like those discovered in 2012, were not precluded.^[50] If hot Jupiters were to exist in close orbit, they would likely disrupt the star's habitable zone; their exclusion was thus considered positive for the possibility of Earth-like planets.^[46][51] General research has shown a positive correlation between the presence of planets and a relatively high-metallicity parent star, suggesting that stars with lower metallicity such as Tau Ceti have a lower chance of having planets.^[52]

Discovery

On December 19, 2012, evidence was presented that suggested a system of five planets orbiting Tau Ceti.^[7] The planets' estimated minimum masses were between 2 and 6 Earth masses, with orbital periods ranging from 14 to 640 days. One of them, Tau Ceti e, appears to orbit about half as far from Tau Ceti as Earth does from the Sun. With Tau Ceti's luminosity of 52% that of the Sun and a distance from the star of 0.552 AU, the planet would receive 1.71 times as much stellar radiation as Earth does, slightly less than Venus with 1.91 times Earth's. Nevertheless, some research places it within the star's habitable zone.^[11][12] The Planetary Habitability Laboratory has estimated that Tau Ceti f, which receives 28.5% as much starlight as Earth, would be within the star's habitable zone, albeit narrowly.^[13]

New results were published in August 2017.^[43] They confirmed Tau Ceti e and f as candidates but failed to consistently detect planets b (which may be a false negative), c (whose weakly defined apparent signal was correlated to stellar rotation), and d (which did not show up in all data sets). Instead, they found two new planetary candidates, g and h, with orbits of 20 and 49 days. The signals detected from the candidate planets have radial velocities as low as 30 cm/s, and the experimental method used in their detection, as it was applied to HARPS, could in theory have detected down to around 20 cm/s.^[43] The updated 4-planet model is dynamically packed and potentially stable for billions of years.

However, with further refinements, even more candidate planets have been detected. In 2019, a paper published in Astronomy & Astrophysics suggested that Tau Ceti could have a Jupiter or super-Jupiter based on a tangential astrometric velocity of around 11.3 m/s. The exact size and position of this conjectured object have not been determined, though it is at most 5 Jupiter masses if it orbits between 3 and 20 AU.^{[14][nb 4]} A 2020 Astronomical Journal study by astronomers Jeremy Dietrich and Daniel Apai analyzed the orbital stability of the known planets and, considering statistical patterns identified from hundreds of other planetary systems, explored the orbits in which the presence of additional, yet-undetected planets are most likely. This analysis predicted three planet candidates at orbits coinciding with planet candidates b, c, and d.^[54] The close match between the independently predicted planet periods and the periods of the three planet candidates previously identified in radial velocity data supports the genuine planetary nature of candidates b, c, and d. Furthermore, the study also predicts at least one yet-undetected planet between planets e and f, i.e., within the habitable zone.^[54] This predicted exoplanet is identified as PxP-4.^{[nb 5]}

Since Tau Ceti is likely aligned in such a way that it is nearly pole-on to Earth (as indicated by its rotation),^[6] if its planets share this alignment and have nearly face-on orbits, they would be less similar to Earth's mass and more to Neptune, Saturn, or Jupiter. For example, were Tau Ceti f's orbit inclined 70 degrees from being face-on to Earth, its mass would be 4.18+1.12
−1.46 Earth masses, making it a middle-to-low end super-Earth. However, these scenarios aren't necessarily true; since Tau Ceti's debris disk has an inclination of 35±10, the planets' orbits could be similarly inclined. If the debris disk and f's orbits were assumed to be equal, f would be between 5.56+1.48
−1.94 and 9.30+2.48
−3.24 Earth masses, making it slightly more likely to be a mini-Neptune. On top of that, the lower the inclination of the planetary orbits the less stable they tend to be over a given time period, as the planets would have greater masses and therefore more gravitational pull which would in turn disturb the orbital stability of neighbouring planets. So, for example, if as estimated in the Korolik et al 2023 study Tau Ceti has a pole-on inclination of around 7 degrees, and the postulated planets do as well, then those planets' orbits would be verging on instability within just a 10 million year timeframe, and therefore it is extremely unlikely they would have survived for the billions of years that make up the lifetime of the star system.^[6]

