bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Hubble Catalog of Variables (HCV)
Authors: Sokolovsky K. V. , Bonanos A. Z. , Gavras P. , Yang M. , Hatzidimitriou D. , Moretti M. I. , Karampelas A. , Bellas-Velidis I. , Spetsieri Z. , Pouliasis E. , Georgantopoulos I. , Charmandaris V. , Tsinganos K. , Laskaris N. , Kakaletris G. , Nota A. , Lennon D. , Arviset C. , Whitmore B. C. , Budavari T. , Downes R. , Lubow S. , Rest A. , Strolger L. , White R. 
Published: August 2019

AbstractThe Hubble Source Catalog (HSC) combines lists of sources detected on images obtained with the WFPC2, ACS and WFC3 instruments aboard the Hubble Space Telescope (HST) and now available in the Hubble Legacy Archive. The catalogue contains time-domain information for about two million of its sources detected using the same instrument and filter on at least five HST visits. The Hubble Catalog of Variables (HCV) aims to identify HSC sources showing significant brightness variations. A magnitude-dependent threshold in the median absolute deviation of photometric measurements (an outlier-resistant measure of light-curve scatter) is adopted as the variability detection statistic. It is supplemented with a cut in χred2 that removes sources with large photometric errors. A pre-processing procedure involving bad image identification, outlier rejection and computation of local magnitude zero-point corrections is applied to the HSC light-curves before computing the variability detection statistics. About 52 000 HSC sources have been identified as candidate variables, among which 7,800 show variability in more than one filter. Visual inspection suggests that ∼70% of the candidates detected in multiple filters are true variables, while the remaining ∼30% are sources with aperture photometry corrupted by blending, imaging artefacts or image processing anomalies. The candidate variables have AB magnitudes in the range 15–27m, with a median of 22m. Among them are the stars in our own and nearby galaxies, and active galactic nuclei.
Measuring and Decoding Gravito-Inertial Modes in Intermediate- and High-Mass Stars
Authors: Aerts C. , Pedersen M. G. , Van Reeth T. 
Published: August 2019

AbstractThis talk discussed the basics of gravito-inertial asteroseismology as recently developed for stars born with a convective core. Photometric space missions originally built for exoplanet hunting, notably Kepler, have opened up the low-frequency regime of stellar oscillations and revealed a larger diversity in variability than anticipated prior to the era of high-precision space photometry. The talk explained the basics of forward seismic modelling based on gravito-inertial modes, which probe the deep stellar interior. It described how a hierarchical fitting approach allows us to derive the near-core rotation period, the amount and shape of convective core overshooting, and the level of chemical mixing in the radiative envelope for stars born with a convective core and burning hydrogen in their core. A summary of the current status, covering the mass range 1.4 ≲ M ≲ 5 M⊙, is provided here through references to numerous recent papers.
Transient X-ray Binaries in the Magellanic Clouds and Milky Way
Authors: Charles P. C. , Buckley D. , Mata Sánchez D. , Meintjes P. , Rajoelimanana A. , Townsend L. 
Published: August 2019

AbstractThis contribution gave three examples of X-ray transients in the Magellanic Clouds and the Milky Way that have been observed as part of the SALT Transients Large Programme. The transients (SMC X-3, MAXI J1957+032 and ASASSN-16oh) have been triggered from both space-based wide-field monitoring facilities (Swift/XRT, MAXI) and ground-based ones (ASASSN, the All Sky Automated Survey for SN), providing insights into the physics of super-Eddington accretion onto neutron stars and white dwarfs, and also into the long-term properties of accreting millisecond X-ray pulsars.
Discovery and Opportunity in the X-Ray Time Domain
Authors: Haggard D. 
Published: August 2019

