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   Image courtesy of Katrien Uytterhoeven

From: Katrien Uytterhoeven
McDonald Observatory, Texas, August 1, 2010

Stellar Properties and Lone Star Monsoons

Hi from McDonald Observatory in Texas! From the Lone Star State I am observing several dozen targets of the Kepler space mission. All the stars are asteroseismic targets, which means that they show stellar oscillations, and that it is possible to infer information about the stellar interiors by studying the pulsations. To be able to model the stellar interiors we not only need a good characterization of the stellar oscillations, but also an accurate estimate of general properties of the stars. The general properties include surface temperature, surface gravity, rotation rate, and a description of the chemical composition of the star. Stars consist of huge amounts of hydrogen along with helium, and smaller amounts of heavier elements. By decomposing the star light into different wavelengths with a spectrograph, it is possible to study and determine all these properties.

Tonight is my last night of eight nights of observations with the cs23 echelle spectrograph on the 107-inch telescope. The goal is to obtain a good quality spectrum for a selection of Kepler stars to derive general stellar properties. Unfortunately, my observing run has been plagued by thunderstorms and clouds. It is the Monsoon season! So far, I observed 3.5 nights out of seven. Currently, the sky looks promising!

The hills around McDonald observatory and Fort Davis look exceptionally green this summer due to the Monsoon rains of past weeks, and the views are amazing. There are also several interesting insects and birds to spot such as ladybirds, grasshoppers, crickets, butterflies, hummingbirds, and flycatchers. Why don't you come and visit McDonald Observatory and see the telescopes, nature and wildlife yourself? The observatory has a visitor center and organizes tours to visit the telescopes. You also can enjoy the night sky by experiencing a real star party!

Postcards from the Observatory

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