Day 5/5, Session 1: Direct Imaging of Exoplanets


Hi, Nathan Mayne here with the summary of our last session of the momentous exoclimes 2012 conference in Aspen (I have an end of school summer holidays feeling).

We start with Rémi Soummer (Space Telescope Institute), the attendance, over the week, has followed some combination of an exponential decay, and a phase term minimised at 8am and directly after a skiing break. Rémi’s talk, however, is worth getting up early for, a good overview of direct imaging techniques for exoplanets. This requires planets both well separated from, and with extremely high luminosity, compared to their parent star. This means a young system (<100Myr, after years of deriving ages for young stars it’s hard to stay quiet-nobody cares how wrong the ages could be, except me, stellar chronology is a lonely hobby). HR 8799 system (imaged below), is the poster child for this technique, however the upcoming Gemini Planet ImagerVLT-Sphere and Project 1640 should dramatically increase the number of available systems. Rémi finishes by describing a cool satellite setup involving a space telescope, and a physical coronograph which opens up in a rather excellent petal, sci-fi type fashion and floats 50,000 km from the telescope.

No, this is not an explosion from a 8-bit Nintendo game. Instead it is a archival hubble image of the HR 8799 planetary system made visible due to the LOCI algorithm. Credit: NASA/ESA/STScI

Excellent, a GCM talk in the instrumentation session! Yohai Kaspi presents models of gas giants at and beyond the orbit of Jupiter (these are the types of planets direct imaging will detect). Such planets are dominated by internal heat flux, not irradiation, and the structure of the winds depends on the Rossby number (balance between inertial and coriolis forces).

Now time for a coffee break, a lonely time for me as I don’t drink tea or coffee, I always end up, ostracized standing by my poster clutching a glass of water….(this is why I decided to place my poster right over the coffee preparation area-eureka!).

The late morning session comprises three talks, and to keep strict order during this potentially deathly struggle for the best direct imaging system, Christiane Helling sets an audible alarm when a speakers time is up, an excellent but brutal idea.

In the blue corner an energetic Kerri Cahoy, who I found engaging in spite of my natural allergy to instrumentation. Usefully, the process of separating the light coming from a planet from that of its parent star i.e. a description of the extreme AO system (which I am dissapointed to hear doesn’t involve crocodiles or death rays or anything I would consider extreme!) and the coronograph. Kerri’s particular interest is how such instruments would perform in space, and she plans to, using a 10cm cube, fire $300-400K of precision equipment into space to look at…… A LIGHT BULB! This test is designed to test the optics and not pointing and guidance. Key point: space mission!

In the red corner is, Gautam Vasisht who is extremely cool and shares “first light” results of a next generation high contrast imager called Palomar 1640, which can currently observe to a star-planet flux contrast of 107. As a brief aside he shows a movie of the deformable mirror shaped like Che Guevara, Gautum’s favourite revolutionary. There is a  moment I fear we might have lost him as he intones: dark, bright, bright, dark, dark, bright, bright, dark… in time with the video frames. Currently, the instrument is performing a factor 10 worse than expected, probably due to and the “crud” on the primary (and secondary) mirror (probably thumbs prints or dents from dropped hammers). The thousands of wires required for the actuators on the deformable mirror mean three lucky technicians must have spent a Gyr soldering. Key point: it is working!

Finally, in the urm… purple corner is Eugene Serabyn, opening with “I know you like to go to a telescope and take a picture then go home with no fuss”, yes, that is exactly what I like, in fact (I am ashamed to admit) I prefer service mode (does that make me a bad astronomer?). This instrument includes a novel coronograph using phase blocking, called a Vortex coronograph. He presents some results for HR 8799 and eta Ceph achieving a contrast of 108 using only a 1.5m section of the Palomar mirror. His last slide states “Now go Ski!”. Key point: cool name (who doesn’t like vortex)!

So after the three second session talks I know you are all eager to know who was the winner…… SCIENCE! Thats right science is the winner with so many excellent people willing to fiddle around with soldering irons and welders so that we can turn photons into papers.

And that is it, the end of the conference. I don’t want to sound gushing like someone picking up an Oscar but it really has been an excellent conference and I would like to thank the LOC & SOC, and in particular Nick Cowen, the Aspen Centre for Physics, the exoclimes team, my mum, HD 209458 b, Thor (thunder god) and the lady who cleaned my hotel room.


About Author

I am a Postdoctoral researcher at the University of Exeter. I started working with Prof. Isabelle Baraffe in November 2011 on a project to model the atmospheres of Hot Jupiters using a Global Circulation Model (GCM). My research history includes a Masters level research project on Surface Plasmon Resonance, a PhD in Stellar ages and observational astrophysics and a postdoctoral project on radiative transfer in brown dwarf accretion discs. (More)