bluuebunny/crossref_metadata_2025_split huggingface dataset:
The radial extent of the Fornax cluster Low Surface Brightness galaxy population
Authors: Davies J.I. , Kambas A. , Morshidi-Esslinger Z. , Smith R. 
Published: July 2016

AbstractIn this paper we compare the radial distribution of Fornax cluster galaxies selected at different surface brightness values. The bright galaxy (RC3) sample surface brightness distribution peaks at a μBx = 21.5, the Low Surface Brightness (LSB) sample at μBx = 23.7 and the very Low Surface Brigthness (VLSB) sample at μBx = 25.7. The bright galaxy surface density decreases with an exponential scale length of α = 0.5°, the LSB galaxies with α = 1.3° and the VLSB galaxies with α = 2.0°. Thus the LSB and VLSB populations define a mass scale size some 2.5 and 4 times larger than the bright galaxies respectively. The contribution of the VLSB population to the total cluster luminosity is comparible to that of the brighter galaxies. If their mass to light ratios are significantly larger than than that of the bright galaxies they will dominate the mass and possibly account for the missing mass in clusters.
The Discovery of Red Low Surface Brightness Galaxies
Authors: O’Neil Karen 
Published: July 2016

AbstractWe have performed a digital survey for Low Surface Brightness (LSB) galaxies in the spiral-rich Cancer and Pegasus clusters as well as the low density regime defined by the Great Wall. A total of 127 galaxies were found with μB(0) > 22.0 mag arcsec‒2, 119 of which were previously unidentified.Consistent with other surveys, we find a significant number of galaxies with μB(0) > 23.0 mag arcsec‒2 which suggests that the space density of galaxies as a function of μB(0) is not strongly peaked. To more rigorously test this hypothesis we compare the actual surface brightness distribution from our survey with that from two different types of Monte-Carlo based sky images and show that it is not possible to distinguish between the flat distribution and the Gaussian one as the proper description of the underlying surface brightness distribution for this survey beyond 24.0 mag arcsec−2.The colors of the survey galaxies range continuously from very blue to the first discovery of very red LSB galaxies. It also includes a group of old galaxies which show evidence for recent star formation. This continuous range of colors clearly shows that LSB galaxies at the present epoch define a wide range of evolutionary states.
The Structure of the Superthin Spiral Galaxy UGC7321
Authors: Matthews L.D. , Gallagher J.S. , van Driel W. 
Published: July 2016

AbstractUGC 7321 is an edge-on low surface brightness (LSB) spiral galaxy with a number of extraordinary properties. Its vertical scale height (~70 pc) is one of the smallest ever measured for a galaxy disk. Its disk also exhibits strong vertical and radial color gradients. UGC 7321 appears to be an extremely unevolved galaxy in both a dynamical and in a star-formation sense.
VLA HI Imaging of the Low Surface Brightness Dwarf Galaxy DDO 47
Authors: Walter F. , Brinks E. 
Published: July 2016

AbstractWe present high resolution VLA-observations of the nearby Low Surface Brightness Dwarf Galaxy DDO 47. This object shows many hole-like structures in its neutral interstellar medium. The majority of the detected H I-shells are found to be expanding. Their origin is therefore believed to be due to stellar winds of the most massive stars and their subsequent supernova (SN type II) explosions within regions of recent star formation (SF). Current SF in DDO 47 is predominantly present on the rims of the HI-shells suggesting propagating SF. At a projected distance of 20 kpc (adopting a distance to DDO 47 of 4 Mpc), a companion galaxy was detected at almost the same systemic velocity (DDO 47 B). A search for an optical identification suggests that CGCG 087-033 is the optical counterpart of the companion. A preliminary dynamical analysis based on DDO 47’s rotation curve yields that it is dark matter dominated (about 80% of its dynamical mass is in some non-visible form). A simple mass model suggests that DDO 47 is one of the ‘thickest’ dwarf galaxies studied so far.
Results from the Dwingeloo Obscured Galaxies Survey
Authors: Rivers A.J. , Henning P.A. , Kraan-Korteweg R.C. , Lahav O. , Burton W.B. 
Published: July 2016

