2,309 research outputs found
Milkweed blended fabrics and their thermal insulation and UV protection properties
Two sets of milkweed blended weft knitted fabrics have been produced and then tested for their constructional properties like courses/wales per inch, thickness, weight and tightness factor. These fabrics are also evaluated for thermal insulation (TI), water vapour permeability, air permeability and ultraviolet protection factor (UPF) properties and then compared with the only cotton and polyester knitted fabrics. The UPF and TI data of various blends of milkweed fibre with cotton or polyester have beed evaluated using one-way analysis of variance (ANOVA). Results reveal that the thermal insulation and ultraviolet protection factor of the milkweed blended fabric are higher than the corresponding properties of cotton and polyester fabrics, while the air permeability and water permeability properties are lower than the corresponding properties of cotton and polyester knitted fabrics.
An X-Ray Dip in the X-Ray Transient 4U 1630-47
An x-ray dip was observed during a 1996 Rossi X-Ray Timing Explorer
observation of the recurrent x-ray transient 4U 1630-47. During the dip, the
2-60 keV x-ray flux drops by a factor of about three, and, at the lowest point
of the dip, the x-ray spectrum is considerably softer than at non-dip times. We
find that the 4U 1630-47 dip is best explained by absorption of the inner part
of an accretion disk, while the outer part of the disk is unaffected. The
spectral evolution during the dip is adequately described by the variation of a
single parameter, the column density obscuring the inner disk.Comment: 13 pages, 4 figures, Accepted for publication in Ap
Multilingual Android based application for Meteorological Units Conversions and Calculation of empirical relationship.
Meteorological data can be expressed in several units. Various climatological and physical parameters are used for calculating evapotranpiration, irrigation demand, soil moisture etc. from meteorological data. Some of these data are directly measured in weather stations. Other parameters are related to commonly measured data on field and can be derived with the help of a direct or empirical relationship. Many a times on field and on time calculation or conversion are required. Android is a mobile based, free of cost operating system; used by majority of the mobile manufactures and equally appreciated and used by handheld users. Person working on field collects data and an android mobile based multilingual converter and calculator can assist in solving major issues pertaining to on field and on time conversions and calculation in regional language.
DOI: 10.17762/ijritcc2321-8169.15011
A supernova remnant coincident with the slow X-ray pulsar AX J1845-0258
We report on Very Large Array observations in the direction of the
recently-discovered slow X-ray pulsar AX J1845-0258. In the resulting images,
we find a 5-arcmin shell of radio emission; the shell is linearly polarized
with a non-thermal spectral index. We class this source as a previously
unidentified, young (< 8000 yr), supernova remnant (SNR), G29.6+0.1, which we
propose is physically associated with AX J1845-0258. The young age of G29.6+0.1
is then consistent with the interpretation that anomalous X-ray pulsars (AXPs)
are isolated, highly magnetized neutron stars ("magnetars"). Three of the six
known AXPs can now be associated with SNRs; we conclude that AXPs are young
(~<10 000 yr) objects, and that they are produced in at least 5% of
core-collapse supernovae.Comment: 4 pages, 1 embedded EPS file, uses emulateapj.sty. Accepted to ApJ
Letter
High Resolution Chandra Spectroscopy of Gamma Cassiopeia (B0.5IVe)
gamma Cas has long been famous for its unique hard X-ray characteristics. We
report herein on a 53 ks Chandra HETGS observation of this target. An
inspection of our spectrum shows that it is quite atypical for a massive star,
with abnormally weak Fe XXV, XXVI lines, Ly-alpha lines of H-like species from
Fe XVII, XXIII, XXIV, S XVI, Si XIV, Mg XII, Ne X, O VII, VIII, and N VII.
