83 research outputs found

    Binding Energy and the Fundamental Plane of Globular Clusters

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    A physical description of the fundamental plane of Galactic globular clusters is developed which explains all empirical trends and correlations in a large number of cluster observables and provides a small but complete set of truly independent constraints on theories of cluster formation and evolution in the Milky Way. Within the theoretical framework of single-mass, isotropic King models, it is shown that (1) 39 regular (non--core-collapsed) globulars with measured core velocity dispersions share a common V-band mass-to-light ratio of 1.45 +/- 0.10, and (2) a complete sample of 109 regular globulars reveals a very strong correlation between cluster binding energy and total luminosity, regulated by Galactocentric position: E_b \propto (L^{2.05} r_{\rm gc}^{-0.4}). The observational scatter about either of these two constraints can be attributed fully to random measurement errors, making them the defining equations of a fundamental plane for globular clusters. A third, weaker correlation, between total luminosity and the King-model concentration parameter, c, is then related to the (non-random) distribution of globulars on the plane. The equations of the FP are used to derive expressions for any cluster observable in terms of only L, r_{\rm gc}, and c. Results are obtained for generic King models and applied specifically to the globular cluster system of the Milky Way.Comment: 60 pages with 19 figures, submitted to Ap

    The Worst Distortions of Astrometric Instruments and Orthonormal Models for Rectangular Fields of View

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    The non-orthogonality of algebraic polynomials of field coordinates traditionally used to model field-dependent corrections to astrometric measurements, gives rise to subtle adverse effects. In particular, certain field dependent perturbations in the observational data propagate into the adjusted coefficients with considerable magnification. We explain how the worst perturbation, resulting in the largest solution error, can be computed for a given non-orthogonal distortion model. An algebraic distortion model of full rank can be converted into a fully orthonormal model based on the Zernike polynomials for a circular field of view, or a basis of functions constructed from the original model by a variant of the Gram-Schmidt orthogonalization process for a rectangular field of view. The relative significance of orthonormal distortion terms is assessed simply by the numerical values of the corresponding coefficients. Orthonormal distortion models are easily extendable when the distribution of residuals indicate the presence of higher order terms.Comment: 1 figure; submitted in PAS

    Cosmology, Oscillating Physics and Oscilllating Biology

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    According to recent reports there is an excess correlation and an apparent regularity in the galaxy one-dimensional polar distribution with a characteristic scale of 128 h1h^{-1} Mpc. This aparent spatial periodicity can be naturally explained by a time oscillation of the gravitational constant GG. On the other hand, periodic growth features of bivalve and coral fossiles appear to show a periodic component in the time dependence of the number of days per year. In this letter we show that a time oscillating gravitational constant with similar period and amplitude can explain such a feature.Comment: 9 pages. latex using revtex. This revised version is supposed to be free of e-mail nois

    Astrometry and geodesy with radio interferometry: experiments, models, results

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    Summarizes current status of radio interferometry at radio frequencies between Earth-based receivers, for astrometric and geodetic applications. Emphasizes theoretical models of VLBI observables that are required to extract results at the present accuracy levels of 1 cm and 1 nanoradian. Highlights the achievements of VLBI during the past two decades in reference frames, Earth orientation, atmospheric effects on microwave propagation, and relativity.Comment: 83 pages, 19 Postscript figures. To be published in Rev. Mod. Phys., Vol. 70, Oct. 199

    Some remarks on the angular momenta of galaxies, their clusters and superclusters

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    We discuss the relation between angular momenta and masses of galaxy structures base on the Li model of the universe with global rotation. In our previous paper (God{\l}owski et al 2002) it was shown that the model predicts the presence of a minimum in this relation. In the present paper we discuss observational evidence allowing us to verify this relation. We find null angular momentum J=0 for the masses corresponding to mass of galaxy grups and non-vanishing angular momenta for other galactic structures. We check these theoretical predictions analysing Tully's galaxy grups. The existing data comparing alignment in different galactic structure are consistent with obtained theoretical relation J(M)J(M) if we interpret the groving alignment as the galactic increasing angular momenta in the galactic structure.Comment: 20 pages 1 figure. GRG accepte

    Global and Local Three-dimensional Studies of The Residual Vector Field from 2MASS and Hipparcos-2 Catalog