Tau Ceti e

Main article: Tau Ceti e

Tau Ceti e is a candidate^[43] planet orbiting Tau Ceti that was first proposed in 2012 by statistical analyses of the data of the star's variations in radial velocity that were obtained using HIRES, AAPS, and HARPS.^[7][55] Its possible properties were refined in 2017:^[43] if confirmed, it would orbit at a distance of 0.552 AU (between the orbits of Venus and Mercury in the Solar System) with an orbital period of 168 days and has a minimum mass of 3.93 Earth masses. If Tau Ceti e possessed an Earth-like atmosphere, the surface temperature would be around 68 °C (154 °F).^[56] Based upon the incident flux upon the planet, a study by Güdel et al. (2014) speculated that the planet may lie outside the habitable zone and closer to a Venus-like world.^[57]

Tau Ceti f

Main article: Tau Ceti f

Tau Ceti f is a candidate^[43] planet orbiting Tau Ceti that was proposed in 2012 by statistical analyses of the star's variations in radial velocity, and also recovered by further analysis in 2017.^[7] It is of interest because its orbit places it in Tau Ceti's extended habitable zone.^[58] However, a 2015 study implies that it would have been in the temperate zone for less than one billion years, so there may not be a detectable biosignature.^[59]

Few properties of the planet are known other than its orbit and mass. It orbits Tau Ceti at a distance of 1.35 AU (near Mars's orbit in the Solar System) with an orbital period of 642 days and has a minimum mass of 3.93 Earth masses.^[43]

However, a reanalysis of the data in 2021 provided an in-depth study of the HARPS spectrograph systematics, showing that the 600-day signal was likely a spurious combination of instrumental systematics with a potential 1000-day yet unknown signal.^[15]

Debris disk

In 2004, a team of UK astronomers led by Jane Greaves discovered that Tau Ceti has more than ten times the amount of cometary and asteroidal material orbiting it than does the Sun. This was determined by measuring the disk of cold dust orbiting the star produced by collisions between such small bodies.^[60] This result puts a damper on the possibility of complex life in the system, because any planets would suffer from large impact events roughly ten times more frequently than Earth. Greaves noted at the time of her research that "it is likely that [any planets] will experience constant bombardment from asteroids of the kind believed to have wiped out the dinosaurs".^[61] Such bombardments would inhibit the development of biodiversity between impacts.^[62] However, it is possible that a large Jupiter-sized gas giant (such as the proposed planet "i") could deflect comets and asteroids.^[60]

The debris disk was discovered by measuring the amount of radiation emitted by the system in the far infrared portion of the spectrum. The disk forms a symmetric feature that is centered on the star, and its outer radius averages 55 AU. The lack of infrared radiation from the warmer parts of the disk near Tau Ceti implies an inner cut-off at a radius of 10 AU. By comparison, the Solar System's Kuiper belt extends from 30 to 50 AU. To be maintained over a long period of time, this ring of dust must be constantly replenished through collisions by larger bodies.^[60] The bulk of the disk appears to be orbiting Tau Ceti at a distance of 35–50 AU, well outside the orbit of the habitable zone. At this distance, the dust belt may be analogous to the Kuiper belt that lies outside the orbit of Neptune in the Solar System.^[60]

Tau Ceti shows that stars need not lose large disks as they age, and such a thick belt may not be uncommon among Sun-like stars.^[63] Tau Ceti's belt is only 1/20 as dense as the belt around its young neighbor, Epsilon Eridani.^[60] The relative lack of debris around the Sun may be the unusual case: one research-team member suggests the Sun may have passed close to another star early in its history and had most of its comets and asteroids stripped away.^[61] Stars with large debris disks have changed the way astronomers think about planet formation because debris disk stars, where dust is continually generated by collisions, appear to form planets readily.^[63]

