The Kepler Mission: A Gold Mine of Variable Stars

The Kepler Mission was designed to find transiting, Earth-like exoplanets, by continuously observing over 100,000 stars in a field centered in the constellation of Cygnus. Two years into the mission, it is also providing an extraordinarily rich collection of time-series data for studying variability of stars in our Galaxy, especially low-amplitude variability.

Kepler's  field of view in the constellations Cygnus, Lyra and Draco

Kepler's field of view in the constellations Cygnus, Lyra and Draco

On-line tools are becoming available to study this variability. One of the most powerful is the NASA Star and Exoplanet Database’s (NStED)’s periodogram tool. A periodogram finds periodicities present in time-series data sets, and the associated probability that an individual period arises by chance. NStED serves all the public time-series data released by Kepler (permanently archived at the Multimission Archive at the Space Telescope Science Instiutute), and allows users to calculate periodograms of Kepler data by clicking links on search results pages.

The light curve of KIC 12253350, a late type pulsational variable.

The light curve of KIC 12253350, a late type pulsational variable.

The periodogram of KIC 12253350, showing a period of 1.65 days.

The periodogram of KIC 12253350, showing a period of 1.65 days.

We show one example here – the time-series data and periodogram of the star KIC 12253350. It is a late type pulsating star, whose variations in light are  caused by regular swelling and contracting of its outer layers. The periodogram identifies a peak at a period of 1.65 days – the sharp spike in the bottom figure.

To replicate this analysis, go to http://nsted.ipac.caltech.edu/applications/ETSS/Kepler_index.html, type in 12253350 in the Kepler ID box, and hit the button labeled “View.” You will see the light curve, and a button at the bottom called “Compute Periodogram.” Hit that button to see the periodogram.

Finally, Martin Nicholson of Shropshire, United Kingdom has assembled a very nice web page called “Data Mining the Kepler Mission”, which shows in more detail how to navigate the Kepler data set.

Disclosure: I am the Project Manager for NStED. I wish to thank Ms. Marcy Harbut for contributing material to this post.

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This entry was posted in astroinformatics, Astronomy, astronomy surveys, data archives, education, exoplanets, Kepler, Time domain astronomy, time series data, Transiting exoplanets, Uncategorized, variable stars and tagged , , , , , , . Bookmark the permalink.

5 Responses to The Kepler Mission: A Gold Mine of Variable Stars

  1. Thanks for post, Bruce. It is rather interesting what other archives and individual scientist are doing with public data such as the Kepler data. I think this is a sign of what’s to come. Does NStED provide an API access to their tools so that others can use it?

    Also, just a quick note to remind your readers that while “NStED serves all the public time-series data released by Kepler”, the data from the Kepler Mission is processed and archived in the NASA Optical and UV archive (Multimission Archive at Space Telescope Science Institute – MAST).

    Disclaimer: I am the MAST Archive Scientist.

  2. astrocompute says:

    Thank you for the post. Apologies for omitting the reference to MAST: I have updated the post to include this citation.

    We are working on providing an API – should be available at the end of Summer.

  3. John says:

    Hello, I am looking for a list of Delta Scutis found by the Kepler telescope, would you be able to point me in the proper direction? Thanks!

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