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    [EN] The Gaia mission will provide a six-parameter solution for millions of stars, including a tridimensional map of our Galaxy. The estimation of distances has been made for the Tycho-Gaia Astrometric Solution (TGAS), while to contrast the proper motions it is interesting to consider positions from the different Gaia Data Release with older ones given in ground-based massive catalogs. This process has been followed to build, for example, the PMA catalog using the 2MASS. Our aim is to improve the positions of this catalog (although the process is applicable to any other). The first stage, presented here, consists of carrying out a three-dimensional study using vector spherical harmonics (VSH) development of the systematisms in position for the stars common with Hipparcos-2; we take into account the distances, magnitudes, and spectral types. To this aim, we use linear polynomial regression of first order that fits vector fields and the derivatives of their components. We verify that the coefficients of the developments of first order have different behavior according to the characteristics of stars and distances. To deepen the study, we focus on the conservative component of the field, applying the Helmholtz theorem. Each potential function is obtained solving a Poisson equation on the sphere, after finding the divergence of the corresponding vector field. Both vector and potential fields present patterns, at certain points, that depend on the three considered parameters (distance, magnitude, and spectral type); their sources and shrinks correspond to maxima and minima. In this sense, we observe that these critical points are also critical points of the surface that represents the VT magnitude of Tycho-2, which makes sense because this catalog was used in the reduction of 2MASS positions. Finally, we selected some stars near the critical points of the vector fields and apply the adjustments obtained in the previous sections. The difference with the positions in DR1 allows us to compare the proper motions: those from the PMA and those induced after our corrections.This paper was partially supported by the UJI-B2016-18, 16I356 project.Marco Castillo, FJ.; Martínez Uso, MJ.; Lopez, J. (2019). Global and Local Three-dimensional Studies of The Residual Vector Field from 2MASS and Hipparcos-2 Catalog. Publications of the Astronomical Society of the Pacific. 131(998):1-22. https://doi.org/10.1088/1538-3873/aaed5dS122131998Akhmetov, V. S., Fedorov, P. N., Velichko, A. B., & Shulga, V. M. (2017). The PMA Catalogue: 420 million positions and absolute proper motions. Monthly Notices of the Royal Astronomical Society, 469(1), 763-773. doi:10.1093/mnras/stx812Arenou, F., Luri, X., Babusiaux, C., Fabricius, C., Helmi, A., Robin, A. C., … Bragaglia, A. (2017). Gaia Data Release 1. Astronomy & Astrophysics, 599, A50. doi:10.1051/0004-6361/201629895Astraatmadja, T. L., & Bailer-Jones, C. A. L. (2016). ESTIMATING DISTANCES FROM PARALLAXES. II. PERFORMANCE OF BAYESIAN DISTANCE ESTIMATORS ON AGAIA-LIKE CATALOGUE. The Astrophysical Journal, 832(2), 137. doi:10.3847/0004-637x/832/2/137Astraatmadja, T. L., & Bailer-Jones, C. A. L. (2016). ESTIMATING DISTANCES FROM PARALLAXES. III. DISTANCES OF TWO MILLION STARS IN THEGaiaDR1 CATALOGUE. The Astrophysical Journal, 833(1), 119. doi:10.3847/1538-4357/833/1/119Bailer-Jones, C. A. L. (2015). Estimating Distances from Parallaxes. Publications of the Astronomical Society of the Pacific, 127(956), 994-1009. doi:10.1086/683116Davies, G. R., Lund, M. N., Miglio, A., Elsworth, Y., Kuszlewicz, J. S., North, T. S. H., … Schofield, M. (2017). Using red clump stars to correct theGaiaDR1 parallaxes. Astronomy & Astrophysics, 598, L4. doi:10.1051/0004-6361/201630066Gontcharov, G. A. (2017). Systematic error of the Gaia DR1 TGAS parallaxes from data for the red giant clump. Astronomy Letters, 43(8), 545-558. doi:10.1134/s1063773717060044Jeffreys, S. H. (1967). A Completeness Theorem for Expansions of a Vector Function in Spherical Harmonics. Geophysical Journal International, 12(5), 465-468. doi:10.1111/j.1365-246x.1967.tb03126.xLindegren, L., Lammers, U., Bastian, U., Hernández, J., Klioner, S., Hobbs, D., … Butkevich, A. (2016). GaiaData Release 1. Astronomy & Astrophysics, 595, A4. doi:10.1051/0004-6361/201628714Lindegren, L., Lammers, U., Hobbs, D., O’Mullane, W., Bastian, U., & Hernández, J. (2012). The astrometric core solution for theGaiamission. Astronomy & Astrophysics, 538, A78. doi:10.1051/0004-6361/201117905Makarov, V. V., & Murphy, D. W. (2007). The Local Stellar Velocity Field via Vector Spherical Harmonics. The Astronomical Journal, 134(1), 367-375. doi:10.1086/518242Marco, F. J., Martínez, M. J., & López, J. A. (2004). A critical discussion on parametric and nonparametric regression methods applied to Hipparcos-FK5 residuals. Astronomy & Astrophysics, 418(3), 1159-1170. doi:10.1051/0004-6361:20034441Marco, F. J., Martínez, M. J., & López, J. A. (2013). Homogenization in compiling ICRF combined catalogs. Astronomy & Astrophysics, 558, A98. doi:10.1051/0004-6361/201321995Marco, F. J., Martínez, M. J., & López, J. A. (2015). APPLICATION OF VECTOR SPHERICAL HARMONICS AND KERNEL REGRESSION TO THE COMPUTATIONS OF OMM PARAMETERS. The Astronomical Journal, 149(4), 129. doi:10.1088/0004-6256/149/4/129Masry, E., & Jianqing Fan. (1997). Local Polynomial Estimation of Regression Functions for Mixing Processes. Scandinavian Journal of Statistics, 24(2), 165-179. doi:10.1111/1467-9469.00056Michalik, D., Lindegren, L., & Hobbs, D. (2015). TheTycho-Gaiaastrometric solution. Astronomy & Astrophysics, 574, A115. doi:10.1051/0004-6361/201425310Michalik, D., Lindegren, L., Hobbs, D., & Lammers, U. (2014). Joint astrometric solution of HIPPARCOS andGaia. Astronomy & Astrophysics, 571, A85. doi:10.1051/0004-6361/201424606Mignard, F., & Klioner, S. (2012). Analysis of astrometric catalogues with vector spherical harmonics. Astronomy & Astrophysics, 547, A59. doi:10.1051/0004-6361/201219927De Ridder, J., Molenberghs, G., Eyer, L., & Aerts, C. (2016). Asteroseismic versusGaiadistances: A first comparison. Astronomy & Astrophysics, 595, L3. doi:10.1051/0004-6361/201629799Roeser, S., Demleitner, M., & Schilbach, E. (2010). THE PPMXL CATALOG OF POSITIONS AND PROPER MOTIONS ON THE ICRS. COMBINING USNO-B1.0 AND THE TWO MICRON ALL SKY SURVEY (2MASS). The Astronomical Journal, 139(6), 2440-2447. doi:10.1088/0004-6256/139/6/2440Röser, S., Schilbach, E., Schwan, H., Kharchenko, N. V., Piskunov, A. E., & Scholz, R.-D. (2008). PPM-Extended (PPMX) – a catalogue of positions and proper motions. Astronomy & Astrophysics, 488(1), 401-408. doi:10.1051/0004-6361:200809775Schönrich, R., & Aumer, M. (2017). Assessing distances and consistency of kinematics in Gaia/TGAS. Monthly Notices of the Royal Astronomical Society, 472(4), 3979-3998. doi:10.1093/mnras/stx2189Schwan, H. (2001). An analytical representation of the systematic differences HIPPARCOS-FK5. Astronomy & Astrophysics, 367(3), 1078-1086. doi:10.1051/0004-6361:20000521Simonoff, J. S. (1996). Smoothing Methods in Statistics. Springer Series in Statistics. doi:10.1007/978-1-4612-4026-6Skrutskie, M. F., Cutri, R. M., Stiening, R., Weinberg, M. D., Schneider, S., Carpenter, J. M., … Wheelock, S. (2006). The Two Micron All Sky Survey (2MASS). The Astronomical Journal, 131(2), 1163-1183. doi:10.1086/498708Stassun, K. G., & Torres, G. (2016). EVIDENCE FOR A SYSTEMATIC OFFSET OF −0.25 mas IN THE GAIA DR1 PARALLAXES. The Astrophysical Journal, 831(1), L6. doi:10.3847/2041-8205/831/1/l6Van Leeuwen, F. (2007). Validation of the new Hipparcos reduction. Astronomy & Astrophysics, 474(2), 653-664. doi:10.1051/0004-6361:20078357Van Leeuwen, F. (Ed.). (2007). Hipparcos, the New Reduction of the Raw Data. Astrophysics and Space Science Library. doi:10.1007/978-1-4020-6342-8Vityazev, V. V., & Tsvetkov, A. S. (2009). Analysis of the three-dimensional stellar velocity field using vector spherical functions. Astronomy Letters, 35(2), 100-113. doi:10.1134/s1063773709020042Vityazev, V. V., & Tsvetkov, A. S. (2011). Application of vector spherical harmonics for kinematic analysis of stars from zonal catalogues. Astronomy Letters, 37(12), 874-887. doi:10.1134/s1063773711120103Vityazev, V. V., & Tsvetkov, A. S. (2013). UCAC4: Stellar kinematics with vector spherical functions. Astronomische Nachrichten, 334(8), 760-768. doi:10.1002/asna.201311917Vityazev, V. V., & Tsvetkov, A. S. (2014). Intercomparison of kinematics derived from catalogues UCAC4, PPMXL and XPM with vector spherical harmonics. Monthly Notices of the Royal Astronomical Society, 442(2), 1249-1264. doi:10.1093/mnras/stu953Vityazev, V. V., & Tsvetkov, A. S. (2015). Systematic differences between the positions and proper motions of stars from the PPMXL and UCAC4 catalogs. Astronomy Letters, 41(7), 317-333. doi:10.1134/s1063773715070063Vityazev, V. V., Tsvetkov, A. S., Petrov, S. D., Trofimov, D. A., & Kiyaev, V. I. (2017). Properties of the Tycho-2 catalogue from Gaia data release. Astronomy Letters, 43(11), 730-750. doi:10.1134/s106377371711007xVityazev, V. V., Tsvetkov, A. S., Bobylev, V. V., & Bajkova, A. T. (2017). Galactic Kinematics Derived From Data in the RAVE5, UCAC4, PPMXL, and Gaia TGAS Catalogs. Astrophysics, 60(4), 462-483. doi:10.1007/s10511-017-9499-0Vityazev, V. V., Tsvetkov, A. S., Petrov, S. D., & Trofimov, D. A. (2017). Comparison of XPM and UCAC4 catalogues in the galactic coordinate system. Astronomische Nachrichten, 338(4), 489-502. doi:10.1002/asna.201613220Zacharias, N., Finch, C., & Frouard, J. (2017). UCAC5: New Proper Motions UsingGaiaDR1. 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    Rotation of the Universe and the angular momenta of celestial bodies

