'Hidden' planets in Hubble data

A new image processing technology could allow astronomers to discover extraterrestrial planets that might be lurking in the data of more than a decade of the Hubble Space Telescope.

David Lafreniere of the University of Toronto, Ontario, Canada, has succeeded in proving the search for planets by recognizing extraterrestrial planets not discovered in Hubble's 1998 images with Spectrophotometers. Near-infrared and multi-object (NICMOS). In addition to illustrating the capabilities of the new image processing technology, this finding also underscores the value of the Hubble data obtained.

The planet, estimated to be at least 7 times more massive than Jupiter, was first discovered in photographs taken by Keck and Gemini North telescopes in 2007 and 2008. This is the outermost planet in 3 planets. revolving around the young star HR 8799, located 130 light years away from us. NICMOS cannot recognize the other two planets because the coronagraphic spot - the device that dims the star's light - interferes with observing the two planets inside.

Lafreniere said: 'We have demonstrated the power of NICMOS much larger than previously thought. Our new image processing technology can eliminate the light of a star that obscures the planet, allowing us to observe planets with only one tenth the light of Hubble's previous limit. . Lafreniere uses the first developed image processing technology for terrestrial observatories.

Using this new technology, he discovered the planet in NICMOS's observations made 10 years ago by Keck / Gemini. Hubble's picture not only confirms the existence of the planet, but also provides the basis to prove that the object is in orbit of the star. Lafreniere said: 'To be able to determine the orbit of the planet we have to wait a long time because the planet moves very slowly (400-year cycle). Hubble's 10-year-old data is the basis for its trajectory. '

The image of NICMOS also provides new insights into the physical properties of the planet, because NICMOS operates at near-infrared wavelengths, blocked by the Earth's atmosphere due to the absorption of water vapor.

Travis Barman of Lowell Observatory, Flagstaff, Ariz, said: 'The planet seems to be partially covered by clouds and we can detect the absorption of water vapor in the atmosphere. Infrared light measured from Hubble data is also consistent with the spectrum that shows the water absorption properties (1.4 to 1.49 microns), but the absorption level is lower than when the light book did not exist. dust. Dust clouds can remove spectral essences - including water absorption. Measuring water absorption properties will tell us a lot about the temperature and pressure in the atmosphere, as well as the amount of cloud cover. If we can accurately measure the outer planetary water absorption around HR 8799, we will be able to learn a lot about atmospheric properties. Hubble, located far above the Earth's atmosphere, is well suited for this kind of research. '

Illustrative illustration of giant planet HR 8799b. This planet was discovered in 2007 at the Gemini North Observatory. The planet was later identified in the data of the Hubble Infrared and Multi-Object Infrared Spectrometer (NICMOS) after NICMOS's data statistics effort to see if Hubble happened to capture the planet. This is a young and hot planet, temperatures up to 1500 degrees F. It is slightly larger than Jupiter, but has 7 to 10 times the mass. Data analysis of NICMOS shows that the planet has water vapor in the atmosphere and only partially covered by clouds. Scientists still don't know if the planet has a moon or dust ring around it, but the surrounding dust rings are common in planets in the solar system. (Photo: NASA, ESA, and G. Bacon (STScI))

Christian Marois of Herzberg, Victoria, Canada, the Astrophysics Institute, said: 'In the past 10 years, Hubble has been used to observe 200 stars, searching for planets and geospatial. We have a plan to review all the pictures collected and find objects that have not been discovered so far. We will need a few years to detect Keplreian motion of most objects and thereby confirm them as planets. But the most difficult stage is to detect objects'.

If the team found an object with a star in more than one image of NICMOS, and it seems to be moving in an orbit, support observations will be made with a face telescope. land. If they detect an object only once but the brightness and distance to a star match the nature of a planet, they will also perform observations with a ground telescope.

Taking pictures of an extraterrestrial planet is not a simple task. The planet may be billions of times more dense than the stars they orbit around, and the planet's distance to stars is usually equal to 1/2000 the size of the full moon. The planet was discovered from NICMOS data fuzzy 100,000 times more than the star it orbited when observed with near infrared light.

Rene Doyon of the University of Montreal said: 'Even when using the most modern telescope, with the highest resolution, light from the stars will cover the position of the fuzzy planet, making observations of planets That is impossible. Therefore, eliminating the light of the stars from the photos is necessary '.

The stability of the dispersion light in the NICMOS camera, called the point dispersion function (PSF), is the key to using Hubble's image to detect planets. This technology works by capturing images of other stars and combining them to create a star's PSF similar to the star studied. This requires PSF to be quite stable because the images of stars are taken on different days. Atmospheric conditions may change day by day for ground telescopes, but for telescopes the image space of a captured target remains unchanged.