AbstractAmbitious X-ray observatories have enabled a rapid expansion in our knowledge of the X-ray time domain. With state-of-the-art facilities like Chandra, XMM Newton, and Swift performing surveys for over a decade (and counting), variability catalogues are becoming increasingly rich. Meanwhile, high time-resolution from the likes of NuSTAR and NICER (and RXTE before them) continue to uncover the richness of individual systems. These efforts have revealed a likely pulsar-ULX connection and possible magnetar oscillations, and have enabled reverberation mapping of AGN – to name only a few results. The talk reviewed recent highlights from the X-ray time domain, and described briefly what we hope to achieve with up-coming and proposed X-ray missions including HEX-P, Athena, XARM, eROSITA, STROBE-X, eXTP and TAP.
X-Ray Transients in the SRG/eROSITA All-Sky Survey
Authors: Rau A. 
Published: August 2019

AbstracteROSITA (the extended ROentgen Survey with an Imaging Telescope Array) onboard the Spectrum Roentgen Gamma mission will perform a deep all-sky X-ray survey. During the first four years of operation the satellite will scan the entire sky every once every half year, visiting any position between 8 and 500 times. The eROSITA scanning strategy will test a wide range of times-scales, from seconds to years, and thus provide a powerful window into the X-ray transient and variable sky. This contribution summarised the key science opportunities for time-domain studies with eROSITA, and presented strategies for finding transients in the all-sky survey data.
The Future of AGN Variability Studies
Authors: Graham M. J. 
Published: August 2019

AbstractAGNs are an inherently variable population but the physical mechanisms behind optical variability remain poorly constrained or not well understood. The advent of large archival collections of astronomical time series together with new analysis techniques is now driving systematic explorations of these phenomena. They reveal both population behaviours and individual extreme sources. This talk reviewed how the Catalina Real-time Transient Survey is transforming our knowledge of AGN behaviour, mentioning in particular the new CRTS Southern Sky Quasar Catalogue (which covers −70 < Dec < 0 down to V ∼ 19), and the potential of the Zwicky Transient Facility for further discoveries.
Recognition of Temporal Phenomena from LSST Alert Streams
Authors: Saha A. 
Published: August 2019

AbstractLSST will uncover a few million time-domain alerts per night with a latency of a minute. This will provide a huge discovery space, where previously undiscovered rare phenomena may be revealed. The early detection of such previously unknown events from a minimal set of measurements is critical for discovery and follow-up. Analysis methods to recognise such events are being investigated and developed. A discussion of those approaches was presented.
ANTARES: Time-Domain Discovery in the Era of LSST
Authors: Soraisam M. , Matheson T. 
Published: August 2019

AbstractThe revolution in time-domain astronomy has arrived. Large-scale surveys are detecting events at an unparallelled rate, and discoveries of new and exotic objects abound. In just a few short years, the Large Synoptic Survey Telescope will begin operations in Chile. At that point, the rate of production of time-domain events will jump by a factor of at least a hundred. The traditional techniques of handling each detection individually will not scale to those current and future productions. The ANTARES project is a joint venture between NOAO and the University of Arizona Computer Science Department to develop a software infrastructure system to process time-domain events automatically at the scale and rate that LSST will generate them.
Life Beyond PTF
Authors: Bellm E. C. 
Published: August 2019

AbstractIn March 2017, the Intermediate Palomar Transient Factory (iPTF) ceased operations. This Symposium was an appropriate opportunity to review the scientific returns from iPTF and its predecessor survey, the Palomar Transient Factory (PTF), and to summarise the lessons learned. Succeeding iPTF on the Palomar Observatory 48-inch Schmidt telescope is the Zwicky Transient Facility (ZTF), a new survey with an order of magnitude faster survey speed that is now being commissioned. I described the design and scientific rationale for ZTF. ZTF is prototyping new alert stream technologies being explored by the Large Synoptic Survey Telescope (LSST) to distribute millions of transient alerts per night to downstream science users. I described the design of the alert system and discussed it in the context of the wider LSST and community broker ecosystem.
Deep-Learning the Time Domain
Authors: Mahabal A. , Sheth K. , Gieseke F. , Drake A. , Djorgovski G. , Graham M. J. 
Published: August 2019

Abstract“Deep learning” is finding more and more applications everywhere, and astronomy is not an exception. This talk described the application of convolutional neural networks to time-domain astronomy, specifically to light-curves of sources. The work that is discussed is based on a published paper to which reference can be made for more detail. The talk finished with a note cautioning new practitioners about the pitfalls lurking in out-of-the-box use of deep-learning techniques.
TESS Science and Follow-Up in the Southern Hemisphere
Authors: Burt J. 
Published: August 2019

