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One of the fundamental goals of modern astrophysics is to estimate the physical parameters of galaxies. We present a hierarchical Bayesian model to compute age maps from images in the H α line (taken with Taurus tunable filter, TTF), ultraviolet band (GALEX far UV, FUV), and infrared bands (Spitzer 24, 70, and 160 |$\mu$| m). We present the burst ages for young stellar populations in a sample of nearby and nearly face-on galaxies. The H α to FUV flux ratio is a good relative indicator of the very recent star formation history (SFH). As a nascent star-forming region evolves, the H α line emission declines earlier than the UV continuum, leading to a decrease in the H α/FUV ratio. Using star-forming galaxy models, sampled with a probabilistic formalism, and allowing for a variable fraction of ionizing photons in the clusters, we obtain the corresponding theoretical ratio H α/FUV to compare with our observed flux ratios, and thus to estimate the ages of the observed regions. We take into account the mean uncertainties and the interrelationships between parameters when computing H α/FUV. We propose a Bayesian hierarchical model where a joint probability distribution is defined to determine the parameters (age, metallicity, IMF) from the observed data (the observed flux ratios H α/FUV). The joint distribution of the parameters is described through independent and identically distributed (i.i.d.) random variables generated through MCMC (Markov Chain Monte Carlo) techniques. [ABSTRACT FROM AUTHOR]

Insufficient theoretical investigation is being conducted on the spectroscopic characteristics within the infrared wavelength range of SiP, an identified interstellar molecule. Using the ic-MRCI method, potential energy functions and dipole moment functions for the ground state (⁠|${X^2}\Pi $|⁠) and low excited states (⁠|${{\rm{A}}^2}{\Sigma ^ + }$|⁠) of the SiP molecule were calculated. Based on experimental spectroscopy data, least squares fitting was used for the potential energy functions of the |${X^2}\Pi $| and |${{\rm{A}}^2}{\Sigma ^ + }$| states. By combining these potential energy and dipole moment functions, the one-dimensional Schrödinger equation was solved to obtain the vibronic energy levels and Einstein A coefficients for the electronic states. Partition functions of the SiP molecule from 0.1 to 3000 K and the radiative properties of |${X^2}\Pi \leftrightarrow {X^2}\Pi $| and |${X^{\rm{2}}}\Pi \leftrightarrow {{\rm{A}}^2}{\Sigma ^ + }$| were derived. Infrared spectroscopy of the |${X^2}\Pi $| state and ultraviolet spectroscopy of the |${X^{\rm{2}}}\Pi \leftrightarrow {{\rm{A}}^2}{\Sigma ^ + }$| transition at 100 K, a temperature crucial for astronomical research, were calculated. Results indicate that the spectral-line intensity of the |${X^{\rm{2}}}\Pi \leftrightarrow {{\rm{A}}^2}{\Sigma ^ + }$| transition is greater, making it more suitable for astronomical observation. The obtained computational results in this paper yield spectroscopic parameters for the characterization of the interstellar molecule SiP, furnishing theoretical underpinnings for subsequent experimental observations. [ABSTRACT FROM AUTHOR]

Precipitable water vapour (PWV) strongly affects the quality of data obtained from millimetre- and submillimetre-wave astronomical observations, such as those for cosmic microwave background measurements. Some of these observatories have used radiometers to monitor PWV. In this study, PWV was measured from 2021 April to 2022 April using Global Navigation Satellite System (GNSS) instruments in the Atacama Desert, Chile, where several millimetre- and submillimetre-wave telescopes are located. We evaluated the accuracy of these measurements by comparing them to radiometer measurements. We calculated the PWV from GNSS data using csrs-ppp (Canadian Spatial Reference System Precise Point Positioning), an online software package. When using GNSS data alone, the estimated PWV showed a systematic offset of |$+1.08$| mm. When combining GNSS data with data from a barometer, which was co-located with the GNSS receiver, the estimated PWV showed a lower systematic offset of −0.05 mm. The GNSS PWV showed a statistical uncertainty of 0.52 mm with an averaging time of an hour. Compared to other PWV measurement methods, GNSS instruments are robust in bad weather conditions, have sufficient time resolution, and are less expensive. By demonstrating good accuracy and precision in low-PWV conditions, this paper shows that GNSS instruments are valuable tools for PWV measurements for observing site evaluation and data analysis for ground-based telescopes. [ABSTRACT FROM AUTHOR]

Recently, a novel idea has been proposed to use a spacecraft orbiting closely around the L4 or L5 Lagrangian points of the Earth–Moon system as a vantage location for astronomical observations under unique and advantageous conditions, e.g. to investigate the Solar corona or Kordylewski clouds. In this paper, we explore the scientific advantages of this configuration to observe lunar occultations. By using simulations based on actual orbital parameters and detector performance, we find that even a telescope as small as 10 cm in a L4 orbit would enable better light-curve sampling and higher angular resolution than from ground, and open up at the same time new spectral windows such as e.g. in the UV. We focus in particular on angular diameter measurements, which we find would be possible at the 100  |$\mu$| as level even at magnitudes normally considered faint in the context of ground-based LOs. Considerable benefits would also be afforded in the area of small separation binary objects, not just in terms of angular resolution but also by the capability of L4-based observations to repeat an LO scan of a source at multiple different position angles. Additional science cases would be made possible by the high time resolution intrinsic to the LO technique and the access to UV wavelengths. On-board data pipeline codes already exist, greatly simplifying the automatic pre-processing and the data transfer requirements. [ABSTRACT FROM AUTHOR]

Gravitational wave science is a new and rapidly expanding field of observational astronomy. Multimessenger observations of the binary neutron star merger GW170817 have provided some iconic results including the first gravitational-wave standard siren measurement of the Hubble constant, opening up a new way to probe cosmology. The majority of the compact binary sources observed in gravitational waves are, however, without bright electromagnetic counterparts. In these cases, one can fall back on the 'dark standard siren' approach to include information statistically from potential host galaxies. For such a measurement, we need to be cautious about all possible sources of systematic errors. In this paper, we begin to study the possible errors coming from the galaxy catalogue sector, and in particular, look into the effect of galaxy redshift uncertainties for the cases where these are photometry-based. We recalculate the dark standard siren Hubble constant using the latest third Gravitational-Wave Transient Catalog (GWTC-3) events and associated galaxy catalogues, with different galaxy redshift uncertainty models, namely, the standard Gaussian, a modified Lorentzian, and no uncertainty at all. We find that not using redshift uncertainties at all can lead to a potential bias comparable with other potential systematic effects previously considered for the GWTC-3 H 0 measurement (however still small compared to the overall statistical error in this measurement). The difference between different uncertainty models leads to small differences in the results for the current data; their impact is much smaller than the current statistical errors and other potential sources of systematic errors which have been considered in previous robustness studies. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive site survey of the Delingha site on the northern Tibetan Plateau from 2012 to 2014. In this campaign, we investigated 24 h continuous astronomical seeing, meteorological properties, and |$C_{n}^{2}$| in the ground layer (GL). The results show that the median seeing is 3.46 arcsec during the day and 1.80 arcsec during the night. The best nighttime seeing occurs in summer (1.66 arcsec), while the worst occurs in autumn (1.96 arcsec). Seeing exhibits obvious diurnal behaviour, with the worst seeing occurring around mid-day (11:00 to 14:00, Beijing time), and the best seeing just before sunset (18:00 to 20:00, Beijing time). Moreover, the Delingha site has good meteorological properties for astronomical observations during the measurement period, especially the low median wind speed (2.8 m s−1) and great temperature inversion (day: −0.3 K, night: 0.6 K). As for the vertical distribution of |$C_{n}^{2}$|⁠ , the exponential h −0.46 dependence of |$C_{n}^{2}$| varying with height in the GL is also obtained, and its power index is significantly related to the seasons. Furthermore, we calculated the contribution of optical turbulence in the GL to the whole atmosphere. Turbulence within the GL contributes significantly in summer, and its contribution can reach more than 35 per cent. Finally, we present the complete dependence analysis of seeing on meteorological parameters at the Delingha site. The results show that the best seeing tends to occur when the temperature inversion is sufficiently large, but the dependence of seeing on wind speed is not significant. [ABSTRACT FROM AUTHOR]

