Search Publications
Search for Exoplanets around Northern Circumpolar Stars III. Long-Period Radial Velocity Variations in HD 18438 and HD 158996
Lee, Byeong-Cheol; Park, Myeong-Gu; Bang, Tae-Yang +2 more
Detecting exoplanets around giants are useful in understanding the later-stage evolution of planetary systems. We observed the M giant HD 18438 and the K giant HD 158996 as part of a Search for Exoplanets around Northern circumpolar Stars (SENS) and obtained 38 and 24 spectra from 2010 to 2017 using the high-resolution Bohyunsan Observatory Echell…
Excess in the High-frequency Radio Background: Insights from Planck
Chary, Ranga-Ram; Murphy, Eric J.
We conduct a stacking analysis using the combination of 1.4 GHz detections in the NRAO VLA Sky Survey (NVSS) and Planck all-sky maps to estimate the differential source counts down to the few 100 µJy level at 30, 44, 70, and 100 GHz. Using these source count estimates, we are able to measure the integrated extragalactic background light from…
Influence of the Interplanetary Convective Electric Field on the Distribution of Heavy Pickup Ions Around Mars
Fränz, M.; Nilsson, H.; Liemohn, M. W. +3 more
This study obtains a statistical representation of 2-15 keV heavy ions outside of the Martian-induced magnetosphere and depicts their organization by the solar wind convective electric field (<fi>E</fi>SW). The overlap in the lifetime of Mars Global Surveyor (MGS) and Mars Express (MEX) provides a period of nearly three year…
Spectroscopic Measurements of the Ion Velocity Distribution at the Base of the Fast Solar Wind
Fletcher, Lyndsay; Jeffrey, Natasha L. S.; Savin, Daniel W. +1 more
In situ measurements of the fast solar wind reveal non-thermal distributions of electrons, protons, and minor ions extending from 0.3 au to the heliopause. The physical mechanisms responsible for these non-thermal properties and the location where these properties originate remain open questions. Here, we present spectroscopic evidence, from extre…
The duration of reionization constrains the ionizing sources
Theuns, Tom; Frenk, Carlos; Sharma, Mahavir
We investigate how the nature of the galaxies that reionized the Universe affects the duration of reionization. We contrast two sets of models: one in which galaxies on the faint side of the luminosity function dominate the ionizing emissivity, and a second in which the galaxies on the bright side of the luminosity function dominate. The faint end…
Variations of Field Line Eigenfrequencies With Ring Current Intensity
Sandhu, J. K.; Yeoman, T. K.; Rae, I. J.
We present results from the closed magnetosphere (5.9≤L < 9.5 over all magnetic local times) to demonstrate and assess the variations in field line eigenfrequency with geomagnetic activity. Using the time-of-flight technique with realistic magnetic field and mass density models, the spatial distributions of field line eigenfrequencies are deter…
Probing the Hill Sphere of (486958) 2014 MU69: HST FGS Observations during the 2017 July 17 Stellar Occultation
Stern, S. Alan; Spencer, John R.; Buie, Marc W. +6 more
We observed the 2017 July 17 stellar occultation of HD 168233 by the Kuiper Belt Object (486958) 2014 MU69, the close flyby target of the extended New Horizons mission. Rather than capture a solid body occultation by the KBO itself, our program aimed to constrain the opacity of rings, moons, or other debris in the nearby environment. We…
A Chemical and Kinematical Analysis of the Intermediate-age Open Cluster IC 166 from APOGEE and Gaia DR2
Schultheis, M.; Minniti, D.; Mészáros, Sz. +26 more
IC 166 is an intermediate-age open cluster (OC) (∼1 Gyr) that lies in the transition zone of the metallicity gradient in the outer disk. Its location, combined with our very limited knowledge of its salient features, make it an interesting object of study. We present the first high-resolution spectroscopic and precise kinematical analysis of IC 16…
The pristine shape of Olympus Mons on Mars and the subaqueous origin of its aureole deposits
De Blasio, Fabio Vittorio
The tallest volcano in the solar system, Olympus Mons on Mars, is bordered by at least ten enormous sub-circular hummocky deposits forming a welded halo, termed the aureole. The aureole units (or simply aureoles), which are the deposits of landslides from Olympus Mons, have dramatically transformed the pristine size and shape of the volcanic edifi…
Reconstruction of a direction-dependent primordial power spectrum from Planck CMB data
Souradeep, Tarun; Sarkar, Subir; Mukherjee, Suvodip +2 more
We consider the possibility that the primordial curvature perturbation is direction-dependent. To first order this is parameterised by a quadrupolar modulation of the power spectrum and results in statistical anisotropy of the CMB, which can be quantified using `bipolar spherical harmonics'. We compute these for the Planck DR2-2015 SMICA map and e…