The 1998 archive Hubble image of HR 8799 after image analysis - one of the star's exoplanets have been resolved (D. Lafrenière et al., ApJ Letters)
What’s just as exciting as directly imaging an exoplanet in a new observing campaign? To discover an exoplanet in an old observing campaign.
Like so many significant astronomical discoveries, archival images of the cosmos provide a valuable tool to astronomers. On its most basic level, astronomers can compare new images with images taken by the same (or different) observatory months, years or decades ago. This method can lead to the discovery of planets, asteroids and comets (when comparing two pictures of the night sky, a celestial object appears to move relative to the background stars). However, a new technique to analyse archived Hubble data in the search for exoplanets, has just revealed one of three known exoplanets orbiting the star HR 8699. The image in question was captured in 1998, when astronomers thought HR 8799 was an exoplanet-less star… Continue reading “Here’s One We Didn’t Discover Earlier”
It would appear that yet another extrasolar planet has been directly observed!
Only last week, the Hubble Space Telescope released news that it had spotted an exoplanet orbiting the star Fomalhaut. This is the first ever direct observation of an exoplanet in optical wavelengths. On the same day, joint observations by the ground-based (adaptive optics-powered) Keck II and Gemini infrared telescopes discovered a collection of three large alien worlds orbiting a star catalogued as HR 8799.
Today, a completely different observatory appears to have discovered yet another exoplanet orbiting the hot star Beta Pictoris (in the constellation of Pictor). European Southern Observatory (ESO) astronomers have directly imaged β Pictoris b, an alien planet orbiting 8 AU from its host star.
Two of the three confirmed planets orbiting HR 8799 indicated as “b” and “c” on the image above. “b” is the ~7 Jupiter-mass planet orbiting at about 70 AU, “c” is the ~10 Jupiter-mass planet orbiting the star at about 40 AU. Due to the brightness of the central star, it has been blocked and appears blank in this image to increase visibility of the planets (Gemini Observatory)
The day has finally come. We now have direct, infrared and optical observations of planets orbiting other stars. Yesterday, reports from two independent sources surfaced, one from the Gemini and Keck II observatories and the second from the Hubble Space Telescope. Brace yourself for an awe-inspiring display of planets orbiting two stars…
The Gemini/Keck observations were carried out using adaptive optics technology to correct in real-time for atmospheric turbulence. The stunning images of a multiple planetary star system were then constructed from infrared emissions (the image, top, was constructed by Keck II as a follow-up to to the Gemini observations). The system in question is centred around a star called HR 8799, approximately 130 light years from Earth and in the constellation of Pegasus. The entire press release can be found at the Gemini observatory site, where they give the discovery a full run-down.
On the same day, the Hubble Space Telescope team also released images of one extrasolar planet, only this time in optical wavelengths. Although the exoplanet in Hubble’s images is less obvious than the infrared Gemini/Keck II images, incredible detail has been attained, showing a ring of dust around the star Fomalhaut (located in the constellation of Piscis Austrinus). Fomalhaut is 25 light years away and the star’s daughter planet (Fomalhaut b) is only a little under 3 Jupiter masses.
Estimated to be no more than three times Jupiter’s mass, the planet, called Fomalhaut b, orbits the bright southern star Fomalhaut, located 25 light-years away in the constellation Piscis Austrinus (NASA/ESA)
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