We report on a solar jet phenomenon associated with successive flares on 2014 November 10. These explosive events were involved with the satellite spots' emergence around a δ-type sunspot in the decaying active region NOAA 12205. The data for this jet were provided by the Solar Dynamics Observatory, the X-Ray Telescope aboard Hinode, and the Interface Region Imaging Spectrograph and Domeless Solar Telescope at Hida Observatory, Kyoto University. These abundant data enabled us to present this series of papers to discuss the entire process of the observed phenomena, including the energy storage, event trigger, and energy release. In this paper, we focus on the energy build-up and trigger phases, by analyzing the photospheric horizontal flow field around the active region by an optical flow method. The analysis shows the following results: (1) The observed explosive phenomena involved three satellite spots, themagnetic fluxes of which successively reconnected with their pre-existing ambient fields; (2) All of these satellite spots emerged in the moat region of a pivotal δ-type sunspot, especially near its convergent boundary with the neighboring supergranules or moat regions of adjacent sunspots; (3) Around the jet ejection site, the positive polarities of the satellite spot and adjacent emerging flux encountered the global magnetic field with a negative polarity in the moat region of the pivotal δ-type sunspot, and thus the polarity inversion line was formed along the convergent boundary of the photospheric horizontal flow channels. [ABSTRACT FROM AUTHOR]

This paper is the second in a pair of papers on the topic of the generation of a two-colour artificial star [which we term a laser photometric ratio star (LPRS)] of de-excitation light from neutral sodium atoms in the mesosphere, for use in precision telescopic measurements in astronomy and atmospheric physics, and more specifically for the calibration of measurements of dark energy using type Ia supernovae. The two techniques, respectively, described in both this and the previous paper would each generate an LPRS with a precisely 1:1 ratio of yellow (589/590 nm) photons to near-infrared (819/820 nm) photons produced in the mesosphere. Both techniques would provide novel mechanisms for establishing a spectrophotometric calibration ratio of unprecedented precision, from above most of Earth's atmosphere, for upcoming telescopic observations across astronomy and atmospheric physics; thus greatly improving the performance of upcoming measurements of dark energy parameters using type Ia supernovae. The technique described in this paper has the advantage of producing a much brighter (specifically, brighter by approximately a factor of 103) LPRS, using lower power (≤30 W average power) lasers, than the technique using a single 500 W average power laser described in the first paper of this pair. However, the technique described here would require polarization filters to be installed into the telescope camera in order to sufficiently remove laser atmospheric Rayleigh backscatter from telescope images, whereas the technique described in the first paper would only require more typical wavelength filters in order to sufficiently remove laser Rayleigh backscatter. [ABSTRACT FROM AUTHOR]

In a recent paper, we applied a rigorous perturbed matching framework to show the amendment of the mass of rotating stars in Hartle's model. Here, we apply this framework to the tidal problem in binary systems. Our approach fully accounts for the correction to the Love numbers needed to obtain the universal I--Love--Q relations. We compute the corrected mass versus radius configurations of rotating quark stars, revisiting a classical paper on the subject. These corrections allow us to find a universal relation involving the second-order contribution to the mass δM. We thus complete the set of universal relations for the tidal problem in binary systems, involving four perturbation parameters, namely I, Love, Q and δM. These relations can be used to obtain the perturbation parameters directly from observational data. [ABSTRACT FROM AUTHOR]

Cross-matching operation, which is to find corresponding data for the same celestial object or region from multiple catalogues, is indispensable to astronomical data analysis and research. Due to the large amount of astronomical catalogues generated by the ongoing and next-generation large-scale sky surveys, the time complexity of the cross-matching is increasing dramatically. Heterogeneous computing environments provide a theoretical possibility to accelerate the cross-matching, but the performance advantages of heterogeneous computing resources have not been fully utilized. To meet the challenge of cross-matching for substantial increasing amount of astronomical observation data, this paper proposes H eterogeneous-computing-enabled L arge C atalogue C ross-matcher (HLC2), a high-performance cross-matching framework based on spherical position deviation on CPU-GPU heterogeneous computing platforms. It supports scalable and flexible cross-matching and can be directly applied to the fusion of large astronomical catalogues from survey missions and astronomical data centres. A performance estimation model is proposed to locate the performance bottlenecks and guide the optimizations. A two-level partitioning strategy is designed to generate an optimized data placement according to the positions of celestial objects to increase throughput. To make HLC2 a more adaptive solution, the architecture-aware task splitting, thread parallelization, and concurrent scheduling strategies are designed and integrated. Moreover, a novel quad-direction strategy is proposed for the boundary problem to effectively balance performance and completeness. We have experimentally evaluated HLC2 using public released catalogue data. Experiments demonstrate that HLC2 scales well on different sizes of catalogues and the cross-matching speed is significantly improved compared to the state-of-the-art cross-matchers. [ABSTRACT FROM AUTHOR]

The present paper discusses the infrared features of C24 based on the density functional theory calculation and suggests some of the features observed in celestial objects may be attributed to C24. We also calculate the electronic absorption spectra of the C24 isomers to compare with the bump feature at 217 nm in the interstellar extinction curve. The C24 isomers are of four groups viz. cage, planar, bowl, and ring forms, and the present study considers their neutral and charged states. The structural parameters are reported for the first time. The planar structure is the most stable and the ring structure has a significant dipole moment observed. We extract theoretical infrared spectra of fourteen isomers in their neutral and charged states at the B3LYP/6–311++G** level of theory. The time-dependent density functional theory approach is used to calculate the electronic transitions, the absorbance, and the Highest Occupied Molecular Orbitals (HOMO) to Lowest Unoccupied Molecular Orbitals (LUMO) gaps of the 14 C24 isomers in their neutral and charged states. Upon ionization, significant changes are observed in the infrared and electronic absorption spectra, and the structural parameters. Average theoretical spectra of the cage, planar, bowl, and ring of the C24 isomer show the features at 6.2, 7.65, 8.65, 11.3, 12.8, and 35.6 μm, which match with the features in the observed spectra of the reflection nebulae, NGC 2023 and NGC 7023. A sign of a bump in the ultraviolet at around 218 nm is observed in the electronic absorption spectra. [ABSTRACT FROM AUTHOR]