Habitability

Tau Ceti's habitable zone—the locations where liquid water could be present on an Earth-sized planet—spans a radius of 0.55–1.16 AU, where 1 AU is the average distance from the Earth to the Sun.^[64] Primitive life on Tau Ceti's planets may reveal itself through an analysis of atmospheric composition via spectroscopy, if the composition is unlikely to be abiotic, just as oxygen on Earth is indicative of life.^[65]

 

Tau Ceti could have been a search target for the canceled Terrestrial Planet Finder

The most optimistic search project to date was Project Ozma, which was intended to "search for extraterrestrial intelligence" (SETI) by examining selected stars for indications of artificial radio signals. It was run by the astronomer Frank Drake, who selected Tau Ceti and Epsilon Eridani as the initial targets. Both are located near the Solar System and are physically similar to the Sun. No artificial signals were found despite 200 hours of observations.^[66] Subsequent radio searches of this star system have turned up negative.

This lack of results has not dampened interest in observing the Tau Ceti system for biosignatures. In 2002, astronomers Margaret Turnbull and Jill Tarter developed the Catalog of Nearby Habitable Systems (HabCat) under the auspices of Project Phoenix, another SETI endeavour. The list contained more than 17000 theoretically habitable systems, approximately 10% of the original sample.^[67] The next year, Turnbull would further refine the list to the 30 most promising systems out of 5000 within 100 light-years from the Sun, including Tau Ceti; this will form part of the basis of radio searches with the Allen Telescope Array.^[68] She chose Tau Ceti for a final shortlist of just five stars suitable for searches by the (now cancelled)^[69] Terrestrial Planet Finder telescope system, commenting that "these are places I'd want to live if God were to put our planet around another star".^[70]

See also

• Epsilon Eridani
• List of nearest stars and brown dwarfs
• List of potentially habitable exoplanets
• List of nearest terrestrial exoplanet candidates
• Tau Ceti in fiction

Notes

1. From knowing the absolute visual magnitude of Tau Ceti, ${\displaystyle M_{V_{\ast }}=5.69}$ , and the absolute visual magnitude of the Sun, ${\displaystyle M_{V_{\odot }}=4.83}$ , the visual luminosity of Tau Ceti can therefore be calculated: ${\displaystyle L_{V_{\ast }}/L_{V_{\odot }}=10^{0.4(M_{V_{\odot }}-M_{V_{\ast }})}}$ .
2. From Tau Ceti the Sun would appear on the diametrically opposite side of the sky at the coordinates RA = 13^h 44^m 04^s, Dec = 15° 56′ 14″, which is located near Tau Boötis. The absolute magnitude of the Sun is 4.8, so, at a distance of 3.65 pc, the Sun would have an apparent magnitude ${\displaystyle m=M_{v}+5\cdot (\log _{10}3.64-1)=2.6}$ .
3. The net proper motion is given by ${\displaystyle \mu ={\sqrt {\mu _{\delta }^{2}+\mu _{\alpha }^{2}\cdot \cos ^{2}\delta }}=1907.79~{\text{mas/y}}}$ , where μ_α and μ_δ are the components of proper motion in the RA and declination respectively, and δ is the declination. See: Majewski, Steven R. (2006). "Stellar Motions". University of Virginia. Archived from the original on 2012-01-25. Retrieved 2007-09-27.
4. If a planet is confirmed to be the cause of this signal, as of August 2020 it would be designated as Tau Ceti i in accordance with IAU exoplanet naming policies.^[53]
5. If a planet corresponding to this predicted candidate is confirmed, as of August 2020 it would be designated as Tau Ceti i in accordance with IAU exoplanet naming policies,^[53] or Tau Ceti j were the candidate Jovian planet confirmed first.

