bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Modified Restricted Three Body Problems
Authors: Jiang Ing-Guey , Yeh Li-Chin 
Published: June 2019

AbstractThe restricted three body problem is well-known and very important for the dynamics of binary and multiple stars and also planetary systems. We extend the classical version of this problem to the situation that there are some external forces from the belt. We find that both the equilibrium points and solution curves become quite different from the classical case. We also determine the values of Lyapunov exponent for some important orbits.
Planets in Multiple-Star Systems: Properties and Detections
Authors: Udry S. , Eggenberger A. , Mayor M. , Mazeh T. , Zucker S. 
Published: June 2019

AbstractOrbital properties of extra-solar planets are briefly recalled and compared with equivalent features of stellar binaries. Similarities and differences are discussed. Among the more than 115 extra-solar planets discovered to date, 19 are orbiting a component of a binary system. We discuss the properties of this subsample and compare them with the equivalent characteristics of planets around single stars. Differences in the mass-period-eccentricity distributions are observed: exoplanets with m2 sin i > 2 MJup and P≤ 40-100 days are in binaries and present low eccentricities. In the context of the migration scenario, these characteristics are tentatively explained in the light of recent simulations of planet-disk interactions showing an increased accretion and migration rates of planets in case an additional perturbing close stellar companion is present in the system. Finally, different observational approaches to find planets in long-period spectroscopic binaries aiming to improve the still poor available statistics are presented. An important result is the detection of a planetary companion in the HD 41004 triple system.
The Binarity Status of Stars with and without Planets Probed with VLT/NACO
Authors: Udry S. , Eggenberger A. , Beuzit J.-L. , Lagrange A.-M. , Mayor M. , Chauvin G. 
Published: June 2019

AbstractThe properties of planets orbiting a component of a binary or multiple-star system appear different from the ones of planets orbiting isolated stars (Udry et al. 2004). The effect of binarity has, however, still to be better characterized and quantified. In this contribution, we describe a VLT/NACO adaptive optics survey aimed at pointing out the potential effect of stellar duplicity on planet formation and evolution, by comparing the faint-companion statistics of similarly selected subsamples of stars with and without planets. The statistical results of the survey will allow us to possiblydiscriminate between the proposed models of planetary formation (accretion or disk instability), some of them predicting different influences of stellar duplicity. Preliminary results are already very interesting: 20 ± 7% of the “single” stars present companions within ~10″, whereas only 3 ± 3% equivalent companions are found close to stars hosting planets.
Planets in Double Stars: The ϒ Cephei System
Authors: Dvorak R. , Pilat-Lohinger E. , Bois E. , Funk B. , Freistetter F. , Kiseleva-Eggleton L. 
Published: June 2019

AbstractUp to now we have evidence for some 15 planets moving in double stars. They are all of the so-called S-type, which means that they are orbiting one of the primaries. Only two of the binaries have separations in the order of the distances where the planets in our Solar system orbit the Sun, namely Gliese 86 and ϒ Cep. In this study we investigate the stability of the recently discovered planet in ϒ Cep with respect to the orbital parameters of the binary and of the planet. Additionally we check the region inside and outside the planet’s orbit (a = 2.1 AU). Even when the mass of an additional planet in 1 AU would be in the order of that of Jupiter, the discovered planet would be in a stable orbit.
Spectroscopy, Photometry and Micro-Arcsec Astrometry of Binaries with The Gaia Space Mission and with the Rave Experiment
Authors: Zwitter Tomaž , Munari Ulisse 
Published: June 2019

AbstractThe GAIA astrometric mission of ESA will be very efficient in discovering binary and multiple stars with any orbital period, from minutes to millions of years. The main parameters of the revised mission design are presented. Next we estimate the fraction of binary stars discovered by means of astrometry, photometry and on-board spectroscopy. Finally we summarize observations that confirm the ability to measure physical parameters like masses, radii and spectroscopic distance from GAIA data alone. GAIA will fly only in 2010, but the radial velocity experiment (RAVE) has started this year. We show that its spectroscopic observations have the capacity to discover a large fraction of so far unknown binary systems.
Radio Supernovae
Authors: Sramek Richard A. , Weiler Kurt W. , Panagia Nino 
Published: June 2019