AbstractThe Transiting Exoplanet Survey Satellite (TESS) is an MIT-led NASA mission that will spend two years searching for transiting exoplanets via an all-sky survey that starts in the Southern Hemisphere. Launched in 2018 April, TESS is expected to discover thousands of Earth- to Neptune-sized planets, and over ten thousand giant planets, around the closest, brightest, stars. These planets will become our best targets for learning more about planet formation and evolution, planet composition, and atmospheric make-up. More detailed information about TESS, and instructions on how to access and work with the data once they are available, was given in Workshop 3, Getting ready for TESS, held earlier during the Symposium (p. 224).
Symposium 339: Summary
Authors: Breedt E. 
Published: August 2019

AbstractTime-domain astronomy is a key theme on research roadmaps worldwide, as was amply demonstrated by the energy which the participants (coming from 33 different countries) brought to this Symposium, as they shared their experience and expertise through various time-domain projects and discussed the challenges and strategies for the road ahead. This short summary is simply a personal view of the many key topics that were discussed.
Towards Science with LSST: Data Products and Communications
Authors: Graham M. L. 
Published: August 2019

AbstractThe main purpose for holding a Workshop about the Large Synoptic Survey Telescope (LSST) was to move all participants further towards answering the question, “How will I do my science with LSST data?” Presentations included (i) the planned pipelines and products of the data management team, and (ii) the existing channels for communication within the science community and between the community and the LSST Data Management team. In between the formal presentations, small groups discussed matters such as how to select the data products or communications resources that were best suited to individual science goals. The latter discussions were designed both to facilitate engagement with the material and to foster collaboration. Participants should thus have become better equipped to continue on their respective individual paths towards science with LSST.
Supernovæ
Authors: Stritzinger M. , Moriya T. J. 
Published: August 2019

AbstractThis Workshop covered a cornucopia of topics that were featured in short formal presentations, followed by a round-table discussion. G. Hosseinzadeh and H. Kuncarayakti presented the results of their recent researches into interacting supernovæ. They included both the intriguing Type Ibn supernova subclass, and SN 2017dio, which appears to be the first Type Ic supernova to be seen to exhibit signatures of hydrogen-rich circumstellar interaction at all phases. M. Sullivan provided a summary relating to the future of transient science in the era of Big Data, and participants discussed strategies to determine which targets and fields should be selected for spectroscopic follow-up. The Workshop concluded with a rather heated discussion regarding the need for the IAU Supernovæ Working Group to consider modifying the current criterion for a confirmed supernova in order for it to receive an official IAU designation.
New Instrumentation for Transient Follow-Up
Authors: Thöne C. C. , de Ugarte Postigo A. , Mahabal A. , Kann D. A. 
Published: August 2019

AbstractWide-angle surveys at different wavelengths are already providing triggers for very different kinds of transients. The most interesting science is produced when new sources are followed-up and characterised by using the right instrumentation, telescopes and observing strategies. In the coming years, with new large-scale surveys such as ZTF and LSST, the amount of triggers is expected to scale up massively. Furthermore, new observational windows, such as gravitational waves or neutrinos, are now opening and adding complexity to the picture. The instrumentation and strategies that we have been using over recent years may just not be appropriate for those new situations. In this Workshop we discussed the present and projected future of transient discovery, the instrumentation that will be needed for the follow-up of those targets, and the observing strategies, data analysis and community efforts that will be required to tackle the challenges that lie ahead of us.
Nuclear Transients
Authors: Mattila S. , Graham M. J. , Kankare E. , Kool E. , Moriya T. , Perez-Torres M. , Wyrzykowski Ł. 
Published: August 2019

AbstractWorkshop 11 covered the substantial recent progress in studies of supernovæ (SNe), tidal disruption events (TDEs), and other types of luminous transients occurring within the nuclear regions of galaxies. In the past, such transients have largely been missed owing to the substantial extinction of those regions, and to the problems of contrast against the bright (and often complex) nuclear background – or mistaken for normal active galactic nucleus (AGN) variability.
Searching for Pulsating Stars Using Clustering Algorithms
Authors: Kgoadi R. , Whittingham I. , Engelbrecht C. 
Published: August 2019

