bluuebunny/crossref_metadata_2025 huggingface dataset:
Abundance patterns in stars in the bulge and Galactic center
Authors: Cunha Katia , Smith V. V. , Sellgren K. , Blum R. D. , Ramírez S. V. , Terndrup D. M.
Published: July 2008

We discuss oxygen and iron abundance patterns in K and M red-giant members of the Galactic bulge and in the young and massive M-type stars inhabiting the very center of the Milky Way. The abundance results from the different bulge studies in the literature, both in the optical and the infrared, indicate that the [O/Fe]-[Fe/H] relation in the bulge does not follow the disk relation, with [O/Fe] values falling above those of the disk. Based on these elevated values of [O/Fe] extending to large Fe abundances, it is suggested that the bulge underwent a rapid chemical enrichment with perhaps a top-heavy initial mass function. The Galactic Center stars reveal a nearly uniform and slightly elevated (relative to solar) iron abundance for a studied sample which is composed of 10 red giants and supergiants. Perhaps of more significance is the fact that the young Galactic Center M-type stars show abundance patterns that are reminiscent of those observed for the bulge population and contain enhanced abundance ratios of α-elements relative to either the Sun or Milky Way disk at near-solar metallicities.
3-D kinematics in low foreground extinction windows of the Galactic bulge
Authors: Soto M. , Kuijken K. , Rich R. M.
Published: July 2008

We report the progress in our measurement of the 3-D kinematics in several low foreground extinction windows of the Galactic Bulge. In order to complete the 3-D kinematics of as many stars as possible, proper motions and radial velocities have been obtained using HST WFPC2-ACS and VLT VIMOS respectively. Our preliminary results for fields close to the galactic minor axis show a significant vertex deviation, which can be directly related to a signature of triaxility. This is one of the strongest proofs to date of the presence of the stellar bar in the galactic bulge.
JASMINE: constructor of the dynamical structure of the Galactic bulge
Authors: Gouda N. , Kobayashi Y. , Yamada Y. , Yano T. , Tsujimoto T. , Suganuma M. , Niwa Y. , Yamauchi M. ,   JASMINE Working Group
Published: July 2008

We introduce a Japanese space astrometry project which is called JASMINE. JASMINE (Japan Astrometry Satellite Mission for INfrared Exploration) will measure distances and tangential motions of stars in the Galactic bulge with yet unprecedented precision. JASMINE will operate in z-band whose central wavelength is 0.9 micron. It will measure parallaxes, positions with accuracy of about 10 micro-arcsec and proper motions with accuracy of about 10 micro- arcsec/year for the stars brighter than z=14 mag. The number of stars observed by JASMINE with high accuracy of parallaxes in the Galactic bulge is much larger than that observed in other space astrometry projects operating in optical bands. With the completely new “map of the Galactic bulge” including motions of bulge stars, we expect that many new exciting scientific results will be obtained in studies of the Galactic bulge. One of them is the construction of the dynamical structure of the Galactic bulge. Kinematics and distance data given by JASMINE are the closest approach to a view of the exact dynamical structure of the Galactic bulge.

Presently, JASMINE is in a development phase, with a target launch date around 2016. We comment on the outline of JASMINE mission, scientific targets and a preliminary design of JASMINE in this paper.
Uncloaking globular clusters of the inner Galaxy
Authors: Alonso-García Javier , Mateo Mario , Sen Bodhisattva
Published: July 2008

We intend to map the differential extinction and remove their effects in a sample of clusters in the direction of the inner Galaxy using a new dereddening technique. These observations and their analyses will let us produce high quality color-magnitude diagrams of these poorly studied clusters that will allow us to determine these clusters' relative ages, distances and chemistry and to address important questions about the formation and the evolution of the inner Galaxy.
Stellar proper motions in the Galactic bulge with ACS/WFC on HST
Authors: Clarkson Will , Sahu Kailash , Anderson Jay , Smith T. Ed , Brown Thomas M. , Casertano Stefano , Rich R. Michael , Bond Howard E. , Brown Timothy , Livio Mario , Minniti Dante , Panagia Nino , Renzini Alvio , Valenti Jeff , Zoccali Manuela
Published: July 2008

