Kepler out of commission for six days
Kepler, out of commission for six days, is back in operation.
Tag: Kepler
Kepler finds 68 Earthsized planets
Exoplanets galore! The Kepler team announced today the discovery of 68 Earth-sized planets, five in the habitable zone. Key quote:
The discoveries are part of several hundred new planet candidates identified in new Kepler mission science data, released on Tuesday, Feb. 1. The findings increase the number of planet candidates identified by Kepler to-date to 1,235. Of these, 68 are approximately Earth-size; 288 are super-Earth-size; 662 are Neptune-size; 165 are the size of Jupiter and 19 are larger than Jupiter. Of the 54 new planet candidates found in the habitable zone, five are near Earth-sized. The remaining 49 habitable zone candidates range from super-Earth size — up to twice the size of Earth — to larger than Jupiter.
New Kepler results!
Scientists released additional Kepler results [pdf] today, this time describing what they are learning about the stars being observed rather than any planets that might be orbiting them. In studying each star’s minute variations of light, the astronomers can track how the star itself is oscillating like a bell ringing. From this they can do a kind of stellar seismology, finding out a great deal about what is going on inside the star. The data has thus:
- produced the most precise measurements of the size and age of another star beside the Sun. KIC 11026764 has a radius 2.05 times the size of the Sun, and is now believed to be 5.94 billion years old, slightly older than the Sun’s 4.57 billion years. Though larger than the Sun, this star is a G-type star like the Sun. So far, Kepler has observed about 1500 solar-type stars. The astronomers are still analyzing this data, with results to follow.
- measured the oscillations of a thousand red giant stars, ranging from slightly larger to dozens of times larger than the Sun. The larger the star, the faster the oscillation and the larger the amplitude, which in turn has confirmed the theories about how the nuclear processes in the core of stars evolve over time, shifting from burning hydrogen to helium. Since these red giants are what our Sun will be like when it reaches old age, we are thus learning something about the Sun’s future.
- and provided the most precise measurements ever of RR Lyrae stars, a class of unusual variable stars that have puzzled astronomers for more than a century. From this data the astronomers hope to find out exactly why these stars fluctuate as they do.
The variability of stars according to Kepler
More data from Kepler! In a paper [pdf] published today on the astro-ph website, scientists outline Kepler’s census of the variability of stars. Key quote from the abstract:
We have separated the sample in 129,000 dwarfs and 17,000 giants, and further sub-divided, the luminosity classes into temperature bins corresponding approximately to the spectral classes A, F, G, K, and M. G-dwarfs are found to be the most stable with < 20% being variable. The variability fraction increases to 30% for the K dwarfs, 40% for the M and F dwarfs, and 70% for the A-dwarfs. At the precision of Kepler, > 95% of K and G giants are variable.
Kepler finds more than 100 Earthlike planets
In its first six weeks of observation, the Kepler mission apparently found almost 150 planets similar in size to the Earth. The results, learned by accident because a talk given by one of the co-investigators was posted on the web, have not yet been officially announced because the project scientists feel a need for additional time to confirm them. Many of these so-called planets might turn out to be false positives, so some caution is in order.