References

1. 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. Teixeira, T. C.; Kjeldsen, H.; Bedding, T. R.; Bouchy, F.; Christensen-Dalsgaard, J.; Cunha, M. S.; Dall, T.; et al. (January 2009). "Solar-like oscillations in the G8 V star τ Ceti". Astronomy and Astrophysics. 494 (1): 237–242. arXiv:0811.3989. Bibcode:2009A&A...494..237T. doi:10.1051/0004-6361:200810746. S2CID 59353134.
3. Keenan, Philip C; McNeil, Raymond C (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
4. "Tau Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-05.
5. Nidever, David L.; et al. (2002). "Radial Velocities for 889 Late-Type Stars". The Astrophysical Journal Supplement Series. 141 (2): 503–522. arXiv:astro-ph/0112477. Bibcode:2002ApJS..141..503N. doi:10.1086/340570. S2CID 51814894.
6. Korolik, Maria; Roettenbacher, Rachael M.; Fischer, Debra A.; et al. (September 1, 2023). "Refining the Stellar Parameters of τ Ceti: a Pole-on Solar Analog". The Astronomical Journal. 166 (3): 123. arXiv:2307.10394. doi:10.3847/1538-3881/ace906. ISSN 0004-6256.
7. Tuomi, M; Jones, H R A; Jenkins, J S; Tinney, C G; Butler, R P; Vogt, S S; Barnes, J R; Wittenmyer, R A; o'Toole, S; Horner, J; Bailey, J; Carter, B D; Wright, D J; Salter, G S; Pinfield, D (2013). "Signals embedded in the radial velocity noise". Astronomy & Astrophysics. 551: A79. arXiv:1212.4277. Bibcode:2012yCat..35510079T. doi:10.1051/0004-6361/201220509. S2CID 2390534.
8. Baliunas, S.; Sokoloff, D.; Soon, W. (1996). "Magnetic Field and Rotation in Lower Main-Sequence Stars: an Empirical Time-dependent Magnetic Bode's Relation?". Astrophysical Journal Letters. 457 (2): L99. Bibcode:1996ApJ...457L..99B. doi:10.1086/309891.
9. Tang, Y. K.; Gai, N. (February 2011). "Asteroseismic modelling of the metal-poor star τ Ceti". Astronomy & Astrophysics. 526: A35. arXiv:1010.3154. Bibcode:2011A&A...526A..35T. doi:10.1051/0004-6361/201014886. S2CID 119099287.
10. Cox, Arthur N., ed. (2001-04-20), Allen's Astrophysical Quantities (Fourth ed.), Springer, p. 382, ISBN 0-387-95189-X.
11. "Tau Ceti's planets nearest around single, Sun-like star". BBC News. December 19, 2012.
12. . Astrobiology Magazine. December 19, 2012. Archived from the original on 2020-11-06.{{cite news}}: CS1 maint: unfit URL (link)
13. Torres, Abel Mendez (December 28, 2012). . Planetary Habitability Laboratory. University of Puerto Rico. Archived from the original on 2021-03-08. Retrieved 2013-03-22.
14. Kervella, Pierre; Arenou, Frédéric; et al. (2019). "Stellar and substellar companions of nearby stars from Gaia DR2". Astronomy & Astrophysics. 623: A72. arXiv:1811.08902. Bibcode:2019A&A...623A..72K. doi:10.1051/0004-6361/201834371. ISSN 0004-6361. S2CID 119491061. We also detect the signature of a possible planet of a few Jovian masses orbiting τ Ceti…The observed signal could be explained for example, by a Jupiter analog orbiting at 5au.
15. Cretignier, Michael; Dumusque, Xavier.; et al. (September 2021). "YARARA: Significant improvement in RV precision through post-processing of spectral time series". Astronomy & Astrophysics. 653: A43. arXiv:2106.07301. doi:10.1051/0004-6361/202140986.
16. Rutkowski, Chris A. (2010), The Big Book of UFOs, Dundurn, p. 33, ISBN 978-1554887606
17. Knobel, E. B. (June 1895). "Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket". Monthly Notices of the Royal Astronomical Society. 55 (8): 429. Bibcode:1895MNRAS..55..429K. doi:10.1093/mnras/55.8.429.
18. Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 162. ISBN 0-486-21079-0. Retrieved 2010-12-12.
