Search

Black hole X-ray binaries (BHBs) offer insights into extreme gravitational environments and the testing of general relativity. The X-ray spectrum collected by NICER offers valuable information on the properties and behaviour of BHBs through spectral fitting. However, traditional spectral fitting methods are slow and scale poorly with model complexity. This paper presents a new semisupervised autoencoder neural network for parameter prediction and spectral reconstruction of BHBs, showing an improvement of up to a factor of 2700 in speed while maintaining comparable accuracy. The approach maps the spectral features from the numerous outbursts catalogued by NICER and generalizes them to new systems for efficient and accurate spectral fitting. The effectiveness of this approach is demonstrated in the spectral fitting of BHBs and holds promise for use in other areas of astronomy and physics for categorizing large data sets. The code is available via https://github.com/EthanTreg/Spectrum-Machine-Learning. [ABSTRACT FROM AUTHOR]

The discovery of gravitational wave (GW) events and the detection of electromagnetic counterparts from GW170817 has started the era of multimessenger GW astronomy. The field has been developing rapidly, and in this paper, we discuss the preparation for detecting these events with ESA's Gaia satellite, during the 4th observing run of the LIGO–Virgo–KAGRA (LVK) collaboration that has started on 2023 May 24. Gaia is contributing to the search for GW counterparts by a new transient detection pipeline called GaiaX. In GaiaX , a new source appearing in the field of view of only one of the two telescopes on-board Gaia is sufficient to send out an alert on the possible detection of a new transient. Ahead of O4, an experiment was conducted over a period of about two months. During the two weeks around New Moon in this period of time, the MeerLICHT (ML) telescope located in South Africa tried (weather permitting) to observe the same region of the sky as Gaia within 10 min. Any GaiaX detected transient was published publicly. ML and Gaia have similar limiting magnitudes for typical seeing conditions at ML. At the end of the experiment, we had 11 861 GaiaX candidate transients and 15 806 ML candidate transients, which we further analysed and the results of which are presented in this paper. Finally, we discuss the possibility and capabilities of Gaia contributing to the search for electromagnetic counterparts of gravitational wave events during O4 through the GaiaX detection and alert procedure. [ABSTRACT FROM AUTHOR]

We isolate the spectrum of the secondary component of the composite-binary system 93 Leonis by spectrum subtraction, classify it, and measure the mass ratio of the system. An accurate visual orbit and a well-determined parallax provide reliable measurements of orbital inclination and distance, enabling us to determine precisely the individual masses and other stellar parameters. The primary star is of type ∼G7 III, and the secondary is a rapidly rotating star of type A7 IV. Our photographic spectra at 10 Å mm-1 are invaluable for accurate spectral classification in such cases. By combining 23 measurements of the secondary's velocity with 102 of the primary's and deriving a double-lined orbit, we determine the mass ratio (q = M1/M2) of 93 Leo to be 1.09 ± 0.04. The same value is derived by cross-correlating high-dispersion spectra of 93 Leo B extracted from opposite nodal phases. That value of q is consonant with previous research, but its precision is considerably improved. We show that random errors arising from the cross-correlation of broad, weak features constitute a natural limit to that precision. The derived masses of M1 = 2.2 M[This symbol cannot be presented in ASCII format], M2 = 2.0 M[This symbol cannot be presented in ASCII format] for the giant and dwarf, respectively, constrain the choice of models for fitting evolutionary tracks in the (log Teff, log L) plane. The giant is almost certainly on its first ascent of the red giant branch, and the dwarf has evolved significantly from the main sequence. The stars fit an isochrone for log(age) = 8.95, about 0.9 Gyr. Metallicity near to solar is suggested by the close correspondence between the component spectra and those of the respective solar-abundance standards. The primary in 93 Leo displays a marked level of chromospheric activity. By combining our high-dispersion spectra we are able to isolate emission in the Ca II K line. The chromospheric material has a small infall velocity, giving rise to a disc-averaged redshift of about 4 km s-1, and an unchanging velocity profile which can be attributed to a large number of small, active events like prominences across the surface. While we can say that there was no perceptible change in the emission strength over an interval of 4 months, we have not made systematic observations to monitor its long-term stability. We contrast the components of 93 Leo with those of α Equ, whose analysis was the subject of Paper 11 in this series. The primary components are very similar, but the two secondary components are extremely different in nature: whereas 93 Leo B is a broad-lined, apparently normal A star, the secondary of α Equ is a sharp-lined Am star of type ∼kA3hA4mA9. We question why that should be, and recommend that a greater emphasis be placed on extracting accurate stellar parameters from the components of spectroscopic binaries as a means towards a better understanding of the vagaries of stellar evolution. 93 Leo has a 9-mag visual companion which appears to be a physical member of the system and to be a single-lined spectroscopic binary with a period of the order of a century. [ABSTRACT FROM AUTHOR]

We present the S-PLUS Transient Extension Program (STEP): a supernova and fast transient survey conducted in the southern hemisphere using data from the Southern Photometric Local Universe Survey (S-PLUS) Main Survey and the T80-South telescope. Transient astrophysical phenomena have a range of interest that goes through different fields of astrophysics and cosmology. With the detection of an electromagnetic counterpart to the gravitational wave (GW) event GW170817 from a binary neutron stars merger, new techniques and resources to study fast astrophysical transients in the multimessenger context have increased. In this paper, we present the STEP overview, the SN follow-up data obtained, data reduction, analysis of new transients and deep learning algorithms to optimize transient candidate selection. Additionally, we present prospects and optimized strategy for the search of gravitational wave counterparts in the current LIGO/Virgo/Kagra observational run (O4) in the context of T80-South telescope. [ABSTRACT FROM AUTHOR]

We present sibelius-dark , a constrained realization simulation of the local volume to a distance of 200 Mpc from the Milky Way. sibelius-dark is the first study of the ' Simulations Beyond The Local Universe ' (sibelius) project, which has the goal of embedding a model Local Group-like system within the correct cosmic environment. The simulation is dark-matter-only, with the galaxy population calculated using the semi-analytic model of galaxy formation, galform. We demonstrate that the large-scale structure that emerges from the sibelius constrained initial conditions matches well the observational data. The inferred galaxy population of sibelius-dark also match well the observational data, both statistically for the whole volume and on an object-by-object basis for the most massive clusters. For example, the K -band number counts across the whole sky, and when divided between the northern and southern Galactic hemispheres, are well reproduced by sibelius-dark. We find that the local volume is somewhat unusual in the wider context of ΛCDM: it contains an abnormally high number of supermassive clusters, as well as an overall large-scale underdensity at the level of ≈5 per cent relative to the cosmic mean. However, whilst rare, the extent of these peculiarities does not significantly challenge the ΛCDM model. sibelius-dark is the most comprehensive constrained realization simulation of the local volume to date, and with this paper we publicly release the halo and galaxy catalogues at z  = 0, which we hope will be useful to the wider astronomy community. [ABSTRACT FROM AUTHOR]