In 2004 the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) project undertook a very deep ACS/WFC exposure-set of the Sgr-I low-reddening window in the Galactic Bulge, with repeat observations 2.04 years later. The combination of superb first-epoch sampling, wide field of view and high PSF stability of ACS/WFC on Hubble allows proper motions to be extracted for more than 137,000 objects, over 85,000 to accuracy better than 0.3 mas yr−1. We present these proper motions and outline some of the uses to which they have been put, including the separation of a pure-Bulge sample and the inner Galactic rotation curve.
Red-giant branch morphology of metal-poor globular clusters in the Galactic bulge
Authors: Kim J. W. , Kim H. I. , Sohn Y. J.
Published: July 2008

Using the (J − K, K) color-magnitude diagrams (CMDs) of 16 metal-poor globular clusters in the Galactic bulge, we investigate the morphological properties of their red-giant branch (RGB), comparing with those of metal-rich clusters in the Galactic bulge and metal-poor clusters in the Galactic halo. The RGB morphological parameters, such as colors at fixed magnitudes, magnitudes at a fixed color, the RGB slope, and a difference of color indices at two fixed magnitudes have been derived from the near-IR CMDs for each cluster. Metal-poor Galactic bulge clusters follow the previous empirical relations between colors at fixed magnitudes and magnitudes at a fixed color of the RGB and the cluster's metallicity. However, the RGB slope and the color difference parameters of some bulge clusters deviate slightly from the previous empirical linear relations for the other globular clusters, implying that the metal-poor bulge clusters may have different formation origin from the other globular clusters in the Galaxy.
The evolution of the Galactic bulge from planetary nebulae
Authors: Maciel Walter J. , Costa R. D. D. , Escudero A. V.
Published: July 2008

We have used our dataset on the abundances of planetary nebulae (PN) to study the chemical evolution of the Galactic bulge. We have derived several relations involving the chemical abundances and computed three classes of models for the Galactic bulge: (i) one-zone, single-infall models, (ii) one-zone, double-infall models and (iii) multizone, double infall models. We conclude that part of the observational data can be understood in terms of the simpler models, but the full understanding of all observational constraints can only be explained by more complex multizone models.
Evidence of outflow from the Galactic bulge imprinted in stellar elemental abundances
Authors: Tsujimoto Takuji
Published: July 2008

We explore the elemental abundance features of metal-rich disk stars, highlighting the comparisons made with those of the recently revealed Galactic bulge stars. A similarity between two of the comparisons leads to a new theoretical picture of the bulge-disk connection in the Galaxy, where a supermassive black hole resides at the center. We postulate that a metal-rich outflow, triggered by feedback from a black hole, was generated and quenched the star formation, which had lasted several billion years in the bulge. The expelled gas cooled down in the Galactic halo without escaping from the gravitational potential of the Galaxy. The gas gradually started to accrete to the disk around five billion years ago, corresponding to the time of sun's birth, and replaced a low-metallicity halo gas that had been accreting over nearly ten billion years. The metal-rich infalling gas, whose elemental abundance reflects that of metal-rich bulge stars, mixed with the interstellar gas already present in the disk. Stars formed from the mixture compose the metal-rich stellar disk.
The position angle of the Galactic bulge
Authors: Vallenari A. , Ragaini S. , Bertelli G.
Published: July 2008

We present a study of the structure of the Galactic Bulge in the region −6° < b < 3°,−17° < l < 17° using 2MASS archive data. More than 100 fields are used. We make use of the red clump method to derive the distance of the Bulge in the studied regions. We derive a position angle of the Galactic Bulge going from 42° ± 11 to 35° ± 10 depending on the adopted bulge mass distribution.
Properties of luminous spheroids at redshiftsz~ 1 from Keck and HST
Authors: Koo David C. ,   DEEP and CATS Teams
Published: July 2008

Three new and still on-going surveys that combine the power of spectroscopy or adaptive optics from the Keck Telescopes with HST images are DEEP, AEGIS, and CATS. The advantages of each for the study of distant bulges are accompanied by a few highlights. We find that the vast fraction of luminous distant bulges appear very red, independent of the bulge luminosity, bulge fraction, disk color, and environment. Yet early-type galaxies appear to be relatively young at redshiftsz~ 1, are less numerous then, host many X-ray AGN's with some that are highly obscured, and have low but increasing dry-dry and dry-wet merger rates over time.
Star formation in bulges from GALEX
Authors: Yi Sukyoung K.
Published: July 2008

