Comments on: The exoplanet photo gallery is bigger than you think

By: Элитные дети: маленькие и большие

Элитные дети: маленькие и большие — Sun, 01 Feb 2009 11:27:44 +0000

[…] The exoplanet photo gallery is bigger than you think […]

By: Alan Fitzsimmons

Alan Fitzsimmons — Mon, 24 Nov 2008 18:31:48 +0000

You’ve missed the point. The temperature maps derived for previous exoplanets have been derived by subtracting the flux from the parent star to reveal the weak thermal radiation from the exoplanet. All data on exoplanets to date has been inferred from observations of the parent star – be it their detection via radial velocity shifts or transits or similar techniques. These are the first observations where the light from the planet is clearly separated from the light of its parent star, and paves the way for resolved imaging and spectroscopy of other planetary systems.

Oh, and no one has used “photographs” in professional astronomy for many years, but we do obtain images using sensitive electronic detectors from the gamma-ray to radio regimes of the e/m spectrum, as do all other fields of physics.

By: Dave Mosher

Dave Mosher — Mon, 17 Nov 2008 13:19:51 +0000

Hubble does have good PR, but also consider this: HD 189733b was discovered via the transit technique and never directly imaged as the Fomalhaut b exoplanet was (among others).
Some pretty complex techniques had to be used to infer the temperature map, whereas in this case (as devicerandom points out) it’s visible light bouncing off a cooler object.

By: devicerandom

devicerandom — Mon, 17 Nov 2008 11:30:12 +0000

As far as I can tell, HD 189733b has been mapped but not photographed. Being so close to its star, it would have been very hard to photograph it. Mapping has been done by IR spectroscopy and looking at the difference between the star signal and the (star+planet) signal during transits.

There *are* indeed other photos of exoplanets in the IR (see 2M1207b) , but the Hubble one is a historical landmark because:
– it is the first in visible light
– it is the first image by the starlight reflected from the planet, instead of the IR emission of the accreting, still hot planet.

So it is the first image of the sunshine reflected by a cold exoplanet. It is the kind of familiar image we have of *our system* planets. That’s why it is so jaw-dropping.