pinecone/core-2020-05-10-deduplication huggingface dataset:
A transient event in AD 775 reported by al-Tabari: A bolide - not a
  nova, supernova, or kilonova

Given that the cause for the strong increase in 14C in AD 774/5 in Japanese
and German trees is still a matter of debate (e.g. short Gamma-Ray Burst or
solar super-flare), we have searched in Arabic chronicles for reports about
unusual transient celestial events. In the History of al-Tabari we found two
(almost identical) reports about such an event. The group around caliph
al-Mansur observed a transient event while on the way from Baghdad to Mecca on
AD 775 Aug 29 - Sep 1 (Julian calendar). A celestial object (kawkab) was seen
to fall or set (inqadda), and its trace (atharuhu) was seen for at least tens
of minutes (up to 70-90 min) during morning twilight. The reports use the
Arabic words kawkab and athar(uhu), which were also used in the known Arabic
reports about supernovae SN 1006 and 1054, so that one might consider an
interpretation as a nova-like event. The kawkab (celestial object) was observed
only during the morning twilight at a brightness of probably between about -3
and 0 mag. Such a brightness and time-scale would be expected for optical
kilonovae (at 3 to 9 kpc) in the context of short Gamma-Ray Bursts. There are
no similar reports from eastern Asia for this time. However, the short reports
are fully consistent with a bolide: The word kawkab can be used for meteor, the
verb inqadda normally means "falling down", the word atharuhu can mean "its
trace". We therefore prefer the interpretation as bolide. We discuss in detail
how to convert the Muslim calendar date to a date in the Julian calendar using
first the calculated Islamic calendar and then considering the time when the
crescent new moon could be visible at the given location.Comment: 12 pages with three figures, paper in press (Astronomical Notes 2014)
  - small corrections applie
Dynamical evolution of two associated galactic bars

We study the dynamical interactions of mass systems in equilibrium under
their own gravity that mutually exert and experience gravitational forces. The
method we employ is to model the dynamical evolution of two isolated bars,
hosted within the same galactic system, under their mutual gravitational
interaction. In this study we present an analytical treatment of the secular
evolution of two bars that oscillate with respect one another. Two cases of
interaction, with and without geometrical deformation, are discussed. In the
latter case, the bars are described as modified Jacobi ellipsoids. These
triaxial systems are formed by a rotating fluid mass in gravitational
equilibrium with its own rotational velocity and the gravitational field of the
other bar. The governing equation for the variation of their relative angular
separation is then numerically integrated, which also provides the time
evolution of the geometrical parameters of the bodies. The case of rigid,
non-deformable, bars produces in some cases an oscillatory motion in the bodies
similar to that of a harmonic oscillator. For the other case, a deformable
rotating body that can be represented by a modified Jacobi ellipsoid under the
influence of an exterior massive body will change its rotational velocity to
escape from the attracting body, just as if the gravitational torque exerted by
the exterior body were of opposite sign. Instead, the exchange of angular
momentum will cause the Jacobian body to modify its geometry by enlarging its
long axis, located in the plane of rotation, thus decreasing its axial ratios.Comment: Accepted for publication in A
New Radial Velocities for 30 Candidate Runaway Stars and a Possible
  Binary Supernova Origin for HIP 9470 and PSR J0152-1637

We report new radial velocity measurements for 30 candidate runaway stars. We
revise their age estimates and compute their past trajectories in the Galaxy in
order to determine their birthplaces. We find that seven of the stars could be
younger than ~100 Myr, and for five of them we identify multiple young clusters
and associations in which they may have formed. For the youngest star in the
sample, HIP 9470, we suggest a possible ejection scenario in a supernova event,
and also that it may be associated with the young pulsar PSR J0152-1637. Our
spectroscopic observations reveal seven of the stars in the sample of 30 to be
previously unknown spectroscopic binaries. Orbital solutions for four of them
are reported here as well.Comment: accepted for publication in Astronomical Notes, issue 9, 2014 note
  that in the manuscript only a small portion of Table 1 is shown, the
  individual RVs for all stars are given in the file rvs.indi
Control of chaos in the vicinity of the Earth--Moon L5 Lagrangian point
  to keep a spacecraft in orbit

