bluuebunny/crossref_metadata_2025_split huggingface dataset:
The UV-upturn in brightest cluster galaxies
Authors: Loubser S. I. , Sánchez-Blázquez P. 
Published: March 2015

AbstractThis study is part of a series devoted to the investigation of a large sample of brightest cluster galaxies (BCGs), their properties and the relationships between these and the properties of the host clusters. In this paper, we compare the stellar population properties derived from high signal-to-noise, optical long-slit spectra with the GALEX ultraviolet (UV) colour measurements for 36 nearby BCGs to understand the diversity in the most rapidly evolving feature in old stellar systems, the UV-upturn. We investigate: (1) the possible differences between the UV-upturn of BCGs and those of a control sample of ordinary ellipticals in the same mass range, as well as possible correlations between the UV-upturn and other general properties of the galaxies; (2) possible correlations between the UV-upturn and the properties of the host clusters; (3) recently proposed scenarios where helium-sedimentation in the cluster centre can produce an enhanced UV-upturn. We find systematic differences between the UV-colours of BCGs and ordinary ellipticals, but we do not find correlations between these colours and the properties of the host clusters. Furthermore, the observations do not support the predictions made by the helium-sedimentation model as an enhancer of the UV-upturn.
Correlation of morphological fraction with redshift in galaxy clusters
Authors: Yuan Qi-Rong , Dang Qiang-Qiang , Yan Peng-Fei , Chen Wei , Wen Zhong-Lue , Han Jin-Lin , Zhou Xu 
Published: March 2015

AbstractBased on 187 galaxy clusters identified from the photometric redshifts of galaxies in the Cosmic Evolution Survey (COSMOS) field(Wen & Han 2011), cluster galaxies brighter than MV = -20.5 are classified into four categories according to their best-fitting templates of the spectral energy distributions (SEDs) provided by Ilbert et al. (2009): early-type (including elliptical and lenticular) galaxies (E+S0), spiral galaxies (S), irregular galaxies (Irr), and starbursts (SB). The fractions of these four SED types are presented as the functions of redshift in Figure 1. Fraction of each category varies remarkably with cluster redshift: fractions of normal galaxies (E+S0+S+Irr) tend to decrease with redshift, whilst the starburst proportion tends to increase with redshift. For the normal galaxies, there exists a sequence for the decreasing slopes of morphological fractions. Majority of the galaxies in high-redshift clusters (z > 1.0) are experiencing strong star-formation activities, which leads to a very high proportion of starburst.
Meteorites – The Significance of Collection and Curation and Future Developments
Authors: Smith Caroline 
Published: March 2015

AbstractMeteorites are some of the most important and valuable rocks available for scientific study. Approximately 43,000 meteorites are known on Earth and are egeologicalf samples of extraterrestrial bodies - meteorites are known to originate from asteroids, the Moon, Mars and possibly comets. With expanding exploration of our Solar System, meteorites provide the eground truthf to compare data collected by robotic missions with results gained from a variety of more accurate and precise techniques using laboratories on Earth. This talk will give an introduction to the history of meteorite science and the importance of meteorite collections to the field of meteoritics, planetary and solar system science. Curation of extraterrestrial samples is a particularly pertinent issue, especially with regards to particularly rare samples such as those from Mars like the recent Tissint meteorite. Future sample return missions to asteroids and Mars also pose siginificant challenges around the curation of these precious materials. Issues surrounding the curation of samples and how curation and curatorial actions can influence scientific studies will also be discussed.
A list of historical comets observed at plural sites: the beginning of astronomy in Japan and Korea
Authors: Tanikawa Kiyotaka , Sôma Mitsuru 
Published: March 2015

AbstractComets generally stay long in the sky and can be seen from many places on the surface of the Earth. We are interested in historical comets which were observed at plural sites. We have shown in a previous work (Tanikawa & Sôma, 2008) that in the seventh century, five comets were observed independently in China and Japan. From this fact and other data, we deduced that Japanese observational astronomy started in the seventh century. We know that, other than China and Japan, Korea and Vietnam had observational astronomy before the 9th century. We look for historical comets observed at plural sites by surveying the existing literature of respective countries. Examining the independence of the records, we provide a list of comets observed independently at plural sites. This strengthens the reliability of the records of comets. The list can be used for other purposes.
Supplemental ancient Chinese meteor, meteorite fall and comet records with Zhongguo gudai tianxiang jilu zongji (1)
Authors: Nagatoshi Nogami 
Published: March 2015