19. η Cet as Aoul al Naamat or Prima Sthrutionum (the first of the ostriches), θ Cet as Thanih al Naamat or Secunda Sthrutionum (the second of the ostriches), τ Cet as Thalath al Naamat or Tertia Sthrutionum (the third of the ostriches), and ζ Cet as Rabah al Naamat or Quarta Sthrutionum (the fourth of the ostriches). υ Cet should be Khamis al Naamat or Quinta Sthrutionum (the fifth of the ostriches) consistently, but Al Achsasi Al Mouakket designated the title the fifth of the ostriches to γ Gam with uncleared consideration.
20. 陳久金 (2005). 中國星座神話 (in Chinese). 台灣書房出版有限公司. ISBN 978-986-7332-25-7.
21. 陳輝樺, ed. (July 10, 2006). 天文教育資訊網 [Activities of Exhibition and Education in Astronomy (AEEA)] (in Chinese).
22. Reid, Neill (February 23, 2002). "Meeting the neighbours: NStars and 2MASS". Space Telescope Science Institute. Retrieved 2006-12-11.
23. Henry, Todd J. (October 1, 2006). . Research Consortium on Nearby Stars. Archived from the original on November 28, 2006. Retrieved 2006-12-11.
24. Butler, R. P.; Marcy, G. W.; Williams, E.; McCarthy, C.; Dosanjh, P.; Vogt, S. S. (1996). "Attaining Doppler Precision of 3 M s-1". Publications of the Astronomical Society of the Pacific. 108: 500. Bibcode:1996PASP..108..500B. doi:10.1086/133755.
25. Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics, 575: 13, arXiv:1412.3648, Bibcode:2015A&A...575A..35B, doi:10.1051/0004-6361/201425221, S2CID 59039482, A35.
26. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
27. Porto de Mello, G. F.; del Peloso, E. F.; Ghezzi, L. (2006). "Astrobiologically interesting stars within 10 parsecs of the Sun". Astrobiology. 6 (2): 308–331. arXiv:astro-ph/0511180. Bibcode:2006AsBio...6..308P. doi:10.1089/ast.2006.6.308. PMID 16689649. S2CID 119459291.
28. Kaler, James. "Tau Ceti". Stars. University of Illinois. Retrieved 27 July 2015.
29. "00-06 hour section". Washington Double Star Catalog. United States Naval Observatory. Retrieved 27 July 2015.
30. Pijpers, F. P.; Teixeira, T. C.; Garcia, P. J.; Cunha, M. S.; Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J. (2003). "Interferometry and asteroseismology: The radius of τ Ceti". Astronomy & Astrophysics. 401 (1): L15–L18. Bibcode:2003A&A...406L..15P. doi:10.1051/0004-6361:20030837.
31. Di Folco, E.; Thévenin, F.; Kervella, P.; Domiciano de Souza, A.; du Foresto; V. Coudé; Ségransan, D.; et al. (2004). "VLTI near-IR interferometric observations of Vega-Like Stars". Astronomy and Astrophysics. 426 (2): 601–617. Bibcode:2004A&A...426..601D. doi:10.1051/0004-6361:20047189.
32. . Mount Wilson Observatory. Archived from the original on 2006-08-31. Retrieved 2006-11-15.
33. Gray, D. F.; Baliunas, S. L. (1994). "The activity cycle of tau Ceti". Astrophysical Journal. 427 (2): 1042–1047. Bibcode:1994ApJ...427.1042G. doi:10.1086/174210.
34. Hall, J. C.; Lockwood, G. W.; Gibb, E. L. (1995). "Activity cycles in cool stars. 1: Observation and analysis methods and case studies of four well-observed examples". Astrophysical Journal. 442 (2): 778–793. Bibcode:1995ApJ...442..778H. doi:10.1086/175483.
35. Carraro, G.; Ng, Y. K.; Portinari, L. (1999). "Age Metallicity Relation and Star Formation History of the Galactic Disk". Monthly Notices of the Royal Astronomical Society. 296 (4): 1045–1056. arXiv:astro-ph/9707185. Bibcode:1998MNRAS.296.1045C. doi:10.1046/j.1365-8711.1998.01460.x. S2CID 14071760.
