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New Constraints on Spatial Variations of the Fine Structure Constant from Clusters of Galaxies
Ebeling, Harald; Kocevski, Dale; Martins, Carlos J. A. P. +1 more
We have constrained the spatial variation of the fine structure constant using multi-frequency measurements of the thermal Sunyaev-Zeldovich effect of 618 X-ray selected clusters. Although our results are not competitive with the ones from quasar absorption lines, we improved by a factor 10 and ∼2.5 previous results from Cosmic Microwave Backgroun…
Herschel Observations and Updated Spectral Energy Distributions of Five Sunlike Stars with Debris Disks
Green, Joel D.; Su, Kate Y. L.; Bryden, Geoff +2 more
Observations from the Herschel Space Observatory have more than doubled the number of wide debris disks orbiting Sunlike stars to include over 30 systems with R > 100 AU. Here, we present new Herschel PACS and reanalyzed Spitzer MIPS photometry of five Sunlike stars with wide debris disks, from Kuiper Belt size to R > 150 AU. The disk surrou…
Search for a non-equilibrium plasma in the merging galaxy cluster Abell 754
Koyama, Katsuji; Hayashida, Kiyoshi; Tsunemi, Hiroshi +3 more
Abell 754 is a galaxy cluster in which an ongoing merger is evident on the plane of the sky, from the southeast to the northwest. We study the spatial variation of the X-ray spectra observed with Suzaku along the merging direction, centering on the Fe Ly α/Fe He α line ratio to search for possible deviation from ionization equilibrium. Fitting wit…
The Interplanetary Network Response to LIGO GW150914
Zhang, X.; Cline, T.; Hurley, K. +15 more
We have performed a blind search for a gamma-ray transient of arbitrary duration and energy spectrum around the time of the LIGO gravitational-wave event GW150914 with the six-spacecraft interplanetary network (IPN). Four gamma-ray bursts were detected between 30 hr prior to the event and 6.1 hr after it, but none could convincingly be associated …
Suzaku Observation of the High-inclination Binary EXO 0748-676 in the Hard State
Makishima, Kazuo; Nakazawa, Kazuhiro; Xu, Haiguang +4 more
Utilizing archived Suzaku data acquired on 2007 December 25 for 46 ks, the X-ray spectroscopic properties of the dipping and eclipsing low-mass X-ray binary EXO 0748-676 were studied. At an assumed distance of 7.1 kpc, the data provided a persistent unabsorbed luminosity of 3.4× {10}36 erg cm-2 s-1 in 0.6-55 keV. T…
Protostars at Low Extinction in Orion A
Lada, Charles J.; Lewis, John Arban
In the list of young stellar objects (YSOs) compiled by Megeath et al. for the Orion A molecular cloud, only 44 out of 1208 sources found projected onto low extinction ({A}{{K}}\lt 0.8 mag) gas are identified as protostars. These objects are puzzling because protostars are not typically expected to be associated with extended low extinc…
IGR J17451-3022: A dipping and eclipsing low mass X-ray binary
Ponti, G.; Romano, P.; Ferrigno, C. +10 more
In this paper we report on the available X-ray data collected by INTEGRAL, Swift, and XMM-Newton during the first outburst of the INTEGRAL transient IGR J17451-3022, discovered in 2014 August. The monitoring observations provided by the JEM-X instruments on board INTEGRAL and the Swift /XRT showed that the event lasted for about 9 months and that …
Polytropic index of magnetosheath ions based on homogeneous MHD Bernoulli Integral
Ma, Yuduan; Cao, Jinbin; Pang, Xuexia
This paper uses Cluster data during the period from 2001 to 2010 to study the polytropic processes of magnetosheath ions. Utilizing the method of homogeneous magnetohydrodynamic (MHD) Bernoulli integral (MBI), we first identify streamflow tubes, then use the constant of polytropic relation to guarantee that the streamflow tube experiences an uncha…
A High-resolution Multiband Survey of Westerlund 2 with the Hubble Space Telescope. II. Mass Accretion in the Pre-main-sequence Population
Grebel, Eva K.; Bonanos, Alceste Z.; Sabbi, Elena +5 more
We present a detailed analysis of the pre-main-sequence (PMS) population of the young star cluster Westerlund 2 (Wd2), the central ionizing cluster of the H II region RCW 49, using data from a high-resolution multiband survey with the Hubble Space Telescope. The data were acquired with the Advanced Camera for Surveys in the F555W, F814W, and F658N…
GW Librae: Still Hot Eight Years Post-outburst
Szkody, Paula; Sion, Edward M.; Gänsicke, Boris T. +8 more
We report continued Hubble Space Telescope (HST) ultraviolet spectra and ground-based optical photometry and spectroscopy of GW Librae eight years after its largest known dwarf nova outburst in 2007. This represents the longest cooling timescale measured for any dwarf nova. The spectra reveal that the white dwarf still remains about 3000 K hotter …