This news is AMAZING.

A screenshot from the NASA announcement of Kepler-16 b showing Luke Skywalker on Tatooine

NASA, headed by the Kepler team recently announced the discovery of Kepler-16b, an exoplanet which orbits two binary stars. Something seem oddly familiar? Let’s just say it makes perfect sense to have John Knoll there (visual effects supervisor of Industrial Light & Magic, a division of Lucasfilm Ltd.)

For more news on this matter have a look at this NASA website.

There has recently been a lot of talk in the media about the discovery of new Super-Earths (ESO, BBC). The Kepler team has also announced that they will be revealing new discoveries tomorrow. In this post I thought I might write about the Super-Earths Kepler has found so far.

Super-Earths are a class of exoplanets with masses between 1-10 times the mass of Earth. The study of Super-Earths are of great interest as there is no planet in this mass and size regime in our solar system.

Kepler-10 b – The smallest Super-Earth

Kepler-10 b is the smallest Super-Earth discovered to date with a Radius of 1.4 Earth radii. It is also the first rocky planet found by the Kepler spacecraft and also the first terrestrial planet found outside our solar system. Here is a video by NASA about this exoplanet:

Kepler-11 – A planetary system with multiple Super-Earths

The Kepler-11 planetary system has 4 Super-Earths (so far) and is the most compact exoplanet system discovered to date. Kepler-11 is a remarkable planetary system whose architecture and dynamics provide clues to its formation. More information on this in the discovery paper.

Kepler-9 d – Thought to be a Super-Earth

Kepler-9 d is thought to be a Super-Earth. I say “thought to be” as current spectroscopic observations are still insufficient to establish its mass. The discoverers of the planet led by Torres, G say:

Based on several realistic estimates of this frequency, we conclude with very high confidence that this small signal is due to a super-Earth-size planet (Kepler-9 d) in a multiple system, rather than a false positive.

Secret companion found via Transit Timing Variations

Worth mentioning here is last weeks news of the discovery of Kepler-19 b. What made this discovery so special wasn’t so much the exoplanet Kepler-19 b but that a companion of this planet, Kepler-19 c was found using transit timing variations (mentioned in my post here). In short, transit timing variations deals with inferring the presence of one or more planets due to timing variations in the expected transit time. For this to be possible, very high quality data is needed, something Kepler provides.  Although Kepler-19 is not a Super-Earth it is likely that the transit timing variations technique will discover more Super-Earths in the future.

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”

Here I will go through the steps I use when deciding on which exoplanet to observe using an amateur telescope.

Step 1: Find objects which are bright enough.
Go to the exoplanets.org/table and from the drop down menu on the upper left choose transit planets. Then press the big pluss button (+) on the right and choose V mag under stellar params. You can move this table header next to the exoplanet name on the left side for convenience. Click the V mag tab to sort the magnitudes. To only display the transiting exoplanets where the host star has a know V magnitude write TRANSIT == 1 and V in the filter line. The table should now look something like this:

Step 2: Get the ephemeries

Now that you have an idea of which objects are bright enough you want to know when the transit will occur. To find this information go here. On the left you will se the names of the exoplanets. On the right you can click on ephemeris to get the transit times and dates. If you click on the ephemeris for one of the exoplanets you will be presented with a long list of numbers. The left most column is the date and times for when the transit begins. The middle column represents mid transit and the column on the right represents end of transit. At the top you have the transit duration. Remember that all times are given in UT. In this list of dates and times check to see when the next transit will be.

Step 3: Find out if the transit will be visible from your location

Copy the name of the star which the exoplanet is orbiting, like HD209458 and do a search on SIMBAD to find the coordinates. The name might change. The coordinates you are after are the ICRS coordinates. In this case it would be 22 03 10.78 +18 53 03.7 I would recommend you check the coordinates with those listed on the ephemeris page.

Now that you have the coordinates you want to see when the object is up in the sky (if at all). What a lot of professional astronomers use for this is staralt. Start of by choosing the date of  which the transit will occur. Next it is unlikely you are at a professional observatory so here you will have to enter the coordinates of your observing location. A nice and easy way to get these coordinates is using google maps. Navigate to your location on the map, right click and choose directions from here from the drop down menu. That should give you the coordinates in the text box found at the upper left of your screen. As an example of using staralt I will choose the Norman Lockyer Observatory, in the southern UK which I found (using google earth) has the coordinates 50.687901, -3.219783. The observatory is at a height of about 100 meters above sea level so in the observatory text box in staralt I write: 357.00 50.687901 100 The staralt page should look something like this:

Hit retrieve and a graph will appear. On the left y-axis we have elivation whilst on the x-axis we have time in UT. The dottet vertical lines represents astronomical twilight whilst the curved dottet line (if there is one), represents the moon. An ideal target will have a parabola shaped curve peaking at sometime during the night. Here is an example of an output showing two example targets:

Target1 22 00 00.0 +19 00 00.0
Target2 12 00 00.0 +19 00 00.0

Visibility plot showing two example targets

Target1 is seen on the left and it shows us that is is rising during the morning ours. This object would not be very suitable as I would not like to stay awake that long and also once it rises above 30 degrees twilight has begun. Pretty neat huh?

Target2 is on it’s way up in the beginning of the night peaking at a round 22 UT. The object is visible for quite a while not  setting before 4am. A target with such a visibility curve would be ideal.

So there you have it, repeat the 3 steps until you have a suitable target for the night you wish to observe. Keep in mind, if you are looking for transiting exoplanets with a host star brighter than about 10th magnitude you will definitely not have a transit happening every night.

If something was unclear in my description please comment below and I will answer the question. If you find that something is not clear I am sure other people think the same and will be glad you asked.

Clear skies!

The last couple of days I have spent learning Autodesk Maya which is a 3D computer graphics software. The motivation behind it was to be able to illustrate and animate exoplanet science. Below are a few of my initial results.

I learned a lot of Maya from the Maya videos by Stu. I would recommend you have a look at them.

A map showing the regional interest in "Exoplanets"

Recently more and more people have become interested in Exoplanets. Not much of a surprise really when one takes into account that the first exoplanet was discovery in 1995.

The Countries with the most searches of “Exoplanets” are:

1. United States – 100
2. Germany – 97
3. Canada – 94
4. United Kingdom – 83
5. Australia – 72
6. France – 52

The most populars articles about Exoplanets are:

1. Exoplanet Hunter Finds Bounty of Multi-Planet Solar Systems
2. A gaze at exoplanet haze
3. Extragalactic Exoplanet Found Hiding Out in Milky Way
4. A distant Earth-like exoplanet ‘could have life’
5. Exoplanet could be smallest ever found
6. Astronomers detect first superstorm on exoplanet
7. Newly discovered Jupiter-sized exoplanet might become cosmic ‘Rosetta stone’

source: Google