scholarly journals Interstellar oxygen along the line of sight of Cygnus X-2

2020 ◽  
Vol 642 ◽  
pp. A208
Author(s):  
I. Psaradaki ◽  
E. Costantini ◽  
M. Mehdipour ◽  
D. Rogantini ◽  
C. P. de Vries ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Laboratory Data ◽  
Line Of Sight ◽  
Chemical Compositions ◽  
X Ray ◽  
Solar Abundances ◽  
Low Mass ◽  
Phase Data ◽  
The University

Interstellar dust permeates our Galaxy and plays an important role in many physical processes in the diffuse and dense regions of the interstellar medium (ISM). High-resolution X-ray spectroscopy, coupled with modelling based on laboratory dust measurements, provides a unique probe for investigating the interstellar dust properties along our line of sight towards Galactic X-ray sources. Here, we focus on the oxygen content of the ISM through its absorption features in the X-ray spectra. To model the dust features, we perform a laboratory experiment using the electron microscope facility located at the University of Cadiz in Spain, where we acquire new laboratory data in the oxygen K-edge. We study 18 dust samples of silicates and oxides with different chemical compositions. The laboratory measurements are adopted for our astronomical data analysis. We carry out a case study on the X-ray spectrum of the bright low-mass X-ray binary Cygnus X-2, observed by XMM−Newton. We determine different temperature phases of the ISM and parameterise oxygen in both gas (neutral and ionised) and dust form. We find Solar abundances of oxygen along the line of sight towards the source. Due to both the relatively low depletion of oxygen into dust form and the shape of the oxygen cross section profiles, it is challenging to determine the precise chemistry of interstellar dust. However, silicates provide an acceptable fit. Finally, we discuss the systematic discrepancies in the atomic (gaseous phase) data of the oxygen edge spectral region using different X-ray atomic databases as well as consider future prospects for studying the ISM with the Arcus concept mission.

scholarly journals Dust absorption and scattering in the silicon K-edge

2019 ◽  
Vol 627 ◽  
pp. A16 ◽  
Author(s):  
S. T. Zeegers ◽  
E. Costantini ◽  
D. Rogantini ◽  
C. P. de Vries ◽  
H. Mutschke ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Galactic Center ◽  
Interstellar Extinction ◽  
Line Of Sight ◽  
X Rays ◽  
Laboratory Measurements ◽  
Galactocentric Distance ◽  
Synchrotron Facility ◽  
The Galaxy ◽  
Low Mass

Context. The composition and properties of interstellar silicate dust are not well understood. In X-rays, interstellar dust can be studied in detail by making use of the fine structure features in the Si K-edge. The features in the Si K-edge offer a range of possibilities to study silicon-bearing dust, such as investigating the crystallinity, abundance, and the chemical composition along a given line of sight. Aims. We present newly acquired laboratory measurements of the silicon K-edge of several silicate-compounds that complement our measurements from our earlier pilot study. The resulting dust extinction profiles serve as templates for the interstellar extinction that we observe. The extinction profiles were used to model the interstellar dust in the dense environments of the Galaxy. Methods. The laboratory measurements, taken at the Soleil synchrotron facility in Paris, were adapted for astrophysical data analysis and implemented in the SPEX spectral fitting program. The models were used to fit the spectra of nine low-mass X-ray binaries located in the Galactic center neighborhood in order to determine the dust properties along those lines of sight. Results. Most lines of sight can be fit well by amorphous olivine. We also established upper limits on the amount of crystalline material that the modeling allows. We obtained values of the total silicon abundance, silicon dust abundance, and depletion along each of the sightlines. We find a possible gradient of 0.06 ± 0.02 dex/kpc for the total silicon abundance versus the Galactocentric distance. We do not find a relation between the depletion and the extinction along the line of sight.

A workflow for exploration sampling in regolith-dominated terranes using portable X-ray fluorescence: comparison with laboratory data and a case study

2017 ◽  
Vol 64 (7) ◽  
pp. 903-917 ◽  
Author(s):  
M. F. Gazley ◽  
L. C. Bonnett ◽  
L. A. Fisher ◽  
W. Salama ◽  
J. H. Price
Keyword(s):  
Laboratory Data ◽  
X Ray

The Calibration of the UVIT Detectors for the ASTROSAT Observatory

2018 ◽  
Vol 14 (A30) ◽  
pp. 487-491
Author(s):  
Denis Leahy ◽  
J. Postma ◽  
J. B. Hutchings ◽  
S. N. Tandon
Keyword(s):  
Laboratory Data ◽  
Space Research ◽  
Research Organization ◽  
X Ray ◽  
Indian Space Research Organization ◽  
University Of Calgary ◽  
The University