AbstractClustering algorithms constitute a multi-disciplinary analytical tool commonly used to summarise large data sets. Astronomical classifications are based on similarity, where celestial objects are assigned to a specific class according to specific physical features. The aim of this project is to obtain relevant information from high-dimensional data (at least three input variables in a data-frame) derived from stellar light-curves using a number of clustering algorithms such as K-means and Expectation Maximisation. In addition to identifying the best performing algorithm, we also identify a subset of features that best define stellar groups. Three methodologies are applied to a sample of Kepler time series in the temperature range 6500–19,000 K. In that spectral range, at least four classes of variable stars are expected to be found: δ Scuti, γ Doradus, Slowly Pulsating B (SPB), and (the still equivocal) Maia stars.
Meteor Sky in Time-Domain Astronomy
Authors: Kolomiyets S. V. 
Published: August 2019

AbstractMulti-wave astronomy provides a means for researchers to see and ‘hear’ the sky. But that is only part of their perception of the cosmos. The hot handshake of the Universe in the form of a meteor substance burning in the Earth’s atmosphere, sometimes with the precipitation of meteorites threatening the environment, occurs every second. A major present challenge for meteor research is organizing observations and processing existing and new data in order to obtain information in the time domain of meteor astronomy for solving special problems. This poster discusses the concept of the meteor sky, and some approaches for constructing models of it. The database of meteors of Kharkiv National University of Radio Electronics was used.
The X-Ray Spectrum of the X-Ray Binary 4U 1728-34, observed with Suzaku
Authors: Lei Y. , Zhang H. , Yuan H. , Zhang Y. 
Published: August 2019

AbstractThis poster reported our spectroscopy of the neutron-star X-ray binary 4U 1728-34, observed with Suzaku in 2010 October. It is classified as an atoll source. Its continuous X-ray spectrum can be fitted by a combination of a multicolour accretion-disk model for the soft energy, plus a power-law model for the hard energy. A broad emission line at 6–7 keV can be fitted well using a simple Gaussian component with an equivalent width of ∼322 eV. However, for this object the presence of that feature is disputed, even though our results from Suzaku do suggest the presence of a broad Fe emission line that is consistent with results from XMM-Newton. Nevertheless, the parameters of the line (the line centroid and the equivalent width) are a little different, but that could be due to a difference in modelling the continuum.
Evaluating the Fraction of Obscured Supernovæ in Luminous Infrared Galaxies with Adaptive Optics Surveys
Authors: Reynolds T. , Mattila S. , Kool E. , Kankare E. , Ryder S. , Pérez-Torres M. A. 
Published: August 2019

AbstractDespite the expectation of a high supernova rate in luminous infra-red galaxies (LIRGs), a deficit has been discovered in optical surveys that is due to high levels of extinction by dust and to issues of contrast against the bright nuclear background. Searching in the near infra-red enables observations to penetrate that dust, while using adaptive-optics achieves the resolution required to observe supernovæ close to the nuclei of those galaxies. Over the last decade multiple observing programmes using the best AO instrumentation mounted on large telscopes have accumulated a dataset of many LIRGs, and met with much greater success in discovering nuclear supernovæ. However, a significant proportion is still being missed. By using techniques to evaluate our detection efficiency in these data, and simulations of the supernovæ occuring in the galaxies, we can evaluate the nature of these transients.
Stellar Parameterisation using KPCA and SVM
Authors: Yuan H. , Zhang Y. , Lei Y. , Dong Y. , Bai Z. , Li G. , Zhang W. , Zhang H. , Zhao Y. 
Published: August 2019

