pinecone/core-2020-05-10-deduplication huggingface dataset:
The association between sunspot magnetic fields and superpenumbral
  fibrils

Spectropolarimetric observations of a sunspot were carried out with the
Tenerife Infrared Polarimeter at Observatorio del Teide, Tenerife, Spain. Maps
of the physical parameters were obtained from an inversion of the Stokes
profiles observed in the infrared Fe i line at 15648 angstrom. The regular
sunspot consisted of a light bridge which separated the two umbral cores of the
same polarity. One of the arms of the light bridge formed an extension of a
penumbral filament which comprised weak and highly inclined magnetic fields. In
addition, the Stokes V profiles in this filament had an opposite sign as the
sunspot and some resembled Stokes Q or U. This penumbral filament terminated
abruptly into another at the edge of the sunspot, where the latter was
relatively vertical by about 30 degrees. Chromospheric H-alpha and He 304
angstrom filtergrams revealed three superpenumbral fibrils on the limb-side of
the sunspot, in which one fibril extended into the sunspot and was oriented
along the highly inclined penumbral counterpart of the light bridge. An
intense, elongated brightening was observed along this fibril that was
co-spatial with the intersecting penumbral filaments in the photosphere. Our
results suggest that the disruption in the sunspot magnetic field at the
location of the light bridge could be the source of reconnection that led to
the intense chromospheric brightening and facilitated the supply of cool
material in maintaining the overlying superpenumbral fibrils.Comment: Accepted for publication in Astronomische Nachrichten: 8 pages, 7
  figure
The loss-limited electron energy in SN 1006: effects of the shock
  velocity and of the diffusion process

The spectral shape of the synchrotron X-ray emission from SN 1006 reveals the
fundamental role played by radiative losses in shaping the high-energy tail of
the electron spectrum. We analyze data from the XMM-Newton SN 1006 Large
Program and confirm that in both nonthermal limbs the loss-limited model
correctly describes the observed spectra. We study the physical origin of the
observed variations of the synchrotron cutoff energy across the shell. We
investigate the role played by the shock velocity and by the electron
gyrofactor. We found that the cutoff energy of the syncrotron X-ray emission
reaches its maximum value in regions where the shock has experienced its
highest average speed. This result is consistent with the loss-limited
framework. We also find that the electron acceleration in both nonthermal limbs
of SN 1006 proceeds close to the Bohm diffusion limit, the gyrofactor being in
the range 1.5-4. We finally investigate possible explanations for the low
values of cutoff energy measured in thermal limbs.Comment: Accepted for publication in Astronomische Nachrichten. Proceedings of
  the XMM-Newton Science Workshop 201
The stability of strong waves and its implications for pulsar wind
  shocks

Strong waves can mediate a shock transition between a pulsar wind and its
surroundings, playing the role of an extended precursor, in which the energy is
effectively transferred from fields to non-thermal particles. The damping of
such precursors results in an essentially unmagnetized shock near the equator.
In this context, we discuss the stability of strong waves and its implications
for the properties of shocks. Those with stable precursors can exist in the
winds of most of isolated pulsars, but the precursors may be unstable if the
external pressure in the nebula is high, as in Vela-like pulsars. Pulsar wind
shocks in eccentric binary systems, such as B1259-63, can acquire precursors
only at certain orbital phases, and this process should be accompanied by
enhanced synchro-Compton and inverse Compton emission from the precursor. The
same scenario may be at work in the binary HESS J0632+057.Comment: 6 pages, 2 figures, proceedings of XMM-Newton 2013 Science Workshop,
  submitted to Astronomical Note
Unifying neutron stars: getting to GUNS