AbstractThe UVIT ultraviolet and visual band detectors and electronics for the ASTROSAT observatory were calibrated in the vacuum laboratory at the University of Calgary. This work was supported by the Canadian Space Agengy and carried out prior to integration with the UVIT optical assembly and the ASTROSAT spacecraft. The multiband (X-ray, ultraviolet and optical) ASTROSAT observatory was successfully launched by the Indian Space Research Organization on Sept. 28, 2015, with subsequent in-orbit verification and ongoing calibration activities. Here we discuss the current issues of calibrating the UVIT data, such as distortion corrections, and how the laboratory data is being used to address these issues.

scholarly journals Spectral analysis of the quiescent low-mass X-ray binary in the globular cluster M30

2020 ◽  
Vol 495 (4) ◽  
pp. 4508-4517 ◽  
Author(s):  
C S Echiburú ◽  
S Guillot ◽  
Y Zhao ◽  
C O Heinke ◽  
F Özel ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Nuclear Physics ◽  
Thermal Emission ◽  
Equations Of State ◽  
Light Element ◽  
Small Radius ◽  
Chemical Compositions ◽  
Pure Hydrogen ◽  
X Ray ◽  
Low Mass

ABSTRACT We present a recent Chandra observation of the quiescent low-mass X-ray binary containing a neutron star (NS), located in the globular cluster M30. We fit the thermal emission from the NS to extract its mass and radius. We find no evidence of flux variability between the two observations taken in 2001 and 2017, nor between individual 2017 observations, so we analyse them together to increase the signal-to-noise ratio. We perform simultaneous spectral fits using standard light-element composition atmosphere models (hydrogen or helium), including absorption by the interstellar medium, correction for pile-up of X-ray photons on the detector, and a power law for count excesses at high photon energy. Using a Markov chain Monte Carlo approach, we extract mass and radius credible intervals for both chemical compositions of the atmosphere: $\mbox{$R_{\rm NS}$}=7.94\mbox{{$\scriptstyle ^{ + 0.76}_{- 1.21}$}}$ km and $\mbox{$M_{\rm NS}$}\lt 1.19$ M⊙ assuming pure hydrogen, and $\mbox{$R_{\rm NS}$}=10.50\mbox{{$\scriptstyle ^{ + 2.88}_{- 2.03}$}}$ km and $\mbox{$M_{\rm NS}$}\lt 1.78$ M⊙ for helium, where the uncertainties represent the 90 per cent credible regions. For H, the small radius is difficult to reconcile with most current nuclear physics models (especially for nucleonic equations of state) and with other measurements of NS radii, with recent preferred values generally in the 11–14 km range. Whereas for He, the measured radius is consistent with this range. We discuss possible sources of systematic uncertainty that may result in an underestimation of the radius, identifying the presence of surface temperature inhomogeneities as the most relevant bias. According to this, we conclude that either the atmosphere is composed of He or it is anH atmosphere with a significant contribution of hotspots to the observed radiation.

scholarly journals MKT J170456.2–482100: the first transient discovered by MeerKAT

2019 ◽  
Vol 491 (1) ◽  
pp. 560-575 ◽  
Author(s):  
L N Driessen ◽  
I McDonald ◽  
D A H Buckley ◽  
M Caleb ◽  
E J Kotze ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Spectral Feature ◽  
Line Of Sight ◽  
Optical Photometry ◽  
X Ray ◽  
Velocity Amplitude ◽  
Optical Light Curve ◽  
Low Mass ◽  
Pm 10 ◽  
Changes Over Time

ABSTRACT We report the discovery of the first transient with MeerKAT, MKT J170456.2–482100, discovered in ThunderKAT images of the low-mass X-ray binary GX339–4. MKT J170456.2–482100 is variable in the radio, reaching a maximum flux density of $0.71\pm 0.11\, \mathrm{mJy}$ on 2019 October 12, and is undetected in 15 out of 48 ThunderKAT epochs. MKT J170456.2–482100 is coincident with the chromospherically active K-type sub-giant TYC 8332-2529-1, and $\sim 18\, \mathrm{yr}$ of archival optical photometry of the star shows that it varies with a period of $21.25\pm 0.04\, \mathrm{d}$. The shape and phase of the optical light curve changes over time, and we detect both X-ray and UV emission at the position of MKT J170456.2–482100, which may indicate that TYC 8332-2529-1 has large star spots. Spectroscopic analysis shows that TYC 8332-2529-1 is in a binary, and has a line-of-sight radial velocity amplitude of $43\, \mathrm{km\, s^{-1}}$. We also observe a spectral feature in antiphase with the K-type sub-giant, with a line-of-sight radial velocity amplitude of $\sim 12\pm 10\, \mathrm{km\, s^{-1}}$, whose origins cannot currently be explained. Further observations and investigation are required to determine the nature of the MKT J170456.2–482100 system.