The concept of Space Manifold Dynamics is a new method of space research. We
have applied it along with the basic idea of the method of Ott, Grebogi and
York (OGY method) to stabilize the motion of a spacecraft around the triangular
Lagrange point L5 of the Earth--Moon system. We have determined the escape rate
of the trajectories in the general three- and four-body problem and estimated
the average lifetime of the particles. Integrating the two models we mapped in
detail the phase space around the L5 point of the Earth--Moon system. Using the
phase space portrait our next goal was to apply a modified OGY method to keep a
spacecraft close to the vicinity of L5. We modified the equation of motions
with the addition of a time dependent force to the motion of the spacecraft. In
our orbit--keeping procedure there are three free parameters: (i) the magnitude
of the thrust, (ii) the start time and (iii) the length of the control. Based
on our numerical experiments we were able to determine possible values for
these parameters and successfully apply a control phase to a spacecraft to keep
it on orbit around L5.Comment: 11 pages, 11 figures (updated Fig. 2), 1 table, accepted for
  publication in Astron. Nach
Difference between the optical flickering colours of cataclysmic
  variables and symbiotic recurrent novae

We performed simultaneous observations in 3 bands (UBV) of the flickering
variability of the recurrent novae RS Oph and T CrB at quiescence. Using new
and published data, we compare the colours of the flickering in cataclysmic
variables and symbiotic recurrent novae. We find a difference between the
colours of the flickering source in these two types of accreting white dwarfs.
The detected difference is highly significant with $ p-value \approx 2 \times
10^{-6}$ for the distributions of $(U-B)_0$ colour and $p \approx 3 \times
10^{-5}$ on (U-B) versus (B-V) diagram. The possible physical reasons are
briefly discussed. The data are available upon request from the authors.Comment: accepted in Astronomische Nachrichten (Astronomical Notes): 2015, AN
  336
Light curve solutions of the ultrashort-period $Kepler$ binaries

We carried out light curve solutions of the ultrashort-period binaries with
MS components observed by $Kepler$. All six targets turned out almost in
thermal contact with contact or slightly overcontact configurations. Two of
them, KID 4921906 and KID 6309193, are not eclipsing but reveal ellipsoidal and
spot variability. One of the components of KID 8108785 exhibits inherent,
quasi-sinusoidal, small-amplitude variability. KID 12055255 turned out a very
rare case of ultrashort-period overcontact binary consisting of two M dwarfs.
Our modeling indicated that the variability of KID 9532219 is due to eclipses
but not to $\delta$ Sct pulsations as it was previously supposed.Comment: 6 pages, 6 figures, 3 tables, accepted for publication in Astron.
  Nachrichte
Multi-epoch time-resolved photometry of the eclipsing polar
  CSS081231:J071126+440405

The eclipsing polar CSS081231 turned bright (V_max ~ 14.5) in late 2008 and
was subsequently observed intensively with small and medium-sized telescopes. A
homogeneous analysis of this comprehensive dataset comprising 109 eclipse
epochs is presented and a linear ephemeris covering the five years of
observations, about 24000 orbital cycles, is derived. Formally this sets rather
tight constraints on the mass of a hypothetical circumbinary planet, M_pl <= 2
M_Jup. This preliminary result needs consolidation by long-term monitoring of
the source. The eclipse lasts 433.08 +- 0.65 s, and the orbital inclination is
found to be i=79.3 - 83.7 degrees. The centre of the bright phase displays
accretion-rate dependent azimuthal shifts. No accretion geometry is found that
explains all observational constraints, suggesting a complex accretion geometry
with possible pole switches and a likely non-dipolar field geometry.Comment: 11 pages, 11 figures, accepted for publication in A
Supernova SN 1006 in two historic Yemeni reports

