pinecone/core-2020-05-10-deduplication huggingface dataset:
Metallicity field and selection effects in spatial distribution of the
  Galactic globular cluster system

The prospects for using the present-day data on metallicity of globular
clusters (GCs) of the Galaxy to put constraints on the distance to the Galactic
center, $R_0$, are considered. We have found that the GCs of the metal-rich and
metal-poor subsystems separately form a bar-like structure in metallicity maps
whose parameters are very close to those for the Galactic bar. The results
indicate the existence of a bar component within both the metal-rich and
metal-poor subsystems of GCs. The bar GCs could have formed within the already
existing Galactic bar or could have later been locked in resonance with the
bar. We conclude that substantial constraints on the $R_0$ value can be
obtained only with non-axisymmetric models for the space distribution of GC
metallicities with the allowance for the subdivision of GCs into subsystems. We
found evidence for a bar extinction component that causes the observational
incompleteness of GCs in the far side of the Galactic bar and in the
"post-central" region. This selection effect should be taken into account when
determining $R_0$ from the spatial distribution of GCs.Comment: 8 pages, 8 figures. Accepted for publication in Astronomische
  Nachrichten (AN
New programs for determining the main parameters of open clusters

A set of computer programs for the determination of the main parameters of open clusters, such as color excess, distance, and age, is developed. The set consists of two units. The first unit is designed to search for open clusters in wide fields using JHKs-photometry from various catalogs (2MASS, UKIDSS, VISTA) by identifying areas of high stellar density. The second unit determines the parameters of open clusters by fitting photometric diagrams. This is the unit described in the paper. Probable cluster members are identified by the proximity to the basic sequences on the J-(J - H) and Q-(J - H) diagrams. The color excess is determined by minimizing the deviations of Q values on the Q-(J - H) diagram. Ages and distance moduli are determined by comparing the color-magnitude diagrams with theoretical isochrones. © 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim
Eclipsing variables: Catalogue and classification

A new version of the Catalogue of Eclipsing Variables is presented. The catalogue contains parameters and morphological types of light curves for some 7200 stars. Spectral classification is also given when available. Recently published information about classification of 1352 systems is also included in the catalogue. Thus, the catalogue represents the largest list of eclipsing binaries classified from observations. The analysis of stellar parameter distributions of catalogued eclipsing systems has been performed, and an algorithm of eclipsing-variable classification has been developed. Classification of some systems is troublesome or contradictory due to lack of modern observational data or their possible rare evolutionary class. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
HARPS spectropolarimetry of Herbig Ae/Be stars

Our knowledge of the presence and the strength of magnetic fields in
intermediate-mass pre-main-sequence stars remains very poor. We present new
magnetic field measurements in six Herbig Ae/Be stars observed with HARPS in
spectropolarimetric mode. We downloaded from the European Southern Observatory
(ESO) archive the publically available HARPS spectra for six Herbig Ae/Be
stars. Wavelength shifts between right- and left-hand side circularly polarised
spectra were interpreted in terms of a longitudinal magnetic field <B_z>, using
the moment technique introduced by Mathys. The application of the moment
technique to the HARPS spectra allowed us in addition to study the presence of
the crossover effect and quadratic magnetic fields. Our search for longitudinal
magnetic fields resulted in first detections of weak magnetic fields in the
Herbig Ae/Be stars HD58647 and HD98922. Further, we confirm the previous
tentative detection of a weak magnetic field in HD104237 by Donati et al. and
confirm the previous detection of a magnetic field in the Herbig Ae star
HD190073. Surprisingly, the measured longitudinal magnetic field of HD190073,
<B_z>=91+-18G at a significance level of 5sigma is not in agreement with the
measurement results of Alecian et al. (2013), <B_z>=-10+-20G, who applied the
LSD method to exactly the same data. No crossover effect was detected for any
star in the sample. Only for HD98922 the crossover effect was found to be close
to 3sigma with a measured value of -4228+-1443 km/s G. A quadratic magnetic
field of the order of 10kG was detected in HD98922, and of ~3.5kG in HD104237.Comment: Eight pages, seven figures, three tables, accepted for publication in
  A
A photometric study of the nova-like variable TT Arietis with the MOST
  satellite

