7,643 research outputs found
Speckle interferometry at SOAR in 2019
The results of speckle interferometric observations at the 4.1 m Southern
Astrophysical Research Telescope (SOAR) in 2019 are given, totaling 2555
measurements of 1972 resolved pairs with separations from 15 mas (median 0.21")
and magnitude difference up to 6 mag, and non-resolutions of 684 targets. We
resolved for the first time 90 new pairs or subsystems in known binaries. This
work continues our long-term speckle program. Its main goal is to monitor
orbital motion of close binaries, including members of high-order hierarchies
and Hipparcos pairs in the solar neighborhood. We give a list of 127 orbits
computed using our latest measurements. Their quality varies from excellent (25
orbits of grades 1 and 2) to provisional (47 orbits of grades 4 and 5).Comment: Accepted by The Astronomical Journal. 10 pages, 5 Figures.
Measurements and non-resolutions, published electronically, are available
from the first author. arXiv admin note: substantial text overlap with
arXiv:1905.1043
Speckle interferometry at SOAR in 2015
The results of speckle interferometric observations at the SOAR telescope in
2015 are given, totalling 1303 measurements of 924 resolved binary and multiple
stars and non-resolutions of 260 targets. The separations range from 12 mas to
3.37" (median 0.17"); the maximum measured magnitude difference is 6.7 mag. We
resolved 27 pairs for the first time, including 10 as inner or outer subsystems
in previously known binaries, e.g. the 50-mas pair in Epsilon Cha. Newly
resolved pairs are commented upon. We discuss three apparently non-hierarchical
systems discovered in this series, arguing that their unusual configuration
results from projection. The resolved quadruple system HIP 71510 is studied as
well.Comment: 10 pages, 8 figures. Accepted for publication in AJ. The online
tables are not included, available from Tokovinin on request. arXiv admin
note: text overlap with arXiv:1506.0571
The Nature of Radio Continuum Emission in the Dwarf Starburst Galaxy NGC 625
We present new multi-frequency radio continuum imaging of the dwarf starburst
galaxy NGC 625 obtained with the Very Large Array. Data at 20, 6, and 3.6 cm
reveal global continuum emission dominated by free-free emission, with only
mild synchrotron components. Each of the major HII regions is detected; the
individual spectral indices are thermal for the youngest regions (showing
strongest H Alpha emission) and nonthermal for the oldest. We do not detect any
sources that appear to be associated with deeply embedded, dense, young
clusters, though we have discovered one low-luminosity, obscured source that
has no luminous optical counterpart and which resides in the region of highest
optical extinction. Since NGC 625 is a Wolf-Rayet galaxy with strong recent
star formation, these radio properties suggest that the youngest star formation
complexes have not yet evolved to the point where their thermal spectra are
significantly contaminated by synchrotron emission. The nonthermal components
are associated with regions of older star formation that have smaller ionized
gas components. These results imply a range of ages of the HII regions and
radio components that agrees with our previous resolved stellar population
analysis, where an extended burst of star formation has pervaded the disk of
NGC 625 over the last ~ 50 Myr. We compare the nature of radio continuum
emission in selected nearby dwarf starburst and Wolf-Rayet galaxies,
demonstrating that thermal radio continuum emission appears to be more common
in these systems than in typical HII galaxies with less recent star formation
and more evolved stellar clusters.Comment: ApJ, in press; 27 pages, 5 figures. Full-resolution version may be
obtained at http://www.astro.umn.edu/~cannon/n625.vla.p
Techniques for Artificial Hybridization in the SelfâPollinated Forage Legume \u3ci\u3eBituminaria bituminosa\u3c/i\u3e and the CrossâPollinated Forage Legume \u3ci\u3eHedysarum coronarium\u3c/i\u3e
Is secure coding education in the industry needed? An investigation through a large scale survey
The Department of Homeland Security in the United States estimates that 90% of software vulnerabilities can be traced back to defects in design and software coding. The financial impact of these vulnerabilities has been shown to exceed 380 million USD in industrial control systems alone. Since software developers write software, they also introduce these vulnerabilities into the source code. However, secure coding guidelines exist to prevent software developers from writing vulnerable code. This study focuses on the human factor, the software developer, and secure coding, in particular secure coding guidelines. We want to understand the software developers' awareness and compliance to secure coding guidelines and why, if at all, they aren't compliant or aware. We base our results on a large-scale survey on secure coding guidelines, with more than 190 industrial software developers. Our work's main contribution motivates the need to educate industrial software developers on secure coding guidelines, and it gives a list of fifteen actionable items to be used by practitioners in the industry. We also make our raw data openly available for further research.info:eu-repo/semantics/acceptedVersio
kHz Quasi Periodic Oscillations in Low Mass X-ray Binaries as Probes of General Relativity in the Strong Field Regime
We consider the interpretation of a pair of kHz Quasi Periodic Oscillations
(QPOs) in the Fourier spectra of two Low Mass X-Ray Binaries, Sco X-1 and
4U1608-52, hosting an old accreting neutron star. The observed frequency
difference of these QPOs decreaseas as their frequency increases, contrary to
simple beat frequency models, which predict a constant frequency difference. We
show that the behaviour of these QPOs is instead well matched in terms of the
fundamental frequencies (in the radial and azimuthal directions) for test
particle motion in the gravitational field of the neutron star, for reasonable
star masses, and nearly independent of the star spin. The radial frequency must
be much smaller than the azimuthal one, testifying that kHz QPOs are produced
close to the innermost stable orbit. These results are not reproduced through
the post--Newtonian (PN) approximation of General Relativity (GR). kHz QPOs
from X-ray binaries likely provide an accurate laboratory for strong field GR.Comment: to appear in Physical Review Letters, PRL Latex plus 2 figures in
standard PostScript forma
Galactic Kinematics Towards the South Galactic Pole. First Results from the Yale-San Juan Southern Proper-Motion Program
The predictions from a Galactic Structure and Kinematic model code are
compared to the color counts and absolute proper-motions derived from the
Southern Proper-Motion survey covering more than 700 toward the South
Galactic Pole in the range . The theoretical assumptions
and associated computational procedures, the geometry for the kinematic model,
and the adopted parameters are presented in detail and compared to other
Galactic Kinematic models of its kind. The data to which the model is compared
consists of more than 30,000 randomly selected stars, and it is best fit by
models with a solar peculiar motion of +5 km s in the V-component
(pointing in the direction of Galactic rotation), a large LSR speed of 270 km
s, and a (disk) velocity ellipsoid that always points towards the
Galactic center. The absolute proper-motions in the U-component indicate a
solar peculiar motion of km s, with no need for a local
expansion or contraction term. The fainter absolute motions show an indication
that the thick-disk must exhibit a rather steep velocity gradient of about -36
km s kpc with respect to the LSR. We are not able to set
constraints on the overall rotation for the halo, nor on the thick-disk or halo
velocity dispersions. Some substructure in the U & V proper-motions could be
present in the brighter bins , and it might be indicative
of (disk) moving groups.Comment: 24 double-column pages, 12 tables, AAS Latex macros v4.0, 19 B&W
figures, 1 color figure. Accepted for publication on The Astronomical Journa
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