SummaryDetailed, multi-frequency radio observations of supernovae have shown that the radio emission can be understood as a blastwave interacting with a structured circumstellar medium (CSM) and modeling of the radio light curves allows estimation of the physical conditions in this medium. CSM structures, properties of the presupernova system, and the evolution of the system in the last stages before explosion can then be derived.
Low Frequency Radio and X-ray Properties of Core-Collapse Supernovae
Authors: Ray A. , Chandra P. , Sutaria F. , Bhatnagar S. 
Published: June 2019

SummaryRadio and X-ray studies of young supernovae probe the interaction between the supernova shock waves and the surrounding medium and give clues to the nature and past of the progenitor star. Here we discuss the early emission from type Ic SN 2002ap and argue that repeated Compton boosting of optical photons by hot electrons presents the most natural explanation of the prompt X-ray emission. We describe the radio spectrum of another type Ic SN 2003dh (GRB030329) obtained with combined GMRT and VLA data. We report on the low frequency radio monitoring of SN 1995N and our objectives of distinguishing between competing models of X-ray emission from this SN and the nature of its progenitor by X-ray spectroscopy. Radio studies on SN 2001gd, SN 2001ig and SN 2002hh are mentioned.
Observational Properties of Type II Plateau Supernovae
Authors: Pastorello A. , Ramina M. , Zampieri L. , Navasardyan H. , Salvo M. , Fiaschi M. 
Published: June 2019

SummaryWe present spectroscopic and photometric data of a sample of Type II plateau Supernovae, covering a wide range of properties from the 56Ni rich, high luminosity events (e.g. SN 1992am) to the low-luminosity, 56Ni poor SNe (e.g. SN 1997D). We provide an observational framework to analyze correlations among observational data, physical parameters and progenitors characteristics of Type II supernovae.
Pre-Supernova Evolution of Rotating Massive Stars
Authors: Hirschi Raphael , Meynet Georges , Maeder André , Goriely Stéphane 
Published: June 2019

SummaryThe Geneva evolutionary code has been modified to study the advanced stages (Ne, O, Si burnings) of rotating massive stars. Here we present the results of four 20 M⊙ stars at solar metallicity with initial rotational velocities, vini, of 0, 100, 200 and 300 km/s in order to show the crucial role of rotation in stellar evolution. As already known, rotation increases mass loss and core masses [4]. A fast rotating 20 M⊙ star has the same central evolution as a non-rotating 26 M⊙. Rotation also increases strongly net total metal yields. Furthermore, rotation changes the SN type so that more SNIb are predicted (see [5] and [6]). Finally, SN1987A-like supernovae progenitor colors can be explained in a single rotating star scenario.
Core-Collapse Supernovae at the Threshold
Authors: Janka H.-Th. , Buras R. , Kifonidis K. , Marek A. , Rampp M. 
Published: June 2019

SummaryRecent progress in modeling core-collapse supernovae is summarized and set in perspective. Two-dimensional simulations with state-of-the-art treatment of neutrino transport still fail to produce powerful explosions, but evidence is presented that they are very close to a success.
On the Stability of Thermonuclear Burning Fronts in Type Ia Supernovae
Authors: Röpke F.K. , Hillebrandt W. 
Published: June 2019

SummaryThe propagation of cellularly stabilized thermonuclear flames is investigated by means of numerical simulations. In Type Ia supernova explosions the corresponding burning regime establishes at scales below the Gibson length. The cellular flame stabilization - which is a result of an interplay between the Landau-Darrieus instability and a nonlinear stabilization mechanism - is studied for the case of propagation into quiescent fuel as well as interaction with vortical fuel flows. Our simulations indicate that in thermonuclear supernova explosions stable cellular flames develop around the Gibson scale and that a deflagration-to-detonation transition is unlikely to be triggered from flame evolution effects here.
Supernova Statistics
Authors: Cappellaro Enrico , Barbon Roberto , Turatto Massimo 
Published: June 2019

SummaryThe statistics of SN discoveries is used to reveal selection biases of past and current SN searches and to gain insight on the progenitor scenarios for the different SN types. We also report estimates of the SN rate per unit mass in galaxies of different types and on the first attempts to study the evolution of the supernova rate with redshift.
Long GRBs and Supernovae from Collapsars
Authors: MacFadyen A.I. 
Published: June 2019