Variability on all time scales between seconds and decades is typical for
cataclysmic variables (CVs). One of the brightest and best studied CVs is TT
Ari, a nova-like variable which belongs to the VY Scl subclass, characterized
by occasional low states in their light curves. It is also known as a permanent
superhumper at high state, revealing "positive" (P_S > P_0) as well as
"negative" (P_S < P_0) superhumps, where P_S is the period of the superhump and
P_0 the orbital period. TT Ari was observed by the Canadian space telescope
MOST for about 230 hours nearly continuously in 2007, with a time resolution of
48 seconds. Here we analyze these data, obtaining a dominant "negative"
superhump signal with a period P_S = 0.1331 days and a mean amplitude of 0.09
mag. Strong flickering with amplitudes up to 0.2 mag and peak-to-peak time
scales of 15-20 minutes is superimposed on the periodic variations. We found no
indications for significant quasi-periodic oscillations with periods around 15
minutes, reported by other authors. We discuss the known superhump behaviour of
TT Ari during the last five decades and conclude that our period value is at
the upper limit of all hitherto determined "negative" superhump periods of TT
Ari, before and after the MOST run.Comment: Accepted for AN. 6 pages, 7 figures, 1 tabl
PAOLO: a Polarimeter Add-On for the LRS Optics at a Nasmyth focus of the
  TNG

We describe a new polarimetric facility available at the Istituto Nazionale
di AstroFisica / Telescopio Nazionale Galileo at La Palma, Canary islands. This
facility, PAOLO (Polarimetric Add-On for the LRS Optics), is located at a
Nasmyth focus of an alt-az telescope and requires a specific modeling in order
to remove the time- and pointing position-dependent instrumental polarization.
We also describe the opto-mechanical structure of the instrument and its
calibration and present early examples of applications.Comment: 7 pages, 9 figures, AN, in pres
Dense cores in the dark cloud complex LDN1188

We present a molecular line emission study of the LDN1188 dark cloud complex
located in Cepheus. In this work we focused on the densest parts of the cloud
and on the close neighbourhood of infrared point sources. We made ammonia
mapping with the Effelsberg 100-m radio telescope and identified 3 dense cores.
CS(1--0), CS(2--1) and HCO$^{+}$(1--0) measurements performed with the Onsala
20\,m telescope revealed the distribution of dense molecular material. The
molecular line measurements were supplemented by mapping the dust emission at
1.2\,mm in some selected directions using the IRAM 30\,m telescope. With these
data we could work out a likely evolutionary sequence in this dark clould
complex.Comment: YouResAstro2012 conference presentation; accepted to Astronomishen
  Nachrichten (25-July-2013
Newly identified YSO candidates towards the LDN 1188

We present an analysis of Young Stellar Object (YSO) candidates towards the
LDN 1188 molecular cloud. The YSO candidates were selected from the WISE
all-sky catalogue, based on a statistical method. We found 601 candidates in
the region, and classified them as Class I, Flat and Class II YSOs. Groups were
identified and described with the Minimal Spanning Tree (MST) method.
Previously identified molecular cores show evidence of ongoing star formation
at different stages throughout the cloud complex.Comment: 4 pages, 4 figures, 2 table
SPH-based simulation of multi-material asteroid collisions

We give a brief introduction to smoothed particle hydrodynamics methods for
continuum mechanics. Specifically, we present our 3D SPH code to simulate and
analyze collisions of asteroids consisting of two types of material: basaltic
rock and ice. We consider effects like brittle failure, fragmentation, and
merging in different impact scenarios. After validating our code against
previously published results we present first collision results based on
measured values for the Weibull flaw distribution parameters of basalt.Comment: Accepted and to be published in Astronomical Note
Statistical properties of twin kHz QPO in neutron star LMXBs