We present two Arabic texts of historic observations of supernova SN 1006
from Yemen as reported by al-Yamani and Ibn al-Dayba (14th to 16th century AD).
An English translation of the report by the latter was given before (Stephenson
& Green 2002), but the original Arabic text was not yet published. In addition,
we present for the first time the earlier report, also from Yemen, namely by
al-Yamani in its original Arabic and with our English translation. It is quite
obvious that the report by Ibn al-Dayba is based on the report by al-Yamani (or
a common source), but the earlier report by al-Yamani is more detailed and in
better (Arabic) language. We discuss in detail the dating of these
observations. The most striking difference to other reports about SN 1006 is
the apparent early discovery in Yemen in the evening of 15th of Rajab of the
year 396h (i.e. AD 1006 Apr 17 \pm 2 on the Julian calendar), as reported by
both al-Yamani and Ibn al-Dayba. i.e. about 1.5 weeks earlier than the
otherwise earliest known reports. We also briefly discuss other information
from the Yemeni reports on brightness, light curve, duration of visibility,
location, stationarity, and color.Comment: 9 pages with 3 figure
The power of low-resolution spectroscopy: On the spectral classification
  of planet candidates in the ground-based CoRoT follow-up

Planetary transits detected by the CoRoT mission can be mimicked by a
low-mass star in orbit around a giant star. Spectral classification helps to
identify the giant stars and also early-type stars which are often excluded
from further follow-up.
  We study the potential and the limitations of low-resolution spectroscopy to
improve the photometric spectral types of CoRoT candidates. In particular, we
want to study the influence of the signal-to-noise ratio (SNR) of the target
spectrum in a quantitative way. We built an own template library and
investigate whether a template library from the literature is able to reproduce
the classifications. Including previous photometric estimates, we show how the
additional spectroscopic information improves the constraints on spectral type.
  Low-resolution spectroscopy ($R\approx$1000) of 42 CoRoT targets covering a
wide range in SNR (1-437) and of 149 templates was obtained in 2012-2013 with
the Nasmyth spectrograph at the Tautenburg 2m telescope. Spectral types have
been derived automatically by comparing with the observed template spectra. The
classification has been repeated with the external CFLIB library.
  The spectral class obtained with the external library agrees within a few
sub-classes when the target spectrum has a SNR of about 100 at least. While the
photometric spectral type can deviate by an entire spectral class, the
photometric luminosity classification is as close as a spectroscopic
classification with the external library. A low SNR of the target spectrum
limits the attainable accuracy of classification more strongly than the use of
external templates or photometry. Furthermore we found that low-resolution
reconnaissance spectroscopy ensures that good planet candidates are kept that
would otherwise be discarded based on photometric spectral type alone.Comment: accepted for publication in Astronomische Nachrichten; 12 pages, 4
  figures, 7 table
Stellar populations of the bulges of four spiral galaxies

Key information to understand the formation and evolution of disk galaxies
are imprinted in the stellar populations of their bulges. This paper has the
purpose to make available new measurements of the stellar population properties
of the bulges of four spiral galaxies. Both the central values and radial
profiles of the line strength of some of the most common Lick indices are
measured along the major- and minor- axis of the bulge-dominated region of the
sample galaxies. The corresponding age, metallicity, and {\alpha}/Fe ratio are
derived by using the simple stellar population synthesis model predictions. The
central values and the gradients of the stellar population properties of
ESO-LV1890070, ESO-LV4460170, and ESO-LV 5140100 are consistent with previous
findings for bulges of spiral galaxies. On the contrary, the bulge of ESO-LV
4500200 shows peculiar chemical properties possibly due to the presence of a
central kinematically-decoupled component. The negative metallicity gradient
found in our bulges sample indicates a relevant role for the dissipative
collapse in bulge formation. However, the shallow gradients found for the age
and {\alpha}/Fe ratio suggests that merging can not be completely ruled out for
the sample bulges. This is confirmed by the properties of ESO-LV 4500200 which
can hardly be explained without invoking the capture of external material.Comment: 11 pages. 7 figures, AN in press. arXiv admin note: text overlap with
  arXiv:1203.428
Element spots in Ap- and HgMn-stars from current-driven diffusion

The stars of the middle main sequence often have spot-like chemical
structures at their surfaces. We consider the diffusion process caused by
electric currents that can lead to the formation of such chemical spots.
Diffusion is considered using the partial momentum equations derived by the
Chapman-Enskog method. We argue that diffusion caused by electric currents can
substantially change the surface chemistry of stars and form spotted chemical
structures even in a relatively weak magnetic field. The considered mechanism
can be responsible for a formation of element spots in HgMn- and Ap-stars.Comment: 5 page
Solar activity around AD 775 from aurorae and radiocarbon