The variety of the observational appearance of young isolated neutron stars
must find an explanation in the framework of some unifying approach. Nowadays
it is believed that such scenario must include magnetic field decay, the
possibility of magnetic field emergence on a time scale $\lesssim 10^4$--$10^5$
yrs, significant contribution of non-dipolar fields, and appropriate initial
parameter distributions. We present our results on the initial spin period
distribution, and suggest that inconsistences between distributions derived by
different methods for samples with different average ages can uncover field
decay or/and emerging field. We describe a new method to probe the magnetic
field decay in normal pulsars. The method is a modified pulsar current
approach, where we study pulsar flow along the line of increasing
characteristic age for constant field. Our calculations, performed with this
method, can be fitted with an exponential decay for ages in the range $8\times
10^4$--$3.5 \times 10^5$ yrs with a time scale $\sim 5 \times 10^5$ yrs. We
discuss several issues related to the unifying scenario. At first, we note that
the dichotomy, among local thermally emitting neutron stars, between normal
pulsars and the Magnificent Seven remains unexplained. Then we discuss the role
of high-mass X-ray binaries in the unification of neutron star evolution. We
note, that such systems allow to check evolutionary effects on a time scale
longer than what can be probed with normal pulsars alone. We conclude with a
brief discussion of importance of discovering old neutron stars accreting from
the interstellar medium.Comment: 6 pages, submitted to AN, proceedings of the workshop "The Fast and
  the Furious: Energetic Phenomena in Isolated Neutron Stars, Pulsar Wind
  Nebulae and Supernova Remnants" ESAC, Madrid, Spain 22nd - 24th May 201
Nustar Results and Future Plans for Magnetar and Rotation-Powered Pulsar Observations

The Nuclear Spectroscopic Telescope Array (NuSTAR) is the first focusing hard X-ray mission in orbit and operates in the 3–79 keV range. NuSTAR's sensitivity is roughly two orders of magnitude better than previous missions in this energy band thanks to its superb angular resolution. Since its launch in 2012 June, NuSTAR has performed excellently and observed many interesting sources including four magnetars, two rotation-powered pulsars and the cataclysmic variable AE Aquarii. NuSTAR also discovered 3.76-s pulsations from the transient source SGR J1745–29 recently found by Swift very close to the Galactic center, clearly identifying the source as a transient magnetar. For magnetar 1E 1841–045, we show that the spectrum is well fit by an absorbed blackbody plus broken power-law model with a hard power-law photon index of ∼ 1.3. This is consistent with previous results by INTEGRAL and RXTE. We also find an interesting double-peaked pulse profile in the 25–35 keV band. For AE Aquarii, we show that the spectrum can be described by a multi-temperature thermal model or a thermal plus non-thermal model; a multi-temperature thermal model without a non-thermal component cannot be ruled out. Furthermore, we do not see a spiky pulse profile in the hard X-ray band, as previously reported based on Suzaku observations. For other magnetars and rotation-powered pulsars observed with NuSTAR, data analysis results will be soon availableUnited States. National Aeronautics and Space Administration (NASA Contract No. NNG08FD60C)United States. National Aeronautics and Space Administration (NASA grant NNX10AI72G)United States. National Aeronautics and Space Administration (NASA Grant NNX13AI34G)United States. Dept. of Energy (Lawrence Livermore National Laboratory Contract DE- AC52-07NA27344
Magnetic Field Instabilities in Neutron Stars

Magnetic fields represent a crucial aspect of the physics and astrophysics of
neutron stars. Despite its great relevance, the internal magnetic field
configuration of neutron stars is very poorly constrained by the observations,
and understanding its properties is a long-standing theoretical challenge. The
investigation on the subject is focused on the search for those magnetic field
geometries which are stable on several Alfv\`en timescales, thus constituting a
viable description of neutron star interiors. Assesing the stability of a given
magnetic field geometry is therefore an important part of this research. So far
only simple configurations, such as the purely poloidal or purely toroidal
ones, have been studied in detail in perturbation theory and, most recently, by
means of nonlinear magnetohydrodynamic simulations. Here we review the basic
results of the state-of-the-art general relativistic nonlinear studies,
discussing the present status of the field and its future directions.Comment: 6 pages, 4 figures. Proceedings of the XMM-Newton Science Workshop
  201
Modeling statistical properties of the X-ray emission from aged Pulsar
  Wind Nebulae