SummaryLong duration gamma-ray bursts are associated with the death of massive stars as earlier observations and theoretical arguments had suggested. Supernova 2003dh observed with GRB030329 confirms this picture. Current progress in developing numerical special relativistic hydrodynamics codes with adaptive mesh refinement is allowing for high-resolution simulations of relativistic flow relevant for simulations of GRBs.
Gamma-ray Bursts
Authors: Castro-Tirado Alberto J. 
Published: June 2019

SummarySince their discovery in 1967 Gamma-ray bursts (GRBs) have been puzzling to astrophysicists. With the advent of a new generation of X–ray satellites in the late 90’s, it was possible to carry out deep multi-wavelength observations of the counterparts associated with the long duration GRBs class just within a few hours of occurrence, thanks to the observation of the fading X-ray emission that follows the more energetic gamma-ray photons once the GRB event has ended. The fact that this emission (the afterglow) extends at longer wavelengths, led to the discovery of optical/IR/radio counterparts in 1997-2003, greatly improving our understanding of these sources. The classical, long duration GRBs, have been observed to originate at cosmological distances in a range of redshifts with 0.1685 ≤ z ≤ 4.50 implying energy releases of ~ 1051 ergs. The recent results on GRB 021004 and GRB 030329 confirm that the central engines that power these extraordinary events are due to be collapse of massive stars rather than the merging of compact objects as previously also suggested. Short GRBs still remain a mystery as no counterparts have been detected so far.
Brane Universes Tested by Supernovae
Authors: Godłewski Włodzimierz , Szydłowski Marek 
Published: June 2019

SummaryWe discuss observational constrains coming from supernovae Ia imposed on the behavior of the Randall-Sundrum models. It is interesting that brane models predict brighter galaxies for such redshifts which is in agreement with the measurement of the z = 1.7 supernova. We also demonstrate that the fit to supernovae data can also be obtained, if we admit the “super-negative” dark energy p = − (4/3) ϱ on the brane, where the dark energy in a way mimics the influence of the cosmological constant.
Project ASTRO: A Successful Model for Astronomer/Teacher Partnerships
Authors: Bennett M. , Fraknoi A. , Richter J. 
Published: June 2019

Project ASTRO is designed to improve astronomy education and science literacy in grades 4-9 by creating effective working partnerships between teachers/youth leaders and astronomers (both professional and amateur). Key elements of the program include:•training the teachers/youth leaders and astronomers together in inquiry-based “hands-on, minds-on” learning activities•encouraging an active working partnership between the astronomer and the teacher/youth leader•encouraging multiple visits by the astronomer to the classroom or youth group meetings.
Coping with a New Curriculum: The Evolving Schools Program at the Carter Observatory, New Zealand
Authors: Leather K. , Andrews F. , Hall R. , Orchiston W. 
Published: June 2019

Carter Observatory is the National Observatory of New Zealand and was opened in 1941. For more than ten years the Observatory has maintained an active education program for visiting school groups (see Andrews, 1991), and education now forms one of its four functions. The others relate to astronomical research; public astronomy; and the preservation of New Zealands astronomical heritage (see Orchiston and Dodd, 1995).Since the acquisition of a small Zeiss planetarium and associated visitor centre in 1992, the public astronomy and education programs at the Carter Observatory have witnessed a major expansion (see Orchiston, 1995; Orchiston and Dodd, 1996). A significant contributing factor was the introduction by the government of a new science curriculum into New Zealand schools in 1995 (Science in the New Zealand Curriculum, 1995). “Making Sense of Planet Earth and Beyond” comprises one quarter of this curriculum, and the “Beyond” component is astronomy.
A High School Astronomy Course for a Wide Range of Student Abilities
Authors: Sampson G. E. 
Published: June 2019

Astronomy is, inherently, a high-interest subject. However, at the high school level there is a tendency to teach astronomy using higher- level abstractions and complex mathematics. This teaching approach thus eliminates a large number of students who have difficulties with abstractions and complex mathematics, thereby restricting the study of astronomy to a rather select group of students.The astronomy course offered since 1976 at Wauwatosa West High School was developed to reach a wide range of students with differing abilities. The prerequisite for this one-semester elective course is the successful completion of one year of high school science. Most of the students enrolled in this course are high school juniors and seniors, ages 16–18. Since algebra is not a prerequisite, the “math phobic“students have been attracted to the course.
Astronomy Teaching in the Astronautics Club
Authors: Aleshkina E.Yu. 
Published: June 2019

