Gemini Planet Imager

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The Gemini Planet Imager (GPI) is a high contrast imaging instrument that was built for the

University of Montreal, University of California, Berkeley, University of California, Los Angeles (UCLA), University of California, Santa Cruz (UCSC), University of Georgia.[2]

Specifications

GPI sub-systems diagram.

The Gemini Planet Imager is being used at the Gemini South Telescope, located in

thermal emission. It will operate at near-infrared wavelengths (Y - K bands), where planets will be reasonably bright, but thermal emission from the Earth's atmosphere is not too strong.[3]

The system consists of multiple components, including a high-order adaptive optics system, a

arcseconds, down to an H band magnitude of 23.[5]

Scientific goals

Present day

radial velocity method require observing a star over at least one period of revolution, which is roughly 30 years for a planet at the distance of Saturn. Existing adaptive optics instruments become ineffective at small angular separations, limiting them to semi-major axes larger than about 30 astronomical units. The high contrast of the Gemini Planet Imager at small angular separations will allow it to detect gas giants with semi-major axes of 5–30 astronomical units.[6]

The Gemini Planet Imager will be most effective at detecting young gas giants, one million to one billion years old. The reason for this is that young planets retain heat from their formation, and only gradually cool. While a planet is still hot, it remains bright, and is thus more easily detected. This limits GPI to younger targets, but means that it will yield information about

how gas giants form. In particular, the spectrograph will allow determination of the temperature and surface gravity, which yield information about the atmospheres and thermal evolution of gas giants.[6]

In addition to its main goal of imaging exoplanets, GPI will be capable of studying

planet formation. The technique used to image disks with this instrument is called polarization differential imaging. Another science case is to study Solar System objects at high spatial resolution and high Strehl ratio. Asteroids and their moons, the satellites of Jupiter and Saturn, and the planets Uranus and Neptune are all good targets for GPI. The final ancillary science case is to study the mass loss from evolved stars via their outflow.[citation needed
]

Achievements

The planet 51 Eridani b is the first exoplanet discovered by the Gemini Planet Imager. It is a million times fainter than its parent star and shows the second strongest methane signature ever detected on an alien planet (after only GJ 504b), which should yield additional clues as to how the planet formed.[7]

Evolution

In 2022, GPI was removed from the

Gemini North
telescope and is expected to see first light in late 2024 or early 2025.

Gallery

  • GPI Image of star HR4796a showing the debris disk as seen through polarization measurements.
    GPI Image of star HR4796a showing the debris disk as seen through polarization measurements.

References

  1. ^ Macintosh et al. (2006), p. 1.
  2. ^ a b "GPI: Gemini Planet Imager". Retrieved 2010-03-07.
  3. ^ Graham et al. (2007), p 2.
  4. S2CID 122904075
    .
  5. ^ Macintosh et al. (2006), p. 3.
  6. ^ a b Macintosh et al. (2006), p. 2.
  7. ^ Bjorn, Carey. "Astronomers discover 'young Jupiter' exoplanet". ScienceDaily. Stanford University. Retrieved 17 August 2015.
  8. ^ "GPI 2.0". Retrieved 7 January 2024.

Bibliography

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