We collect the data of twin kilohertz quasi-periodic oscillations (kHz QPOs)
published before 2012 from 26 neutron star (NS) low-mass X-ray binary (LMXB)
sources, then we analyze the centroid frequency (\nu) distribution of twin kHz
QPOs (lower frequency \nu_1 and upper frequency \nu_2) both for Atoll and Z
sources. For the data without shift-and-add, we find that Atoll and Z sources
show the different distributions of \nu_1, \nu_2 and \nu_2/\nu_1, but the same
distribution of \Delta\nu (difference of twin kHz QPOs), which indicates that
twin kHz QPOs may share the common properties of LXMBs and have the same
physical origins. The distribution of \Delta\nu is quite different from
constant value, so is \nu_2/\nu_1 from constant ratio. The weighted mean values
and maxima of \nu_1 and \nu_2 in Atoll sources are slightly higher than those
in Z sources. We also find that shift-and-add technique can reconstruct the
distribution of \nu_1 and \Delta\nu. The K-S test results of \nu_1 and
\Delta\nu between Atoll and Z sources from data with shift-and-add are quite
different from those without it, and we think that this may be caused by the
selection biases of the sample. We also study the properties of the quality
factor (Q) and the root-mean-squared (rms) amplitude of 4U 0614+09 with the
data from the two observational methods, but the errors are too big to make a
robust conclusion. The NS spin frequency (\nu_s) distribution of 28 NS-LMXBs
show a bigger mean value (about 408Hz) than that (about 281 Hz) of the radio
binary millisecond pulsars (MSPs), which may be due to the lack of the spin
detections from Z sources (systematically lower than 281 Hz). Furthermore, on
the relations between the kHz QPOs and NS spin frequency \nu_s, we find the
approximate correlations of the mean values of \Delta\nu with NS spin and its
half, respectively.Comment: 10 pages, 5 figures, 5 table
High resolution study of the abundance pattern of the heavy elements in
  very metal-poor field stars

The abundances of heavy elements in EMP stars are not well explained by the
simple view of an initial basic "rapid" process. In a careful and homogeneous
analysis of the "First stars" sample (eighty per cent of the stars have a
metallicity [Fe/H]=-3.1$\pm$0.4), it has been shown that at this metallicity
[Eu/Ba] is constant, and therefore the Eu-rich stars (generally called
"r-rich") are also Ba-rich. The very large variation of [Ba/Fe] (existence of
"r-poor" and "r-rich" stars) induces that the early matter was not perfectly
mixed. On the other hand, the distribution of the values of [Sr/Ba] vs. [Ba/Fe]
appears with well defined upper and lower envelopes. No star was found with
[Sr/Ba]<-0.5 and the scatter of [Sr/Ba] increases regularly when [Ba/Fe]
decreases. To explain this behavior, we suggest that an early "additional"
process forming mainly first peak elements would affect the initial composition
of the matter. For a same quantity of accreted matter, this additional Sr
production would barely affect the r-rich matter (which already contains an
important quantity of Sr) but would change significantly the composition of the
r-poor matter. The abundances found in the CEMP-rs stars reflect the transfer
of heavy elements from a defunct AGB companion. But the abundances of the heavy
elements in CEMP-no stars present the same characteristics as the the
abundances in the EMP stars.Comment: 9 page
XMM-Newton Publication Statistics

We assessed the scientific productivity and data usage statistics of
XMM-Newton by examining 3272 refereed papers published until the end of 2012
that directly use XMM-Newton data. The SAO/NASA Astrophysics Data System (ADS)
was accessed for information on each paper including the number of citations.
For each paper, the XMM-Newton observation identifiers and instruments were
determined and used extract detailed information from the XMM-Newton archive on
the parameters of the observations. The information obtained from these sources
was then combined to allow the scientific productivity of the mission to be
assessed. Since three years after the launch, about 300 refereed papers per
year were published that directly use XMM-Newton data. After more than 13 years
in operation, this rate shows no decline. Since 2002, around 100 scientists per
year have become lead authors for the first time. Each refereed XMM-Newton
paper receives around four citations per year in the first few years with a
long-term citation rate of three citations per year, more than five years after
publication. About half of the articles citing XMM-Newton articles are not
primarily X-ray observational papers. The distribution of elapsed time between
observations taken under the Guest Observer programme and first article peaks
at 2 years with a possible second peak at 3.25 years. Observations taken under
the Target of Opportunity programme are published significantly faster, after
one year on average. 90% of science time taken until the end of 2009 has been
used in at least one article. Most observations were used more than once,
yielding on average a factor of two in usage on available observing time per
year. About 20% of all slew observations have been used in publications. The
scientific productivity of XMM-Newton remains extremely high with no evidence
that it is decreasing after more than 13 years of operations.Comment: In press in Astronomische Nachrichte
Deep high spectral resolution spectroscopy and chemical composition of
  ionized nebulae