Early-type galaxies, considered as large bulges, have been found to have had a much-more-than-boring star formation history in recent years by the UV satellite GALEX. The most massive bulges, brightest cluster galaxies, appear to be relatively free of young stars. But smaller bulges, normal ellipticals and lenticulars, often show unambiguous sign of recent star formation in their UV flux. The fraction of such UV-bright bulges in the volume-limited sample climbs up to the staggering 30%. The bulges of spirals follow similar trends but a larger fraction showing signs of current and recent star formation. The implication on the bulge formation and evolution is discussed.
Young stellar populations in early-type galaxies in the SDSS
Authors: Nolan Louisa A. , Kabán Ata , Harva Markus , Benson Andrew , Raychaudhury Somak
Published: July 2008

We use a purely data-driven rectified factor analysis to identify early-type galaxies with young (≲ 4 Gyr) stellar populations in the Sloan Digital Sky Survey Spectroscopic Catalogue. We call these galaxies E+F galaxies, analogous to E+A galaxies. These galaxies lie in the ‘Green Valley’, between the blue cloud and the red sequence on the colour-magnitude diagram. As such, these galaxies may represent an important transient stage in the evolution of galaxies from blue and star-forming to red and passive. We investigate the distribution in projected local galaxy surface density of the E+F galaxies, and compare it with the environment of early-type and E+A galaxies. We find that i) the E+A distribution peaks strongly in projected local galaxy surface density, Σ5, at ~ 0.1−0.2 Mpc−2, ii) early-types have a flatter peak at ~ 0.06−0.2 Mpc−2, iii) the E+Fs lie somewhere in between, and iv) the distributions of the models do not agree well with the data, peaking at higher densities, and under-predicting the number of E+As at low (Σ5 < 0.3 Mpc−2) densities. The dearth of E+A and E+F galaxies in dense environments confirms that E+A and E+F galaxies are most likely the products of galaxy-galaxy merging or interactions, rather than star-forming galaxies whose star formation has been quenched by processes unique to dense environments, such as ram-pressure stripping or galaxy harassment. The similarity of the environments in which the E+F population and the E+A galaxy sample are found, together with the spectral evidence, suggests that E+F galaxies are E+A galaxies, which have evolved by a further ~ one to a few Gyr.
Galaxy scaling relations from the ACS Virgo and Fornax Cluster Surveys: no evidence for a dwarf-giant dichotomy
Authors: Côté Patrick , Ferrarese Laura , Jordán Andrés , Blakeslee John P. , Chen Chin-Wei , Infante Leopoldo , Mei Simona , Peng Eric W. , Tonry John L. , West Michael J.
Published: July 2008

We examine the photometric and structural properties of early-type galaxies derived from theACS Virgo and Fornax Cluster Surveys, supplementing these data with previously published or newly reanalysed data for additional early-type galaxies in Virgo, Fornax and the Local Group. As we have noted elsewhere, Sérsic models are found to provide accurate representations of the observed brightness profiles on scales greater than a few percent of the effective radius,Re. On smaller scales, the brightness profiles of bright (MB≳ −20) galaxies show centraldeficitswith respect to the inward extrapolation of the Sérsic models; fainter galaxies usually show centralexcesses. Fainter thanMB≈ −20, we find a continuity in the photometric and structural scaling relations: i.e., between absolute magnitude, central surface brightness, Sérsic index, effective radius, and the surface brightness measured at, and averaged within, the effective radius. There is no evidence for a “dwarf/giant dichotomy” — a conclusion consistent with a number of recent studies but contrary to some earlier claims.
The 6dF Galaxy Survey: a low-redshift benchmark for bulge-dominated galaxies
Authors: Colless Matthew , Jones Heath , Proctor Rob , Harrison Craig , Campbell Lachlan , Lah Philip
Published: July 2008