AbstractApproximately 25% of the extragalactic sky is obscured by dust in our own Milky Way galaxy. Diligent optical and infrared surveys are successful at detecting galaxies through moderate Galactic dust extinction, but in the most heavily obscured regions near the Galactic plane, only radio surveys are effective.The Dwingeloo Obscured Galaxies Survey (DOGS) is a 21-cm blind survey out to 4000 km s−1 in the northern “Zone of Avoidance” (ZOA). The DOGS project is designed to reveal hidden dynamically important nearby galaxies and to help “fill in the blanks” in the local large scale structure.
Chemical Constraints, Baryonic Mass and the Chemical Evolution of Low Surface Brightness Galaxies
Authors: Edmunds M.G. 
Published: July 2016

AbstractA brief review of primordial helium and deuterium abundances suggests a baryonic mass density of ΩB ≈ 0.04 – 0.045 (for Ho = 70). This mass may be dominated by intergalactic gas in clusters and groups of galaxies. The observed low chemical abundances in evolved dwarf galaxies might suggest that outflow was the origin for such gas, and we make general suggestions for the interpretation of the data from the next generation of X-ray spectroscopic satellites. The effects of both outflow and inflow on the chemical evolution of galaxies is discussed, particularly in the context of low surface brightness galaxies, and we comment on their dust content.
Kinematic analysis of Sculptor Group galaxies
Authors: Schoenmakers R. H. M. 
Published: July 2016

AbstractAn analysis of the kinematics of the five major spiral galaxies in the Sculptor Group is presented. These galaxies are analyzed using the method of harmonic expansion of the velocity field as described in Schoenmakers, Franx and de Zeeuw (1997). Three different types of kinematic distortions were found: warps, lopsidedness and elongation. All the Sculptor galaxies show kinematic lopsidedness, two show signs of global elongation and two are kinematically warped. The detected kinematic distortions are well in excess of those typically found for isolated galaxies.
Dynamics of Galaxies in Compact Groups I
Authors: de Oliveira C. Mendes , Amram P. 
Published: July 2016

AbstractWe describe a long-term program based on Fabry-Perot Hα velocity field data of compact groups taken at the ESO and the CFH 3.6m telescopes. The main goals of our project are: 1) determine the evolutionary stages of the studied groups, 2) search for tidal dwarf galaxy candidates in interacting systems and 3) in combination with photometry available in the literature, determine the Tully-Fisher relation for the group galaxies. In this paper we summarize all the Hα Fabry-Perot data we have obtained to date and present a preliminary discussion of point 1).The sample of 18 systems (with 64 galaxies) studied here contain groups at a variety of dynamical stages: from a false group that is in fact one single irregular galaxy with several star-forming blobs (e.g. HCG 18) to a group whose members are strongly interacting and possibly forming tidal dwarf galaxies (e.g. HCG 92) to a group in the final process of merging (e.g. HCG 31). A companion paper (Amram and Mendes de Oliveira, 2000) shows examples of galaxy velocity fields for groups in different dynamical stages.
Two color photometry of dwarf galaxies within 10 Mpc
Authors: Bremnes Torbjϕrn 
Published: July 2016

AbstractTwo-color CCD photometry of dwarf galaxies in and around the M81, M101 and CVnI groups is presented. These observations are part of a long term project aimed at obtaining surface photometry data of all known dwarf galaxies within 10 Mpc. The global photometric parameters derived will serve as the basis for a comparison between dwarf galaxies in different galactic environments.
Vorontsov-Velyaminov’ nests: what are they?
Authors: Zasov A. V. , Arkhipova V. P. 
Published: July 2016

AbstractWe give a short review of optical observations of the objects classified by Vorontsov-Vel’yaminov as “nests” of galaxies, describing their luminosity, color, structure and star formation properties. Some ideas on the nature of single dwarf “nests” are discussed.
Tracing interactions in HCGs through the H I
Authors: Verdes-Montenegro L. , Yun M. S. , Williams B. A. , Huchtmeier W. K. , Del Olmo A. , Perea J. 
Published: July 2016