High spectral resolution spectroscopy has proved to be very useful for the
advancement of chemical abundances studies in photoionized nebulae, such as H
II regions and planetary nebulae (PNe). Classical analyses make use of the
intensity of bright collisionally excited lines (CELs), which have a strong
dependence on the electron temperature and density. By using high resolution
spectrophotometric data, our group has led the determination of chemical
abundances of some heavy element ions, mainly O++, O+ and C++ from faint
recombination lines (RLs), allowing us to deblend them from other nearby
emission lines or sky features. The importance of these lines is that their
emissivity depends weakly on the temperature and density structure of the gas.
The unresolved issue in this field is that recombination lines of heavy element
ions give abundances that are about 2-3 times higher than those derived from
CELs -in H II regions- for the same ion, and can even be a factor of 70 times
higher in some PNe. This uncertainty puts into doubt the validity of face
values of metallicity that we use as representative not only for ionized
nebulae in the Local Universe, but also for star-forming dwarf and spiral
galaxies at different redshifts. Additionally, high-resolution data can allow
us to detect and deblend faint lines of neutron capture element ions in PNe.
This information would introduce further restrictions to evolution models of
AGBs and would help to quantify the chemical enrichment in s-elements produced
by low and intermediate mass stars. The availability of an echelle spectrograph
at the E-ELT will be of paramount interest to: (a) extend the studies of heavy
element recombination lines to low metallicity objects, (b) to extend abundance
determinations of s-elements to planetary nebulae in the extragalactic domain
and to bright Galactic and extragalactic H II regions.Comment: 6 pages, 6 figures, Accepted for publication in Astronomische
  Nachrichte
Fundamental constants and high resolution spectroscopy

Absorption-line systems detected in high resolution quasar spectra can be
used to compare the value of dimensionless fundamental constants such as the
fine-structure constant, alpha, and the proton-to-electron mass ratio, mu =
m_p/m_e, as measured in remote regions of the Universe to their value today on
Earth. In recent years, some evidence has emerged of small temporal and also
spatial variations in alpha on cosmological scales which may reach a fractional
level of 10 ppm . We are conducting a Large Programme of observations with VLT
UVES to explore these variations. We here provide a general overview of the
Large Programme and report on the first results for these two constants,
discussed in detail in Molaro et al. and Rahmani et al. A stringent bound for
Delta(alpha)/Alpha is obtained for the absorber at_abs = 1.6919 towards HE
2217-2818. The absorption profile is complex with several very narrow features,
and is modeled with 32 velocity components. The relative variation in alpha in
this system is +1.3+-2.4_{stat}+-1.0_{sys} ppm if Al II lambda 1670AA and three
Fe II transitions are used, and +1.1+-2.6_{stat} ppm in a lightly different
analysis with only Fe II transitions used. The expectation at this sky position
of the recently-reported dipolar variation of alpha is (3.2--5.4)+-1.7 ppm
depending on dipole model. This constraint of Delta(alpha)/alpha at face value
is not supporting this expectation but is not inconsistent with it at the 3
sigma level. For the proton-to-electron mass ratio the analysis of the H_2
absorption lines of the z_{abs}~2.4018 damped Ly alpha system towards HE 0027-
1836 provides Delta(mu)/mu = (-7.6 +- 8.1_{stat} +- 6.3_{sys}) ppm which is
also consistent with a null variation. (abridged)Comment: Invited talk at the 10th AIP Thinkshop, AN, in pres
The chemical composition of the Small Magellanic Cloud

The Small Magellanic Cloud is a close, irregular galaxy that has experienced
a complex star formation history due to the strong interactions occurred both
with the Large Magellanic Cloud and the Galaxy. Despite its importance, the
chemical composition of its stellar populations older than 1-2 Gyr is still
poorly investigated. I present the first results of a spectroscopic survey of
200 Small Magellanic Cloud giant stars performed with FLAMES@VLT. The derived
metallicity distribution peaks at [Fe/H] -0.9/-1.0 dex, with a secondary peak
at [Fe/H] -0.6 dex. All these stars show [alpha/Fe] abundance ratios that are
solar or mildly enhanced (+0.1 dex). Also, three metal-poor stars (with [Fe/H]
solar or mildly enhanced (+0.1 dex). Also, three metal-poor stars (with [Fe/H
-2.5 dex and enhanced [alpha/Fe] ratios compatible with those of the Galactic
Halo) have been detected in the outskirts of the SMC: these giants are the most
metal-poor stars discovered so far in the Magellanic Clouds.Comment: AIP Thinkshop 10 "High resolution optical spectroscopy", AN in pres
HERMES at Mercator, competitive high-resolution spectroscopy with a
  small telescope