AbstractZhongguo guidai tianxiang jilu zongji pressed in 1988 containes ancient Chinese astronomical records including that of meteor, meteorite fall and comet until 1911 from the Standard Histories and local gazetteers existed in China. On the other hand, many local gazetteers lost in China at present have been collected in university and public libraries in Japan. Especially the library of Chinese section in the Research Institute for Humanistic Studies in Kyoto University and the Oriental Library in Tokyo have big collection. This presentation will give a few dozens supplemential ancient records with that big book from local gazetteers in above mentioned libraries.
Spectrophotometric properties of Moon's and Mars's surfaces exploration by shadow mechanism
Authors: Morozhenko Alexandr , Vidmachenko Anatolij , Kostogryz Nadiia 
Published: March 2015

AbstractTypically, to analyze the data of the phase dependence of brightness atmosphereless celestial bodies one use some modification of the shadow mechanism involving the coherent mechanism. There are several modification of B.Hapke [2] model divided into two groups by the number of unknown parameters: the first one with 4 parameters [3,4] and the second one with up to 10 unknown parameters [1] providing a good agreement of observations and calculations in several wavelengths. However, they are complicated by analysing of the colorindex C(α) dependence and photometric contrast of details with phase K(α) and on the disk (μ o = cos i). We have got good agreement between observed and calculated values of C(α) = U(α)-I(α), K(α), K(muo) for Moon and Mars with a minimum number of unknown parameters [4]. We used an empirical dependence of single scattering albedo (ω) and particle semi-transparency(æ): æ = (1-ω)n. Assuming that [χ (0°)/χ(5°)] = χ (5°)/χ (0°)], where χ(α) is scattering function, using the phase dependence of brightness and opposition effect in a single wavelength, we have defined ω,χ(α),g (particle packing factor), and the first term expansion of χ(α) in a series of Legendre polynomials x1. Good agreement between calculated and observed data of C(α) = U(α)-I(α) for the light and dark parts of the lunar surface and the integral disk reached at n ≈ 0,25, g = 0,4 (porosity 0,91), x1 = -0,93, ω = 0,137 at λ = 359nm and 0,394 at λ = 1064nm;, for Mars with n ≈ 0,25,g = 0,6 (porosity 0,84), x1 ≈ 0, ω = 0,210 at λ = 359nm and ω = 0,784 at λ = 730nm.1. Bowell E., Hapke B., Domingue D., Lumme K., et al. Applications of photometric models to asteroids, in Asteroids II. Tucson: Univ. Arizona Press. p.524-556. (1989)2. Hapke B. A theoretical function for the lunar surface, J.Geophys.Res. 68, No.15., 4571-4586(1963).3. Irwine W. M., The shadowing effect in diffuse reflection, J.Geophys.Res. 71,No.12, 2931-2937(1966).4. Morozhenko A. V., Yanovitskij E.G., An optical model of the Martian surface in the visible region of spectrum, Astronomy Reports 48, No.4, 795-809(1971).
SOFA—an IAU service fit for the future
Authors: Hohenkerk C. 
Published: March 2015

AbstractStandards of Fundamental Astronomy (SOFA) is an International Astronomical Union (IAU) service that provides accessible and authoritative algorithms and procedures that implement standard models used in fundamental astronomy. This paper summaries the current status, noting the changes during 2009-2012, and discusses issues that may arise in the future.
Multiple Sequences of M-dwarfs in NGC 2808 and ω Centauri.
Authors: Milone A. P. 
Published: March 2015

AbstractThe infrared channel of the Wide-Field Camera 3 on the Hubble Space Telescope revealed multiple main sequences of very low-mass stars in the globular clusters NGC 2808 and ω Cen. In this paper I summarize the observational facts and provide a possible interpretation.
Rapid Mass Segregation in Massive Star Clusters
Authors: McMillan Stephen , Vesperini Enrico , Kruczek Nicholas 
Published: March 2015

AbstractSeveral dynamical scenarios have been proposed that can lead to prompt mass segregation on the crossing time scale of a young cluster. They generally rely on cool and/or clumpy initial conditions, and are most relevant to small systems. As a counterpoint, we present a novel dynamical mechanism that can operate in relatively large, homogeneous, cool or cold systems. This mechanism may be important in understanding the assembly of large mass-segregated clusters from smaller clumps.
Galactic rings and secular evolution in barred galaxies
Authors: Knapen Johan H. 
Published: March 2015