The 6dF Galaxy Survey provides a very large sample of galaxies with reliable measurements of Lick line indices and velocity dispersions. This sample can be used to explore the correlations between mass and stellar population parameters such as age, metallicity and [α/Fe]. Preliminary results from such an analysis are presented here, and show that age and metallicity are significantly anti-correlated for both passive and star-forming galaxies. Passive galaxies have strong correlations between mass and metallicity and between age and α-element over-abundance, which combine to produce a downsizing relation between age and mass. For old passive galaxies, the different trends of M/L with mass and luminosity in different passbands result from the differential effect of the mass–metallicity relation on the luminosities in each passband. Future work with this sample will examine the Fundamental Plane of bulge-dominated galaxies and the influence of environment on relations between stellar population parameters and mass.
Ages and metallicities of faint red galaxies in the Shapley Supercluster
Authors: Smith Russell J. , Lucey John R. , Hudson Michael J.
Published: July 2008

We present results on the stellar populations of 232 quiescent galaxies in the Shapley Supercluster, based on spectroscopy from the AAOmega spectrograph at the AAT. The key characteristic of this survey is its coverage of many low-luminosity objects (σ ~ 50 kms−1), with high signal-to-noise (~45 Å−1). Balmer-line age estimates are recovered with ~25% precision even for the faintest sample members. We summarize the observations and absorption line data, and present correlations of derived ages and metallicities with mass and luminosity. We highlight the strong correlation between age and α-element abundance ratio, and the anti-correlation of age and metallicity at fixed mass, which is shown to extend into the low-luminosity regime.
Measuring the cosmic star-formation rate density using deep radio surveys
Authors: Dwelly T. , Seymour N. , McHardy I. M. , Moss D. , Page M. , Hopkins A. , Loaring N. , Zhogbi A.
Published: July 2008

There is now good agreement between the various methods of estimating the space density of the star-formation rate (SFRD) at low redshifts (z < 1), with uncertainties around 30–50%. However, the situation at higher redshifts remains much less clear, with uncertainties in the SFRD, due to e.g. poorly known dust absorption corrections, of as much as 300–500%. Radio emission from star-forming galaxies is unaffected by absorption and scales linearly with star-formation rate, thus the radio luminosity of star-forming galaxies provides an excellent independent, unbiased measure of their star-formation rate. The current deepest ‘blank field’ radio surveys (reaching <10 μJy rms at 1.4 GHz) are sensitive enough to detect starburst galaxies out to z ~ 3, and so potentially offer an excellent way to measure the SFRD. Indeed, modelling of the sub-mJy source counts requires an additional population of faint steep spectrum objects, that are very likely to be starburst galaxies.
Finding galaxy clusters with spectro-photometric density in SDSS
Authors: Yoon Joo H. , Schawinski Kevin , Sheen Yun-Kyeong , Ree Chang H. , Yi Sukyoung K.
Published: July 2008

We have attempted to overcome the incompleteness of spectroscopic survey and found galaxy clusters by measuring the spectro-photometric density of galaxies.
The z = 0.8 precursors of today's bulges
Authors: Balcells Marc , Domínguez-Palmero Lilian
Published: July 2008

We study the color structure of disk galaxies in the Groth strip at redshifts 0.1 < z < 1.2. Our aim is to test formation models in which bulges form before/after the disk. We find smooth color distributions with gentle outward blueing across the galaxy image: bulges are not distinctly redder than their disks; and bulge colors strongly correlate with global colors. The results suggest a roughly coeval evolution of bulges and disks. About 50% of the nuclei of galaxies with central light excesses above the outer exponential profile hold passively evolving red populations. The remainder 50% are galaxies with central blue colors similar to their disks. They may be bulges in formation, or the central parts of disks with non-exponential surface brightness profiles.
Adaptive optics imaging of Lyman break galaxies as progenitors of spheroids in the local Universe
Authors: Akiyama M. , Minowa Y. , Kobayashi N. , Ohta K. , Iwata I.
Published: July 2008