There is no necessity to argue about a vital need of an extension of astronomy and space knowledge equivalent to a modern state of the natural sciences. Astronomy teaching both professionally and for amateurs in the form of general courses is particularly needed nowadays because of the spread of various forms of mysticism in Russia.The main goal of astronomy teaching is to help students to become aware of the place of humanity in the Universe. In this connection it is necessary to study not only astronomy but also other relevant courses simultaneously. Such complex astronomy study plays a significant role. It is necessary to show a close interaction of astronomy with other sciences such as traditionally mathematics, physics, chemistry and also biology and psychology, which just begin to be integrated in the field of space sciences.
Spectral Energy Distribution and Interstellar Reddening (Review Paper)
Authors: Houziaux L. , Manfroid J. 
Published: June 2019

AbstractWe review the recent results on flux distribution of Be stars from 320 to 850nm. It appears that data are available for only 10 to 15 % of the objects recognized as “normal” Be stars. The main current problems appear to be the variability of the continuous radiation, and the correction for interstellar reddening. Various attempts to solve these matters are discussed. We stress the need for fairly high (lnm) resolution spectral scans obtained simultaneously with data in other spectral ranges, repeated at appropriate intervals of time. Such requirements make it necessary to restrict the observing programmes to a limited sample of carefully chosen objects.
Structure of the Envelope of EW Lac in 1971–1984
Authors: Kogure T. , Suzuki M. 
Published: June 2019

Kogure and Suzuki (1984) have noticed that EW Lac (HD217050, B2 III pe) has revealed the long-term variation notably different before and after about 1976. Before 1976, the profiles of spectral lines were sufficiently symmetric and stable, suggesting a circular disk or ring for the structure of envelope. In contrast, since 1977, EW Lac entered a phase of anomalous V/R variation.We have obtained about 180 coudé spectra in 16 years by 1985 with the 188 cm reflector at the Okayama Astrophysical Observatory. Most of them were measured using the PDS densitometer at the Kwasan Observatory, University of Kyoto for the radial velocities and line profiles. A part of results were reported by Suzuki and Kogure (1986).
Red and Infrared Photometry of Be Stars
Authors: Kilambi G. C. , Vivekananda Rao P. , Sarma M. B. K. 
Published: June 2019

All programme stars including standard stars were observed with the standard RI filters of the Johnson system with a 20-arcsec diaphragm for 4 nights during the 1982–83 observing season. A photoelectric photometer attached to the 1.2 meter reflecting telescope of the Japal— Rangapur Observatory was used for these observations. A dry-ice cooled EMI 9558B photomultiplier tube was used as the detector and the photo-current was recorded by means of a GR 1230A DC-amplifier and a Honeywell Brown chart recorder.The extinction coefficients for R and (R-I) were determined from the observations of standard stars taken from the list of Johnson (1966) and also from the observations of an early and a late spectral type star on each night and all the observations were corrected for atmospheric extinction. The instrumental magnitudes of a programme star were transformed to the standard system through normal procedures.
High-Resolution Emission-Line Spectroscopy of Be Stars: Comparison of Hα and Weak Emission Lines
Authors: Hanuschik Reinhard W. 
Published: June 2019

AbstractFor a number of bright southern Be stars, high-resolution, high S/N spectroscopy has been performed for Hα, Si II λ6371 and four Fe II emission lines. With the exception of four stars, both Hα and weak emission line profiles exhibit resolved double-peak structure. Peak separation increases with stellar projected rotational velocity. In many cases, Hα profiles (but not Fe II lines) show resolved fine-structure (inflections in the flanks) indicating a two-component structure of the disk. Envelope models with arbitrary density and rotational velocity laws have been fitted to the Fe II line profiles with satisfactory results. It is found that the innermost Hα disk component also emits the Fe II lines and has an average outer radius of 5 r*; density falls off as r-l.5 or more rapidly. The outer disk component emits the faint and narrow secondary component of Hα lines with average outer radius 20 r*. The envelopes of the four stars with a strong, dominating single peak both in Hα and Fe II either are dominated by strong radial motions or, more likely, have elliptical disk-like structure.
Near Infrared Spectra of 103 Bright Be Stars
Authors: Andrillat Y. 
Published: June 2019