Also, line ratios of the rif-triplet of for a few He-like ions XVII are
consistent with the dominance of collisional atomic processes. Yet, the
presence of Fe and Si fluorescence K features indicates that photoionization
also occurs in nearby cold gas. The line profiles indicate a mean velocity at
rest and a broadening of 500 km/s. A global fitting analysis of the line and
continuum spectrum finds that there are 3-4 plasma emission components. The
dominant hot (12 keV) component and has a Fe abundance of 0.22 solar. Some
fraction of this component (10-30%) is heavily absorbed. The other 2-3
components, with temperatures 0.1, 0.4, 3 keV, are "warm," have a nearly solar
composition, a lower column absorption, and are responsible for most other
emission lines. The strength of the fluorescence features and the dual-column
absorption model for the hot plasma component suggest the presence near the hot
sites of a cold gas structure with a column density of 10^23 cm^-2. Since this
value is consistent with theoretical estimates of the vertical disk column of
this star, these attributes suggest that the X-rays originate near the star or
disk. It is possible that the Fe anomaly in the hot component is related to the
First Ionization Potential effect found in coronal structures around active
cool stars. This would be yet another indication that the X-rays -rays are
produced in the immediate vicinity of the Be star.Comment: 32 pages, 4 figures (Fig. 3 colorized.) To be published in 01/10/04
Astrophysical Journal, Main Journal; included figures and updated formattin
Hard X-ray Bursts Recorded by the IBIS Telescope of the INTEGRAL Observatory in 2003-2009
To find X-ray bursts from sources within the field of view of the
IBIS/INTEGRAL telescope, we have analysed all the archival data of the
telescope available at the time of writing the paper (the observations from
January 2003 to April 2009). We have detected 834 hard (15-25 keV) X-ray
bursts, 239 of which were simultaneously recorded by the JEM-X/INTEGRAL
telescope in the standard X-ray energy range. More than 70% of all bursts (587
events) have been recorded from the well-known X-ray burster GX 354-0. We have
found upper limits on the distances to their sources by assuming that the
Eddington luminosity limit was reached at the brightness maximum of the
brightest bursts.Comment: 18 pages, 2 figures, 2 table
4U2206+54 - an Unusual High Mass X-ray Binary with a 9.6 Day Orbital Period but No Strong Pulsations
Rossi X-ray Timing Explorer All-Sky Monitor observations of the X-ray source
4U2206+54, previously proposed to be a Be star system, show the X-ray flux to
be modulated with a period of approximately 9.6 days. If the modulation is due
to orbital variability then this would be one of the shortest orbital periods
known for a Be star X-ray source. However, the X-ray luminosity is relatively
modest whereas a high luminosity would be predicted if the system contains a
neutron star accreting from the denser inner regions of a Be star envelope.
Although a 392s pulse period was previously reported from EXOSAT observations,
a reexamination of the EXOSAT light curves does not show this or any other
periodicity. An analysis of archival RXTE Proportional Counter Array
observations also fails to show any X-ray pulsations. We consider possible
models that may explain the properties of this source including a neutron star
with accretion halted at the magnetosphere and an accreting white dwarf.Comment: Accepted for publication in the Astrophysical Journa
X-Ray Eclipse Time Delays in 4U2129+47
4U 2129+47 was discovered in the early 80's and classified as an accretion
disk corona source due to its broad and partial X-ray eclipses. The 5.24 hr
binary orbital period was inferred from the X-ray and optical light curve
modulation, implying a late K or M spectral type companion star.
The source entered a low state in 1983, during which the optical modulation
disappeared and an F8 IV star was revealed, suggesting that 4U 2129+47 might be
part of a triple system. The nature of 4U 2129+47 has since been investigated,
but no definitive conclusion has been reached.
Here, we present timing and spectral analyses of two XMM-Newton observations
of this source, carried out in May and June, 2005. We find evidence for a delay
between two mid-eclipse epochs measured ~22 days apart, and we show that this
delay can be naturally explained as being due to the orbital motion of the
binary 4U 2129+47 around the center of mass of a triple system. This result
thus provides further support in favor of the triple nature of 4U 2129+47.Comment: 6 pages, 5 figures, accepted by A&
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