AbstractRings are common in galaxies. Several kinds of rings are known: collisional, polar, and resonance rings, of which the latter is by far most common. Resonance rings are prime tracers of the underlying dynamical structure of disk galaxies, in particular of orbital resonances and of manifolds. Rings are also indicators of angular momentum transport, and this is a key factor in secular evolution (see the various reviews in Falcón-Barroso & Knapen 2012).Resonance rings come in three flavours, primarily defined by their size, namely nuclear, inner, and outer rings. From studies like those of Buta (1995), Knapen (2005) and Comerón et al. (2010, 2013) we know that the radii of nuclear rings range from a few tens of parsec to some 3.5 kpc, while inner rings and outer rings have typical radii of 1.2 and 2.5–3 times the length of the bar. Many host galaxies of rings are barred, but so are most galaxies in general. Some 20% of all rings occur in non-barred galaxies, which implies that rings do not, or hardly, occur preferentially in barred galaxies (Knapen 2005, Comerón et al. 2010, 2013). In most non-barred ringed galaxies an oval, a past interaction, or even a prominent spiral pattern lies at the dynamical origin of the ring, but this needs additional scrutiny.From an inventory of all known nuclear rings, Comerón et al. (2010) reach the following conclusions. Star-forming nuclear rings occur in 20 ± 2% of disk galaxies with −3 < T < 7; 18/96 occur in disk galaxies without a bar (19%); they are found in S0 to Sd galaxies, peaking in types Sab Sb; when nuclear rings occur in barred galaxies, the ring radius is limited to one quarter of the bar radius; and stronger bars host smaller rings (cf. Knapen 2005).We are now using the Spitzer Survey of Spiral Structure in Galaxies (S4G; Sheth et al. 2010) to expand our survey to inner and outer rings (Comerón et al. 2013). We aim to study the relations between ring and host properties – as we did before for nuclear rings. We will use the S4G sample size and image depth to reach further insight into the secular evolution of galaxies by measuring structural properties of rings, as well as those of components like bars and disks. We will then be able to tackle outstanding questions such as the origin of rings in non-barred galaxies, and how exactly ring properties are determined by the bar.
Rejuvenation of bulges by bars: evidence from stellar population analysis
Authors: Gadotti Dimitri A. , Coelho Paula 
Published: March 2015

AbstractWe obtained stellar ages and metallicities via spectrum fitting for a sample of 575 bulges with spectra available from the SDSS. Using the whole sample, where galaxy stellar mass distributions for barred and unbarred galaxies are similar, we find that the distribution of bulge ages in barred galaxies shows an excess of populations younger than 4 Gyr, when compared to bulges in unbarred galaxies. KS statistics confirm that the age distributions are different with a significance of 99.94%. If we select sub-samples for which the bulge stellar mass distributions are similar for barred and unbarred galaxies, this excess vanishes for galaxies with low-mass bulges, while for more massive bulges we find a bimodal stellar age distribution for barred galaxies only, corresponding to two normal distributions with mean ages of 10.4 and 4.7 Gyr (see Fig. 1). These results lend strong support to models in which bars trigger star formation activity in the centers of galaxies. We also find twice as much AGN among barred galaxies, as compared to unbarred galaxies, for low-mass bulges. Full results are in Coelho & Gadotti (2011).
The downplayed role of secular processes in the co-evolution of galaxies and black holes
Authors: Cisternas Mauricio , Jahnke Knud 
Published: March 2015