We have observed 103 bright Be stars in the near infrared up to 10500 A with a dispersion of 230 and 50 A mm-1. The observations were performed with a Reticon (1024 diodes) attached to the ROUCAS spectrograph at the 193 cm telescope of the Haute Provence Observatory.In this spectral range, the Be stars are characterized by the lines of HI (Paschen series), 0I(7772-74-75, 8446 A), CaII(8542, 8662, 8498 A), FeII(7712, 9997 A) and NI(8686-83-80, 8719-12-03, 8629 A).On our spectra, the CaII triplet is always blended with P13, P15, P16, and only the enhancement of these lines permits to conclude to the CaII presence. The 0I 8446 A is perturbed by the Paschen lines P17 and P18 (low dispersion spectra) and P18 (high dispersion spectra). The NI 8686-83-80 A lines also perturb the P13 profile.
Be Binary Systems with a Cool Companion: Are they Interacting?
Authors: Floquet M. , Hubert A.M. , Maillard J.P. , Chauville J. 
Published: June 2019

AbstractHigh resolution spectrograms of the two well known Be binary systems ζ Tau and KX And were obtained , in the IR ( 2-2.5µ ), with the Fourier Transform Spectrometer of the CFHT. They do not reveal evidence of a cool giant companion.
A Photometric Study of Herbig Ae/Be Stars
Authors: E. Eugenio , V. Mendoza 
Published: June 2019

It is well known (cf. Mendoza 1983) that “classical“ Be stars, and Herbig Ae/Be objects, in addition to hydrogen lines in emission, also share at least two photometric characteristics, namely, light varitions, and infrared color excesses.We have selected the α(16)⋀(9) {Mendoza 1979}, and the JHKL-photometric systems, in order to study some photometric properties of Be stars. The observations have been carried out at the National Astronomical Observatory (San Pedro Martir, B.C.N., and Tonantzintla, Pue.), Mexico, from 1976 to 1986.
A Preliminary Distance to the Small Magellanic Cloud by the Surface Brightness Technique
Authors: Barnes Thomas G. , Moffett Thomas J. , Gieren Wolfgang P. 
Published: June 2019

AbstractWe present a new distance determination to the Small Magellanic Cloud from the surface brightness technique applied to the Cepheid variable HV 829. Although this is a preliminary distance based on only one star, it illustrates the power of the surface brightness technique to extragalactic Cepheid distances, it develops the technique which we will apply to additional SMC and LMC Cepheids, and the distance is of intrinsic interest because of the current controvery concerning distances for the Magellanic Clouds.For HV 829 itself we obtain a distance modulus of 18.91 ± 0.20 mag. From other evidence we infer that HV 829 is slightly in front of the SMC centroid distance. Correcting to the SMC centroid yields a distance to the SMC of 19.05 ± 0.20 mag. We stress that this distance modulus is fully independent of any other distance modulus for the SMC, including those based upon Cepheids. Even so, our result agrees more closely with other, independent Cepheid distances than with RR Lyrae distances and main sequence fitting distances.
HR 8762: Low-amplitude Photometric Variation in a Pre-shell Phase
Authors: Gonzàlez-Bedolla S. , Sareyan J. P. , Chauville J. , Morel P. J. , Alvarez M. 
Published: June 2019

Longitude-coordinated high-precision photometry has been obtained a few weeks before the beginning of a strong Be and shell phase (1988) in HR 8762 (o And). The star showed variations of a few millimagnitudes in amplitude; i.e., just over the detection threshold. The classical 1.57-day double-wave period is still detected, showing that it probably never fades out completely, whatever the phase of the star. These variations can be interpreted as normal photospheric activity in a regular rotating B star. Although the variations of HR 8762 during our campaign were quite small, we could detect their amplitudes at a level of a few mmag.We still have to check whether they are still “in phase” with previous photometric observations: if this is the case, it means that in the “spot” hypothesis, these (superficial?) features would remain in the same position on the photosphere, changing only in surface area and/or brightness with the star's activity.