36. de Strobel; G. Cayrel; Hauck, B.; François, P.; Thevenin, F.; Friel, E.; Mermilliod, M.; et al. (1991). "A catalogue of Fe/H determinations". Astronomy and Astrophysics Supplement Series. 95 (2) (1991 ed.): 273–336. Bibcode:1992A&AS...95..273C.
37. Flynn, C.; Morell, O. (1997). "Metallicities and kinematics of G and K dwarfs". Monthly Notices of the Royal Astronomical Society. 286 (3): 617–625. arXiv:astro-ph/9609017. Bibcode:1997MNRAS.286..617F. doi:10.1093/mnras/286.3.617. S2CID 15818154.
38. Frick, P.; Baliunas, S. L.; Galyagin, D.; Sokoloff, D.; Soon, W. (1997). "Wavelet Analysis of Stellar Chromospheric Activity Variations". The Astrophysical Journal. 483 (1): 426–434. Bibcode:1997ApJ...483..426F. doi:10.1086/304206.
39. Judge, P. G.; Saar, S. H. (July 18, 1995). "The outer solar atmosphere during the Maunder Minimum: A stellar perspective". The Astrophysical Journal. 663 (1). High Altitude Observatory: 643–656. Bibcode:2007ApJ...663..643J. doi:10.1086/513004.
40. Judge, Philip G.; Saar, Steven H.; Carlsson, Mats; Ayres, Thomas R. (2004). "A Comparison of the Outer Atmosphere of the "Flat Activity" Star τ Ceti (G8 V) with the Sun (G2 V) and α Centauri A (G2 V)". The Astrophysical Journal. 609 (1): 392–406. Bibcode:2004ApJ...609..392J. doi:10.1086/421044.
41. Smith, G.; Drake, J. J. (July 1987). "The wings of the calcium infrared triplet lines in solar-type stars". Astronomy and Astrophysics. 181 (1): 103–111. Bibcode:1987A&A...181..103S.
42. Lawler, S. M.; et al. (2014). "The debris disc of solar analogue τ Ceti: Herschel observations and dynamical simulations of the proposed multiplanet system" (PDF). Monthly Notices of the Royal Astronomical Society. 444 (3): 2665. arXiv:1408.2791. Bibcode:2014MNRAS.444.2665L. doi:10.1093/mnras/stu1641. S2CID 5102812. Retrieved 2018-11-04.
43. Feng, Fabo; et al. (2017). "Color Difference Makes a Difference: Four Planet Candidates around Tau Ceti". The Astronomical Journal. 154 (4): 135. arXiv:1708.02051. Bibcode:2017AJ....154..135F. doi:10.3847/1538-3881/aa83b4. S2CID 53500995.
44. MacGregor, Meredith A; et al. (2016). "ALMA Observations of the Debris Disk of Solar Analogue Tau Ceti". The Astrophysical Journal. 828 (2): 113. arXiv:1607.02513. Bibcode:2016ApJ...828..113M. doi:10.3847/0004-637X/828/2/113. S2CID 55806829.
45. Hall, J. C.; Lockwood, G. W. (2004). "The Chromospheric Activity and Variability of Cycling and Flat Activity Solar-Analog Stars". The Astrophysical Journal. 614 (2): 942–946. Bibcode:2004ApJ...614..942H. doi:10.1086/423926.
46. Campbell, Bruce; Walker, G. A. H. (August 1988). "A Search for Substellar Companions to Solar-Type Stars". Astrophysical Journal. 331: 902–921. Bibcode:1988ApJ...331..902C. doi:10.1086/166608.
47. . Extrasolar Planets Encyclopaedia. Archived from the original on 2007-10-12. Retrieved 2007-09-28.
48. Endl, M.; Kurster M.; Els S. (2002). "The planet search program at the ESO Coud´e Echelle spectrometer". Astronomy & Astrophysics. 392 (2): 585–594. arXiv:astro-ph/0207512. Bibcode:2002A&A...392..671E. doi:10.1051/0004-6361:20020937. S2CID 17393347.
49. Walker, Gordon A. H.; Walker Andrew H.; Irwin W. Alan; et al. (1995). "A Search for Jupiter-Mass Companions to Nearby Stars". Icarus. 116 (2): 359–375. Bibcode:1995Icar..116..359W. doi:10.1006/icar.1995.1130. However, this does not exclude the possibility of a large planet with a mass greater than Jupiter's and an orbital plane that is nearly perpendicular to the line of sight.
50. Schroeder, D. J.; Golimowski, D. A.; Brukardt, R. A.; et al. (2000). "A Search for Faint Companions to Nearby Stars Using the Wide Field Planetary Camera 2". Astronomical Journal. 119 (2): 906–922. Bibcode:2000AJ....119..906S. doi:10.1086/301227.