With the aim of pushing the limiting magnitude of interferometric instruments, the need for wide-band detection channels and for a coordinated operation of different instruments has considerably grown in the field of long-baseline interferometry. For this reason, the Center for High Angular Resolution Astronomy (CHARA), an array of six telescopes, requires a new configuration of longitudinal dispersion compensators to keep the fringe contrast above 95 per cent simultaneously in all spectral bands, while preserving the transmission above 85 per cent. In this paper, we propose a new method for defining the longitudinal dispersion compensators (LDC) suited for multiband observations. A literal approximation of the contrast loss resulting from the dispersion residues enables us to define a general criterion for fringe contrast maximization on several bands simultaneously. The optimization of this criterion leads to a simple solution with only two LDC stages per arm and existing differential delay lines, to the glass choice and a simple linear formula for thickness control of all these media. A refined criterion can also take into account glass transmission. After presenting this criterion, we give the optimal solution (medium, configuration) and its expected performance for the planned observing modes on CHARA. [ABSTRACT FROM AUTHOR]

In several disciplines, it is common to find time series measured at irregular observational times. In particular, in astronomy there are a large number of surveys that gather information over irregular time gaps and in more than one passband. Some examples are Pan-STARRS, ZTF, and also the LSST. However, current commonly used time series models that estimate the time dependence in astronomical light curves consider the information of each band separately (e.g, CIAR, IAR, and CARMA models) disregarding the dependence that might exist between different passbands. In this paper, we propose a novel bivariate model for irregularly sampled time series, called the Bivariate Irregular Autoregressive (BIAR) model. The BIAR model assumes an autoregressive structure on each time series; it is stationary, and it allows to estimate the autocorrelation, the cross-correlation and the contemporary correlation between two unequally spaced time series. We implemented the BIAR model on light curves, in the g and r bands, obtained from the ZTF alerts processed by the ALeRCE broker. We show that if the light curves of the two bands are highly correlated, the model has more accurate forecast and prediction using the bivariate model than a similar method that uses only univariate information. Further, the estimated parameters of the BIAR are useful to characterize long-period variable stars and to distinguish between classes of stochastic objects, providing promising features that can be used for classification purposes. [ABSTRACT FROM AUTHOR]

In several disciplines, it is common to find time series measured at irregular observational times. In particular, in astronomy there are a large number of surveys that gather information over irregular time gaps and in more than one passband. Some examples are Pan-STARRS, ZTF, and also the LSST. However, current commonly used time series models that estimate the time dependence in astronomical light curves consider the information of each band separately (e.g, CIAR, IAR, and CARMA models) disregarding the dependence that might exist between different passbands. In this paper, we propose a novel bivariate model for irregularly sampled time series, called the Bivariate Irregular Autoregressive (BIAR) model. The BIAR model assumes an autoregressive structure on each time series; it is stationary, and it allows to estimate the autocorrelation, the cross-correlation and the contemporary correlation between two unequally spaced time series. We implemented the BIAR model on light curves, in the g and r bands, obtained from the ZTF alerts processed by the ALeRCE broker. We show that if the light curves of the two bands are highly correlated, the model has more accurate forecast and prediction using the bivariate model than a similar method that uses only univariate information. Further, the estimated parameters of the BIAR are useful to characterize long-period variable stars and to distinguish between classes of stochastic objects, providing promising features that can be used for classification purposes. [ABSTRACT FROM AUTHOR]

In studying the formation of massive stars, it is essential to consider the strong radiative feedback on the stars’ natal environments from their high luminosities (104–106L⊙). Given that massive stars contract to main-sequence-like radii before accretion finishes, one form this feedback takes is UV line-acceleration, resulting in outflows much like those expected from main-sequence massive stars. As shown by the prior papers in this series, in addition to driving stellar winds, such line forces also ablate the surface layers off of circumstellar discs within a few stellar radii of the stellar photosphere. This removal of material from an accretion disc in turn results in a decreased accretion rate onto the forming star. Quantifying this, however, requires accounting for the continuum optical depth of the disc along the non-radial rays required for the three-dimensional line-acceleration prescription used in this paper series. We introduce the ‘thin-disc approximation’, allowing these continuum optical depths arising from an optically thick but geometrically thin disc to be dynamically treated in the context of radiation-hydrodynamics simulations. Using this approximation in full dynamical simulations, we show that such continuum optical depth effects only reduce the disc ablation by 30 per cent or less relative to previous simulations that ignored continuum absorption. [ABSTRACT FROM AUTHOR]

Wolfgang Steinicke celebrates the centenary of a famous publication. [ABSTRACT FROM AUTHOR]

During the last decade, there has been an explosive growth in survey data and deep learning techniques, both of which have enabled great advances for astronomy. The amount of data from various surveys from multiple epochs with a wide range of wavelengths, albeit with varying brightness and quality, is overwhelming, and leveraging information from overlapping observations from different surveys has limitless potential in understanding galaxy formation and evolution. Synthetic galaxy image generation using physical models has been an important tool for survey data analysis, while deep learning generative models show great promise. In this paper, we present a novel approach for robustly expanding and improving survey data through cross survey feature translation. We trained two types of neural networks to map images from the Sloan Digital Sky Survey (SDSS) to corresponding images from the Dark Energy Survey (DES). This map was used to generate false DES representations of SDSS images, increasing the brightness and S/N while retaining important morphological information. We substantiate the robustness of our method by generating DES representations of SDSS images from outside the overlapping region, showing that the brightness and quality are improved even when the source images are of lower quality than the training images. Finally, we highlight images in which the reconstruction process appears to have removed large artefacts from SDSS images. While only an initial application, our method shows promise as a method for robustly expanding and improving the quality of optical survey data and provides a potential avenue for cross-band reconstruction. [ABSTRACT FROM AUTHOR]

We extend the formalism of a previous paper to include the effects of flybys and instantaneous perturbations such as supernovae on the long-term secular evolution of hierarchical multiple systems with an arbitrary number of bodies and hierarchy, provided that the system is composed of nested binary orbits. To model secular encounters, we expand the Hamiltonian in terms of the ratio of the separation of the perturber with respect to the barycentre of the multiple system, to the separation of the widest orbit. Subsequently, we integrate over the perturber orbit numerically or analytically. We verify our method for secular encounters and illustrate it with an example. Furthermore, we describe a method to compute instantaneous orbital changes to multiple systems, such as asymmetric supernovae and impulsive encounters. The secular code, with implementation of the extensions described in this paper, is publicly available within amuse, and we provide a number of simple example scripts to illustrate its usage for secular and impulsive encounters and asymmetric supernovae. The extensions presented in this paper are a next step towards efficiently modelling the evolution of complex multiple systems embedded in star clusters. [ABSTRACT FROM AUTHOR]

Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2m Subaru telescope on the summit of Maunakea in Hawaii. A team of scientists from Japan, Taiwan and Princeton University is using HSC to carry out a 300-night multi-band imaging survey of the high-latitude sky. The survey includes three layers: the Wide layer will cover 1400 deg2 in five broad bands (grizy), with a 5σ point-source depth of r≈26. The Deep layer covers a total of 26~deg2 in four fields, going roughly a magnitude fainter, while the UltraDeep layer goes almost a magnitude fainter still in two pointings of HSC (a total of 3.5 deg2). Here we describe the instrument, the science goals of the survey, and the survey strategy and data processing. This paper serves as an introduction to a special issue of the Publications of the Astronomical Society of Japan, which includes a large number of technical and scientific papers describing results from the early phases of this survey. [ABSTRACT FROM AUTHOR]

In an earlier paper (2007), we used follow-up observations of a sample of sources from the 9C survey at 15.2 GHz to derive a set of spectral-index distributions up to a frequency of 90 GHz. These were based on simultaneous measurements made at 15.2 GHz with the Ryle telescope and at 22 and 43 GHz with the Karl G. Jansky Very Large Array (VLA). We used these distributions to make empirical estimates of source counts at 22, 30, 43, 70 and 90 GHz. In a later paper (2013), we took data at 15.7 GHz from the Arcminute Microkelvin Imager (AMI) and data at 93.2 GHz from the Combined Array for Research in Millimetre-wave Astronomy (CARMA) and estimated the source count at 93.2 GHz. In this paper, we re-examine the data used in both papers and now believe that the VLA flux densities we measured at 43 GHz were significantly in error, being on average only about 70 per cent of their correct values. Here, we present strong evidence for this conclusion and discuss the effect on the source-count estimates made in the 2007 paper. The source-count prediction in the 2013 paper is also revised. We make comparisons with spectral-index distributions and source counts from other telescopes, in particular with a recent deep 95 GHz source count measured by the South Pole Telescope. We investigate reasons for the problem of the low VLA 43-GHz values and find a number of possible contributory factors, but none is sufficient on its own to account for such a large deficit. [ABSTRACT FROM AUTHOR]

Dedicated transiting surveys, such as the Kepler space telescope, have provided the astronomy community with a rich data set resulting in many new discoveries. In this paper, we look at eight Kepler objects identified by Wheeler & Kipping with a periodic, broad increase in flux, that look distinctly different from intrinsic star variability. We consider two physical phenomena as explanations for these observed Kepler light curves; the first being the classical explanation while the second being an alternative scenario: (i) tidal interactions in a binary star system, and (ii) forward scattering from an optically thin cloud around an exoplanet. We investigate the likelihood of each model by modelling and fitting to the observed data. The binary system qualitatively does a good job of reproducing the shape of the observed light curves due to the tidal interaction of the two stars. We do, however, see a mismatch in flux right before or after the peak brightness. We find that six out of the eight systems require an F-type primary star with a K-type companion with large eccentricities. At the same time, we find that optically thin discs, modelled using a Henyey–Greenstein phase function are also able to generate these broad brightening events. Five of the eight observed objects can be described with this new hypothesis in the absence of RV observations. As the other three are not well-described by the disc model, we conclude that they are indeed heartbeat stars. [ABSTRACT FROM AUTHOR]

One of the unsolved questions in γ-ray astronomy is whether the extragalactic γ-ray background is of the discrete-source origin. To respond to this question, one first needs to reduce the data by differentiating charged particles from γ-rays. This procedure is usually performed on the basis of the detector responses. In this paper, we showed that the geomagnetic shielding effect at GeV energies can, to some extent, be used for this purpose for γ-ray telescopes in a low Earth orbit. We illustrated this method by applying it to the Fermi Large Area Telescope data. To partially decompose the charge-filtered background, we examined the contribution from star-forming galaxies by implying a radio/γ-ray connection in consideration of next-generation radio surveys. [ABSTRACT FROM AUTHOR]

In this paper, we simulate the cyclic circularly polarized pulses of the ultracool dwarf TVLM 513-46546, observed with the Very Large Array at 4.88 and 8.44 GHz on 2006 May, by using a three-dimensional model of the auroral radio emission from the stellar magnetosphere. During this epoch, the radio light curves are characterized by two pulses left-hand polarized at 4.88 GHz, and one doubly peaked (of opposite polarizations) pulse at 8.44 GHz. To take into account the possible deviation from the dipolar symmetry of the stellarmagnetic-field topology, the model described in this paper is also able to simulate the auroral radio emission from a magnetosphere shaped like an offset dipole. To reproduce the timing and pattern of the observed pulses, we explored the space of parameters controlling the auroral beaming pattern and the geometry of the magnetosphere. Through the analysis of the TVLM 513-46546 auroral radio emission, we derive some indications on the magnetospheric field topology that is able to simultaneously reproduce the timing and patterns of the auroral pulses measured at 4.88 and 8.44 GHz. Each set of model solutions simulates two auroral pulses (singly or doubly peaked) per period. To explain the presence of only one 8.44 GHz pulse per period, we analyse the case of auroral radio emission limited only to a magnetospheric sector activated by an external body, like the case of the interaction of Jupiter with its moons. [ABSTRACT FROM AUTHOR]

Classification of stars and galaxies is a well-known astronomical problem that has been treated using different approaches, most of them relying on morphological information. In this paper, we tackle this issue using the low-resolution spectra from narrow-band photometry, provided by the Physics of the Accelerating Universe survey. We find that, with the photometric fluxes from the 40 narrow-band filters and without including morphological information, it is possible to separate stars and galaxies to very high precision, |$98.4{{\ \rm per\ cent}}$| purity with a completeness of |$98.8{{\ \rm per\ cent}}$| for objects brighter than I  = 22.5. This precision is obtained with a convolutional neural network as a classification algorithm, applied to the objects' spectra. We have also applied the method to the ALHAMBRA photometric survey and we provide an updated classification for its Gold sample. [ABSTRACT FROM AUTHOR]

JINGLE is a new JCMT legacy survey designed to systematically study the cold interstellar medium of galaxies in the local Universe. As part of the survey we perform 850 µm continuum measurements with SCUBA-2 for a representative sample of 193 Herschel -selected galaxies with M *> 109M⊙, as well as integrated CO(2–1) line fluxes with RxA3m for a subset of 90 of these galaxies. The sample is selected from fields covered by the Herschel- ATLAS survey that are also targeted by the MaNGA optical integral-field spectroscopic survey. The new JCMT observations combined with the multiwavelength ancillary data will allow for the robust characterization of the properties of dust in the nearby Universe, and the benchmarking of scaling relations between dust, gas, and global galaxy properties. In this paper we give an overview of the survey objectives and details about the sample selection and JCMT observations, present a consistent 30-band UV-to-FIR photometric catalogue with derived properties, and introduce the JINGLE Main Data Release. Science highlights include the non-linearity of the relation between 850 µm luminosity and CO line luminosity (log L CO(2–1)=  1.372 log L 850–1.376), and the serendipitous discovery of candidate z > 6 galaxies. [ABSTRACT FROM AUTHOR]