AbstractWe present a global study of Hɪ spectral line mapping for 16 Hickson Compact Groups (HCGs) combining new and unpublished VLA data, plus the analysis of the Hɪ content of individual galaxies. Sixty percent of the groups show morphological and kinematical signs of perturbations (from multiple tidal features to concentration of the Hɪ in a single enveloping cloud) and sixty five of the resolved galaxies are found to be Hɪ deficient with respect to a sample of isolated galaxies. In total, 77% of the groups suffer interactions among all its members which provides strong evidence of their reality. We find that dynamical evolution does not always produce Hɪ deficiency, but when this deficiency is observed, it appears to correlate with a high group velocity dispersion and in some cases with the presence of a first-ranked elliptical. The X-ray data available for our sample are not sensitive enough for a comparison with the Hɪ mass; however this study does suggest a correlation between Hɪ deficiency and hot gas since velocity dispersions are known from the literature to correlate with X-ray luminosity.
Statistical Properties of the Mid and Far IR Emission in Mixed Morphology (E+S) Pairs of Galaxies
Authors: Toledo H. M. Hernández , Dultzin-Hacyan D. , Sulentic J. W. 
Published: July 2016

We report the results of a detailed statistical analysis of the Mid and Far IR (MIR/FIR) emission properties in a mixed morphology (E+S) sample of galaxy pairs from the Karachentsev (1972) Catalogue. The sample is large and diverse enough (≃ 130 pairs) to permit discrimination of pairs by morphological types and interaction classes. It samples a large enough volume to enable a non-parametric estimate of a Far-Infrared Luminosity Function (FIRLF). We find average factors of 3 and 5 enhancement in FIR and 25μm luminosities of the late-type pair components relative to an isolated galaxy control sample from Karachentseva (1973) Catalogue. This is interpreted as the MIR/FIR signature of the link between interaction and star formation. Although the spirals in (E+S) pairs fail to show a trend towards higher FIR luminosity with decreasing companion separation, a high-order comparison that takes into account information on the interaction classes, morphological types and the HI content suggests that:•a clear correlation between the IR luminosities and interaction classes is present suggesting that a subsample of the (E+S) pairs is more closely related to recent events of star formation,•the ratio of present to past star formation (as measured by the IR luminosities scaled to LB luminosity), increases measurably along the sequence Sa-Sc in paired spirals,•no Hɪ depletion in the star formation-enhanced spirals in mixed pairs is found, and•the high mass (M ≥ 10 M⊙) star formation rate (SFR) in paired Sc spirals is higher than that of the isolated Sc’s by a factor ~ 2 – 3.
FIR Infrared Emission as Indicator of Interaction in Hickson Compact Groups
Authors: Merluzzi P. , Shaker A. A. , Longo G. 
Published: July 2016

Due to their very high spatial density and relatively low velocity dispersion, Hickson’s compact groups of galaxies (hereafter HCGs, Hickson et al. 1989a, H89a) are ideal test grounds where to study the physics of galaxy interaction.Tidal shocks induced by galaxy interaction are expected to trigger rapid bursts of star formation in the circumnuclear region of galaxies. The increases in density and temperature caused locally by such shocks produce an enhancement in both the total FIR luminosity and in the ratio between the FIR fluxes at 60 and 100 μm. These enhancements have been actually observed in the circumnuclear regions of both interacting and ”putative” merging galaxies and should therefore be found also in all galactic environments where the frequency of interaction is higher than in the field. However, while interactions are more frequent among HCGs members than in the field (e.g. Hickson 1994, Shaker et al. 1999), there are conflicting arguments on whether HCGs present or do not present a FIR excess. As stressed by many authors, the critical point is the IRAS data resolution which prevents to map the spatial distribution of the FIR emission. We investigate the FIR properties of a selected sample of HCGs by sing the new high spatial resolution data from Allam et al. 1996 (A96). In particular, we address the problem whether or not there is any FIR enhancement in the compact groups and the reasons of that. This is a short presentation of the analysis performed and of the results obtained (Merluzzi et al. 1999).
Dynamical explorations of nuclear structures in barred galaxies
Authors: Anosova J. , Benedict G. F. 
Published: July 2016

AbstractWe construct models of a galaxy in order to provide a possible identification of the dynamical processes that lead to the formation of structure observed in galactic nuclei. We assume that the center of our model contains a very massive double black hole, surrounded by relatively low-mass particles - star clusters, gas, and dust complexes. Our previous work (Anosova et al. 1994, 1995) snowed that the dynamical evolution of such a model produces many structures similar to those observed in the nuclei of galaxies, including rings and various types of flows and jets. In such models the ’gravitational slingshot’ effect frequently occurs.We consider a number of such models with different initial parameters. Comparison of our models with the observed structure of NGC 4314 shows good agreement at one stage of the evolution for certain combinations of initial parameters. The model predicts the velocity field observed in NGC 4314.
Presence and Absence of Outer Rings in Barred Galaxies
Authors: Rautiainen P. , Salo H. 
Published: July 2016