51. "Tau Ceti". Sol Company. Retrieved 2007-09-25.
52. Gonzalez, G. (March 17–21, 1997). "The Stellar Metallicity – Planet Connection". Brown Dwarfs and Extrasolar Planets. 134. ASP Conference Series: 431. Bibcode:1998ASPC..134..431G.
53. "Naming of Exoplanets". IAU. Retrieved August 12, 2020.
54. Dietrich, Jeremy; Apai, Dániel (2020-10-27). "An Integrated Analysis with Predictions on the Architecture of the tau Ceti Planetary System, Including a Habitable Zone Planet". The Astronomical Journal. 161: 17. arXiv:2010.14675. doi:10.3847/1538-3881/abc560. S2CID 225094415.
55. "Four Exoplanets Detected around Nearby Star Tau Ceti | Astronomy". Breaking Science News | Sci-News.com. Retrieved 2020-10-07.
56. Giovanni F. Bignami (2015). The Mystery of the Seven Spheres: How Homo sapiens will Conquer Space. Springer. ISBN 9783319170046., Page 110.
57. Güdel, M.; et al. (2014). "Astrophysical Conditions for Planetary Habitability". In Beuther, Henrik; Klessen, Ralf S.; Dullemond, Cornelis P.; Henning, Thomas (eds.). Protostars and Planets VI. Tucson: University of Arizona Press. pp. 883–906. arXiv:1407.8174. Bibcode:2014prpl.conf..883G. doi:10.2458/azu_uapress_9780816531240-ch038.
58. . Planetary Habitability Laboratory @ UPR Arecibo. Archived from the original on 2021-03-08. Retrieved 2014-01-08.
59. Wall, Mike (April 24, 2015). "Nearby Alien Planets Not So Life-Friendly After All". Space.com. Retrieved 2018-02-05.
60. J. S. Greaves; M. C. Wyatt; W. S. Holland; W. R. F. Dent (2004). "The debris disc around tau Ceti: a massive analogue to the Kuiper Belt". Monthly Notices of the Royal Astronomical Society. 351 (3): L54–L58. Bibcode:2004MNRAS.351L..54G. doi:10.1111/j.1365-2966.2004.07957.x.
61. McKee, Maggie (July 7, 2004). . New Scientist. Archived from the original on December 24, 2007.
62. Schirber, Michael (March 12, 2009). . NASA Astrobiology. Archived from the original on 2011-05-27. Retrieved 2009-03-12.{{cite web}}: CS1 maint: unfit URL (link)
63. Greaves, Jane S. (January 2005). "Disks Around Stars and the Growth of Planetary Systems". Science. 307 (5706): 68–71. Bibcode:2005Sci...307...68G. doi:10.1126/science.1101979. PMID 15637266. S2CID 27720602.
64. Cantrell, Justin R; et al. (October 2013). "The Solar Neighborhood XXIX: The Habitable Real Estate of Our Nearest Stellar Neighbors". The Astronomical Journal. 146 (4): 99. arXiv:1307.7038. Bibcode:2013AJ....146...99C. doi:10.1088/0004-6256/146/4/99. S2CID 44208180.
65. Woolf, Neville; Angel, J. Roger (September 1998). "Astronomical Searches for Earth-like Planets and Signs of Life". Annual Review of Astronomy and Astrophysics. 36 (1): 507–537. Bibcode:1998ARA&A..36..507W. doi:10.1146/annurev.astro.36.1.507. S2CID 45235649.
66. Alexander, Amir (2006). . The Planetary Society. Archived from the original on 2007-09-29. Retrieved 2006-11-08.
67. Turnbull, Margaret C.; Tarter, Jill (March 2003). "Target Selection for SETI. I. A Catalog of Nearby Habitable Stellar Systems". Astrophysical Journal Supplement Series. 145 (1): 181–198. arXiv:astro-ph/0210675. Bibcode:2003ApJS..145..181T. doi:10.1086/345779. S2CID 14734094.
68. . Sol Company. Archived from the original on 2011-06-28. Retrieved 2007-09-21.
69. . Planetary Society. 2006-02-06. Archived from the original on 2006-06-16. Retrieved 2006-07-17.
70. . American Association for the Advancement of Science. February 18, 2006. Archived from the original on July 22, 2011. Retrieved 2007-09-21.