scholarly journals Interstellar dust along the line of sight of GX 3+1

2019 ◽  
Vol 630 ◽  
pp. A143 ◽  
Author(s):  
D. Rogantini ◽  
E. Costantini ◽  
S. T. Zeegers ◽  
C. P. de Vries ◽  
M. Mehdipour ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Chemical Properties ◽  
Line Of Sight ◽  
X Ray ◽  
Interstellar Dust Grains ◽  
Composition And Structure ◽  
The Galaxy ◽  
Distribution Composition ◽  
Physical And Chemical ◽  
Absorption Features

Context. Studying absorption and scattering of X-ray radiation by interstellar dust grains allows us to access the physical and chemical properties of cosmic grains even in the densest regions of the Galaxy. Aims. We aim at characterising the dust silicate population which presents clear absorption features in the energy band covered by the Chandra X-ray Observatory. Through these absorption features, in principle, it is possible to infer the size distribution, composition, and structure of silicate in the interstellar medium. In particular, in this work we investigate magnesium and silicon K-edges. Methods. We built X-ray extinction models for 15 dust candidates using newly acquired synchrotron measurements. These models were adapted for astrophysical analysis and implemented in the SPEX spectral fitting program. We used the models to reproduce the dust absorption features observed in the spectrum of the bright low mass X-ray binary GX 3+1, which is used as a background source. Results. With the simultaneous analysis of the two edges we test two different size distributions of dust: one corresponding to the standard Mathis-Rumpl-Nordsieck model and one considering larger grains (n(a) ∝ ai−3.5 with 0.005 μm < a1 < 0.25 μm and 0.05 μm < a2 < 0.5 μm, respectively, with a the grain size). These distributions may be representative of the complex Galactic region towards this source. We find that up to 70% of dust is constituted by amorphous olivine. We discuss the crystallinity of the cosmic dust found along this line of sight. Both magnesium and silicon are highly depleted into dust (δZ = 0.89 and 0.94, respectively), while their total abundance does not depart from solar values.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx&gt; 10 keV is likely due to fluorescence outside the He II ionization front.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Imaging of Al-Li-Cu alloys with a Scanning Ion Microprobe

1990 ◽  
Vol 48 (2) ◽  
pp. 314-315
Author(s):  
K.K. Soni ◽  
D.B. Williams ◽  
J.M. Chabala ◽  
R. Levi-Setti ◽  
D.E. Newbury
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Equilibrium Phase ◽  
Icosahedral Symmetry ◽  
Ion Microprobe ◽  
X Ray ◽  
Cu Alloys ◽  
Two Phases ◽  
The University ◽  
Secondary Ion

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.

Sharing of Worldwide Spread Knowledge Using Hypermedia Facilities & Fast Communication Protocols (Mosaic and World Wide Web): The Example of ExPASy

1995 ◽  
Vol 34 (01/02) ◽  
pp. 75-78 ◽  
Author(s):  
R. D. Appel ◽  
O. Golaz ◽  
Ch. Pasquali ◽  
J.-C. Sanchez ◽  
A. Bairoch ◽  
...  
Keyword(s):  
World Wide Web ◽  
World Wide ◽  
Relevant Literature ◽  
Communication Protocols ◽  
Laboratory Data ◽  
Central Element ◽  
University Hospital ◽  
New Information ◽  
The University ◽  
Link Information

Abstract:The sharing of knowledge worldwide using hypermedia facilities and fast communication protocols (i.e., Mosaic and World Wide Web) provides a growth capacity with tremendous versatility and efficacy. The example of ExPASy, a molecular biology server developed at the University Hospital of Geneva, is striking. ExPASy provides hypermedia facilities to browse through several up-to-date biological and medical databases around the world and to link information from protein maps to genome information and diseases. Its extensive access is open through World Wide Web. Its concept could be extended to patient data including texts, laboratory data, relevant literature findings, sounds, images and movies. A new hypermedia culture is spreading very rapidly where the international fast transmission of documents is the central element. It is part of the emerging new “information society”.

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