AbstractAccording to the current co-evolution picture, most present-day galaxies experienced at least one phase of vigorous black hole (BH) activity in the past, during which a tight link between galaxy and BH gets established. While during the last two decades we have witnessed tremendous progress in the field, additional robust observational constraints are required on how galaxy and BH related at earlier times, and which mechanisms are responsible for triggering these BH growth phases. In our recent studies, we analyzed a large sample of active galactic nuclei (AGN) out to z ~ 1 from the COSMOS survey (Scoville et al. 2007), allowing us to study in detail growing BHs together with their host galaxies. In Cisternas et al. (2011b) we found that, for a sample of 32 active galaxies at z ~ 0.7, BH mass scales with total galaxy stellar mass in the same way as it does locally, at z = 0, with galactic bulge mass. I will argue that for these galaxies to obey the local relation only a disk-to-bulge stellar mass redistribution is needed, likely driven by passive secular evolution. I will also present the results from Cisternas et al. (2011a), aiming to understand the relevance of major mergers as AGN activity triggering mechanisms. By looking for merging signatures on the morphologies of 140 AGN (some examples shown in Figure 1), and comparing them with a sample of over 1200 matched inactive galaxies, we found that the merger fraction between samples is statistically the same, at roughly 15%. Together with the fact that the majority of the AGN host galaxies are disk-dominated, unlikely relics of a recent major merger, these results are the strongest evidence to date that secular evolution rather than major merging has dominated BH fueling at least since z ~ 1.
Chemical fingerprinting of stellar populations in the Milky Way halo
Authors: Chou Mei-Yin 
Published: March 2015

AbstractThe idea of “chemically fingerprinting“ stars to their birth systems has been discussed over the last decade. Here we present an investigation of the chemical abundance patterns of halo substructures using high-resolution spectra. In particular, we study the abundances of the α-like element titanium (Ti) and the s-process elements yttrium (Y) and lanthanum (La) for M giant candidates of the Galactic Anticenter Stellar Structure (GASS, also known as the Monoceros Ring) and the Triangulum-Andromeda (TriAnd) Star Cloud. We apply “chemical fingerprinting“ to the GASS/Monoceros Ring and TriAnd Star Cloud, to explore the origins of the two systems and the hypothesized connections between them. GASS has been debated either to originate from a part (e.g., warp) of the Galactic disk or tidal debris of a disrupted Milky Way (MW) satellite galaxy. Our exploration shows that GASS is indeed made of stars from a dwarf spheroidal (dSph) galaxy, although we still can not rule out the possibility that GASS was dynamically created out of a previously formed outer MW disk. And whereas the TriAnd Star Cloud has been assumed to come from the tidal disruption of the same accreted MW satellite as the GASS/Monoceros Ring, our comparison of the abundance patterns in GASS and TriAnd M giants suggests that the TriAnd Star Cloud is likely an independent halo substructure unrelated to the GASS/Monoceros Ring. Furthermore, our findings also suggest that the MW may have accreted other satellites in addition to the on-going, well-known Sagittarius (Sgr) dwarf galaxy.
The outskirts of spiral galaxies: probing stellar migration theory
Authors: Bakos Judit , Trujillo Ignacio 
Published: March 2015

AbstractOne of the most outstanding predictions of the radial migration theory was a progressive increase in the age of the stellar populations toward the galaxy outskirts. This gradual change in the age is caused by a net flux of old stars formed in the inner disk moving toward the outskirts. Thanks to the fact that the age of stellar populations can be interpreted in terms of colors, this prediction was confirmed observationally a few years ago with deep surface brightness profiles of a large sample of nearby galaxies. Our group has now taken a step forward on this as we have explored the properties of the stellar populations beyond the star formation threshold using ultra deep data from SDSS Stripe82. These data allowed us to study the faint outskirts of disks in detail down to a surface brightness level of 30 mag/arcsec2 in the r'-band. At these surface brightness levels spiral galaxies reveal new and exciting structural components which could not have been seen by regular SDSS imaging: outer disks extend farther out, tidal streams and satellites become visible. We will present deep color profiles of the regions of the galaxies where the disks starts to be confused with the stellar haloes. We confront these colors with model predictions. For some galaxies, the very outer regions are so red that conventional IMFs can not explain their colors. We will discuss whether our new results can be explained within the radial migration scheme.
A test for radial mixing using local star samples
Authors: Yu Jincheng , Sellwood Jerry , Pryor Carlton , Chen Li , Hou Jinliang 
Published: March 2015

AbstractWe use samples of local main-sequence stars to show that the radial gradient of [Fe/H] in the thin disk of the Milky Way decreases with mean effective stellar temperature. We use the angular momentum of each star about the Galactic center to eliminate the effects of epicyclic motion, which would otherwise blur the estimated gradients. We use the effective temperatures as a proxy for mean age, and conclude that the decreasing gradient is consistent with the predictions of radial mixing due to transient spiral patterns. We find some evidence that the trend of decreasing gradient with increasing mean age breaks to a constant gradient for samples of stars whose main-sequence life-times exceed the likely age of the thin disk.
Quantifying secular evolution through structural decomposition
Authors: Kelvin Lee 
Published: March 2015

