Search Publications
Statistical Properties of Superflares on Solar-type Stars: Results Using All of the Kepler Primary Mission Data
Notsu, Yuta; Maehara, Hiroyuki; Namekata, Kosuke +5 more
We report the latest statistical analyses of superflares on solar-type (G-type main-sequence; effective temperature is 5100-6000 K) stars using all of the Kepler primary mission data and Gaia Data Release 2 catalog. We updated the flare detection method from our previous studies by using a high-pass filter to remove rotational variations caused by…
Photometric Study and Absolute Parameter Estimation of Six Totally Eclipsing Contact Binaries
Guo, Ya-Ni; Li, Kai; Xia, Qi-Qi +6 more
High precision CCD observations of six totally eclipsing contact binaries were presented and analyzed. It is found that only one target is an A-type contact binary (V429 Cam), while the others are W-type contact ones. By analyzing the times of light minima, we discovered that two of them exhibit secular period increase while three manifest long-te…
Structures of Dwarf Satellites of Milky Way-like Galaxies: Morphology, Scaling Relations, and Intrinsic Shapes
Greene, Jenny E.; Beaton, Rachael L.; Carlsten, Scott G. +2 more
The structure of a dwarf galaxy is an important probe of the effects of stellar feedback and environment. Using an unprecedented sample of 223 low-mass satellites from the ongoing Exploration of Local Volume Satellites survey, we explore the structures of dwarf satellites in the mass range 105.5 < M ⋆ < 108.5…
Circumgalactic Mg II Emission from an Isotropic Starburst Galaxy Outflow Mapped by KCWI
Hennawi, Joseph F.; Prochaska, J. Xavier; Coil, Alison L. +3 more
We present spatially resolved spectroscopy from the Keck Cosmic Web Imager (KCWI) of a star-forming galaxy at z = 0.6942, which shows emission from the Mg II λλ2796, 2803 doublet in the circumgalactic medium (CGM) extending ∼37 kpc at 3σ significance in individual spaxels (1σ detection limit 4.8 × 10-19 erg s-1 cm-2
A Volume-limited Sample of Ultracool Dwarfs. I. Construction, Space Density, and a Gap in the L/T Transition
Magnier, Eugene A.; Dupuy, Trent J.; Liu, Michael C. +1 more
We present a new volume-limited sample of L0-T8 dwarfs out to 25 pc defined entirely by parallaxes, using our recent measurements from UKIRT/WFCAM along with Gaia DR2 and literature parallaxes. With 369 members, our sample is the largest parallax-defined volume-limited sample of L and T dwarfs to date, yielding the most precise space densities for…
On the duration of the embedded phase of star formation
Kruijssen, J. M. Diederik; Leroy, Adam K.; Chevance, Mélanie +23 more
Feedback from massive stars plays a key role in molecular cloud evolution. After the onset of star formation, the young stellar population is exposed by photoionization, winds, supernovae, and radiation pressure from massive stars. Recent observations of nearby galaxies have provided the evolutionary timeline between molecular clouds and exposed y…
Selecting accreted populations: metallicity, elemental abundances, and ages of the Gaia-Sausage-Enceladus and Sequoia populations
Feuillet, Diane K.; Casagrande, Luca; Feltzing, Sofia +1 more
Identifying stars found in the Milky Way as having formed in situ or accreted can be a complex and uncertain undertaking. We use Gaia kinematics and APOGEE elemental abundances to select stars belonging to the Gaia-Sausage-Enceladus (GSE) and Sequoia accretion events. These samples are used to characterize the GSE and Sequoia population metallicit…
Primordial black holes and stochastic gravitational wave background from inflation with a noncanonical spectator field
Cai, Rong-Gen; Chen, Chao; Fu, Chengjie
We investigate the enhancement of the curvature perturbations in a single-field slow-roll inflation with a spectator scalar field kinetically coupled to the inflaton. The coupling term with a periodic function of inflaton triggers the exponential growth of the spectator field perturbations, which indirectly amplifies the curvature perturbations to…
The Detection and Characterization of Be+sdO Binaries from HST/STIS FUV Spectroscopy
Gies, Douglas R.; Lester, Kathryn V.; Wang, Luqian +4 more
The B emission-line stars are rapid rotators that were probably spun up by mass and angular momentum accretion through mass transfer in an interacting binary. Mass transfer will strip the donor star of its envelope to create a small and hot subdwarf remnant. Here we report on Hubble Space Telescope/STIS far-ultraviolet spectroscopy of a sample of …
Final Targeting Strategy for the Sloan Digital Sky Survey IV Apache Point Observatory Galactic Evolution Experiment 2 North Survey
Cohen, Roger E.; Bizyaev, Dmitry; Bovy, Jo +58 more
The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is a dual-hemisphere, near-infrared (NIR), spectroscopic survey with the goal of producing a chemodynamical mapping of the Milky Way. The targeting for APOGEE-2 is complex and has evolved with time. In this paper, we present the updates and additions to the initial targeting s…