AbstractWith so many spectroscopic surveys, both past and upcoming, such as SDSS and LAMOST, the number of accessible stellar spectra is continuously increasing. There is therefore a great need for automated procedures that will derive estimates of stellar parameters. Working with spectra from SDSS and LAMOST, we put forward a hybrid approach of Kernel Principal Component Analysis (KPCA) and Support Vector Machine (SVM) to determine the stellar atmospheric parameters effective temperature, surface gravity and metallicity. For stars with both APOGEE and LAMOST spectra, we adopt the LAMOST spectra and APOGEE parameters, and then use KPCA to reduce dimensionality and SVM to measure parameters. Our method provides reliable and precise results; for example, the standard deviation of effective temperature, surface gravity and metallicity for the test sample come to approximately 47–75 K, 0.11–0.15 dex and 0.06–0.075 dex, respectively. The impact of the signal:noise ratio of the observations upon the accuracy of the results is also investigated.
Δa Photometric Survey of the Small Magellanic Cloud
Authors: Zejda M. , Paunzen E. , Mikulášek Z. 
Published: August 2019

AbstractThe narrow-band Δa photometric system measures the flux depression at λ5200 Å by comparing the flux at the band centre to adjacent regions. It has been shown that virtually all peculiar stars with magnetic fields (mCPs) have significant positive Δa values (of up to +100 mmag), whereas Be/Ae/B[e] and metal weak stars (including lambda Bootis types) exhibit significant negative values of Δa. By using this photometric system we are therefore able to detect chemically peculiar (CP), emission types and metal-weak stars in an efficient way. The poster presented the first results of our survey of the Small Magellanic Cloud. In the selected field we found only 0.5 % of bona fide CP stars against 15 % in our Galaxy.
Impact of Snow Initialization in Subseasonal‐to‐Seasonal Winter Forecasts With the Norwegian Climate Prediction Model
Authors: Li F. , Orsolini Y. J. , Keenlyside N. , Shen M.‐L. , Counillon F. , Wang Y. G. 
Published: August 2019

AbstractSnow initialization has been previously investigated as a potential source of predictability at the subseasonal‐to‐seasonal (S2S) timescale in winter and spring, through its local radiative, thermodynamical, and hydrological feedbacks. However, previous studies were conducted with low‐top models over short periods only. Furthermore, the potential role of the land surface‐stratosphere connection upon the S2S predictability had remained unclear. To this end, we have carried out twin 30‐member ensembles of 2‐month (November and December) retrospective forecasts over the period 1985–2016, with either realistic or degraded snow initialization. A high‐top version of the Norwegian Climate Prediction Model is used, based on the Whole Atmosphere Community Climate Model, to insure improved coupling with the stratosphere. In a composite difference of high versus low initial Eurasian snow, the surface temperature is strongly impacted by the presence of snow, and wave activity fluxes into the stratosphere are enhanced at a 1‐month lag, leading to a weakened polar vortex. Focusing further on 7 years characterized by a strongly negative phase of the Arctic Oscillation, we find a weak snow feedback contributing to the maintenance of the negative Arctic Oscillation. By comparing the twin forecasts, we extracted the predictive skill increment due to realistic snow initialization. The prediction of snow itself is greatly improved, and there is increased skill in surface temperature over snow‐covered land in the first 10 days, and localized skill increments in the mid‐latitude transition regions on the southern flanks of the snow‐covered land areas, at lead times longer than 30 days.
Parameterizing a borosilicate waste glass degradation model
Authors: Ebert William L. , Jerden James L. 
Published: August 2019

AbstractBorosilicate waste glass degradation models must quantify the effects of the solution composition on the dissolution rate. Here, we present results of modified ASTM C1285 tests conducted at 90 °C with AFCI and LRM glasses to determine whether dependencies of dissolution rates on the pH, Al, and Si concentrations must be included. Solution compositions were modified from those generated by glass dissolution alone by adding small amounts of K4SiO4 glass, Al(OH)3•2H2O, and a concentrated NaOH solution when the tests were initiated. Results show rate laws for the initial and resumption regimes must include pH dependences, but the residual rate can be modeled independent of the pH, Al, and Si concentrations. Triggering the resumption rate probably depends on the pH, Si, and Al concentrations and perhaps other aspects of the glass composition. A waste glass degradation model using is being parameterized using tests with a range of waste glass compositions to quantify these dependencies.