A large variation in 14 C around AD 775 has been considered to be caused by
one or more solar super-flares within one year. We critically review all known
aurora reports from Europe as well as the Near, Middle, and Far East from AD
731 to 825 and find 39 likely true aurorae plus four more potential aurorae and
24 other reports about halos, meteors, thunderstorms etc., which were
previously misinterpreted as aurorae or misdated; we assign probabilities for
all events according to five aurora criteria. We find very likely true aurorae
in AD 743, 745, 762, 765, 772, 773, 793, 796, 807, and 817. There were two
aurorae in the early 770s observed near Amida (now Diyarbakir in Turkey near
the Turkish-Syrian border), which were not only red, but also green-yellow -
being at a relatively low geo-magnetic latidude, they indicate a relatively
strong solar storm. However, it cannot be argued that those aurorae
(geo-magnetical latitude 43 to 50 deg, considering five different
reconstructions of the geo-magnetic pole) could be connected to one or more
solar super-flares causing the 14 C increase around AD 775: There are several
reports about low- to mid-latitude aurorae at 32 to 44 deg geo-magnetical
latitude in China and Iraq; some of them were likely observed
(quasi-)simultaneously in two of three areas (Europe, Byzantium/Arabia, East
Asia), one lasted several nights, and some indicate a particulary strong
geo-magnetic storm (red colour and dynamics), namely in AD 745, 762, 793, 807,
and 817 - always without 14 C peaks. We use 39 likely true aurorae as well as
historic reports about sunspots together with the radiocarbon content from tree
rings to reconstruct solar activity: From about AD 733 to 823, we see at least
nine Schwabe cycles ...Comment: 24 pages with 1 table and 2 figures, paper to appear in Astronomical
  Notes 24 Apr 201
Magnetic field measurements of $\epsilon$ Eridani from Zeeman broadening

We present new magnetic field measurements of the K2 main-sequence star
$\epsilon$ Eridani based on principal components analysis (PCA) line-profile
reconstructions. The aim of this paper is to quantify the surface-averaged
magnetic field and search for possible variations. A total of 338 optical
echelle spectra from our robotic telescope facility STELLA with a spectral
resolution of 55,000 were available for analysis. This time-series was used to
search for the small line-profile variations due to a surface magnetic field
with the help of a PCA. Evidence for a spatial and temporal inhomogeneous
magnetic field distribution is presented. The mean, surface averaged, magnetic
field strength was found to be $\langle B \rangle = 186 \pm 47\,\mathrm{G}$ in
good agreement with previous Zeeman-broadening measurements. Clear short-term
variations of the surface averaged magnetic field of up to few tens Gauss were
detected together with evidence for a three-year cycle in the surface-averaged
magnetic field of $\epsilon$ Eridani
Planet formation in post-common-envelope binaries

To understand the evolution of planetary systems, it is important to
investigate planets in highly evolved stellar systems, and to explore the
implications of their observed properties with respect to potential formation
scenarios. Observations suggest the presence of giant planets in
post-common-envelope binaries (PCEBs). A particularly well-studied system with
planetary masses of 1.7 M_J and 7.0 M_J is NN Ser. We show here that a pure
first-generation scenario where the planets form before the common envelope
(CE) phase and the orbits evolve due to the changes in the gravitational
potential is inconsistent with the current data. We propose a second-generation
scenario where the planets are formed from the material that is ejected during
the CE, which may naturally explain the observed planetary masses. In addition,
hybrid scenarios where the planets form before the CE and evolve due to the
accretion of the ejected gas appear as a realistic possibility.Comment: 7 pages, 5 figures. Plenary talk given at the 2014 Fall Meeting of
  the Astronomische Gesellschaft (AG 2014) in Bamberg, submitted for the
  yearbook series "Reviews in Modern Astronomy", volume 27, of the
  Astronomische Gesellschaf
Comparing modal noise and FRD of circular and non-circular cross-
  section fibres