In order to reveal the stellar mass distribution of z ~ 3 galaxies, we are conducting deep imaging observations of U-dropout Lyman Break Galaxies (LBGs) with Adaptive Optics (AO) systems in K-band, which corresponds to rest-frame V-band of z ~ 3 galaxies. The results of the Subaru intensive-program observations with AO36/NGS/IRCS indicate that 1) the K-band peaks of some of the LBGs brighter than K = 22.0 mag show significant offset from those in the optical images, 2) the z ~ 3 $M_{V}^{*}$ LBGs and serendipitously observed Distant Red Galaxies (DRGs) have flat profiles similar to disk galaxies in the local universe (i.e., Sérsic with n < 2), and 3) the surface stellar mass densities of the $M_{V}^{*}$ LBGs are 3-6 times larger than those of disk galaxies at z = 0 − 1. Considering the lack of n > 2 systems among the luminous z ~ 3 LBGs and DRGs, and their strong spatial clustering, we infer that the dense n < 2 disk-like structures evolve into the n > 2 spheroids of nearby galaxies through relaxations due to major merger events.
Spitzer view of Lyman break galaxies
Authors: Magdis Georgios E. , Rigopoulou Dimitra
Published: July 2008

Using a combination of deep MID-IR observations obtained by IRAC, MIPS and IRS on board Spitzer we investigate the MID-IR properties of Lyman Break Galaxies (LBGs) at z~3, establish a better understanding of their nature and attempt a complete characterisation of the population. With deep mid-infrared and optical observations of ~1000 LBGs covered by IRAC/MIPS and from the ground respectively, we extend the spectral energy distributions (SEDs) of the LBGs to mid-infrared. Spitzer data reveal for the first time that the mid-infrared properties of the population are inhomogeneous ranging from those with marginal IRAC detections to those with bright rest-frame near-infrared colors and those detected at 24μm MIPS band revealing the newly discovered population of the Infrared Luminous Lyman Break Galaxies (ILLBGs). To investigate this diversity, we examine the photometric properties of the population and we use stellar population synthesis models to probe the stellar content of these galaxies. We find that a fraction of LBGs have very red colors and large estimated stellar masses M∗>5×1010M⊙. We discuss the link between these LBGs and submm-luminous galaxies and we report the detection of rest frame 6.2 and 7.7 μm emission features arising from Polycyclic Aromatic Hydrocarbons (PAH) in the Spitzer/IRS spectrum of an infrared-luminous Lyman break galaxy at z=3.01.
Symposium summary: dynamics
Authors: Binney James
Published: July 2008

Pseudobulges form from unstable disks, while classical bulges form in violent episodes of star formation when a merger sweeps cold gas to a galactic centre. It seems unlikely that smashed disks contribute much to classical bulges. During mergers central black holes make cusps shallower and inflate kinematically decoupled cores. The abundance of galaxies with no detected classical bulge can perhaps be understood if galaxies exchange gas with the IGM more freely than is often supposed.
Symposium summary: stellar populations in bulges
Authors: Barbuy Beatriz
Published: July 2008

Stellar populations in the Milky Way and in external galaxies are reviewed, based on the conferences and posters presented at this meeting.
Colours of intermediate z bulges in Groth and GOODS-N
Authors: Domínguez-Palmero Lilian , Balcells Marc
Published: July 2008

The chronology of bulge and disk formation is a major unsolved issue in galaxy formation, which impacts on our global understanding of the Hubble sequence. We present colours of the nuclear regions of intermediate-redshift disk galaxies, with the aim of obtaining empirical information of ages of bulges at intermediate z. We work with a sample of 248 galaxies (123 inclined + 125 face-on) from the HST Groth Strip Survey (Groth et al. 1994) and another one with 404 objects (214 inclined + 190 face-on) from the HST GOODS-N field (Giavalisco et al. 2004), covering redshifts 0.1 < z < 1.3. Those samples are apparent-diameter limited at R > 1.4″. We find that, as in the Local Universe, the minor axis color profiles are negative (bluer outward), and fairly gentle, indicating that bulge colours are not distinctly different from disk colours. We apply a conservative criterion to identify bulges and potential precursors of present-day bulges, based on nuclear excess surface brightness above the exponential profile of the outer parts. For galaxies with central brightness excesses, rest-frame colour distributions show a red sequence that confirms the finding of very red bulges by Koo et al. (2005), using independent methods. In contrast, galaxies without central brightness excesses show typical colours of star-forming populations. Clearly, something had truncated star formation in many high-density cores, already at z ~ 1. The truncation epoch is uncertain, 1.5 < z < 10. The colour-magnitude distribution of intermediate-z bulges shows more colour dispersion than that of bulges in the Local Universe. About 50% of bulges are as red as local bulges, while the remainder are significantly bluer, a possible sign of late bulge formation. We also find that bulge colours correlate with integrated galaxy colours and with their disk colours.
Intense starbursts at z~5: first significant stellar mass assembly in the progenitors of present-day spheroids
Authors: Verma Aprajita , Lehnert Matthew , Schreiber Natascha Förster , Bremer Malcolm , Douglas Laura
Published: July 2008

