Related papers: The K2 Bright Star Survey I: Methodology and Data …
We present results from the first two quarters of a survey to search for pulsations in compact stellar objects with the Kepler spacecraft. The survey sample and the various methods applied in its compilation are described, and spectroscopic…
In its Campaign 9, K2 observed dense regions toward the Galactic bulge in order to constrain the microlensing parallaxes and probe for free-floating planets. Photometric reduction of the \emph{K2} bulge data poses a significant challenge…
This paper proposes k-medoids clustering method to reveal the distinct groups of 1,318 variable stars in the Galaxy based on their light curves, where each light curve represents the graph of brightness of the star against time. To overcome…
We carried out spectroscopic observations with Subaru/HDS of 50 solar-type superflare stars found from Kepler data. More than half (34 stars) of the target stars show no evidence of the binary system, and we confirmed atmospheric parameters…
Archives of long photometric surveys, like the Kepler database, are a gold mine for studying flares. However, identifying them is a complex task; while in the case of single-target observations it can be easily done manually by visual…
K2 is the mission concept for a repurposed Kepler mission that uses two reaction wheels to maintain the satellite attitude and provide ~85 days of coverage for ten 105-deg^2 fields along the ecliptic in the first 2.5 years of operation. We…
We develop a general framework for interpreting and analyzing high-precision lightcurves from eccentric stellar binaries. Although our methods are general, we focus on the recently discovered Kepler system KOI-54, a face-on binary of two A…
Context: OB stars are important in the chemistry and evolution of the Universe, but the sample of targets well understood from an asteroseismological point of view is still too limited to provide feedback on the current evolutionary models.…
We report on two major surveys for metal-poor stars in the galactic halo, the HK survey, and the Hamburg/ESO survey, which have been undertaken in order to provide targets for high-resolution spectroscopy with the Subaru HDS and other large…
A recent analysis of high precision photometry obtained using the Kepler spacecraft has revealed two surprising discoveries: (1) over 860 main sequence A-type stars -- approximately 40% of those identified in the Kepler field -- exhibit…
We present a catalog of 11 multi-planet systems from Campaigns 1 and 2 of the K2 mission. We report the sizes and orbits of 26 planets split between seven 2-planet systems and four 3-planet systems. These planets stem from a systematic…
We measure the total stellar halo luminosity using red giant branch (RGB) stars selected from Gaia data release 2. Using slices in magnitude, colour and location on the sky, we decompose RGB stars belonging to the disc and halo by fitting…
Using light curves from the HATNet survey for transiting extrasolar planets we investigate the optical broad-band photometric variability of a sample of 27,560 field K and M dwarfs selected by color and proper-motion. A total of 2120 stars…
Using the weak gravitational lensing data from the Hyper Suprime-Cam Subaru Strategic Program (HSC survey), we study the potential of different stellar mass estimates in tracing halo mass. We consider galaxies with $\log…
We present a spectroscopic sample of 910 distant halo stars from the Hypervelocity Star survey from which we derive the velocity dispersion profile of the Milky Way halo. The sample is a mix of 74% evolved horizontal branch stars and 26%…
We use A-type stars selected from Sloan Digital Sky Survey data release 9 photometry to measure the outer slope of the Milky Way stellar halo density profile beyond 50 kpc. A likelihood-based analysis is employed that models the ugr…
The Galactic stellar halo is predicted to have formed at least partially from the tidal disruption of accreted dwarf galaxies. This assembly history should be detectable in the orbital and chemical properties of stars. The H3 Survey is…
The Kepler spacecraft is providing photometric time series with micro-magnitude precision for thousands of variable stars. The continuous time-series of unprecedented time span open up opportunities to study the pulsational variability in…
High resolution imaging is an important tool for follow-up study of exoplanet candidates found via transit detection with the Kepler Mission. We discuss here HST imaging with the WFC3 of 23 stars that host particularly interesting Kepler…
Accurate and precise radius estimates of transiting exoplanets are critical for understanding their compositions and formation mechanisms. To know the planet, we must know the host star in as much detail as possible. We present complete…