Many barred spiral galaxies have an outer ring (R) or a pseudoring (R') in their outer disk. R. Buta (e.g. Buta 1995) has developed a detailed classification for different types of outer rings. Two main families of outer rings are recognized. In R1 family the major axis of the ring is perpendicular to the bar and the spiral arms wind 180° before meeting the other arm. In R2 family the major axis of the ring is parallel to the bar and the spiral arms wind 270°.The outer rings are usually considered to be related to the outer Lindblad resonance (OLR) of a rotating stellar bar. The ring shapes correspond to families of closed orbits in the vicinity of this resonance (e.g. Contopoulos & Grosbøl 1989), and also the sizes of the outer rings relative to the bar component fit to this suggestion. Furthermore, test-particle simulations which use analytical bar potentials can produce different types of outer rings near the OLR (Schwarz 1981; Byrd et al. 1994). We have obtained similar results when we modelled ringed galaxy IC 4214 by constructing the gravitational potential from near-IR observations (Buta et al. 1999; Salo et al. 1999).
BCD Classification of Stars with the B[e] Phenomenon
Authors: Cidale L. , Zorec J. , Morrell N. 
Published: July 2016

AbstractStars in different evolutionary stages and/or environments can show the B[e] phenomenon. In order to establish possible relations between the stellar evolutionary stage and the presence of this phenomenon, the fundamental parameters of these stars need to be determined, as in most cases they are unknown. With this aim we undertook systematic low resolution spectroscopic observations of stars with the B[e] phenomenon. Preliminary determinations of fundamental parameters based on the BCD (Barbier-Chalonge-Divan Paris spectrophotometric system) analysis are reported in this paper.
Interferometry and Stellar Magnetism
Authors: Chesneau O. , Rousselet-Perraut K. , Vakili F. 
Published: July 2016

AbstractThe classical detection of magnetic fields in Be stars remains a challenge due to the sensitivity threshold and geometrical cancelation of the field effects. We propose to study the Zeeman effect using Spectro-Polarimetric INterferometry (SPIN) which consists of the simultaneous use of polarimetry and very high angular resolution provided by long baseline interferometers. As monitoring of the instrumental polarisation is mandatory in order to calibrate interferometric observations in any case, the polarised signal is a natural by-product of interferometers. This method will be tested on the GI2T interferometer thanks to its high spectral resolution and its polarimetric capabilities.
A UV Spectrophotometric Technique for Measuring Temperatures of CS Structures over B Stars
Authors: Smith Myron A. 
Published: July 2016

Do optical/UV variations of spectra of Be stars arise from pulsations or structures hanging over them? There is a need for a temperature-sensitive discriminator for circumstellar structures above Be stars to determine whether their UV flux variations are due to occulting structures or photospheric pulsations.To address this question, we acquired far-UV (SWP camera) echellograms covering λλ1150–2100 from the IUE final archive. For selected B stars we have selected suitably exposed spectra observed within a short timespan, typically 1–3 days. We summed all the valid net fluxes within each of 60 echelle orders and placed them into an order vs. time array. We identify those times corresponding to high and low fluxes over several reference orders and form the quantity 1 - Fmin(λ)/Fmax(λ), for all echelle orders. The result is a low-resolution spectrum sensitive to absorptions at certain wavelengths, either strong lines such as Lyman α and several UV resonance lines or aggregates of metallic lines. All these are potentially sensitive to temperature variations.
Non-radial Pulsation Modeling of μ Centauri
Authors: Rivinius Th. 
Published: July 2016

AbstractIt is shown that the line profile variability (lpv) of μ Cen can be modeled as non-radial pulsations (nrp). The use of the most recent available modeling technique for the nrp and carefully computed stellar observables (intrinsic line profile and flux) are, however, mandatory to take full advantage of present high-quality data.
Tracing the Transient Periods in the Be Star 28 ω CMa
Authors: Štefl S. , Budovičová A. , Baade D. , Kaufer A. , Rivinius T. , Stahl O. , Wolf B. 
Published: July 2016