High redshift galaxies play a key role in our developing understanding of galaxy formation and evolution. Since such galaxies are being studied within a Gyr of the big bang, they provide a unique probe of the physics of one of the first generations of large-scale star-formation. We have performed a complete statistical study of the physical properties of a robust sample of z~5 UV luminous galaxies selected using the Lyman-break technique. The characteristic properties of this sample differ from LBGs at z~3 of comparable luminosity in that they are a factor of ten less massive (~few×109 M⊙) and the majority (~70%) are considerably younger (<100Myr). Our results support no more than a modest decline in the global star formation rate density at high redshifts and suggest that ~1% of the stellar mass density of the universe had already assembled at z~5. The constraint derived for the latter is affected by their young ages and short duty cycles which imply existing z~5 LBG samples may be highly incomplete. These intense starbursts have high unobscured star formation rate surface densities (~100s M⊙ yr−1 kpc−2), suggesting they drive outflows and winds that enrich the intra- and inter-galactic media with metals. These properties imply that the majority of z~5 LBGs are in formation meaning that most of their star-formation has likely occurred during the last few crossing times. They are experiencing their first (few) generations of large-scale star formation and are accumulating their first significant stellar mass. As such, z~5 LBGs are the likely progenitors of the spheroidal components of present-day massive galaxies (supported by their high stellar mass surface densities and their core phase-space densities).
Astrometry with ground-based interferometers
Authors: Boden A. , Quirrenbach A.
Published: July 2008

We review the status of ground-based interferometric astrometry. This will include a review of technology and results in differential techniques (e.g. relative orbit determination), as well as global astrometry techniques (globally-registered parallax and proper-motion estimates).
Taming the binaries
Authors: Pourbaix D.
Published: July 2008

Astrometric binaries are both a gold mine and a nightmare. They are a gold mine because they are sometimes the unique source of orbital inclination for spectroscopic binaries, thus making it possible for astrophysicists to get some clues about the mass of the often invisible secondary. However, this is an ideal situation in the sense that one benefits from the additional knowledge that it is a binary for which some orbital parameters are somehow secured (e.g. the orbital period). On the other hand, binaries are a nightmare, especially when their binary nature is not established yet. Indeed, in such cases, depending on the time interval covered by the observations compared to the orbital period, either the parallax or the proper motion can be severely biased if the successive positions of the binary are modelled assuming it is a single star. With large survey campaigns sometimes monitoring some stars for the first time ever, it is therefore crucial to design robust reduction pipelines in which such troublesome objects are quickly identified and either removed or processed accordingly. Finally, even if an object is known not to be a single star, the binary model might turn out not to be the most appropriate for describing the observations. These different situations will be covered.
A new all-sky catalog of stars with large proper motions
Authors: Lépine S. , Shara M. M. , Rich R.-M. , Wittenberg A. , Halmo M. , Bongiorno B.
Published: July 2008

A new all-sky catalog of stars with proper motions μ > 0.15″ yr−1 is presented. The catalog is largely a product of the SUPERBLINK survey, a data-mining initiative in which the entire Digitized Sky Surveys are searched for moving stellar sources. Findings from earlier proper motions surveys are also incorporated. The new all-sky catalog supersedes the great historic proper motion catalogs assembled by W. J. Luyten (LHS, NLTT), and provides a virtually complete > 98% census of high proper motion stars down to magnitude R = 19.
Brown Dwarf Kinematics Project (BDKP)
Authors: Faherty J. , Cruz K. , Burgasser A. , Walter F. , Shara M.
Published: July 2008