AbstractStructure within a galaxy is not random, instead emerging as a direct function of its evolutionary path. It is thought that secular evolutionary processes leave behind distinct structural tracers in the form of bars, pseudo-bulges and rings. We have developed a robust automated structural analysis pipeline (Kelvin et al., 2012) able to accurately map structure across a range of ground and space-based datasets. Using reprocessed SDSS and UKIDSS data from the GAMA survey: an imaging and spectroscopic survey with over 300,000 redshifts across 300 square degrees (Driver et al., 2009); we measure the relative abundance and stellar mass locked up within these structures in the local (z<0.06) Universe. Future robust calculations of the stellar mass budget within bulges, bars, disks and pseudo-bulges should allow us to measure the relative importance of secular evolution against other mechanisms across cosmic time.
Galaxies driven only by secular evolution?
Authors: Verdes-Montenegro Lourdes ,   on behalf of the AMIGA team
Published: March 2015

AbstractThe AMIGA project (Analysis of the interstellar Medium of Isolated GAlaxies, http://amiga.iaa.es) has identified a significant sample of very isolated (Tcc(nearest-neighbor) ≈2-3Gyr) galaxies in the local Universe and revealed that they have different properties than galaxies in richer environments. Our analysis of a multiwavelength database includes quantification of degree of isolation, morphologies, as well as FIR and radio line/continuum properties.Properties usually regarded as susceptible to interaction enhancement show lower averages in AMIGA–lower than any galaxy sample yet identified. We find lower MIR/FIR measures (Lisenfeld et al. 2007), low levels of radio continuum emission (Leon et al. 2008), no radioexcess above the radioFIR correlation (0%, Sabater et al.2008), a small number of AGN (22%, Sabater et al. 2012), and lower molecular gas content (Lisenfeld et al. 2011). The late-type spiral majority in our sample show very small bulge/total ratios (largely <0.1) and Sersic indices consistent with an absence of classical bulges (Durbala et al. 2008). They show redder g-r colors and lower color dispersion for AMIGA subtypes (Fernandez-Lorenzo et al. 2012) and show the narrowest (gaussian) distribution of HI profile asymmetries of any sample yet studied.This work has been supported by Grant AYA2011-30491-C02-01 co-financed by MICINN and FEDER funds, and the Junta de Andalucia (Spain) grants P08-FQM-4205 and TIC-114.
Hoag's object: the quintessential ring galaxy
Authors: Brosch Noah , Finkelman Ido , Moiseev Alexei 
Published: March 2015

AbstractWe present new observations of Hoag's Object, known as “the most perfect ring galaxy,“ that show that a preferred explanation for this object is (a) the formation of a triaxial elliptical galaxy some 10 Gyr ago, (b) the accretion of a large disk of neutral hydrogen at about the same time, (c) low-level star formation in the HI disk for all the time since that event triggered by the triaxial potential of the core.
Shaping Disk Galaxy Stellar Populations via Internal and External Processes
Authors: Roškar Rok 
Published: March 2015

AbstractIn recent years, effects such as the radial migration of stars in disks have been recognized as important drivers of the properties of stellar populations. Radial migration arises due to perturbative effects of disk structures such as bars and spiral arms, and can deposit stars formed in disks to regions far from their birthplaces. Migrant stars can significantly affect the demographics of their new locales, especially in low-density regions such as in the outer disks. However, in the cosmological environment, other effects such as mergers and filamentary gas accretion also influence the disk formation process. Understanding the relative importance of these processes on the detailed evolution of stellar population signatures is crucial for reconstructing the history of the Milky Way and other nearby galaxies. In the Milky Way disk in particular, the formation of the thickened component has recently attracted much attention due to its potential to serve as a diagnostic of the galaxy's early history. Some recent work suggests, however, that the vertical structure of Milky Way stellar populations is consistent with models that build up the thickened component through migration. I discuss these developments in the context of cosmological galaxy formation.
RM due to magnetic fields in the cosmic web and SKA observations
Authors: Akahori Takuya , Ryu Dongsu 
Published: March 2015

AbstractWe estimated that rotation measure (RM) due to the intergalactic magnetic field (IGMF) in the cosmic web is ~ 1–10 rad m−2. The RMs could be tested with the Square Kilometer Array (SKA) and SKA pathfinders.