We present a structural and morphological catalogue for 45 million objects selected from the first year data of the Dark Energy Survey (DES). Single Sérsic fits and non-parametric measurements are produced for g, r, and i filters. The parameters from the best-fitting Sérsic model (total magnitude, half-light radius, Sérsic index, axis ratio, and position angle) are measured with galfit ; the non-parametric coefficients (concentration, asymmetry, clumpiness, Gini, M20) are provided using the Zurich Estimator of Structural Types (zest +). To study the statistical uncertainties, we consider a sample of state-of-the-art image simulations with a realistic distribution in the input parameter space and then process and analyse them as we do with real data: this enables us to quantify the observational biases due to PSF blurring and magnitude effects and correct the measurements as a function of magnitude, galaxy size, Sérsic index (concentration for the analysis of the non-parametric measurements) and ellipticity. We present the largest structural catalogue to date: we find that accurate and complete measurements for all the structural parameters are typically obtained for galaxies with SExtractor |$\tt {MAG\_AUTO\_I} \le 21$|⁠. Indeed, the parameters in the filters i and r can be overall well recovered up to |$\tt {MAG\_AUTO} \le 21.5$|⁠, corresponding to a fitting completeness of |${\sim } 90{{\ \rm per\ cent}}$| below this threshold, for a total of 25 million galaxies. The combination of parametric and non-parametric structural measurements makes this catalogue an important instrument to explore and understand how galaxies form and evolve. The catalogue described in this paper will be publicly released alongside the DES collaboration Y1 cosmology data products at the following URL: https://des.ncsa.illinois.edu/releases. [ABSTRACT FROM AUTHOR]

Studies of the kinematics of NGC 1407 have revealed complex kinematical structure, consisting of the outer galaxy, an embedded disc within a radius of ∼60 arcsec, and a kinematically decoupled core (KDC) with a radius of less than 30 arcsec. However, the size of the KDC and the amplitude of the kinematic misalignment it induces have not yet been determined. In this paper, we explore the properties of the KDC using observations from the Multi-Unit Spectroscopic Explorer (MUSE) Integral Field Spectrograph to map out the kinematics in the central arcminute of NGC 1407. Velocity and kinemetry maps of the galaxy reveal a twist of ∼148° in the central 10 arcsec of the galaxy, and the higher order moments of the kinematics reveal that within the same region, this slowly rotating galaxy displays no net rotation. Analysis of the stellar populations across the galaxy found no evidence of younger stellar populations in the region of the KDC, instead finding uniform age and super-solar α-enhancement across the galaxy, and a smoothly decreasing metallicity gradient with radius. We therefore conclude that NGC 1407 contains a triaxial, kiloparsec-scale KDC with distinct kinematics relative to the rest of the galaxy, and that is likely to have formed through either a major merger or a series of minor mergers early in the lifetime of the galaxy. With a radius of ∼5 arcsec or ∼0.6 kpc, NGC 1407 contains the smallest KDC mapped by MUSE to date in terms of both its physical and angular size. [ABSTRACT FROM AUTHOR]

The computation of microlensing light curves represents a bottleneck for the modelling of planetary events, making broad searches in the vast parameter space of microlensing extremely time-consuming. The release of the first version of VBBinaryLensing (based on the advanced contour integration method presented in a previous paper) has represented a considerable advance in the field, with the birth of several analysis platforms running on this code. Here, we present the version 2.0 of VBBinaryLensing, which contains several upgrades with respect to the first version, including new decision trees that introduce important optimizations in the calculations. The package is publicly available at https://github.com/valboz/VBBinaryLensing. [ABSTRACT FROM AUTHOR]

One of the aims of the BCool programme is to search for cycles in other stars and to understand how similar they are to the Sun. In this paper, we aim to monitor the evolution of τ Boo’s large-scale magnetic field using high-cadence observations covering its chromospheric activity maximum. For the first time, we detect a polarity switch that is in phase with τ Boo’s 120-day chromospheric activity maximum and its inferred X-ray activity cycle maximum. This means that τ Boo has a very fast magnetic cycle of only 240 days. At activity maximum τ Boo’s large-scale field geometry is very similar to the Sun at activity maximum: it is complex and there is a weak dipolar component. In contrast, we also see the emergence of a strong toroidal component which has not been observed on the Sun, and a potentially overlapping butterfly pattern where the next cycle begins before the previous one has finished. [ABSTRACT FROM AUTHOR]

In this paper, we use two hydrodynamic simulations to study the barycentre offsets r off between the entire halo and the gas or dark matter subhalo with largest overdensity. We restrict our analysis to those haloes with large rescaled offsets, i.e. r off/ r 200 ≳ 0.05. The haloes which are less massive and at higher redshifts are more likely to have larger r off/ r 200. The 3D velocity dispersion of the subhaloes with largest overdensity is found to have a similar mass and redshift dependence as r off/ r 200. We also find that the gas subhaloes with maximum overdensity and larger gas velocity dispersion $$\sigma _{v}^{\rm ICM,sub}/\sigma _{200}$$ tend to have smaller barycentre offsets r off/ r 200. Similar result is found for the highest overdensity dark matter subhaloes but with less significance. This anticorrelation is more significant for the snapshot z  = 0 than z  = 0.2 and 0.5. The underlying physical mechanism for this anticorrelation remains to be explored. [ABSTRACT FROM AUTHOR]

This work is the second part of a project that attempts to analyse the formation of Solar system analogues (SSAs) from the gaseous to the post-gas phase, in a self-consistently way. In the first paper (PI) we presented our model of planet formation during the gaseous phase which provided us with embryo distributions, planetesimal surface density, eccentricity, and inclination profiles of SSAs, considering different planetesimal sizes and type I migration rates at the time the gas dissipates. In this second work we focus on the late accretion stage of SSAs using the results obtained in PI as initial conditions to carry out N -body simulations. One of our interests is to analyse the formation of rocky planets and their final water contents within the habitable zone. Our results show that the formation of potentially habitable planets (PHPs) seems to be a common process in this kind of scenarios. However, the efficiency in forming PHPs is directly related to the size of the planetesimals. The smaller the planetesimals, the greater the efficiency in forming PHPs. We also analyse the sensitivity of our results to scenarios with type I migration rates and gap-opening giants, finding that both phenomena act in a similar way. These effects seem to favour the formation of PHPs for small planetesimal scenarios and to be detrimental for scenarios formed from big planetesimals. Finally, another interesting result is that the formation of water-rich PHPs seems to be more common than the formation of dry PHPs. [ABSTRACT FROM AUTHOR]

The Coma supercluster (100 h −1 Mpc) offers an unprecedented contiguous range of environments in the nearby Universe. In this paper, we present a catalogue of spectroscopically confirmed galaxies in the Coma supercluster detected in the ultraviolet (UV) wavebands. We use the arsenal of UV and optical data for galaxies in the Coma supercluster covering ∼500 deg2 on the sky to study their photometric and spectroscopic properties as a function of environment at various scales. We identify the different components of the cosmic-web: large-scale filaments and voids using Discrete Persistent Structures Extractor, and groups and clusters using Hierarchical Density-based spatial clustering of applications with noise, respectively. We find that in the Coma supercluster the median emission in H α inclines, while the g  −  r and FUV  −  NUV colours of galaxies become bluer moving further away from the spine of the filaments out to a radius of ∼1 Mpc. On the other hand, an opposite trend is observed as the distance between the galaxy and centre of the nearest cluster or group decreases. Our analysis supports the hypothesis that properties of galaxies are not just defined by its stellar mass and large-scale density, but also by the environmental processes resulting due to the intrafilament medium whose role in accelerating galaxy transformations needs to be investigated thoroughly using multiwavelength data. [ABSTRACT FROM AUTHOR]