The number of known PWNe has recently increased considerably, and the
majority of them are now middle-age objects. Recent studies have shown a clear
correlation of both X-ray luminosity and size with the PWN age, but fail in
providing a thorough explanation of the observed trends. Here I propose a
different approach to these effects, based on the hypothesis that the observed
trends do not simply reproduce the evolution of a "typical" PWN, but are a
combined effect of PWNe evolving under different ambient conditions, the
leading parameter being the ambient medium density. Using a simple analytic
approach, I show that most middle-age PWNe are more likely observable during
the reverberation phase, and I succeed in reproducing trends consistent with
those observed, provided that the evolution of the X-ray emitting electrons
keeps adiabatic over the whole reverberation phase. As a direct consequence, I
show that the X-ray spectra of older PWNe should be harder: also this is
consistent with observations.Comment: 6 pages, 3 figures. Proceedings of the XMM-Newton 2013 Science
  Workshop "The Fast and the Furious: Energetic Phenomena in Isolated Neutron
  Stars, Pulsar Wind Nebulae and Supernova Remnants". ESAC, Madrid, Spain,
  22nd-24th May 2013. Accepted for publication on Astronomische Nachrichte
Intrabinary Shock Emission from Black Widows and Redbacks

Eclipsing millisecond pulsars in close ($P_b < 1$~day) binary systems provide
a different view of pulsar winds and shocks than do isolated pulsars. Since
2009, the numbers of these systems known in the Galactic field has increased
enormously. We have been systematically studying many of these newly discovered
systems at multiple wavelengths. Typically, the companion is nearly Roche-lobe
filling and heated by the pulsar which drives mass loss from the companion. The
pulsar wind shocks with this material just above the surface of the companion.
We discuss various observational properties of this shock, including radio
eclipses, orbitally modulated X-ray emission, and the potential for
$\gamma$-ray emission. Redbacks, whose companions are likely non-degenerate and
significantly more massive, generally have more luminous shocks than black
widows which have very low mass companions. This is expected since the more
massive redback companions intercept a greater fraction of the pulsar wind. We
also compare these systems to accreting millisecond pulsars, which may be
progenitors of black widows and in some cases can pass back and forth between
redback and accretion phases.Comment: 8 pages, 2 figures, Proceedings of the XMM-Newton Workshop, The Fast
  and the Furious: Energetic Phenomena in Isolated Neutron Stars, Pulsar Wind
  Nebulae and Supernova Remnants, ESAC, Madrid, Spain, 22nd - 24th May 201
Beyond the 2nd Fermi Pulsar Catalog

Over thirteen times more gamma-ray pulsars have now been studied with the
Large Area Telescope on NASA's Fermi satellite than the ten seen with the
Compton Gamma-Ray Observatory in the nineteen-nineties. The large sample is
diverse, allowing better understanding both of the pulsars themselves and of
their roles in various cosmic processes. Here we explore the prospects for even
more gamma-ray pulsars as Fermi enters the 2nd half of its nominal ten-year
mission. New pulsars will naturally tend to be fainter than the first ones
discovered. Some of them will have unusual characteristics compared to the
current population, which may help discriminate between models. We illustrate a
vision of the future with a sample of six pulsars discovered after the 2nd
Fermi Pulsar Catalog was written.Comment: 6 pages, to appear in the proceedings of "The Fast and the Furious:
  Energetic Phenomena in Isolated Neutron Stars, Pulsar Wind Nebulae and
  Supernova Remnants",ESAC, Madrid, Spain, 22 - 24 May 2013
  http://xmm.esac.esa.int/external/xmm_science/workshops/2013_science/, to be
  published as a regular issue of the Astronomische Nachrichten / Astronomical
  Notes (AN
Transmission profile of the Dutch Open Telescope H$\alpha$ Lyot filter

Accurate knowledge of the spectral transmission profile of a Lyot filter is
important, in particular in comparing observations with simulated data. The
paper summarizes available facts about the transmission profile of the DOT
H$\alpha$ Lyot filter pointing to a discrepancy between sidelobe-free
Gaussian-like profile measured spectroscopically and signatures of possible
leakage of parasitic continuum light in DOT H$\alpha$ images. We compute
wing-to-center intensity ratios resulting from convolutions of Gaussian and
square of the sinc function with the H$\alpha$ atlas profile and compare them
with the ratios derived from observations of the quiet Sun chromosphere at disk
center. We interpret discrepancies between the anticipated and observed ratios
and the sharp limb visible in the DOT H$\alpha$ image as an indication of
possible leakage of parasitic continuum light. A method suggested here can be
applied also to indirect testing of transmission profiles of other Lyot
filters. We suggest two theoretical transmission profiles of the DOT H$\alpha$
Lyot filter which should be considered as the best available approximations.
Conclusive answer can only be given by spectroscopic re-measurement of the
filter.Comment: 7 pages, 9 figures, 2 tables, The final publication is available at
  Wiley via http://onlinelibrary.wiley.com/doi/10.1002/asna.201312048/ful
Spectra of faint sources in crowded fields with FRODOSpec on the
  Liverpool Robotic Telescope

