51 Pegasi b

Coordinates: Sky map 22h 57m 28.0s, +20° 46′ 08″
Source: Wikipedia, the free encyclopedia.
"Dimidium" redirects here. For the value, see
half. For C. dimidium, see Caladenia dimidia
.
Dimidium/51 Pegasi b
K

51 Pegasi b, officially named Dimidium

extrasolar planet approximately 50 light-years (15 parsecs) away in the constellation of Pegasus. It was the first exoplanet to be discovered orbiting a main-sequence star,[2] the Sun-like 51 Pegasi, and marked a breakthrough in astronomical research. It is the prototype for a class of planets called hot Jupiters.[3]

In 2017, traces of water were discovered in the planet's atmosphere.[4] In 2019, the Nobel Prize in Physics was awarded in part for the discovery of 51 Pegasi b.[5]

Name

51 Pegasi is the Flamsteed designation of the host star. The planet was originally designated 51 Pegasi b by Michel Mayor and Didier Queloz, who discovered the planet in 1995. The following year it was unofficially dubbed "Bellerophon" /bɛˈlɛrəfɒn/ by astronomer Geoffrey Marcy, who followed the convention of naming planets after Greek and Roman mythological figures (Bellerophon is a figure from Greek mythology who rode the winged horse Pegasus).[6]

In July 2014, the

Latin for 'half', referring to the planet's mass of approximately half the mass of Jupiter.[10]

Discovery

The location of 51 Pegasi in Pegasus

The

Observatoire de Haute-Provence telescope in France and made world headlines with their announcement. For this discovery, they were awarded the 2019 Nobel Prize in Physics.[5]

The planet was discovered using a sensitive

gravitational
effects from just 7 million kilometres' distance from the star.

Within a week of the announcement, the planet was confirmed by another team using the Lick Observatory in California.[12]

Physical characteristics

Promotional "Exoplanet Travel Bureau" poster from NASA

After its discovery, many teams confirmed the planet's existence and obtained more observations of its properties. It was discovered that the planet orbits the star in around four days. It is much closer to it than

orbital migration.[3]

Assuming the planet is perfectly grey with no greenhouse or tidal effects, and a Bond albedo of 0.1, the temperature would be 1,265 K (992 °C; 1,817 °F). This is between the predicted temperatures of HD 189733 b and HD 209458 b (1,180 K (910 °C; 1,660 °F)–1,392 K (1,119 °C; 2,046 °F)), before they were measured.[13]

In the report of the discovery, it was initially speculated that 51 Pegasi b was the stripped core of a brown dwarf of a decomposed star and was therefore composed of heavy elements, but it is now believed to be a gas giant. It is sufficiently massive that its thick atmosphere is not blown away by the star's solar wind.

51 Pegasi b probably has a greater

silicates
may exist in the atmosphere.

The planet is tidally locked to its star, always presenting the same face to it.

The planet (with

VLTI Spectro-Imager".[13]

Claims of direct detection of visible light

The first ever direct detection of the

visible light spectrum reflected from an exoplanet has been made by an international team of astronomers on 51 Pegasi b. The astronomers studied light from 51 Pegasi b using the High Accuracy Radial velocity Planet Searcher (HARPS) instrument at the European Southern Observatory's La Silla Observatory in Chile.[15] This detection allowed the inference of a mass of 0.46 Jupiter masses.[16] The optical detection could not be replicated in 2020, implying the planet has an albedo below 0.15.[17] Measurements in 2021 have marginally detected a polarized reflected light signal, which, while they cannot place limits on the albedo without assumptions made about the scattering mechanisms, could suggest a high albedo.[18]

See also

References

  1. ISSN 0004-6361
    .
  2. ^ a b c How the Universe Works 3. Vol. Jupiter: Destroyer or Savior?. Discovery Channel. 2014.
  3. ^
    doi:10.1146/knowable-101019-2
    . Retrieved 4 April 2022.
  4. ^ "Water detected in the atmosphere of hot Jupiter exoplanet 51 Pegasi b". phys.org. February 1, 2017.
  5. ^
    Nobel Media AB
    . Retrieved 8 October 2019.
  6. ^ University of California at Berkeley News Release 1996-17-01
  7. ^ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
  8. ^ "NameExoWorlds The Process". Archived from the original on 2015-08-15. Retrieved 2015-09-05.
  9. ^ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
  10. ^ "NameExoWorlds The Approved Names". Archived from the original on 2018-02-01. Retrieved 2015-12-21.
  11. S2CID 4339201
    .
  12. Bibcode:1995IAUC.6251....1M
    .
  13. ^
    S2CID 119268109
    .
  14. doi:10.1111/j.1365-2966.2008.14182.x
    .
  15. ^ physicsworld.com 2015-04-22 First visible light detected directly from an exoplanet
  16. S2CID 119224213
    .
  17. doi:10.1051/0004-6361/202039271
    .
  18. doi:10.1093/mnras/stab172

Further reading

External links

Wikimedia Commons has media related to 51 Pegasi b.


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