Stacked lensing is a powerful means of measuring the average mass distribution around large-scale structure tracers. There are two stacked lensing estimators used in the literature, denoted as ΔΣ and γ+, which are related as ΔΣ = Σcrγ+, where Σcr(z l, z s) is the critical surface mass density for each lens–source pair (z l and z s are lens and source redshifts, respectively). In this paper, we derive a formula for the covariance matrix of ΔΣ-estimator focusing on ‘weight’ function to improve the signal-to-noise ratio (S/N). We assume that the lensing fields and the distribution of lensing objects obey the Gaussian statistics. With this formula, we show that, if background galaxy shapes are weighted by an amount of $$\Sigma_{\rm cr}^{-2}(z_\mathrm{ l},z_\mathrm{ s})$$, the ΔΣ-estimator maximizes the S/N in the shot-noise-limited regime. We also show that the ΔΣ-estimator with the weight $$\Sigma_{\rm cr}^{-2}$$ gives a greater (S/N)2 than that of the γ+-estimator by about 5–25 per cent for lensing objects at redshifts comparable with or higher than the median of source galaxy redshifts for hypothetical Subaru Hyper Suprime-Cam and Dark Energy Survey. However, for low-redshift lenses such as $$z_\mathrm{ l}\,\lesssim \,0.3$$, the γ+-estimator has higher (S/N)2 than ΔΣ. We also discuss that the (S/N)2 for ΔΣ at large separations in the sample-variance-limited regime can be boosted, by up to a factor of 1.5, if one adopts a weight of $$\Sigma_{\rm cr}^{-\alpha }$$ with α > 2. Our formula allows one to explore how the combination of the different estimators can approach an optimal estimator in all regimes of redshifts and separation scales. [ABSTRACT FROM AUTHOR]

The spectrum of a galaxy contains information about its physical properties. Classifying spectra using templates helps to elucidate the nature of a galaxy’s energy sources. In this paper, we investigate the use of self-organizing maps in classifying galaxy spectra against templates. We trained semi-supervised self-organizing map networks using a set of templates covering the wavelength range from far ultraviolet to near-infrared. The trained networks were used to classify the spectra of a sample of 142 galaxies with 0.5 < $$z$$ < 1 and the results compared to classifications performed using K -means clustering, a supervised neural network, and chi-squared minimization. Spectra corresponding to quiescent galaxies were more likely to be classified similarly by all methods while starburst spectra showed more variability. Compared to classification using chi-squared minimization or the supervised neural network, the galaxies classed together by the self-organizing map had more similar spectra. The class ordering provided by the 1D self-organizing maps corresponds to an ordering in physical properties, a potentially important feature for the exploration of large data sets. [ABSTRACT FROM AUTHOR]

The gas is the dominant component of baryonic matter in most galaxy groups and clusters. The spatial offsets of the gas centre from the halo centre could be an indicator of the dynamical state of cluster. Knowledge of such offsets is important for estimating the uncertainties when using clusters as cosmological probes. In this paper, we study the centre offsets r off of the gas and that of all matter within halo systems in Lambda cold dark matter (ΛCDM) cosmological hydrodynamic simulations. We focus on two kinds of centre offsets: One is the 3D potential minimum-barycentre (PB) offsets between the gravitational potential minimum of the entire halo and the barycentre of the intra-cluster medium (ICM), and the other is the 2D potential minimum-X-ray centroid (PX) offsets between the potential minimum of the halo and the iterative centroid of the projected synthetic X-ray emission of the halo. Haloes at higher redshifts tend to have larger values of rescaled offsets r off/ r 200 and larger gas velocity dispersion $$\sigma _{v}^{\rm gas}/\sigma _{200}$$. For both types of offsets, we find that the correlation between the rescaled centre offsets r off/ r 200 and the rescaled 3D gas velocity dispersion $$\sigma _v^{\rm gas}/\sigma _{200}$$ can be approximately described by a quadratic function as $$r_{{\rm off}}/r_{200} \propto (\sigma _{v}^{\rm gas}/\sigma _{200} - k_2)^{2}$$. A Bayesian analysis with the Markov-chain Monte Carlo method is employed to estimate the model parameters. Dependence of the correlation on redshifts and the gas mass fraction is also investigated. [ABSTRACT FROM AUTHOR]

Understanding how bulges grow in galaxies is a critical step towards unveiling the link between galaxy morphology and star-formation. To do so, it is necessary to decompose large sample of galaxies at different epochs into their main components (bulges and discs). This is particularly challenging, especially at high redshifts, where galaxies are poorly resolved. This work presents a catalog of bulge-disc decompositions of the surface brightness profiles of ∼17.600 H-band-selected galaxies in the CANDELS fields (F 160 W < 23, 0 < $$z$$ < 2) in 4 to 7 filters covering a spectral range of 430 - 1600 $$\mathrm{nm}$$. This is the largest available catalog of this kind up to $$z$$ = 2. By using a novel approach based on deep learning to select the best model to fit, we manage to control systematics arising from wrong model selection and obtain less-contaminated samples than previous works. We show that the derived structural properties are within $${\sim }10\hbox{--}20{\rm} \, \%$$ of random uncertainties. We then fit stellar population models to the decomposed spectral energy distributions of bulges and discs and derive stellar masses (and stellar mass bulge-to-total ratios) as well as rest-frame colors (U,V,J) for bulges and discs separately. All data products are publicly released with this paper and through the web page https://lerma.obspm.fr/huertas/form_CANDELS and will be used for scientific analysis in forthcoming works. [ABSTRACT FROM AUTHOR]

The oscillation spectrum of a perturbed neutron star is intimately related to the physical properties of the star, such as the equation of state. Observing pulsating neutron stars therefore allows one to place constraints on these physical properties. However, it is not obvious exactly how much can be learnt from such measurements. If we observe for long enough, and precisely enough, is it possible to learn everything about the star? A classical result in the theory of spectral geometry states that one cannot uniquely 'hear the shape of a drum'. More formally, it is known that an eigenfrequency spectrum may not uniquely correspond to a particular geometry; some 'drums' may be indistinguishable from a normal-mode perspective. In contrast, we show that the drum result does not extend to perturbations of simple neutron stars within general relativity – in the case of axial (toroidal) perturbations of static, perfect fluid stars, a quasi-normal mode spectrum uniquely corresponds to a stellar profile. We show in this paper that it is not possible for two neutron stars, with distinct fluid profiles, to oscillate in an identical manner. This result has the information-theoretic consequence that gravitational waves completely encode the properties of any given oscillating star: unique identifications are possible in the limit of perfect measurement. [ABSTRACT FROM AUTHOR]

