The shadow of a shadow of a planet… and other fun Kepler discoveries

Exoplanets in Multi-body Systems in the Kepler Era is a conference currently under way at the Aspen Center for Physics

Kepler 2013

Physicists hard at work

The meeting is very vibrant, with a mostly very young crowd of active researchers.

There have been a number of very interesting talks reporting some very interesting discoveries, many of which are embargoed…

One, still unpublished discovery, from Josh Carter et al, for a KOI-not-to-be-named, used transit geometry from two planets and measurements of the stellar spin from astroseismology to show that the stellar spin was misaligned to the plane of the transiting planets, but that the two planets were very close to coplanar.
This is somewhat puzzling, because the disk the planets form from carries a lot of angular momentum and should also accrete onto the star and align its spin, but there is a hint of a third planet in the system, which may be misaligned with the other two. If it is aligned with the stellar spin axis, things will get very interesting.

A very cute discovery was presented by Hirano et al: Planet-Planet Eclipse and the Rossiter-McLaughlin Effect of a Multiple Transiting System: Joint Analysis of the Subaru Spectroscopy and the Kepler Photometry

What they found is a two planet transiting system – two separate planets cross in front of the star. The planets are in 10 and 22 day orbits,
but, the planets are closely aligned, and they have caught one planet shadowing the other during transit!


Double shadow transit of KOI-94 – from Hirano et al 2012

ie there are times when both planets are crossing the star, and their tracks are so closely aligned that some of the time one planet shadows the other while they are crossing in front of the star!
This shows up as a very slight re-brightening of the star.
That is the little bump in the middle of the transit dip.
The bump fits the predictions of Ragozzine and Holman (2010).
This is a very cute result.

I’ll add more interesting results as they come and as I have time to do so, except of course those embargoed, we’ll hear about them soon enough… and they’re Soooo COOL! ZOMG!

I did a poster – done enough talking for now:



This is from The SDSS-HET Survey of Kepler Eclipsing Binaries: Spectroscopic Dynamical Masses of the Kepler-16 Circumbinary Planet Hosts – Bender et al, ApJL 2012. Ours is the poster on the right, the one on the left is from John John.

We, by which I mean “they”, since I am but a Pet Theorer, got spectra of the rather faint secondary of Kepler-16 – the first Kepler circumbinary planet – which allowed an independent test of the transit timing variation model to confirm the discovery.
Tricky bit of observation, if I say so meself, using the HRS spectrograph on HET…

More later, hopefully, it is a busy week.


  1. #1 crd2
    February 14, 2013

    Sounds like some new and exciting things are on the horizon. I will be checking in here often to see when the embargo is lifted. Maybe we can somehow get Julian Asange involved so we dont have to wait for the actual release!

  2. #2 Steinn Sigurðsson
    February 14, 2013

    Julian Assange may yet beat the DoJ but I wouldn’t fancy his chances against Leslie Sage.