Here’s One We Didn’t Discover Earlier

The 1998 archive Hubble image of HR 8799 after image analysis - one of the star's exoplanets have been resolved (NASA/HST)
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

I was just discussing this incredible discovery with my friend Jorge Candeias (@jorgecandeias) on Twitter and he said something rather profound:

I’m a long-time hardcore SF fan. And I’d never even imagined I’d be able to see photos of exoplanets in my lifetime.

I began to think about that myself. Having started “professionally” (as in, “it’s all I do”) blogging about science a little over a year ago, I’ve written about some of the most stunning scientific endeavours imaginable (I won’t list them here, just have a trawl through to see what I mean). Barriers are constantly being broken, the technological envelope is constantly being stretched and there appears to be no end to the astronomical discoveries constantly shaping our perspective of the Universe.

I am in love, that is for certain.

I love the deep complexity of the subatomic world, all the way out to the vast structures that permeate through the cosmos. I also revel in the fact that studies of the very small are directly related to the very big (i.e. the LHC colliding protons will help to boost our knowledge of how our Universe was born 13.7 billion years ago). The stuff we are doing often defies imagination, and in reference to Jorge’s Tweet, I never imagined, just a year ago, that we could ever directly image worlds orbiting other stars.

Keck II follow-up image of planetary system HR 8799 showing all three planets (W.M. Keck Observatory)
Keck II follow-up image of planetary system HR 8799 showing all three planets (W.M. Keck Observatory)

It’s not even as if I considered it would be a possibility, it never even crossed my mind. And now, we have ground-breaking observatories on the ground and in space doing the stuff I didn’t even think would be possible, ever. The first direct imaging results were revealed in November 2008, and already it is becoming “routine” for observatories to find these exoplanets.

Today, a research group from the University of Toronto revealed their new technique of taking old Hubble images, re-analysing them and uncovering the near-infrared emissions from an exoplanet orbiting a star 140 light years away. HR 8799 was the first star to reveal it’s three massive gas giants (two of them 10× and one 7× the size of Jupiter) last year in an observing campaign carried out by the Keck observatory in Hawaii. The Toronto astronomers therefore knew this star had a system of planets, so they took the 1998 Hubble observation and had a play. They eventually managed to cancel out the glare of the star, revealing the outermost exoplanet. The other two are orbiting too close to the star to be resolved.

This technique will hopefully open up more discoveries of exoplanets in the Hubble archive, some estimates predict that there could be hundreds more hiding like precious gems in years of astronomical imagery. What an astounding era for astronomy

For more, check out New Technique Allows Astronomers to Discover Exoplanets in Old Hubble Images

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