Astrometric and spectroscopic monitoring of individual stars orbiting the supermassive black hole in the Galactic Center offer a promising way to detect general relativistic effects. While low-order effects are expected to be detected following the periastron passage of S2 in Spring 2018, detecting higher order effects due to black hole spin will require the discovery of closer stars. In this paper, we set out to determine the requirements such a star would have to satisfy to allow the detection of black hole spin. We focus on the instrument GRAVITY, which saw first light in 2016 and which is expected to achieve astrometric accuracies |$10\hbox{--}100 \, \mu$| as. For an observing campaign with duration T years, total observations N obs, astrometric precision σ x , and normalized black hole spin χ, we find that |$a_{\rm orb}(1-e^2)^{3/4} \lesssim 300 R_{\rm S} \sqrt{\frac{T}{4\, {\rm {yr}}}} \left(\frac{N_{\rm obs}}{120}\right)^{0.25} \sqrt{\frac{10\, \mu {\rm as}}{\sigma _x}} \sqrt{\frac{\chi }{0.9}}$| is needed. For χ = 0.9 and a potential observing campaign with |$\sigma _x = 10 \, \mu$| as, 30 observations yr−1 and duration 4–10 yr, we expect ∼0.1 star with K  < 19 satisfying this constraint based on the current knowledge about the stellar population in the central 1 arcsec. We also propose a method through which GRAVITY could potentially measure radial velocities with precision ∼50 km s−1. If the astrometric precision can be maintained, adding radial velocity information increases the expected number of stars by roughly a factor of 2. While we focus on GRAVITY, the results can also be scaled to parameters relevant for future extremely large telescopes. [ABSTRACT FROM AUTHOR]

Ring galaxies are amazing objects exemplified by the famous case of Hoag's Object. Here the mass of the central galaxy may be comparable to the mass of the ring, making it a difficult case to model mechanically. In a previous paper, it was shown that the outer potential of a torus (ring) can be represented with good accuracy by the potential of a massive circle with the same mass. This approach allows us to simplify the problem of the particle motion in the gravitational field of a torus associated with a central mass by replacing the torus with a massive circle. In such a system, there is a circle of unstable equilibrium that we call 'Lagrangian circle' (LC). Stable circular orbits exist only in some region limited by the last possible circular orbit related to the disappearance of the extrema of the effective potential. We call this orbit 'the outermost stable circular orbit' (OSCO) by analogy with the innermost stable circular orbit (ISCO) in the relativistic case of a black hole. Under these conditions, there is a region between OSCO and LC where the circular motion is not possible due to the competition between the gravitational forces by the central mass and the ring. As a result, a gap in the matter distribution can form in Hoag-like system with massive rings. [ABSTRACT FROM AUTHOR]

Pulsar-like compact stars provide us a unique laboratory to explore properties of dense matter at supra-nuclear densities. One of the models for pulsar-like stars is that they are totally composed of "strangeons", and in this paper, we studied the pulsar glitches in a strangeon star model. Strangeon stars would be solidified during cooling, and the solid stars would be natural to have glitches as the result of starquakes. Based on the starquake model established before, we proposed that when the starquake occurs, the inner motion of the star which changes the moment of inertia and has impact on the glitch sizes, is divided into plastic flow and elastic motion. The plastic flow which is induced in the fractured part of the outer layer, would move tangentially to redistribute the matter of the star and would be hard to recover. The elastic motion, on the other hand, changes its shape and would recover significantly. Under this scenario, we could understand the behaviors of glitches without significant energy releasing, including the Crab and the Vela pulsars, in an uniform model. We derive the recovery coefficient as a function of glitch size, as well as the time interval between two successive glitches as the function of the released stress. Our results show consistency with observational data under reasonable ranges of parameters. The implications on the oblateness of the Crab and the Vela pulsars are discussed. [ABSTRACT FROM AUTHOR]

We present a detailed analysis of the selection function of the LAMOST Spectroscopic Survey of the Galactic Anti-centre (LSS-GAC). LSS-GAC was designed to obtain low-resolution optical spectra for a sample of more than 3 million stars in the Galactic anti-centre. The second release of value-added catalogues of the LSS-GAC (LSS-GAC DR2) contains stellar parameters, including radial velocity, atmospheric parameters, elemental abundances, and absolute magnitudes deduced from 1.8 million spectra of 1.4 million unique stars targeted by the LSS-GAC between 2011 and 2014. For many studies using this data base, such as those investigating the chemodynamical structure of the Milky Way, a detailed understanding of the selection function of the survey is indispensable. In this paper, we describe how the selection function of the LSS-GAC can be evaluated to sufficient detail and provide selection function corrections for all spectroscopic measurements with reliable parameters released in LSS-GAC DR2. The results, to be released as new entries in the LSS-GAC value-added catalogues, can be used to correct the selection effects of the catalogue for scientific studies of various purposes. [ABSTRACT FROM AUTHOR]

By analysing a sample of galaxies selected from the H  i Parkes All Sky Survey (Hipass) to contain more than 2.5 times their expected H  i content based on their optical properties, we investigate what drives these H  i eXtreme (H  ix) galaxies to be so H  i -rich. We model the H  i kinematics with the Ti lted Ri ng Fi tting C ode TiRiFiC and compare the observed H  ix galaxies to a control sample of galaxies from Hipass as well as simulated galaxies built with the semi-analytic model Dark Sage. We find that (1) H  i discs in H  ix galaxies are more likely to be warped and more likely to host H  i arms and tails than in the control galaxies, (2) the average H  i and average stellar column density of H  ix galaxies is comparable to the control sample, (3) H  ix galaxies have higher H  i and baryonic specific angular momenta than control galaxies, (4) most H  ix galaxies live in higher spin haloes than most control galaxies. These results suggest that H  ix galaxies are H  i -rich because they can support more H  i against gravitational instability due to their high specific angular momentum. The majority of the H  ix galaxies inherits their high specific angular momentum from their halo. The H  i content of H  ix galaxies might be further increased by gas-rich minor mergers. This paper is based on data obtained with the Australia Telescope Compact Array through the large program C 2705. [ABSTRACT FROM AUTHOR]

Whether ground based or space based, any optical instrument suffers from some amount of optical geometric distortion. Recently, the diffraction-limited image quality afforded by spacebased telescopes and by instruments corrected with adaptive optics on ground-based telescope has increased the relative importance of the error terms induced by optical distortions. In particular, the variable distortion in multi-conjugate adaptive optics (MCAO) data limits the astrometric and photometric accuracy of such high-resolution instruments. These phenomena have become a critical issue for high-precision studies. We present in this paper an optimal method of distortion correction for high-angular-resolution images. Based on prior knowledge of the static distortion, the method aims to correct the dynamic distortion for each observation set and each frame. The method follows an inverse problem approach based on the work by Gratadour, Mugnier & Rouan on image re-centring, and we aim to generalize this to any kind of distortion mode. The complete formalism of a weighted least-squares minimization as well as a detailed characterization of the error budget are presented. In particular, we study the influence of different parameters such as the number of frames, the density of the field (sparse or crowed images), the noise level and the aliasing effect. Finally, we show the first application of the method on real observations collected with the Gemini MCAO instrument, GeMS/GSAOI. The performance of as well as the gain brought by this method are presented. [ABSTRACT FROM AUTHOR]

