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Chemical Cartography. II. The Assembly History of the Galactic Stellar Halo Traced by Carbon-enhanced Metal-poor Stars
Beers, Timothy C.; Lee, Young Sun; Kim, Young Kwang
We present an analysis of the kinematic properties of stellar populations in the Galactic halo, making use of over 100,000 main-sequence turnoff (MSTO) stars observed in the Sloan Digital Sky Survey. After dividing the Galactic halo into an inner-halo region (IHR) and outer-halo region (OHR), based on the spatial variation of carbon-to-iron ratios…
A Dynamical Model for Clustered Star Formation in the Galactic Disk
Conroy, Charlie; Ting, Yuan-Sen; Cargile, Phillip +3 more
The clustered nature of star formation should produce a high degree of structure in the combined phase and chemical space in the Galactic disk. To date, observed structure of this kind has been mostly limited to bound clusters and moving groups. In this paper, we present a new dynamical model of the Galactic disk that takes into account the cluste…
Revisiting the potassium feature of WASP-31b at high resolution
Nikolov, Nikolay; de Mooij, Ernst J. W.; Gibson, Neale P. +4 more
The analysis and interpretation of exoplanet spectra from time-series observations remains a significant challenge to our current understanding of exoplanet atmospheres, due to the complexities in understanding instrumental systematics. Previous observations of the hot Jupiter WASP-31b using transmission spectroscopy at low resolution have present…
Superflares on AB Doradus observed with TESS
Schmitt, J. H. M. M.; Czesla, S.; Robrade, J. +2 more
We present short-cadence data of the ultra-active star AB Dor measured by the Transiting Exoplanet Survey Satellite (TESS). In the TESS light curves of AB Dor, we found numerous flare events in addition to time-variable rotational modulation with an amplitude of up to 7%. We identified eight superflares (releasing more than 1034 erg) an…
First Observations of Irregular Surface of Interplanetary Shocks at Ion Scales by Cluster
Kajdič, Primož; Blanco-Cano, Xóchitl; Burgess, David +2 more
We present the first observational evidence of the irregular surface of interplanetary (IP) shocks by using multispacecraft observations of the Cluster mission. In total we discuss observations of four IP shocks that exhibit moderate Alfvénic Mach numbers (M A ≤ 6.5). Three of them are high-β shocks with upstream β = 2.2-3.7. During the…
On the Relation Between Jovian Aurorae and the Loading/Unloading of the Magnetic Flux: Simultaneous Measurements From Juno, Hubble Space Telescope, and Hisaki
Kurth, W. S.; Bagenal, F.; Yoshioka, K. +20 more
We present simultaneous observations of aurorae at Jupiter from the Hubble Space Telescope and Hisaki, in combination with the in situ measurements of magnetic field, particles, and radio waves from the Juno Spacecraft in the outer magnetosphere, from 80RJ to 60RJ during 17 to 22 March 2017. Two cycles of accumulation and rel…
K2-146: Discovery of Planet c, Precise Masses from Transit Timing, and Observed Precession
Kruse, Ethan; Montet, Benjamin T.; Fabrycky, Daniel C. +2 more
K2-146 is a mid-M dwarf (M ⋆ = 0.331 ± 0.009M ⊙ R ⋆ = 0.330 ± 0.010R ⊙), observed in Campaigns 5, 16, and 18 of the K2 mission. In Campaign 5 data, a single planet was discovered with an orbital period of 2.6 days and large transit timing variations due to an unknown perturber. Here, we analyze data from…
BVRCIC Observations, Analysis, and Spectra of The Most Extreme Mass Ratio (Totally Eclipsing) W UMa Binary, V1187 Herculis
Hill, Robert; Samec, Ronald G.; Chamberlain, Heather +4 more
CCD, BVRI primary light curves of V1187 Her were taken in 2017 May and 2018 May at the Dark Sky Observatory in North Carolina with the 0.81-m reflector of Appalachian State University. A spectrum was taken earlier at Dominion Astrophysical Observatory (DAO) with the 1.8 m telescope. The spectral type is F(8.5 ± 1)V, resulting in a surface temperat…
Characterization of a Sample of Southern M Dwarfs Using Harps and X-shooter Spectra
del Burgo, C.; Pavlenko, Ya. V.; Kuznetsov, M. K. +1 more
We present the homogeneous analysis of a sample of Southern early-type M dwarfs in the solar neighborhood (d < 60 pc). We used the MCAL technique to derive the effective temperature T eff, metallicity [Fe/H], and activity index i a (H alpha) of 420 M stars using HARPS spectra. The effective temperature T e…
Detection of Planetary and Stellar Companions to Neighboring Stars via a Combination of Radial Velocity and Direct Imaging Techniques
Butler, R. Paul; Kane, Stephen R.; Wittenmyer, Robert A. +13 more
The sensitivities of radial velocity (RV) surveys for exoplanet detection are extending to increasingly longer orbital periods, where companions with periods of several years are now being regularly discovered. Companions with orbital periods that exceed the duration of the survey manifest in the data as an incomplete orbit or linear trend, a feat…