The X-ray spectrum of GRS1915+105 is known to have a "broad iron spectral feature" in the spectral hard state. Similar spectral features are often observed in active galactic nuclei (AGNs) and other black-hole binaries (BHBs), and several models have been proposed for explaining it. In order to distinguish spectral models, time variation provides an important key. In AGNs, variation amplitude has been found to drop significantly at the iron K-energy band at timescales of ~10 ks. If spectral variations of black holes are normalized by their masses, the spectral variations of BHBs on timescales of sub-seconds should exhibit similar characteristics to those of AGNs. In this paper, we investigated spectral variations of GRS1915+105 at timescales down to ~10 ms. This was made possible for the first time with the Suzaku XIS Parallel-sum clocking (P-sum) mode, which has the CCD energy-resolution as well as a time-resolution of 7.8 ms. Consequently, we found that the variation amplitude of GRS1915+105 does not drop at the iron K-energy band on any timescales from 0.06 s to 63000 s, and that the entire X-ray flux and the iron feature are independently variable at timescales of hours. These are naturally understood in the framework of the "partial covering" model, in which variation timescales of the continuum flux and partial absorbers are independent. The difference of the energy dependence of the variation amplitude between AGNs and BHBs is presumably due to different mechanisms of the outflow winds, i.e., the partial absorbers are due to UV-line driven winds (AGNs) or thermally driven winds (BHBs). [ABSTRACT FROM AUTHOR]

The October 2024 issue of Astronomy & Geophysics covers a range of topics in the field. Some highlights include the announcement of a new annual prize for the best paper published by a student scientist in the Monthly Notices of the Royal Astronomical Society, the first International Astronomical Union General Assembly held in Africa, UK-led teams receiving funding to develop technologies for extracting water from lunar ice, the discovery of a surprising ring structure in a Hyper Luminous Infrared Galaxy, and the development of online tools to predict the positions and brightness of satellites to mitigate their effects on astronomical observations. Other topics covered include new findings on gamma-ray bursts, exoplanets, coronal heating, dark comets, supernova remnants, and more. A recent study analyzing samples from asteroid Bennu collected by NASA's OSIRIS-REx mission suggests that the asteroid may have originated from a primitive ocean world. The presence of magnesium-sodium phosphate in the sample indicates a possible watery past for Bennu. However, the asteroid remains chemically primitive, with elemental proportions similar to those of the Sun. This research provides valuable insights into the origins of asteroids and their composition. [Extracted from the article]

21 cm power spectrum observations have the potential to revolutionize our understanding of the epoch of reionization and dark energy, but require extraordinarily precise data analysis methods to separate the cosmological signal from the astrophysical and instrumental contaminants. This analysis challenge has led to a diversity of proposed analyses, including delay spectra, imaging power spectra, m-mode analysis, and numerous others. This diversity of approach is a strength, but has also led to a confusion within the community about whether insights gleaned by one group are applicable to teams working in different analysis frameworks. In this paper, we show that all existing analysis proposals can be classified into two distinct families based on whether they estimate the power spectrum of the measured or reconstructed sky. This subtle difference in the statistical question posed largely determines the susceptibility of the analyses to foreground emission and calibration errors, and ultimately the science different analyses can pursue. In this paper, we detail the origin of the two analysis families, categorize the analyses being actively developed, and explore their relative sensitivities to foreground contamination and calibration errors. [ABSTRACT FROM AUTHOR]

The 21-cm line brightness temperature brings rich information about Epoch of Reionizaton (EoR) and high-z universe (Cosmic Dawn and Dark Age). While the power spectrum is a useful tool to investigate the EoR signal statistically, higher order statistics such as bispectrum are also valuable because the EoR signal is expected to be highly non-Gaussian. In this paper, we develop a formalism to calculate the bispectrum contributed from the thermal noise taking array configuration of telescopes into account, by extending a formalism for the power spectrum. We apply our formalism to the ongoing and future telescopes such as expanded Murchison Widefield Array (MWA), LOw Frequency ARray (LOFAR), Hydrogen Epoch of Reionization Array (HERA) and Square Kilometre Array (SKA). We find that expanded MWA does not have enough sensitivity to detect the bispectrum signal. On the other hand, LOFAR has better sensitivity and will be able to detect the peaks of the bispectrum as a function of redshift at large scales with comoving wavenumber k ≲ 0.03 Mpc-1. The SKA has enough sensitivity to detect the bispectrum for much smaller scales k &#8818 0.3Mpc-1 and redshift z ≲ 20. [ABSTRACT FROM AUTHOR]

The Kepler space mission and its K2 extension provide photometric time series data with unprecedented accuracy. These data challenge our current understanding of the metalliclined A stars (Am stars) for what concerns the onset of pulsations in their atmospheres. It turns out that the predictions of current diffusion models do not agree with observations. To understand this discrepancy, it is of crucial importance to obtain ground-based spectroscopic observations of Am stars in the Kepler and K2 fields in order to determine the best estimates of the stellar parameters. In this paper, we present a detailed analysis of high-resolution spectroscopic data for seven stars previously classified as Am stars. We determine the effective temperatures, surface gravities, projected rotational velocities, microturbulent velocities and chemical abundances of these stars using spectral synthesis. These spectra were obtained with CAOS, a newinstrument recently installed at the observing station of the CataniaAstrophysical Observatory on Mt Etna. Three stars have already been observed during quarters Q0-Q17, namely: HD 180347, HD 181206 and HD 185658, while HD 43509 was already observed during K2 C0 campaign. We confirm that HD 43509 and HD 180347 are Am stars, while HD 52403, HD 50766, HD 58246, HD 181206 and HD 185658 are marginal Am stars. By means of non-LTE (local thermodynamic equilibrium) analysis, we derived oxygen abundances from O I λ7771-5 Å triplet and we also discussed the results obtained with both non-LTE and LTE approaches. [ABSTRACT FROM AUTHOR]

A very long-term near-infrared variable star survey towards the Large and Small Magellanic Clouds (LMC and SMC) was carried out using the 1.4 m InfraRed Survey Facility at the South African Astronomical Observatory. This project was initiated in 2000 December in the LMC, and in 2001 July in the SMC. Since then an area of 3 deg2along the bar in the LMC and an area of 1 deg2in the central part of the SMC have been repeatedly observed. This survey is ongoing, but results obtained with data taken until 2017 December are reported in this paper. Over more than 15 yr we have observed the two survey areas more than one hundred times. This is the first survey that provides near-infrared time-series data with such a long time baseline and on such a large scale. This paper describes the observations in the SMC and publishes a point source photometric catalogue, a variable source catalogue, and time-series data. [ABSTRACT FROM AUTHOR]

The next decade will see two large-scale space-based near-infrared surveys, Euclid and WFIRST. This paper shows that the subtle differences between the filters proposed for these surveys and those from ground-based photometric systems will produce a ground-space colour term that is dependent on water absorption in the spectra of astronomical objects. This colour term can be used to identify free-floating planets in star-forming regions, mimicking a successful ground-based technique that uses a filter sensitive to water absorption. This paper shows that this colour term is an effective discriminant between reddened background stars and ultracool dwarfs. This represents just one science justification for a Galactic Plane survey in the event of an extension to the Euclid mission beyond its original time frame. [ABSTRACT FROM AUTHOR]

We have initiated a program to systematically observe lunar occultations from the SAO RAS 6-m telescope (BTA). So far, 25 events have been recorded with some of them leading to accurate measurements of angular diameters in late-type stars and of binary stars. One interesting aspect is that the observations are carried out by the same group and with the same equipment dedicated also to speckle interferometry, so that many of the target objects are being investigated by two independent and complementary techniques almost simultaneously. This represents a novel approach with a potential to provide more complete and extended results than possible until now. In this paper we focus on a general description of the scientific aim and methods, and we provide an overview of the results including an assessment of the quantitative performance, showing that milliarcsecond resolution is achieved on sources as faint as ≈12 mag. Among the sources we discuss in detail are the binary stars SAO 98270 and μ Cet, and the resolved late-type stars 74 Gem, DE Psc, and IRC+00213. Other stars with positive results are the subject of dedicated papers. We foresee to continue routine observations with this facility in the immediate future, and to coordinate with other observatories equipped with similar instrumentation. [ABSTRACT FROM AUTHOR]