AbstractSpectra of the Be star 28 CMa obtained with the HEROS echelle spectrograph in 1996 and 1997 were used to check the presence of transient periods in commonly measured scalar parameters of absorption and emission lines. Transient periods can be convincingly detected in modes of higher absorption and single peak emission lines of the Balmer series as well as in the V/R ratio of Fell lines. Consequences for the frequency analyses of datasets containing radial velocities derived from different ions are discussed. The significant differences in amplitudes of radial velocities of different ions and in individual seasons were confirmed and a mean ephemeris derived.
Line Profile Variability in the Be Star α Eridani
Authors: Leister N. V. , Janot-Pacheco E. , Leyton Z. J. , Hubert A. M. , Floquet M. 
Published: July 2016

AbstractWe present an analysis of line profile variability of the Be star α Eri (Achernar). Spectra of He I λ667.8nm were collected at Brazilian Laboratório Nacional de Astrofísica (LNA) during 10 observing runs covering 27 nights in 6 years. The presence of a 1.26 days period reported previously is confirmed and we report also the detection of other periods (0.73 and 0.53 days) and a possible 12.5 days modulation. A transient high-velocity absorption component with RV = −500 km/s, higher than −υsini (−220 km/s) has appeared at the end of 1993, near the presumed maximum of the Hα emission phase.
Physical Requirements for Flares in Stars
Authors: Haisch Bernhard 
Published: July 2016

AbstractA wide range of stellar analogs of solar X-ray flares has been observed. During the maximum of the solar activity cycle, one or two Mclass flares peaking at Lx ~ 1026 erg s−1 in the GOES 1−8 Å passband take place on average every day on the Sun. Such run-of-the-mill events have been measured by ASCA on our nearest neighbor, Proxima Centauri, a dM5.5e flare star (Haisch, Antunes & Schmitt 1995). At the other extreme, RS CVn systems and T Tauri stars have been observed to flare with peak luminosities of Lx ~ ×1032 ergs s−1 (Haisch & Schmitt 1996 and references therein). Current wisdom has it that this wide range of flares spanning at least six order of magnitude (and another factor of 10–100 if one counts even lower level solar flares) on the young T Tauri stars, main sequence G, K and M stars, and in evolved RS CVn subgiants and giants can all be understood as versions of solar flares originating ultimately in a convectively-driven magnetic dynamo. There is evidence pointing to two distinct types of dynamo perhaps even in the Sun (Durney, Young and Roxburgh 1993): the α − ω dynamo generated in a rather thin boundary layer near — in some interpretations just below — the interface between a star’s radiative core and convective envelope; and a turbulent distributed dynamo operative more or less throughout a convection zone. But what is one to make of the evidence for flares on Be stars (Smith, Robinson and Corbet 1998) where there is no subsurface convection to drive a dynamo? (Convective envelopes are thought to begin among the late-A spectral type stars, and steadily deepen for cooler stars.) This paper does not attempt to provide an answer, but it does attempt to outline the characteristics and requirements of magnetically-powered flaring.
Be Phenomena in Young Early-type Stars: Various Forms of Interaction between the Star and the Circumstellar Gaseous Envelope
Authors: Pogodin M. 
Published: July 2016

AbstractNew results of high-resolution spectroscopy of four pre-main sequence Ae/Be stars are presented. An analysis of parameters of lines originating in different regions of the circumstellar (CS) envelope (Hα, Hβ, He I 5876, DNal) allows to reconstruct a picture of the interaction between the star and the CS environment which can be displayed in different forms. At least two separate processes seem to impact the structural and kinematical properties of the envelope: the stellar wind from the stellar surface and the matter infall onto the star from the CS media. A possible relation between these two phenomena is discussed in the framework of different models. Some similarity between observational phenomena in Herbig Ae/Be and classical Be stars is noted in spite of their difference in evolutionary status.
Short-lived and Long-lived Outbursts in B and Be Stars from Hipparcos Photometry and Modelling
Authors: Hubert A. M. , Floquet M. , Zorec J. 
Published: July 2016

AbstractThe number of Be stars which showed short- and long-lived outbursts during the Hipparcos photometric survey, previously reported in Hubert and Floquet (1998), have been increased by examination of light curves of fainter objects. Long-lived outbursts have been modelled as being due to an ejected layer/slab which becomes gradually diluted.