By Wes Traub
The Kepler Science Conference on 5-9 Dec. 2011 was the big event this quarter. The meeting inspired many news reports, including a full page article on planet hunting in the NYT by Dennis Overbye on the eve of the meeting: http://www.nytimes.com/2011/12/03/science/space/scientists-are-hot-on-trail-of-exoplanets-suitable-for-life.html?_r=1&scp=2&sq=planets&st=cse
The Kepler Science Conference was attended by over 400 astronomers from around the world. Here is a personal bullet list of topics from the meeting:
The Kepler project announced the discovery of Kepler-22b, a 2.5 Earth-radii sized planet located within the habitable zone of its host star. The planet has an orbital period of 298 and orbits a Sun-like star.
The Kepler team plans a December 2011 release of 1094 new planet candidates. Photometric time series profiles for Q1-2 were released in Feb. 2011, Q3 was released in Sept. 2011, and Q4-5-6 will be released in mid-Jan. 2012. The 1094 candidates were found with a new pipeline that stitches quarters and removes stellar variability better than the previous algorithm. However, the previously-released candidates have not yet been examined with the new stitching algorithm, so improvements in that list can be expected in the future. The combined lists from Q1-6 are expected to be complete for periods less than 150 days for large planets, but not necessarily for small ones (radius less than 2 Earth radii).
The Allen array of radio telescopes was reported to be back in operation as of the first day of the conference, by coincidence, owing to private donations. It will use the phased array technique to focus on three targets at a time, chosen from the list of habitable-zone planets in the Kepler field.
Transit timing variations, caused by gravitational interactions among planets in multi-planet systems, are becoming popular for providing planet masses, but also in some cases a measure of orbital eccentricity and inclination. TTVs can also be used to obtain a measure of the presence of a third body, such as a long-period companion. Since TTV accuracy increases as the 2.5 power of time, it will become especially valuable if the Kepler mission can be extended beyond its current 3.5-year limit in fall 2012.
Kepler’s important discovery that most FGK dwarf stars are photometrically noisier than the sun led to the quip that “the sun is a not a solar-type star”.
There are now three ways to estimate the angle between the spin axis of a star and the planet orbital angular momentum axis: the Rossiter-McLaughlin effect, transits of starspots, and the new gravity darkening method.
“The Thing” is the name of an eclipsing binary system with a central star and two sets of binary stars orbiting it, a total of five stars.
Non-eclipsing binary stars have been found in the Kepler data using the BEER method: beaming ellipsoidal reflection effect, the surprising feature of which is the measurable effect of relativistic beaming of starlight in the direction of travel.
The Kepler conference was featured on both Jimmy Kimmel and David Letterman, with extensive comments by the hosts, “interpreting” our efforts for the general (taxpaying) public.
Long-lived starspots on tens of thousands of stars are showing that the dominant source of photometric variation is not the evolution of the spots themselves but rather the overlapping slow and fast periods of spots at presumably different latitudes on the star, showing that differential rotation is common on stars, as it is on the sun.
Geochronology could get a huge boost in accuracy from Kepler stellar starspot rotation data from stars in about five star clusters, using the fact that the stars in a given cluster are of the same age, and these ages range from about 1 to 9 Gyr.
RR Lyrae star distances are likely to be improved from Kepler observations of oscillations in these standard candles that will lead to a better understanding of the slightly different types of RR Lyrae pulsation mechanisms.
Stellar oscillations give us good estimates of star radius and mass, but the mass value depends somewhat on the abundance of helium and metals, as well as the depth of the convective zone of the star, so independent estimates of the latter quantities will help improve the oscillation mass and radius data for stars.
Stellar oscillation “mode 1” is narrow, and is split into two equal peaks if the star is rotating, giving an independent measure of rotation. Furthermore, if the star has an orbiting companion, the intensities are rendered unequal, giving a measure of the existence of that companion, independent of RV or transits.
AGNs: Finally, Kepler data may become useful for observations of the size of the light-emitting area immediately around a black hole, the accretion disk, roughly one light day, by analyzing the shape of the power spectral density of photometry from the AGN.
The Kepler Science Conference talks, as presented, can be seen at http://kepler.nasa.gov/Science/ForScientists/keplerconference/
Members of the UV astrophysics community met in early Dec. at a workshop sponsored by the Keck Institute for Space Studies (KISS, http://www.kiss.caltech.edu/) to develop ideas for UV technology, including a focus on wide band coatings for telescope mirrors for the 100-1100nm range that could be used on a joint Exoplanet-UV mission for direct imaging of exoplanets and UV astrophysics, and a focus on wide band detectors for the same type of mission.