There have been increasing theoretical speculations and observational indications that certain globular clusters (GCs) could contain a sizeable population of stellar mass black holes (BHs). In this paper, we shortlist at least 29 Galactic GCs that could be hosting a subsystem of BHs (BHS). In a companion paper, we analysed results from a wide array of GC models (simulated with the MOCCA code for cluster simulations) that retained few tens to several hundreds of BHs at 12 Gyr and showed that the properties of the BHS in those GCs correlate with the GC's observable properties. Building on those results, we use available observational properties of 140 Galactic GCs to identify 29 GCs that could potentially be harbouring up to a few hundreds of BHs. Utilizing observational properties and theoretical scaling relations, we estimate the density, size, and mass of the BHS in these GCs. We also calculate the total number of BHs and the fraction of BHs contained in a binary system for our shortlisted Galactic GCs. Additionally, we mention other Galactic GCs that could also contain a significant number of single BHs or BHs in binary systems. [ABSTRACT FROM AUTHOR]

This paper presents a kinetic theory model of gravitational collapse due to a small perturbation. Solving the relevant equations yields a pattern of entropy destruction in a spherical core around the perturbation, and entropy creation in a surrounding halo. This indicates collisional 'de-relaxation' in the core, and collisional relaxation in the halo. Core-halo patterns are ubiquitous in the astrophysics of gravitational collapse and are found here without any of the prior assumptions of such a pattern usually made in analytical models. Motivated by this analysis, the paper outlines a possible scheme for identifying structure formation in a set of observations or a simulation. This scheme involves a choice of coarse-graining scale appropriate to the structure under consideration, and might aid exploration of hierarchical structure formation, supplementing the usual density-based methods for highlighting astrophysical and cosmological structure at various scales. [ABSTRACT FROM AUTHOR]

We introduce and present results from the COCOA (Cluster simulatiOn Comparison with ObservAtions) code that has been developed to create idealized mock photometric observations using results from numerical simulations of star cluster evolution. COCOA is able to present the output of realistic numerical simulations of star clusters carried out using Monte Carlo or N-body codes in a way that is useful for direct comparison with photometric observations. In this paper, we describe the COCOA code and demonstrate its different applications by utilizing globular cluster (GC)models simulated with the MOCCA (MOnte Carlo Cluster simulAtor) code. COCOA is used to synthetically observe these different GC models with optical telescopes, perform point spread function photometry, and subsequently produce observed colour-magnitude diagrams. We also use COCOA to compare the results from synthetic observations of a cluster model that has the same age and metallicity as the Galactic GC NGC2808 with observations of the same cluster carried out with a 2.2m optical telescope. We find that COCOA can effectively simulate realistic observations and recover photometric data. COCOA has numerous scientific applications that maybe be helpful for both theoreticians and observers that work on star clusters. Plans for further improving and developing the code are also discussed in this paper. [ABSTRACT FROM AUTHOR]

Winds arising from galaxies, star clusters, and active galactic nuclei are crucial players in star and galaxy formation, but it has proven remarkably difficult to use observations of them to determine physical properties of interest, particularly mass fluxes. Much of the difficulty stems from a lack of a theory that links a physically realistic model for winds' density, velocity and covering factors to calculations of light emission and absorption. In this paper we provide such a model. We consider a wind launched from a turbulent region with a range of column densities, derive the differential acceleration of gas as a function of column density, and use this result to compute winds' absorption profiles, emission profiles and emission intensity maps in both optically thin and optically thick species. The model is sufficiently simple that all required computations can be done analytically up to straightforward numerical integrals, rendering it suitable for the problem of deriving physical parameters by fitting models to observed data. We show that our model produces realistic absorption and emission profiles for some example cases, and argue that the most promising methods of deducing mass fluxes are based on combinations of absorption lines of different optical depths, or on combining absorption with measurements of molecular line emission. In the second paper in this series, we expand on these ideas by introducing a set of observational diagnostics that are significantly more robust than those commonly in use, and that can be used to obtain improved estimates of wind properties. [ABSTRACT FROM AUTHOR]

The periodic motion near non-principal-axis (NPA) rotation asteroids is proved to be markedly different from that near uniformly rotating bodies due to the complex spin statewith precession, raising challenges in terms of the theoretical implications of dynamical systems. This paper investigates the various periodic motions near the typical NPA asteroid 4179 Toutatis, which will contribute to the understanding of the dynamical environments near the widespread asteroids in the Solar system. A novel method with the incorporation of the ellipsoid–mascon gravitational field model and global optimization is developed to efficiently locate periodic solutions in the system. The numerical results indicate that abundant periodic orbits appear near the NPA asteroids. These various orbits are theoretically classified into five topological types with special attention paid to the cycle stability. Although the concept of classical family disappears in our results, some orbits with the same topological structure constitute various generalized 'families' as the period increases. Among these 'families' a total of 4 kinds of relationships between orbits, including rotation, evolution, distortion and quasi-symmetry, are found to construct the global mapping of these types. To cover the rotation statuses of various NPA asteroids, this paper also discusses the variation of periodic orbits with diverse asteroid spin rates, showing that the scales of some orbits expand, shrink or almost annihilate as the system period changes; meanwhile, their morphology and topology remain unchanged. [ABSTRACT FROM AUTHOR]

ABSTRACT Using the results of a previous X-ray photoionization modelling of blueshifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this Letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval ∼0.0003-0.03 pc ( ∼ 102- 104 rs) from the central black hole, consistent with what is expected for accretion disc winds/outflows. The mass outflow rates are constrained between ∼0.01 and 1 M ⊙ yr −1, corresponding to > rsim5-10 per cent of the accretion rates. The average lower/upper limits on the mechanical power are log 42.6-44.6 erg s −1. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN cosmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyfert galaxies. [ABSTRACT FROM AUTHOR]

We test the bandpass smoothness performance of two prototype Square Kilometre Array (SKA) SKA1-Low log-periodic dipole antennas, SKALA2 and SKALA3 ('SKA Log-periodic Antenna'), and the current dipole from the Murchison Widefield Array (MWA) precursor telescope. Throughout this paper, we refer to the output complex-valued voltage response of an antenna when connected to a low-noise amplifier, as the dipole bandpass. In Paper I, the bandpass spectral response of the log-periodic antenna being developed for the SKA1-Low was estimated using numerical electromagnetic simulations and analysed using low-order polynomial fittings, and it was compared with the HERA antenna against the delay spectrum metric. In this work, realistic simulations of the SKA1-Low instrument, including frequency-dependent primary beam shapes and array configuration, are used with a weighted leastsquares polynomial estimator to assess the ability of a given prototype antenna to perform the SKA Epoch of Reionisation (EoR) statistical experiments. This work complements the ideal estimator tolerances computed for the proposed EoR science experiments in Trott & Wayth, with the realized performance of an optimal and standard estimation (calibration) procedure. With a sufficient sky calibration model at higher frequencies, all antennas have bandpasses that are sufficiently smooth to meet the tolerances described in Trott & Wayth to perform the EoR statistical experiments, and these are primarily limited by an adequate sky calibration model and the thermal noise level in the calibration data. At frequencies of the Cosmic Dawn, which is of principal interest to SKA as one of the first next-generation telescopes capable of accessing higher redshifts, the MWA dipole and SKALA3 antenna have adequate performance, while the SKALA2 design will impede the ability to explore this era. [ABSTRACT FROM AUTHOR]