We check the performance of the FRODOSpec integral-field spectrograph for
observations of faint sources in crowded fields. Although the standard
processing pipeline L2 yields too noisy fibre spectra, we present a new
processing software (L2LENS) that gives rise to accurate spectra for the two
images of the gravitationally lensed quasar Q0957+561. Among other things, this
L2LENS reduction tool accounts for the presence of cosmic-ray events,
scattered-light backgrounds, blended sources, and chromatic source
displacements due to differential atmospheric refraction. Our non-standard
reduction of Q0957+561 data shows the ability of FRODOSpec to provide useful
information on a wide variety of targets, and thus, the big potential of
integral-field spectrographs on current and future robotic telescopes.Comment: 12 pages, 12 figures, 1 appendix (User's guide for the L2LENS
  software; see also http://grupos.unican.es/glendama/LQLM_tools.htm); correct
  versions of figures 1 (top panel) and
Determination of a temporally and spatially resolved Supernova rate from
  OB-stars within 5kpc

We spatially and temporally resolve the future Supernova (SN) rate in the
Solar vicinity and the whole Galaxy by comparing observational parameters of
massive stars with theoretical models for estimating age and mass and, hence,
the remaining life-time until the SN explosion. Our SN rate derived in time and
space for the future (few Myr) should be the same as in the last few Myr by
assuming a constant rate. From BVRIJHK photometry, parallax, spectral type, and
luminosity class we compile a Hertzsprung-Russell diagram (H-R D) for 25027
massive stars and derive extinction, and luminosity, then mass, age, and
remaining life-time from evolutionary models. Within 600pc our sample of SN
progenitors and, hence, SN prediction, is complete, and all future SN events of
our sample stars take place in 8% of the area of the sky, whereas 90% of the
events take place in 7% of the area of the sky. The current SN rate within
600pc is increased by a factor of 5-6 compared with the Galactic rate. For a
distance of 5kpc our sample is incomplete, nevertheless 90% of those SN events
take place in only 12% of the area of the projected sky. If the SN rate in the
near future is the same as the recent past, there should be unknown young
neutron stars concentrated in those areas. Our distribution can be used as
input for constraints of gravitational waves detection and for neutron star
searches.Comment: 14 pages, 22 figures, 12 tables, accepted for publication in
  Astronomische Nachrichte
Studying the dwarf galaxies in nearby groups of galaxies: spectroscopic
  and photometric data

Galaxy evolution by interaction driven transformation is probably highly
efficient in groups of galaxies. Dwarf galaxies with their shallow potential
are expected to reflect the interaction most prominently in their observable
structure. The major aim of this series of papers is to establish a data base
which allows to study the impact of group interaction onto the morphology and
star-forming properties of dwarf galaxies. Firstly, we present our selection
rules for target groups and the morphological selection method of target dwarf
member candidates. Secondly, the spectroscopic follow-up observations with the
HET are present. Thirdly, we applied own reduction methods based on adaptive
filtering to derive surface photometry of the candidates. The spectroscopic
follow-up indicate a dwarf identification success rate of roughly 55%, and a
group member success rate of about 33%. A total of 17 new low surface
brightness members is presented. For all candidates, total magnitudes, colours,
and light distribution parameters are derived and discussed in the context of
scaling relations. We point out short comings of the SDSS standard pipeline for
surface photometry for these dim objects. We conclude that our selection
strategy is rather efficient to obtain a sample of dim, low surface brightness
members of groups of galaxies within the Virgo super-cluster. The photometric
scaling relation in these X-ray dim, rather isolated groups does not
significantly differ from those of the galaxies within the Local Volume.Comment: 24 pages, 12 figures, 8 tables, accepted for publication in
  Astronomische Nachrichte
CoRoT Data Reduction By Example

