→ Widely unknown Exoplanet Astronomer

An artists impression of ultracool dwarfs, and how they might look like to the naked eye, should you ever travel out into space to have a look at them directly. The hotter ultracool dwarf is on the left. Credit: NASA/JPL-Caltech

The direct imaging method, whereby the exoplanet is photographed directly, is one of the most difficult methods for studying exoplanets. To date, less than 30 exoplanets have been studied this way. The type of exoplanets studied using the direct imaging technique are usually big, bright planets with big orbits. Exoplanets too close to the host star simply get lost in the glare of the star, a bit like looking at a firefly really close to the sun on a bright summers day. One way in which we astronomers can learn something about the exoplanet is by performing what is known as photometry. That is, observing how the amount of light from the planet varies over a period of time. This can give ut some hints as to what the upper visible atmosphere is like.

The ultracool approach

By studying ultracool dwarfs (really cool “small” stars) it will be possible to learn more about the atmospheres of exoplanets. These ultracool dwarfs are similar in temperature to the exoplanets discovered by direct imaging method and also have the advantage of not having a great big blinding star close by. Studying their atmospheres might give us a hint as to what conditions give dusty or clear atmospheres. It is an interesting field of study as it might give us a better understanding of cloud formations in cool atmospheres. Our own solar system show banding and persistent storm systems. How common it is for planets to have these features is something astronomers are trying to figure out.

The Red Spot of Jupiter.

Credit: NASA

Exomoons are moons expected to orbit exoplanets. Although no exomoon discovery has been published to date, there is no doubt that we will find them.

In a recent paper by Simon et. al titeled: Signals of exomoons in averaged light curves of exoplanets they set out to suggest a new method for discovering these exomoons, the so called “Scatter Peak” method. The idea is to study the local scatter in a number folded lightcurves (ideally a 100 or more). It is thought to that this method will allow the discovery of moons around planets with a period of 10-20 days assuming the observations are done during 3 to 5 year long observing campaigns using space observatories.

I find the Scatter Peak method for detecting exomoons very promising provided the three conditions imposed by the authors of the paper are met:

1. The stacking of the individual lightcurves has to be extremely accurate  so that the transit times coincide.
2. The transit observation has to have a continuum (flat part of the lightcurve) which is at least as long as the transit duration itself.
3. The trend filtering must be done so that small deviations immediately before and after the transit of the exoplanet remain unaffected.

A great resource to find out more about exomoons is the recently submitted PhD thesis of David Kipping titled:

“The Transits of Extrasolar Planets with Moons”