Motivated by the large number of compact extrasolar planetary systems discovered by the Kepler mission, this paper considers perturbations due to possible additional outer planets. The discovered compact systems sometimes contain multiple transiting planets, so that their orbital angular momentum vectors are tightly aligned. Since planetary orbits are susceptible to forced oscillations of their inclination angles, the highly aligned nature of these systems places constraints on possible additional (non-transiting) planets. If planets in the outer regions of these solar systems have sufficiently large mass or sufficiently small semi-major axis, they will induce the compact inner orbits to oscillate in and out of a transiting configuration. This paper considers the dynamics of the compact systems discovered to host five or more planets. In order not to perturb these systems out of a continually, mutually transiting state, additional planetary companions must generally have periastron p > 10 au. Specific constraints are found for each of the 18 planetary systems considered, which are obtained by marginalizing over other orbital parameters using three different choices of priors for the companion properties (a uniform prior, a transit-inspired prior and a non-transiting disc prior). A separate ensemble of numerical experiments shows that these compact systems generally cannot contain Jupiter analogues without disrupting the observed orbits. We also consider how these constraints depend on system properties and find that the surface density of the planetary system is one of the most important variables. Finally, we provide specific results for two systems, WASP-47 and Kepler-20, for which this analysis provides interesting constraints. [ABSTRACT FROM AUTHOR]

Graph New ESA Director of Science Graph ESA has appointed as Director of Science Carole Mundell, currently President of the UK Science Council, and Professor of Extragalactic Astronomy and founding Head of Astrophysics at the University of Bath, UK. WEAVE was produced by an international team led from the UK, coordinated by the Science and Technology Facilities Research Council. bit.ly/3HXtjQm JWST resets redshift record Graph: (NASA, ESA, CSA, and M. Zamani (ESA/Webb). Now that the report is published, RAS Council has decided that, while the acronym JWST is preferred to the full name, its use in RAS publications and communications is no longer compulsory. go.nasa.gov/3FKUZFD Ancient heart of Milky Way found Graph: (H.-W. Rix / MPIA) Ancient metal-poor stars in the heart of the Milky Way galaxy formed some 12.5 billion years ago, soon after the formation of its core. [Extracted from the article]

Tidally enhanced stellar wind may affect horizontal branch (HB) morphology in globular clusters (GCs) by enhancing the mass loss of primary star during binary evolution. Lei et al. (2013a, A&A, 549, 145; 2013b, A&A, 554, 130) studied the effect of this kind of wind on HB morphology in detail, and their results indicated that a binary is a possible second-parameter (2P) candidate in GCs. Binary fraction is a very important fact in the tidally-enhanced-stellar-wind model. In this paper, we studied the effect of binary fraction on HB morphology by removing the effects of metallicity and age. Five different binary fractions (i.e., 10%, 15%, 20%, 30%, and 50%) are adopted in our model calculations. The synthetic HB morphologies with different binary fractions are obtained at different metallicities and ages. We found that, due to the great influence of metallicity and age, the effect of binary fraction on HB morphology may be masked by these two parameters. However, when the effects of metallicity and age are removed, the tendency of HB morphologies becoming bluer with increasing binary fractions is clearly presented. Furthermore, we compared our results with the observation by Milone et al. (2012, A&A, 540, 16). Our results are consistent with the observation at metal-rich and metal-poor GCs. For the GCs with intermediate metallicity, when the effect of age on HB morphology is removed, a weak tendency of HB morphologies becoming bluer with increasing binary fractions is presented in all regions of GCs, which is consistent with our results obtained in this metallicity range. [ABSTRACT FROM PUBLISHER]

Differential atmospheric dispersion is a wavelength-dependent effect introduced by Earth's atmosphere that affects astronomical observations performed using ground-based telescopes. It is important, when observing at a zenithal angle different from zero, to use an Atmospheric Dispersion Corrector (ADC) to compensate this atmospheric dispersion. The design of an ADC is based on atmospheric models that, to the best of our knowledge, were never tested against on-sky measurements. We present an extensive models analysis in the wavelength range of 315–665 nm. The method we used was previously described in the paper I of this series. It is based on the use of cross-dispersion spectrographs to determine the position of the centroid of the spatial profile at each wavelength of each spectral order. The accuracy of the method is 18 mas. At this level, we are able to compare and characterize the different atmospheric dispersion models of interest. For better future ADC designs, we recommend to avoid the Zemax model, and in particular in the blue range of the spectra, when expecting residuals at the level of few tens of milli-arcseconds. [ABSTRACT FROM AUTHOR]

This paper is the second in a pair of papers presenting data release 1 (DR1) of the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS), the largest single open-time key project carried out with the Herschel Space Observatory. The H-ATLAS is a wide-area imaging survey carried out in five photometric bands at 100, 160, 250, 350 and 500 µm covering a total area of 600 deg². In this paper, we describe the identification of optical counterparts to submillimetre sources in DR1, comprising an area of 161 deg² over three equatorial fields of roughly 12 × 4.5 deg centred at 9h, 12h and 14. h 5, respectively. Of all the H-ATLAS fields, the equatorial regions benefit from the greatest overlap with current multiwavelength surveys spanning ultraviolet (UV) to mid-infrared regimes, as well as extensive spectroscopic coverage. We use a likelihood ratio technique to identify Sloan Digital Sky Survey counterparts at r < 22.4 for 250-μm-selected sources detected at ≥4σ (28 mJy). We find 'reliable' counterparts (reliability R ≥ 0.8) for 44 835 sources (39 per cent), with an estimated completeness of 73.0 per cent and contamination rate of 4.7 per cent. Using redshifts and multi-wavelength photometry from GAMA and other public catalogues, we show that H-ATLAS-selected galaxies at z < 0.5 span a wide range of optical colours, total infrared (IR) luminosities and IR/UV ratios, with no strong disposition towards mid-IR-classified active galactic nuclei in comparison with optical selection. The data described herein, together with all maps and catalogues described in the companion paper, are available from the H-ATLAS website at www.h-atlas.org. [ABSTRACT FROM AUTHOR]

We report and provide fitting functions for the abundance of dark matter halos and subhalos as a function of mass, circular velocity, and redshift from the new Bolshoi-Planck and MultiDark-Planck ΛCDM cosmological simulations, based on the Planck cosmological parameters. We also report the halo mass accretion rates, which may be connected with galaxy star formation rates. We show that the higher cosmological matter density of the Planck parameters compared with the WMAP parameters leads to higher abundance of massive halos at high redshifts. We find that the median halo spin parameter λB=J(√2MvirRvirVvir)−1 is nearly independent of redshift, leading to predicted evolution of galaxy sizes that is consistent with observations, while the significant decrease with redshift in median λP=J|E|−1/2G−1M−5/2 predicts more decrease in galaxy sizes than is observed. Using the Tully-Fisher and Faber-Jackson relations between galaxy velocity and mass, we show that a simple model of how galaxy velocity is related to halo maximum circular velocity leads to increasing overprediction of cosmic stellar mass density as redshift increases beyond redshifts z∼1, implying that such velocity-mass relations must change at redshifts z ≳ 1. By making a realistic model of how observed galaxy velocities are related to halo circular velocity, we show that recent optical and radio observations of the abundance of galaxies are in good agreement with our ΛCDM simulations. Our halo demographics are based on updated versions of the \rockstar\ and \ctrees\ codes, and this paper includes appendices explaining all of their outputs. This paper is an introduction to a series of related papers presenting other analyses of the Bolshoi-Planck and MultiDark-Planck simulations. [ABSTRACT FROM AUTHOR]