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    We discuss the equation of motion of the rotating homogenous and isotropic model of the Universe. We show that the model predicts the presence of a minimum in the relation between the mass of an astronomical object and its angular momentum. We show that this relation appears to be universal, and we predict the masses of structures with minimal angular momenta in agreement with observations. In such a manner we suggest the possibility at acquirement of angular momenta of celestial bodies during their formation from the global rotation of the Universe.Comment: 10 pages 2 figure

    Metabolomic and transcriptomic analysis of the rice response to the bacterial blight pathogen Xanthomonas oryzae pv. oryzae

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    Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae (Xoo), gives rise to devastating crop losses in rice. Disease resistant rice cultivars are the most economical way to combat the disease. The TP309 cultivar is susceptible to infection by Xoo strain PXO99. A transgenic variety, TP309_Xa21, expresses the pattern recognition receptor Xa21, and is resistant. PXO99△raxST, a strain lacking the raxST gene, is able to overcome Xa21-mediated immunity. We used a single extraction solvent to demonstrate comprehensive metabolomics and transcriptomics profiling under sample limited conditions, and analyze the molecular responses of two rice lines challenged with either PXO99 or PXO99△raxST. LC–TOF raw data file filtering resulted in better within group reproducibility of replicate samples for statistical analyses. Accurate mass match compound identification with molecular formula generation (MFG) ranking of 355 masses was achieved with the METLIN database. GC–TOF analysis yielded an additional 441 compounds after BinBase database processing, of which 154 were structurally identified by retention index/MS library matching. Multivariate statistics revealed that the susceptible and resistant genotypes possess distinct profiles. Although few mRNA and metabolite differences were detected in PXO99 challenged TP309 compared to mock, many differential changes occurred in the Xa21-mediated response to PXO99 and PXO99△raxST. Acetophenone, xanthophylls, fatty acids, alkaloids, glutathione, carbohydrate and lipid biosynthetic pathways were affected. Significant transcriptional induction of several pathogenesis related genes in Xa21 challenged strains, as well as differential changes to GAD, PAL, ICL1 and Glutathione-S-transferase transcripts indicated limited correlation with metabolite changes under single time point global profiling conditions

    Myelin Proteomics: Molecular Anatomy of an Insulating Sheath

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    Fast-transmitting vertebrate axons are electrically insulated with multiple layers of nonconductive plasma membrane of glial cell origin, termed myelin. The myelin membrane is dominated by lipids, and its protein composition has historically been viewed to be of very low complexity. In this review, we discuss an updated reference compendium of 342 proteins associated with central nervous system myelin that represents a valuable resource for analyzing myelin biogenesis and white matter homeostasis. Cataloging the myelin proteome has been made possible by technical advances in the separation and mass spectrometric detection of proteins, also referred to as proteomics. This led to the identification of a large number of novel myelin-associated proteins, many of which represent low abundant components involved in catalytic activities, the cytoskeleton, vesicular trafficking, or cell adhesion. By mass spectrometry-based quantification, proteolipid protein and myelin basic protein constitute 17% and 8% of total myelin protein, respectively, suggesting that their abundance was previously overestimated. As the biochemical profile of myelin-associated proteins is highly reproducible, differential proteome analyses can be applied to material isolated from patients or animal models of myelin-related diseases such as multiple sclerosis and leukodystrophies
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