Data reduction techniques published so far for the CoRoT N2 data product were
targeted primarily on the detection of extrasolar planets. Since the whole
dataset has been released, specific algorithms are required to process the
lightcurves from CoRoT correctly. Though only unflagged datapoints must be
chosen for scientific processing, some flags might be reconsidered. The
reduction of data along with improving the signal-to-noise ratio can be
achieved by applying a one dimensional drizzle algorithm. Gaps can be filled by
linear interpolated data without harming the frequency spectrum. Magnitudes
derived from the CoRoT color channels might be used to derive additional
information about the targets. Depending on the needs, various filters in the
frequency domain remove either the red noise background or high frequency
noise. The autocorrelation function or the least squares periodogram are
appropriate methods to identify periodic signals.The methods described here are
not strictly limited to CoRoT data but may also be applied on Kepler data or
the upcoming Plato mission
Investigation of a transiting planet candidate in Trumpler 37: an
  astrophysical false positive eclipsing spectroscopic binary star

We report our investigation of the first transiting planet candidate from the
YETI project in the young (~4 Myr old) open cluster Trumpler 37. The
transit-like signal detected in the lightcurve of the F8V star
2M21385603+5711345 repeats every 1.364894+/-0.000015 days, and has a depth of
54.5+/-0.8 mmag in R. Membership to the cluster is supported by its mean radial
velocity and location in the color-magnitude diagram, while the Li diagnostic
and proper motion are inconclusive in this regard. Follow-up photometric
monitoring and adaptive optics imaging allow us to rule out many possible blend
scenarios, but our radial-velocity measurements show it to be an eclipsing
single-lined spectroscopic binary with a late-type (mid-M) stellar companion,
rather than one of planetary nature. The estimated mass of the companion is
0.15-0.44 solar masses. The search for planets around very young stars such as
those targeted by the YETI survey remains of critical importance to understand
the early stages of planet formation and evolution.Comment: 12 pages, 8 figure
Wide-Field Plate Archive of the University Observatory Jena

We present the archive of the wide-field plate observations obtained at the
University Observatory Jena, which is stored at the Astrophysical Institute of
the Friedrich Schiller University Jena. The archive contains plates taken in
the period February 1963 to December 1982 with the 60/90/180-cm Schmidt
telescope of the university observatory. A computer-readable version of the
plate metadata catalogue (for 1257 plates), the logbooks, as well as the
digitized Schmidt plates in low and high resolution are now accessible to the
astronomical community.This paper describes the properties of the archive, as
well as the processing procedure of all plates in detail.Comment: 10 pages, 7 figures; accepted for publication in A
A hydrodynamical study of multiple-shell planetary nebulae. III.
  Expansion properties and internal kinematics: Theory versus observation

We present the result of a study on the expansion properties and internal
kinematics of round/elliptical planetary nebulae of the Milky Way disk, the
halo, and of the globular cluster M15. The purpose of this study is to
considerably enlarge the small sample of nebulae with precisely determined
expansion properties. To this aim, we selected a representative sample of
objects with different evolutionary stages and metallicities and conducted
high-resolution echelle spectroscopy. In most cases, we succeeded in detecting
the weak signals from the outer nebular shell which are attached to the main
line emission from the bright nebular rim. Next to the measurement of the
motion of the rim gas by decomposition of the main line components into
Gaussians, we were able to measure separately, for most objects for the first
time, the gas velocity immediately behind the leading shock of the shell, i.e.
the post-shock velocity. We more than doubled the number of objects for which
the velocities of both rim and shell are known and confirm that the overall
expansion of planetary nebulae is accelerating with time. There are, however,
differences between the expansion behaviour of the shell and the rim. This
observed distinct velocity evolution of both rim and shell is explained by
radiation-hydrodynamics simulations, at least qualitatively. Because of the
time-dependent boundary conditions, a planetary nebula will never evolve into a
simple self-similar expansion. Also the metal-poor objects behave as theory
predicts: The post-shock velocities are higher and the rim flow velocities are
equal or even lower compared to disk objects at similar evolutionary stage. We
detected, for the first time, in some objects an asymmetric expansion
behaviour: The relative expansions between rim and shell appear to be different
for the receding and approaching parts of the nebular envelope.Comment: 32 pages, 19 Figures; accepted for publication in "Astronomical Notes
  / Astronomische Nachrichten