Microvariability (intranight variability) is a low amplitude flux change at short time-scales (i.e. hours). It has been detected in unobscured type 1 active galactic nuclei (AGN) and blazars. However in type 2AGN, the detection is hampered by the lowcontrast between the presumably variable nucleus and the host galaxy. In this paper, we present a search for microvariability in a sample of four type 2 quasars as an astrostatistical problem. We are exploring the use of a newly introduced enhanced F-test, proposed by Diego. The presented results show that out of four observed target, we are able to apply this statistical method to three of them. Evidence of microvariations is clear in the case of quasar J0802+2552 in all used filters (g', r' and i') during both observing nights, and they are present in one of the nights of observations, J1258+5239 in one filter (i'), while for the J1316+4452, there is evidence for microvariability within our detection levels during one night and two filters (r' and i'). We demonstrate the feasibility of the enhanced F-test to detect microvariability in obscured type 2 quasars. At the end of this paper, we discuss possible causes of microvariability. One of the options is the misclassification of the targets. A likely scenario for explanation of the phenomenon involves optically thin gaps in a clumpy obscuring medium, in accordance with the present view of the circumnuclear medium. There is a possible interesting connection between the merging state of the targets and detection of microvariability. [ABSTRACT FROM AUTHOR]

This paper reports on the Suzaku result of the Galactic supernova remnant (SNR) G337.2-0.7. The X-ray spectrum iswell explained by three components in ionizing phase. One is a plasma with a low temperature kT = 0.70+0.02 -0.03 keV, solar abundances, and an ionization parameter net = 5.7+0.7 -0.4 × 1011 s cm-3. The second is amiddle-temperature plasma with kT = 1.54+0.13 -0.02 keV and high metal abundances in a highly ionized state of net = 3.6+0.2 -0.5 × 1011 s cm-3, and the third is a high-temperature plasma with kT = 3.1+0.2 -0.1 keV and high metal abundances in a low-ionized state of net = 2.1+0.4 -0.2 × 1010 s cm-3. The high metal-abundance plasmas are likely to be of an ejecta origin, while the solar abundance plasma would be of an interstellar-gas origin. The abundance pattern and mass of the ejecta confirm that G337.2-0.7 is a remnant of a Type Ia supernova (SN). The derived Fe mass of ejecta MFe =0.025-0.039M☉ is far smaller than that expected from any Type Ia model, suggesting that most Fe has not yet been heated by the reverse shock. The ejecta has enhanced distribution in the northeastern region compared to the central region, and therefore the SN explosion or SNR evolution would be asymmetric. [ABSTRACT FROM AUTHOR]

This paper reports on results of a Suzaku observation of the supernova remnant (SNR) Kes 79 (G33.6+0.☉). The X-ray spectrum is best fitted by a two-temperaturemodel: a nonequilibrium ionization (NEI) plasma and a collisional ionization equilibrium (CIE) plasma. The NEI plasma is spatially confined within the inner radio shell with kT ~ 0.8 keV, while the CIE plasma is found in more spatially extended regions associated with the outer radio shell with kT ~ 0.2 keV and solar abundance. Therefore, the NEI plasma is attributable to the SN ejecta, and the CIE plasma is the forward shocked interstellar medium. In the NEI plasma, we discovered K-shell lines of Al, Ar, and Ca for the first time. The abundance pattern and estimated mass of the ejecta are consistent with a core-collapse supernova explosion of a ~30-40M☉ progenitor star. An Fe line with a center energy of ~6.4 keV is also found in the southeast (SE) portion of the SNR, a close peripheral region around dense molecular clouds. One possibility is that the line is associated with the ejecta. However, the centroid energy of ~6.4 keV and the spatial distribution of enhancement near the SE peripheral do not favor this scenario. Since the ~6.4 keV emitting region coincides with the molecular clouds, we propose another possibility, that the Fe line is due to K-shell ionization of neutral Fe by the interaction of locally accelerated protons (LECRp) with the surrounding molecular cloud. Both of these possibilities, heated ejecta or LECRp origin, are discussed based on the observational facts. [ABSTRACT FROM AUTHOR]

Spectropolarimetric observations have been used to map stellar magnetic fields, many of which display strong bands of azimuthal fields that are toroidal. A number of explanations have been proposed to explain how such fields might be generated though none are definitive. In this paper, we examine the toroidal fields of a sample of 55 stars with magnetic maps, with masses in the range 0.1-1.5 M⊙. We find that the energy contained in toroidal fields has a power-law dependence on the energy contained in poloidal fields. However the power index is not constant across our sample, with stars less and more massive than 0.5 M⊙ having power indices of 0.72 ± 0.08 and 1.25 ± 0.06, respectively. There is some evidence that these two power laws correspond to stars in the saturated and unsaturated regimes of the rotation-activity relation. Additionally, our sample shows that strong toroidal fields must be generated axisymmetrically. The latitudes at which these bands appear depend on the stellar rotation period with fast rotators displaying higher latitude bands than slow rotators. The results in this paper present new constraints for future dynamo studies. [ABSTRACT FROM AUTHOR]

Dome A in Antarctica has many characteristics that make it an excellent site for astronomical observations, from the optical to the terahertz. Quantitative site testing is still needed to confirm the site's properties. In this paper, we present a statistical analysis of cloud cover and aurora contamination from the Kunlun Cloud and Aurora Monitor (KLCAM). KLCAM is an automatic unattended all-sky camera aiming for long-term monitoring of the usable observing time and optical sky background at Dome A. It was installed at Dome A in January 2017, worked through the austral winter, and collected over 47 000 images over 490 d. A semi-quantitative visual data analysis of cloud cover and auroral contamination was carried out by five individuals. The analysis shows that the night sky was free of clouds for 83 per cent of the time, which ranks Dome A highly in a comparison with other observatory sites. Although aurorae were detected somewhere on an image for nearly 45 per cent of the time, the chance of a point on the sky being affected by an aurora is small. The strongest auroral emission lines can be filtered out with customized filters. [ABSTRACT FROM AUTHOR]

Among all the interstellar complex organic molecules, acetaldehyde is one of the most widely detected species. The question of its formation route(s) is, therefore, of a major interest regarding astrochemical models. In this paper, we provide an extensive review of the gas-phase formation paths that were, or are, reported in the literature and the major astrochemical data bases. Four different gas-phase formation routes stand out : (1) CH3OCH3  + H+/CH3CHOH+  + e−, (2) C2H5  + O(3P), (3) CH3OH  + CH, and (4) CH3CH2OH  + OH/CH3CHOH  + O(3P). Paths (2) and (3) were not studied neither via laboratory nor theoretical works in the low temperature and density regime valid for the interstellar medium (ISM). Thus, we carried out new accurate quantum chemistry computations. A theoretical kinetics study at low temperatures (7 ÷ 300 K), adopting the Rice–Ramsperger–Kassel–Marcus scheme, was also performed. We confirm that reaction (2) is efficient in forming acetaldehyde in the 7–300 temperature range (α  = 1.21 × 10−10 cm3 s−1 and β = 0.16). On the contrary, our new computations disprove the formation of acetaldehyde through reaction (3) (α = 1.84 ÷ 0.67 × 10−13 cm3 s−1 and β = −0.07 ÷ −0.95). Path (1) was showed to be inefficient too by recent computations, while path (4) was formerly considered for glycolaldehyde formation, having acetaldehyde as a byproduct. In conclusions, of the four above paths, only two, the (2) and (4), are potentially efficient gas-phase reaction routes for the formation of acetaldehyde and we encourage astrochemical modellers to consider only them. Comparison with astronomical observations suggests that path (4) may actually play the major role. [ABSTRACT FROM AUTHOR]

