Tau Boötis b

Coordinates: Sky map 13h 47m 15.7s, +17° 27′ 25″
Source: Wikipedia, the free encyclopedia.
Tau Boötis b
Doppler Spectroscopy
Orbital characteristics
0.0481 AU
Eccentricity0.023 ± 0.015 [1]
3.312463 ± 0.000014 [1] d
Inclination44[2]
2,446,957.81 ± 0.54
188
Semi-amplitude461.1
StarTau Boötis
Physical characteristics
Mean radius
1.06[3] RJ
Mass5.5–6[2] MJ
Temperature1,700 K (1,430 °C; 2,600 °F)

Tau Boötis b, or more precisely Tau Boötis Ab, is an

extrasolar planet approximately 51 light-years away. The planet and its host star is one of the planetary systems selected by the International Astronomical Union as part of NameExoWorlds, their public process for giving proper names to exoplanets and their host star (where no proper name already exists).[4][5] The process involved public nomination and voting for the new names, and the IAU planned to announce the new names in mid-December 2015.[6] However, the IAU annulled the vote as the winning name was judged not to conform with the IAU rules for naming exoplanets.[7]

Discovery

Discovered in 1996, the planet is one of the first extrasolar planets found. It was discovered orbiting the star Tau Boo (HR 5185) by

San Francisco Planet Search Project)[8] using the highly successful radial velocity method. Since the star is visually bright and the planet is massive, it produces a very strong velocity signal of 469 ± 5 metres per second, which was quickly confirmed by Michel Mayor and Didier Queloz from data collected over 15 years. It was later confirmed also by the AFOE Planet Search Team
.

Orbit and mass

VLT's wide-field view of the parent star of Tau Boötis b[9]

Tau Boötis b is rather massive, with a

grey with no Greenhouse effect or tidal effects, and a Bond albedo of 0.1, the temperature would be close to 1600 K.[10] Although it has not been detected directly, it is certain that the planet is a gas giant
. As Tau Boötis b is more massive than most known "
transiting planet HD 209458 b
.

In December 1999, a group led by

inclination
of 29° and thus the absolute mass of the planet would be about 8.5 times that of Jupiter. They also suggested that the planet is blue in color. Unfortunately, their observations could not be confirmed and were later proved to be spurious.

A better estimate came from the assumption of tidal lock with the star, which rotates at 40 degrees;[11] fixing the planet's mass between 6 and 7 Jupiter masses. In 2007, magnetic field detection confirmed this estimate.[12]

In 2012 two teams independently distinguished the radial velocity of the planet from the radial velocity of the star by observing the shifting of the spectral lines of carbon monoxide. This enabled calculation of the inclination of the planet's orbit and hence the planet's mass. One team found an inclination of 44.5±1.5 degrees and a mass of 5.95±0.28 MJ.[13] The other team found an inclination of 47−6+7 and a mass of 5.6±0.7 MJ.[14]

Characteristics

Sudarsky class
is V; which is supposed to yield a highly reflective albedo of 0.55.

It has been a candidate for "near-infrared characterization.... with the

VLTI Spectro-Imager".[10] When its atmosphere was measured in 2011, "the new observations indicated an atmosphere with a temperature that falls higher up. This result is the exact opposite of the temperature inversion – an increase in temperature with height – found for other hot Jupiter exoplanets".[2] In 2014, direct detection of water vapor in atmosphere of the planet was announced.[17] Later atmosphere characterization in 2021 have resulted in measured carbon abundance similar to that of Jupiter, in the form of 0.35% carbon monoxide volume admixture to hydrogen-helium atmosphere. The upper limit only of water below 2 parts per million (0.72% of that expected for solar composition) was estimated.[18]

In 2020, a radio emission in the 14-30 MHz band was detected from the Tau Boötis system, likely associated with cyclotron radiation from the poles of Tau Boötis b a signature of a planetary magnetic field.[19][20]

See also

References

  1. ^
    S2CID 119067572
    .
  2. ^ a b c "New Way of Probing Exoplanet Atmospheres" in Science Daily (27 June 2012), https://www.sciencedaily.com/releases/2012/06/120627132051.htm; reporting on Nature (28 June 2012)
  3. doi:10.1111/j.1365-2966.2011.19600.x
    .
  4. ^ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
  5. ^ NameExoWorlds Archived 2016-12-31 at the Wayback Machine.
  6. ^ NameExoWorlds Archived 2015-08-15 at the Wayback Machine.
  7. ^ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
  8. doi:10.1086/310444
    .
  9. ^ "New Way of Probing Exoplanet Atmospheres". ESO Press Release. Retrieved 28 June 2012.
  10. ^
    S2CID 119268109
    .
  11. ^
    S2CID 18584158
    .
  12. S2CID 16003580
    .
  13. S2CID 4368217
    .
  14. S2CID 119177983
    .
  15. S2CID 8684361
    .
  16. doi:10.1093/mnras/stab172
  17. ^ Near-IR Direct Detection of Water Vapor in Tau Boo b: Alexandra C. Lockwood, John A. Johnson, Chad F. Bender, John S. Carr, Travis Barman, Alexander J.W. Richert, Geoffrey A. Blake
  18. S2CID 235166843
  19. S2CID 212883637
  20. ^ O'Callaghan, Jonathan (2023-08-07). "Exoplanets Could Help Us Learn How Planets Make Magnetism". Quanta Magazine. Retrieved 2023-08-07.

External links


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