Further reading

• Pagano, Michael; et al. (April 2015), "The Chemical Composition of τ Ceti and Possible Effects on Terrestrial Planets", The Astrophysical Journal, 803 (2): 90, arXiv:1503.04189, Bibcode:2015ApJ...803...90P, doi:10.1088/0004-637X/803/2/90, S2CID 119103881, 90.
• Teixeira, T. C.; et al. (January 2009), "Solar-like oscillations in the G8 V star τ Ceti", Astronomy and Astrophysics, 494 (1): 237–242, arXiv:0811.3989, Bibcode:2009A&A...494..237T, doi:10.1051/0004-6361:200810746, S2CID 59353134.
• di Folco, E.; et al. (November 2007), "A near-infrared interferometric survey of debris disk stars. I. Probing the hot dust content around ɛ Eridani and τ Ceti with CHARA/FLUOR", Astronomy and Astrophysics, 475 (1): 243–250, arXiv:0710.1731, Bibcode:2007A&A...475..243D, doi:10.1051/0004-6361:20077625, S2CID 9594917.
• Rammacher, W.; Cuntz, M. (September 2003), "Acoustic Heating Models for the Basal Flux Star τ Ceti Including Time-dependent Ionization: Results for Ca II and Mg II Emission", The Astrophysical Journal, 594 (1): L51–L54, Bibcode:2003ApJ...594L..51R, doi:10.1086/378312, S2CID 120328068.
• Gray, David F.; Baliunas, Sallie L. (June 1994), "The Activity Cycle of tau Ceti", Astrophysical Journal, 427: 1042, Bibcode:1994ApJ...427.1042G, doi:10.1086/174210.
• Arribas, S.; Martinez-Roger, C. (1988), Cayrel de Strobel, G.; Spite, Monique (eds.), "Iron Lines and Surface Gravity Determination for τ Ceti", The Impact of Very High S/N Spectroscopy on Stellar Physics: Proceedings of the 132nd Symposium of the International Astronomical Union held in Paris, France, June 29-July 3, 1987. International Astronomical Union. Symposium no. 132, vol. 132, Dordrecht: Kluwer Academic Publishers, p. 445, Bibcode:1988IAUS..132..445A.

External links

 

Wikimedia Commons has media related to Tau Ceti.

• Near Star Catalog
• at Jim Kaler's STARS site
• Tau Ceti: Life Amidst Catastrophe? at Centauri Dreams