In this paper, we describe the optical imaging data processing pipeline developed for the Subaru Telescope's Hyper Suprime-Cam (HSC) instrument. The HSC Pipeline builds on the prototype pipeline being developed by the Large Synoptic Survey Telescope's Data Management system, adding customizations for HSC, large-scale processing capabilities, and novel algorithms that have since been reincorporated into the LSST codebase. While designed primarily to reduce HSC Subaru Strategic Program (SSP) data, it is also the recommended pipeline for reducing general-observer HSC data. The HSC pipeline includes high level processing steps that generate coadded images and science-ready catalogs as well as low-level detrending and image characterizations. [ABSTRACT FROM AUTHOR]

Simulations play a vital role in testing and validating HI 21-cm power spectrum estimation techniques. Conventional methods use techniques like N-body simulations to simulate the sky signal which is then passed through a model of the instrument. This makes it necessary to simulate the HI distribution in a large cosmological volume, and incorporate both the lightcone effect and the telescope&'s chromatic response. The computational requirements may be particularly large if one wishes to simulate many realizations of the signal. In this paper, we present an analytical method to simulate the HI visibility signal. This is particularly efficient if one wishes to simulate a large number of realizations of the signal. Our method is based on theoretical predictions of the visibility correlation which incorporate both the light-cone effect and the telescope&'s chromatic response. We have demonstrated this method by applying it to simulate the HI visibility signal for the upcoming Ooty Wide Field Array Phase I. [ABSTRACT FROM AUTHOR]

In this paper, we describe the first data release of the Visible and Infrared Survey Telescope for Astronomy (VISTA) Deep Extragalactic Observations (VIDEO) survey. VIDEO is a ∼12 deg2 survey in the near-infrared Z, Y, J, H and Ks bands, specifically designed to enable the evolution of galaxies and large structures to be traced as a function of both epoch and environment from the present day out to z = 4, and active galactic nuclei (AGNs) and the most massive galaxies up to and into the epoch of reionization. With its depth and area, VIDEO will be able to fully explore the period in the Universe where AGN and starburst activity were at their peak and the first galaxy clusters were beginning to virialize. VIDEO therefore offers a unique data set with which to investigate the interplay between AGN, starbursts and environment, and the role of feedback at a time when it was potentially most crucial.We provide data over the VIDEO-XMM3 tile, which also covers the Canada–France–Hawaii Telescope Legacy Survey Deep-1 field (CFHTLS-D1). The released VIDEO data reach a 5σ AB-magnitude depth of Z = 25.7, Y = 24.5, J = 24.4, H = 24.1 and Ks = 23.8 in 2 arcsec diameter apertures (the full depth of Y = 24.6 will be reached within the full integration time in future releases). The data are compared to previous surveys over this field and we find good astrometric agreement with the Two Micron All Sky Survey, and source counts in agreement with the recently released UltraVISTA survey data. The addition of the VIDEO data to the CFHTLS-D1 optical data increases the accuracy of photometric redshifts and significantly reduces the fraction of catastrophic outliers over the redshift range 0 < z < 1 from 5.8 to 3.1 per cent in the absence of an i-band luminosity prior. However, we expect that the main improvement in photometric redshifts will come in the redshift range 1 < z < 4 due to the sensitivity to the Balmer and 4000 Å breaks provided by the near-infrared VISTA filters. All images and catalogues presented in this paper are publicly available through ESO’s phase 3 archive and the VISTA Science Archive. [ABSTRACT FROM PUBLISHER]

In this paper, we investigate the statistical properties of the Tully-Fisher relation (TFr) for a sample of 32 galaxies with measured distances from the Cepheid period-luminosity relation and/or TRGB stars. We take advantage of panchromatic photometry in 12 bands (from FUV to 4.5 μm) and of spatially resolved HI kinematics. We use these data together with three kinematic measures (Wi50, Vmax and Vflat) extracted from the global HI profiles or HI rotation curves, so as to construct 36 correlations allowing us to select the one with the least scatter. We introduce a tightness parameter σ ⊥ of the TFr, in order to obtain a slope-independent measure of the goodness of fit. We find that the tightest correlation occurs when we select the 3.6 μm photometric band together with the Vflat parameter extracted from the HI rotation curve. [ABSTRACT FROM AUTHOR]

We present a re-analysis of M33 RR Lyrae variables in four different fields: two inner disc fields and two outer disc fields. These are located at 8.5, 8.7, 36 and 46 arcmin from the centre of M33, respectively. We identify 48 new RR Lyrae variable stars and refine the light-curve properties of 51 previously identified variables. From the light curves, we calculate reddenings and metallicities for each star. Using data in this paper and previously published material, we are able to construct a radial density profile for the RR Lyrae stars in M33. This profile, when plotted in log space, has a slope of ~−2.0 ± 0.15 which agrees with the radial distribution of halo stars in the Milky Way and M31. This suggests that the majority of M33 RR Lyrae variables observed so far belong to the halo.We also examine the RR Lyrae specific frequency and absolute magnitude relation in M33 and find good agreement with previous studies. [ABSTRACT FROM AUTHOR]

The time lag between optical and near-infrared continuum emission in active galactic nuclei (AGN) shows a tight correlation with luminosity and has been proposed as a standardizable candle for cosmology. In this paper, we explore the use of these AGN hot-dust time lags for cosmological model fitting under the constraints of the new VISTA Extragalactic Infrared Legacy Survey (VEILS). This new survey will target a 9 deg² field observed in J and Ks band with a 14-d cadence and will run for 3 yr. The same area will be covered simultaneously in the optical griz bands by the Dark Energy Survey, providing complementary time-domain optical data. We perform realistic simulations of the survey setup, showing that we expect to recover dust time lags for about 450 objects out of a total of 1350 optical type 1 AGN, spanning a redshift range of 0.1 < z < 1.2. We use the lags recovered from our simulations to calculate precise distance moduli, establish a Hubble diagram, and fit cosmological models. Assuming realistic scatter in the distribution of the dust around the AGN as well as in the normalization of the lag-luminosity relation, we are able to constrain ΩΛ in ΛCDM with similar accuracy as current supernova samples. We discuss the benefits of combining AGN and supernovae for cosmology and connect the present work to future attempts to reach out to redshifts of z > 4. [ABSTRACT FROM AUTHOR]

In this Paper, we describe how we use stellar dynamics information to constrain the shape of the stellar initial mass function (IMF) in a sample of 27 early-type galaxies from the CALIFA survey.We obtain dynamical and stellar mass-to-light ratios, ♈dyn and ♈*, over a homogenous aperture of 0.5 Re.We use the constraint♈dyn ♈* to test two IMF shapes within the framework of the extended MILES stellar population models. We rule out a single power-law IMF shape for 75 per cent of the galaxies in our sample. Conversely, we find that a double power-law IMF shape with a varying high-mass end slope is compatible (within 1σ) with 95 per cent of the galaxies. We also show that dynamical and stellar IMF mismatch factors give consistent results for the systematic variation of the IMF in these galaxies. [ABSTRACT FROM AUTHOR]

