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A Statistical Detection of Wide Binary Systems in the Ultrafaint Dwarf Galaxy Reticulum II
Loeb, Abraham; Simon, Joshua D.; Safarzadeh, Mohammadtaher
Binary stars can inflate the observed velocity dispersion of stars in dark matter-dominated systems such as ultrafaint dwarf galaxies (UFDs). However, the population of binaries in UFDs is poorly constrained by observations, with preferred binary fractions for individual galaxies ranging from a few percent to near unity. Searching for wide binarie…
The Massive and Distant Clusters of WISE Survey. XI. Stellar Mass Fractions and Luminosity Functions of MaDCoWS Clusters at z 1
Mroczkowski, Tony; Connor, Thomas; Eisenhardt, Peter R. M. +14 more
We present stellar mass fractions and composite luminosity functions (LFs) for a sample of 12 clusters from the Massive and Distant Clusters of WISE Survey (MaDCoWS) in the redshift range 0.951 ≤ z ≤ 1.43. Using spectral energy distribution fitting of optical and deep mid-infrared photometry, we establish the membership of objects along the lines …
A Study of Dimmings, CMEs, and Flares during the STEREO-SOHO Quadrature
Krista, Larisza D.; Manning, Drew; West, Matthew J.
During the quadrature period (2010 December-2011 August) the STEREO-A and B satellites were approximately at right angles to the SOHO satellite. This alignment was particularly advantageous for determining the coronal mass ejection (CME) properties, since the closer a CME propagates to the plane of sky, the smaller the measurement inaccuracies are…
Physical properties of the molecular cloud, N4, in SS 433: Evidence for an interaction of molecular cloud with the jet from SS 433
Nakanishi, Hiroyuki; Yamamoto, Hiroaki; Imai, Hiroshi +3 more
We conducted observations and analyses of the molecular cloud, N4, which is located at ~40 pc from SS 433 and the same line of sight as that of the radio shell, in 12CO(J = 1-0), 12CO(J = 3-2), 13CO(J = 3-2), and grand-state OH emissions. N4 has a strong gradient of the integrated intensity of 12CO(J = 1…
Bulk Properties of Pickup Ions Derived from the Ulysses Solar Wind Ion Composition Spectrometer Data
Zhang, Ming; Gedalin, Michael; Pogorelov, Nikolai V. +3 more
Nonthermal, pickup ions (PUIs) represent an energetic component of the solar wind (SW). While a number of theoretical models have been proposed to describe the PUI flow, of major importance are in situ measurements providing us with the vital source of model validation. The Solar Wind Ion Composition Spectrometer (SWICS) instrument on board the Ul…
The unusually high dark matter concentration of the galaxy group NGC 1600
Walker, S. A.; Mirakhor, M. S.; Runge, J.
We investigate the properties of the dark matter (DM) halo surrounding the nearby galaxy group NGC 1600. Through the use of deep (252 ks) Chandra observations and 64.3 ks of XMM-Newton observations, we construct surface brightness profiles in multiple energy bands in order to perform hydrostatic equilibrium analysis of the hot plasma within NGC 16…
Carbon Abundances in Compact Galactic Planetary Nebulae: An Ultraviolet Spectroscopic Study with the Space Telescope Imaging Spectrograph (STIS)
Ventura, Paolo; Shaw, Richard A.; García-Hernández, D. A. +3 more
We surveyed a sample of compact Galactic planetary nebulae (PNe) with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST) to determine their gas-phase carbon abundances. Carbon abundances in PNe constrain the nature of their asymptotic giant branch (AGB) progenitors, as well as cosmic recycling. We measured the carbon abun…
Unveiling the main sequence to starburst transition region with a sample of intermediate redshift luminous infrared galaxies
Magdis, G. E.; Rigopoulou, D.; Combes, F. +8 more
We present a CO(3-2) study of four systems composed of six (ultra) luminous infrared galaxies (U/LIRGs), located at 0.28 <z < 0.44, that straddle the transition region between regular star-forming galaxies and starbursts. These galaxies benefit from previous multiwavelength analysis allowing in depth exploration of an understudied population…
Standing Solitary Waves as Transitions to Spiral Structures in Gravitationally Unstable Accretion Disks
Deng, Hongping; Ogilvie, Gordon I.
Astrophysical disks that are sufficiently cold and dense are linearly unstable to the formation of axisymmetric rings as a result of the disk's gravity. In practice, spiral structures are formed, which may in turn produce bound fragments. We study a nonlinear dynamical path that can explain the development of spirals in a local model of a gaseous …
Correlated variability of the reflection fraction with the X-ray flux and spectral index for Mrk 478
Jithesh, V.; Medhi, Biman J.; Misra, Ranjeev +2 more
The X-ray spectrum of Mrk 478 is known to be dominated by a strong soft excess that can be described using relativistic blurred reflection. Using observations from XMM-Newton, AstroSat, and Swift, we show that for the long-term (~years) and intermediate-term (days to months) variability, the reflection fraction is anticorrelated with the flux and …