HERMES, a fibre-fed high-resolution (R=85000) echelle spectrograph with good
stability and excellent throughput, is the work-horse instrument of the 1.2-m
Mercator telescope on La Palma. HERMES targets building up time series of
high-quality data of variable stellar phenomena, mainly for asteroseismology
and binary-evolution research. In this paper we present the HERMES project and
discuss the instrument design, performance, and a future upgrade. We also
present some results of the first four years of HERMES observations. We
illustrate the value of small telescopes, equipped with efficient
instrumentation, for high-resolution spectroscopy.Comment: 9 pages, 11 figures, Potsdam Thinkshop 10: High resolution optical
  spectroscopy (Astronomical Notes
Isotope Spectroscopy

The measurement of isotopic ratios provides a privileged insight both into
nucleosynthesis and into the mechanisms operating in stellar envelopes, such as
gravitational settling. In this article, we give a few examples of how isotopic
ratios can be determined from high-resolution, high-quality stellar spectra. We
consider examples of the lightest elements, H and He, for which the isotopic
shifts are very large and easily measurable, and examples of heavier elements
for which the determination of isotopic ratios is more difficult. The presence
of 6Li in the stellar atmospheres causes a subtle extra depression in the red
wing of the 7Li 670.7 nm doublet which can only be detected in spectra of the
highest quality. But even with the best spectra, the derived $^6$Li abundance
can only be as good as the synthetic spectra used for their interpretation. It
is now known that 3D non-LTE modelling of the lithium spectral line profiles is
necessary to account properly for the intrinsic line asymmetry, which is
produced by convective flows in the atmospheres of cool stars, and can mimic
the presence of 6Li. We also discuss briefly the case of the carbon isotopic
ratio in metal-poor stars, and provide a new determination of the nickel
isotopic ratios in the solar atmosphere.Comment: AIP Thinkshop 10 "High resolution optical spectroscopy", invited
  talk, AN in pres
Combining optical spectroscopy and interferometry

Modern optical spectrographs and optical interferometers push the limits in
the spectral and spatial regime, providing important new tools for the
exploration of the universe. In this contribution I outline the complementary
nature of spectroscopic & interferometric observations and discuss different
strategies for combining such data. Most remarkable, the latest generation of
"spectro-interferometric" instruments combine the milliarcsecond angular
resolution achievable with interferometry with spectral capabilities, enabling
direct constraints on the distribution, density, kinematics, and ionization
structure of the gas component in protoplanetary disks. I will present some
selected studies from the field of star- & planet formation and hot star
research in order to illustrate these fundamentally new observational
opportunities.Comment: Proceedings article for the "10th Potsdam Thinkshop". Accepted for
  publication in Astronomische Nachrichte
High-resolution absorption spectroscopy of the circumgalactic medium of
  the Milky Way

In this article we discuss the importance of high-resolution absorption
spectroscopy for our understanding of the distribution and physical nature of
the gaseous circumgalactic medium (CGM) that surrounds the Milky Way.
Observational and theoretical studies indicate a high complexity of the gas
kinematics and an extreme multi-phase nature of the CGM in low-redshift
galaxies. High-precision absorption-line measurements of the Milky Way's gas
environment thus are essential to explore fundamental parameters of
circumgalactic gas in the local Universe, such as mass, chemical composition,
and spatial distribution. We shortly review important characteristics of the
Milky Way's CGM and discuss recent results from our multi-wavelength
observations of the Magellanic Stream. Finally, we discuss the potential of
studying the warm-hot phase of the Milky Way's CGM by searching for extremely
weak [FeX] l6374.5 and [FeIVX] l5302.9 absorption in optical QSO spectra.Comment: 7 pages, 4 figures; accepted for publication in Astronomical Notes
  (paper version of a talk presented at the 10th Thinkshop, Potsdam, 2013