Volvelle diagrams are those woodcut illustrations part of which the reader can physically move, usually by rotating a circular paper disc attached to the page, and their inclusion was one of the most recognisable features of astronomical books published in the sixteenth century. This article proposes, and gives examples of, a three stage methodology for their bibliographical description: 1. the use of lambda λ in the book collation formula to indicate that a book contains cut-out volvelles and where known how many uncut leaves containing volvelle pieces were printed 2. a volvelle collation formula for each volvelle diagram, indicating how many pieces there are in total at each location within the book and how they should be assembled; 3. a rigorous description of each individual volvelle diagram in sufficient detail to construe its precise appearance and use. Finally it is considered how the methodology might be applied to a wider range of printed materials including paper instruments, globe gores and ‘pop-up’ books. [ABSTRACT FROM PUBLISHER]

In this paper, we present new data with interstellar C (Phillips bands ), from observations made with the Ultraviolet-Visual Echelle Spectrograph of the European Southern Observatory. We have determined the interstellar column densities and excitation temperatures of C for nine Galactic lines. For seven of these, C has never been observed before, so in this case the still small sample of interstellar clouds (26 lines of sight), where a detailed analysis of C excitation has been made, has increased significantly. This paper is a continuation of previous works where interstellar molecules (C and diffuse interstellar bands) have been analysed. Because the sample of interstellar clouds with C has increased, we can show that the width and shape of the profiles of some diffuse interstellar bands (6196 and 5797 Å) apparently depend on the gas kinetic and rotational temperatures of C; the profiles are broader because of the higher values of the gas kinetic and rotational temperatures of C. There are also diffuse interstellar bands (4964 and 5850 Å) for which this effect does not exist. [ABSTRACT FROM AUTHOR]

The secondary infall model (described in a previous paper by this author), which takes into account the effect of dynamical friction, ordered and random angular momentum, baryon adiabatic contraction and dark matter (DM) baryon interplay, is used to study how the inner slopes of relaxed ΛCDM haloes with and without baryons (baryons+DM and pure DM) depend on redshift and on halo mass. This method is applied to structures on galactic scales and clusters of galaxies scales. It is found that the inner logarithmic density slope, , of DM haloes with baryons has a significant dependence on halo mass and redshift, with slopes ranging from for dwarf galaxies to for objects of and for clusters of galaxies. Structure slopes increase with increasing redshift, and this trend reduces going from galaxies to clusters. In the case of density profiles constituted just of DM, the mass and redshift dependence of the slope are very slight. In this last case, the analysis of Merritt et al. is used. They compared N-body density profiles with various parametric models, finding systematic variation in the profile shape with halo mass. This last analysis suggests that the galaxy-sized haloes obtained with this model have a different shape parameter (i.e. a different mass distribution) than the cluster-sized haloes obtained with the same model. The results of the present paper argue against universality of density profiles constituted by DM and baryons and confirm the claims of a systematic variation in profile shape with halo mass, for DM haloes. [ABSTRACT FROM AUTHOR]

I derive the physical properties of 30 transiting extrasolar planetary systems using a homogeneous analysis of published data. The light curves are modelled with the code, with special attention paid to the treatment of limb darkening, orbital eccentricity and error analysis. The light from some systems is contaminated by faint nearby stars, which if ignored will systematically bias the results. I show that it is not realistically possible to account for this using only transit light curves: light-curve solutions must be constrained by measurements of the amount of contaminating light. A contamination of 5 per cent is enough to make the measurement of a planetary radius 2 per cent too low. The physical properties of the 30 transiting systems are obtained by interpolating in tabulated predictions from theoretical stellar models to find the best match to the light-curve parameters and the measured stellar velocity amplitude, temperature and metal abundance. Statistical errors are propagated by a perturbation analysis which constructs complete error budgets for each output parameter. These error budgets are used to compile a list of systems which would benefit from additional photometric or spectroscopic measurements. The systematic errors arising from the inclusion of stellar models are assessed by using five independent sets of theoretical predictions for low-mass stars. This model dependence sets a lower limit on the accuracy of measurements of the physical properties of the systems, ranging from 1 per cent for the stellar mass to 0.6 per cent for the mass of the planet and 0.3 per cent for other quantities. The stellar density and the planetary surface gravity and equilibrium temperature are not affected by this model dependence. An external test on these systematic errors is performed by comparing the two discovery papers of the WASP-11/HAT-P-10 system: these two studies differ in their assessment of the ratio of the radii of the components and the effective temperature of the star. I find that the correlations of planetary surface gravity and mass with orbital period have significance levels of only 3.1 and 2.3, respectively. The significance of the latter has not increased with the addition of new data since Paper II. The division of planets into two classes based on Safronov number is increasingly blurred. Most of the objects studied here would benefit from improved photometric and spectroscopic observations, as well as improvements in our understanding of low-mass stars and their effective temperature scale. [ABSTRACT FROM AUTHOR]

The ESA Rosetta mission, launched in 2004 March, will flyby the second asteroid target (21) Lutetia in 2010 July. This asteroid is quite different from (2867) Steins, encountered by Rosetta in 2008 September. Lutetia is in fact a much larger asteroid, approximately 100 km of diameter, as compared to the 5 km of Steins and also its surface composition seems fairly different. A wide international ground-based observational campaign has been carried out and is still going on to obtain information on the object. In this context, we observed Lutetia four times spectroscopically in the visible region totally covering its rotational period. In this paper we have compared all our observations, in order to try to shed more light on its nature. Moreover, an analysis of the geometric configuration of Lutetia during the several observations has also been performed. Our paper points out small variations of reflectance over the surface, possibly due to a large crater. However, the nature of Lutetia remains still elusive, probably because it could be a transition object between X and C taxonomic classes, pointing out to the crucial values of the forthcoming flyby to clarify the situation. Therefore, all the information we have gathered and here discussed have been very useful also to better define the observational strategy of the asteroid by Rosetta. [ABSTRACT FROM AUTHOR]

In this paper, we derive the period-luminosity ( P-L) relation for Large Magellanic Cloud (LMC) Cepheids based on mid-infrared AKARI observations. AKARI's Infrared Camera sources were matched to the Optical Gravitational Lensing Experiment-III (OGLE-III) LMC Cepheid catalogue. Together with the available I-band light curves from the OGLE-III catalogue, potential false matches were removed from the sample. This procedure excluded most of the sources in the and bands; hence, only the P-L relation in the band is derived in this paper. Random-phase corrections were included in deriving the P-L relation for the single-epoch AKARI data; even though the derived P-L relation is consistent with the P-L relation without random-phase correction, however there is an ∼7 per cent improvement in the dispersion of the P-L relation. The final adopted -band P-L relation is , with a dispersion of 0.149. [ABSTRACT FROM AUTHOR]