Modal noise is a common source of noise introduced to the measurements by
optical fibres and is particularly important for fibre-fed spectroscopic
instruments, especially for high-resolution measurements. This noise source can
limit the signal-to-noise ratio and jeopardize photon-noise limited data. The
subject of the present work is to compare measurements of modal noise and
focal-ratio degradation (FRD) for several commonly-used fibres. We study the
influence of a simple mechanical scrambling method (excenter) on both FRD and
modal noise. Measurements are performed with circular and octagonal fibres from
Polymicro Technology (FBP-Series) with diameters of 100, 200 and 300 {\mu}m and
for square and rectangular fibres from CeramOptec, among others. FRD
measurements for the same sample of fibres are performed as a function of
wavelength. Furthermore, we replaced the circular fibre of the
STELLA-echelle-spectrograph (SES) in Tenerife with an octagonal and found a SNR
increase by a factor of 1.6 at 678 nm. It is shown in the laboratory that an
excenter with a large amplitude and low frequency will not influence the FRD
but will reduce modal noise rather effectively by up to 180%
Star formation rates and the kinematics of gas in the spiral arms of NGC
  628

Relations between star formation rates along the spiral arms and the
velocities of gas inflow into the arms in grand-design galaxy NGC 628 were
studied. We found that the radial distribution of average star formation rate
in individual star formation regions in regular spiral arms correlates with the
velocity of gas inflow into the spiral arms. Both distributions have maxima at
a galactocentric distance of 4.5-5 kpc. There are no correlations between the
radial distributions of average star formation rate in star formation regions
in spiral arms and outside spiral arms in the main disc. We also did not find a
correlation between the radial distribution of average star formation rate in
star formation regions in spiral arms and HI column density.Comment: 8 pages, 6 figures, 1 table. Accepted for publication in
  Astronomische Nachrichte
PEPSI: The high-resolution echelle spectrograph and polarimeter for the
  Large Binocular Telescope

PEPSI is the bench-mounted, two-arm, fibre-fed and stabilized Potsdam Echelle
Polarimetric and Spectroscopic Instrument for the 2x8.4 m Large Binocular
Telescope (LBT). Three spectral resolutions of either 43 000, 120 000 or 270
000 can cover the entire optical/red wavelength range from 383 to 907 nm in
three exposures. Two 10.3kx10.3k CCDs with 9-{\mu}m pixels and peak quantum
efficiencies of 96 % record a total of 92 echelle orders. We introduce a new
variant of a wave-guide image slicer with 3, 5, and 7 slices and peak
efficiencies between 96 %. A total of six cross dispersers cover the six
wavelength settings of the spectrograph, two of them always simultaneously.
These are made of a VPH-grating sandwiched by two prisms. The peak efficiency
of the system, including the telescope, is 15% at 650 nm, and still 11% and 10%
at 390 nm and 900 nm, respectively. In combination with the 110 m2
light-collecting capability of the LBT, we expect a limiting magnitude of 20th
mag in V in the low-resolution mode. The R=120 000 mode can also be used with
two, dual-beam Stokes IQUV polarimeters. The 270 000-mode is made possible with
the 7-slice image slicer and a 100- {\mu}m fibre through a projected sky
aperture of 0.74", comparable to the median seeing of the LBT site. The
43000-mode with 12-pixel sampling per resolution element is our bad seeing or
faint-object mode. Any of the three resolution modes can either be used with
sky fibers for simultaneous sky exposures or with light from a stabilized
Fabry-Perot etalon for ultra-precise radial velocities. CCD-image processing is
performed with the dedicated data-reduction and analysis package PEPSI-S4S. A
solar feed makes use of PEPSI during day time and a 500-m feed from the 1.8 m
VATT can be used when the LBT is busy otherwise. In this paper, we present the
basic instrument design, its realization, and its characteristics
Discovery of a New Blue Quasar: SDSS J022218.03-062511.1

We report the discovery of a bright blue quasar: SDSS J022218.03-062511.1.
This object was discovered spectroscopically while searching for hot white
dwarfs that may be used as calibration sources for large sky surveys such as
the Dark Energy Survey or the Large Synoptic Survey Telescope project. We
present the calibrated spectrum, spectral line shifts and report a redshift of
z = 0.521 +/- 0.0015 and a rest-frame g-band luminosity of 8.71 X 10^11 L(Sun).Comment: 5 pages, 5 figures, Accepted for Astron. Nach