Gravitational waves provide a unique tool for observational astronomy. While the first LIGO–Virgo catalogue of gravitational-wave transients (GWTC-1) contains 11 signals from black hole and neutron star binaries, the number of observations is increasing rapidly as detector sensitivity improves. To extract information from the observed signals, it is imperative to have fast, flexible, and scalable inference techniques. In a previous paper, we introduced bilby : a modular and user-friendly Bayesian inference library adapted to address the needs of gravitational-wave inference. In this work, we demonstrate that bilby produces reliable results for simulated gravitational-wave signals from compact binary mergers, and verify that it accurately reproduces results reported for the 11 GWTC-1 signals. Additionally, we provide configuration and output files for all analyses to allow for easy reproduction, modification, and future use. This work establishes that bilby is primed and ready to analyse the rapidly growing population of compact binary coalescence gravitational-wave signals. [ABSTRACT FROM AUTHOR]

Observations with ground-based telescopes are affected by differential atmospheric dispersion due to the wavelength-dependent index of refraction of the atmosphere. The usage of an atmospheric dispersion corrector (ADC) is fundamental to compensate this effect. Atmospheric dispersion correction residuals above the level of ∼100 milliarcseconds (mas) will affect astronomical observations, in particular radial velocity and flux losses. The design of an ADC is based on atmospheric models. To the best of our knowledge, those models have never been tested on-sky. In this paper, we present a new method to measure the atmospheric dispersion on-sky in the optical range. We require an accuracy better than 50 mas that is equal to the difference between atmospheric models. The method is based on the use of cross-dispersion spectrographs to determine the position of the centroid of the spatial profile at each wavelength of each spectral order. The method is validated using cross-dispersed spectroscopic data acquired with the slit spectrograph UVES. We measure an instrumental dispersion of |$\rm 47 ~ mas$| in the blue arm, and 15 and 23 mas in the two ranges of the red arm. We also measure a 4  per cent deviation in the pixel scale from the value cited in UVES manual. The accuracy of the method is ∼17 mas in the range of 315–665 nm. At this level, we can compare and characterize different atmospheric dispersion models for better future ADC designs. [ABSTRACT FROM AUTHOR]

In this paper, we report results of an extensive theoretical study on MgC4H chains conducted at DFT and CCSD(T) levels motivated by the recent discovery of this species in IRC+10216. A detailed characterization of both neutral and charged species is presented, which include structural, chemical bonding and vibrational properties, rotational, centrifugal distortion and Watson l-type doubling constants, dipole moments, Fermi contact, and spin-rotation constants. In addition, we present ab initio estimates needed for subsequent astrochemical evolution modelling (e.g. dissociation energies, acidity, electron attachment, and ionization energies and related chemical reactivity indices). Possible formation pathways are also discussed. They comprise exchange, (radiative) association, dissociative recombination, and ion neutralization reactions. As an important result aiming at stimulating further observational searching, we suggest that MgC4H− anions should also be observable via rovibrational spectroscopy. The reason is twofold: (i) Neutral MgC4H0 chains possess a sufficiently large dipole moment consistent with dipole-bound anion states and large electron attachment cross-sections. (ii) MgC4H− anions possess a dipole substantially larger than MgC4H0 neutrals (and also larger than that estimated earlier for the longest astronomically detected C8H− anion). This makes MgC4H− anion intensities in rovibrational spectrum experimentally accessible even in the unlikely case of a relative abundance MgC4H−/MgC4H0 comparable to that of CH4, whose anion has the lowest relative abundance observed so far in space because weakly polar C4H0 chains do not support dipole-bound anion states. A suggestion on why, counterintuitively, the MgC2H abundance found in IRC+10216 was lower than that of the longer MgC4H is also presented. [ABSTRACT FROM AUTHOR]

According to the standard cosmological scenario, superclusters are objects that have just passed the turn-around point and are collapsing. The dynamics of very few superclusters have been analysed up to now. In this paper, we study the supercluster SC0028-0005, at redshift 0.22, identify the most prominent groups and/or clusters that make up the supercluster, and investigate the dynamic state of this structure. For the membership identification, we have used photometric and spectroscopic data from Sloan Digital Sky Survey Data Release 10, finding sixmain structures in a flat spatial distribution. We have also used a deep multiband observation with MegaCam/Canada-France-Hawaii Telescope to estimate de mass distribution through the weak-lensing effect. For the dynamical analysis, we have determined the relative distances along the line of sight within the supercluster using the Fundamental Plane of early-type galaxies. Finally, we have computed the peculiar velocities of each of the main structures. The 3D distribution suggests that SC0028-005 is indeed a collapsing supercluster, supporting the formation scenario of these structures. Using the spherical collapse model, we estimate that the mass within r = 10 Mpc should lie between 4 and 16 × 1015M☉. The farthest detected members of the supercluster suggest that within ~60 Mpc the density contrast is δ ~ 3 with respect to the critical density at z = 0.22, implying a total mass of ~4.6-16 × 1017M☉, most of which in the form of low-mass galaxy groups or smaller substructures. [ABSTRACT FROM AUTHOR]

We have coupled a fast, parametrized star cluster evolution code to a Markov Chain Monte Carlo code to determine the distribution of probable initial conditions of observed star clusters, that may serve as a starting point for future N-body calculations. In this paper, we validate our method by applying it to a set of star clusters which have been studied in detail numerically with N-body simulations and Monte Carlo methods: the Galactic globular clusters M4, 47 Tucanae, NGC 6397, M22, ω Centauri, Palomar 14 and Palomar 4, the Galactic open cluster M67, and the M31 globular cluster G1. For each cluster, we derive a distribution of initial conditions that, after evolution up to the cluster's current age, evolves to the currently observed conditions. We find that there is a connection between the morphology of the distribution of initial conditions and the dynamical age of a cluster and that a degeneracy in the initial halfmass radius towards small radii is present for clusters that have undergone a core collapse during their evolution. We find that the results of our method are in agreement with N-body and Monte Carlo studies for the majority of clusters. We conclude that our method is able to find reliable posteriors for the determined initial mass and half-mass radius for observed star clusters, and thus forms an suitable starting point for modelling an observed cluster's evolution. [ABSTRACT FROM AUTHOR]

There exist a variety of star-galaxy classification techniques, each with their own strengths and weaknesses. In this paper, we present a novelmeta-classification framework that combines and fully exploits different techniques to produce a more robust star-galaxy classification. To demonstrate this hybrid, ensemble approach, we combine a purely morphological classifier, a supervised machine learning method based on random forest, an unsupervised machine learning method based on self-organizing maps, and a hierarchical Bayesian template-fitting method. Using data from the CFHTLenS survey (Canada-France-Hawaii Telescope Lensing Survey), we consider different scenarios: when a high-quality training set is available with spectroscopic labels from DEEP2 (Deep Extragalactic Evolutionary Probe Phase 2), SDSS (Sloan Digital Sky Survey), VIPERS (VIMOS Public Extragalactic Redshift Survey), and VVDS (VIMOS VLT Deep Survey), and when the demographics of sources in a low-quality training set do not match the demographics of objects in the test data set. We demonstrate that our Bayesian combination technique improves the overall performance over any individual classification method in these scenarios. Thus, strategies that combine the predictions of different classifiersmay prove to be optimal in currently ongoing and forthcoming photometric surveys, such as the Dark Energy Survey and the Large Synoptic Survey Telescope. [ABSTRACT FROM AUTHOR]

We report on CO (J = 2 → 1) mapping with the IRAM 30-m HEtrodyne Receiver Array (HERA) of CGCG 97-079, an irregular galaxy in the merging galaxy cluster Abell 1367 (z = 0.022). We find that â80 per cent of the detected CO (J = 2 → 1) is projected within a 16 arcsec2 (6.5 kpc2) region to the north and west of the optical/NIR centre, with the intensity maximum offset â10 arcsec (4 kpc) NW of the optical/NIR centre and â7 arcsec (3 kpc) south-east of the HI intensity maximum. Evolutionary synthesis models indicate CGCG 97- 079 experienced a burst of star formation â108 yr ago, most likely triggered by a tidal interaction with CGCG 97-073. For CGCG 97-079 we deduce an infall velocity to the cluster of â1000 km sâ'1 and moderate ram pressure (Pram â 10â'11 dyne cmâ'2). The observed offset in CGCG 97-079 of the highest density HI and CO (J = 2→1) from the stellar components has not previously been observed in galaxies currently undergoing ram pressure stripping, although previous detailed studies of gas morphology and kinematics during ram pressure stripping were restricted to significantly more massive galaxies with deeper gravitational potential wells. We conclude the observed cold gas density maxima offsets are most likely the result of ram pressure and/or the high-speed tidal interaction with CGCG 97-073. However ram pressure stripping is likely to be playing a major role in the perturbation of lower density gas. [ABSTRACT FROM AUTHOR]

Four-color light curves of EQUMa were obtainedwith the 1.0m telescope atWeihai Observatory, Shandong University. The light variability of EQUMa is typical of a WUMa-type binary. By analyzing the four-color light curves simultaneously, we found that EQUMa is a semi-detached binary with the less massive component filling its inner Roche lobe. The very short period and the Algol-type configuration make EQUMa a very good target to challenge the formation and evolution theory of low-mass Algols. We investigated the orbital period change of EQUMa by all available times of minimum light. It is shown that the orbital period of EQUMa displays a cyclic oscillation with a period of 12.1 yr superimposed on long-term increase with a rate of dp/dt = 1.77 × 10-7 dyr-1. The long-term period increase should be caused by themass transfer from the less massive component to the more massive one. The cyclic modulation is very probably produced by the light travel time effect of a third component. [ABSTRACT FROM AUTHOR]

In this paper we report the results of a γ -ray study of IceCube's extraterrestrial neutrino candidates detected as track-like events. Using 70 months of Fermi-Large Area Telescope (LAT) observations, a likelihood analysis of all 1-300 GeV photons within 5° of the track-like neutrino candidates' origin was undertaken, to search for spatially coincident γ -ray emission. One of IceCube's HESE (High Energy Starting Event) track events was found to be spatially coincident with a γ -ray bright active galactic nucleus (AGN), PKS 0723-008.We find however that the chance probability for Fermi-LAT detected AGNto be spatially coincident with a single HESE track-like event is high (~37 per cent).We therefore find no evidence of γ -ray emission associated with the detection of IceCube's HESE track-like neutrino candidates. Upper limits were calculated in the energy range of 1-300 GeV, assuming a point source origin for the neutrino events considered. The implications for the non-detection of γ -ray emission from the source of the HESE track-like events are briefly discussed. The large time period analysed in our study did however reveal two new γ -ray point sources. With a flux of (1.28±0.08)×10-9 photons cm-2 s-1, in the 1-300 GeV energy range, and an associated TS value of 220.6, one of these new point sources is positionally coincident with the AGN PKS 1346-112. The other point source has a 1-300 GeV flux of (7.95 ± 1.23) × 10-10 photons cm-2 s-1 and an associated TS value of 92.4. This new point source is spatially coincident with the radio source NVSS J072534 + 021645 suggesting that it too is an AGN. [ABSTRACT FROM AUTHOR]

Galactic archaeology based on star counts is instrumental to reconstruct the past mass assembly of Local Group galaxies. The development of new observing techniques and data reduction, coupled with the use of sensitive large field of view cameras, now allows us to pursue this technique in more distant galaxies exploiting their diffuse low surface brightness (LSB) light. As part of the ATLAS3D project, we have obtained with the MegaCam camera at the Canada–France–Hawaii Telescope extremely deep, multiband images of nearby early-type galaxies (ETGs). We present here a catalogue of 92 galaxies from the ATLAS3D sample, which are located in low- to medium-density environments. The observing strategy and data reduction pipeline, which achieve a gain of several magnitudes in the limiting surface brightness with respect to classical imaging surveys, are presented. The size and depth of the survey are compared to other recent deep imaging projects. The paper highlights the capability of LSB-optimized surveys at detecting new prominent structures that change the apparent morphology of galaxies. The intrinsic limitations of deep imaging observations are also discussed, among those, the contamination of the stellar haloes of galaxies by extended ghost reflections, and the cirrus emission from Galactic dust. The detection and systematic census of fine structures that trace the present and past mass assembly of ETGs are one of the prime goals of the project. We provide specific examples of each type of observed structures – tidal tails, stellar streams and shells – and explain how they were identified and classified. We give an overview of the initial results. The detailed statistical analysis will be presented in future papers. [ABSTRACT FROM AUTHOR]

Optical turbulence greatly impacts the range and quality of astronomical observations. Advanced knowledge of the expected atmospheric optical turbulence provides important guidance that helps astronomers decide which instrument to schedule and enables them to optimize the adaptive optics technology that improves image resolution. Along with forecasts of weather conditions, prediction of the optical observing quality on the Maunakea summit has been a goal for the Maunakea Weather Center (MKWC) since its inception more than 20 yr ago. Forecasting optical turbulence, and its derivative, 'seeing', has proven to be quite challenging because optical turbulence is too small and complex to directly capture with a regional weather model. Fortunately, the permanent installation of a Differential Image Motion Monitor (DIMM) and Multi-Aperture Scintillation Sensor (MASS) at the summit of Maunakea has made seeing observations available during the last decade, providing valuable feedback to the MKWC. This paper summarizes the experience at MKWC in anticipating optical turbulence for the summit of Maunakea accrued through years of daily operational forecasting, and continuous comparison between MKWC official forecasts, model guidance, and observational measures of seeing. Access to a decade seeing observations has allowed quantification the factors that impact seeing, including wind shear, atmospheric stability patterns, and optical turbulence, and to document the seasonal and intra-seasonal variations in seeing. Consequently, the combination of experience gained, and custom model guidance has led to more accurate seeing forecasts (rms errors averaging <0.25 arcsec since 2012) for the Maunakea astronomical observatories. [ABSTRACT FROM AUTHOR]

Trend filtering – first introduced into the astronomical literature in Paper I of this series – is a state-of-the-art statistical tool for denoising 1D signals that possess varying degrees of smoothness. In this work, we demonstrate the broad utility of trend filtering to observational astronomy by discussing how it can contribute to a variety of spectroscopic and time-domain studies. The observations we discuss are (1) the Lyman-α (Lyα) forest of quasar spectra; (2) more general spectroscopy of quasars, galaxies, and stars; (3) stellar light curves with planetary transits; (4) eclipsing binary light curves; and (5) supernova light curves. We study the Lyα forest in the greatest detail – using trend filtering to map the large-scale structure of the intergalactic medium along quasar-observer lines of sight. The remaining studies share broad themes of: (1) estimating observable parameters of light curves and spectra; and (2) constructing observational spectral/light-curve templates. We also briefly discuss the utility of trend filtering as a tool for 1D data reduction and compression. [ABSTRACT FROM AUTHOR]