We report on the progress of the Brown Dwarf Kinematics Project (BDKP), which aims to measure the 6D positions and velocities of all known brown dwarfs within 20 pc of the Sun and select sources of scientific interest. In this paper we report on the status of the 33 targets on our parallax list as well as the results of our proper motion survey where we have measured over 400 new proper motions for known late M, L and T dwarfs.
Non-tidal vertical variations and the past star catalogs
Authors: Li Z. X.
Published: July 2008

Tidal vertical variations have been removed in astrometric observations, but the non-tidal ones remain unknown. From the repeated observations of gravimetric networks in China, the non-tidal vertical variations at Beijing-Tangshan and West Yunnan are determined, which are of the order of 0.″2. Astrometric results, including past star catalogs, based on these observations should be corrected.
Application of MGC method to centering saturated and stretched images
Authors: Mao Y. D. , Li Y. , Tang Z. H.
Published: July 2008

Sometimes saturated and stretched star images with bad data in their central parts may result in astronomical CCD observations. Considering the special characteristics of the saturated and stretched star images, a method known as MGC(Mean-Geometric-Centering) is put forward for determining the centers of these images. The basic principles and processing pipelines of MGC are introduced, and several noteworthy items in the realization of MGC are discussed. Results of applying MGC to simulated and real data are also presented.
A compiled catalogue of reference stars around the selected ERS in the northern sky
Authors: Ryl'kov V. P. , Narizhnaja N. , Dement'eva A. , Maigurova N. , Pinigin G. I. , Protsyuk Y.
Published: July 2008

A compiled catalogue consisting of more than 22000 reference stars in the range of 10m – 16m obtained with 235 fields of δ from −17° to +80° around extragalactic radio sources (ERS) selected from the ICRF list. Initial catalogues were obtained from photographic (PG) and CCD observations.
Astrometry with ALMA: a giant step from 0.1 arcsecond to 0.1 milliarcsecond in the sub-millimeter
Authors: Lestrade J.-F.
Published: July 2008

We discuss astrometric capabilities of the future interferometer ALMA that will be located at a high altitude site (5000m) in Northern Chile to operate in the sub-millimeter range. In this paper, we estimate the astrometric precision of ALMA to be ~0.18 milliarcsecond at the optimum observing frequency of 345 GHz from an error budget including the thermal noise and the systematic errors caused by uncertainties in antenna coordinates, reference source coordinates, Earth orientation parameters, dry atmosphere parameter and by phase fluctuations due to moisture above the site. We briefly discuss three applications: first, astrometric search of exoplanets around 446 nearby stars detectable by ALMA; second, proper motions and parallaxes of pre-stellar cores and protostars; third, the rotation rate of the debris disk around ε Eri to test the theory of dust trapping in mean motion resonances with unseen planets.
The Chinese VLBI network and its astrometric role
Authors: Li J. L. , Guo L. , Zhang B.
Published: July 2008

In this report we present the current status of the Chinese VLBI network (CVN), and the results of satellite tracking experiments in the past few years related to realtime processing of the CVN dataflow and the reliability and precision of the CVN measurements. We briefly outline the prospective astrometric roles of CVN in the studies of long-term monitoring of extragalactic radio sources, densification of radio celestial reference frame, determination of Earth Orientation Parameters and linkage parameters of reference frames as well as the observation of pulsars for deep space autonomous navigation.
The distance to an outer Galaxy star forming region
Authors: Hachisuka K. , Brunthaler A. , Reid M. J. , Menten K. M.
Published: July 2008

We performed phase-referencing VLBI astrometric observations of the H2O maser source IRAS 02395+6244, located well beyond the solar circle. We measured its heliocentric distance to be 5.49 ± 0.80 kpc, implying a Galactocentric distance of 12.5 ± 0.5 kpc and a distance of 270 ± 40 pc above the Galactic plane.
Astrometry with SIM PlanetQuest
Authors: Shao M.
Published: July 2008

SIM PlanetQuest is a very high accuracy space astrometric instrument based on a long baseline stellar interferometer. For global astrometry SIM was designed to be accurate to ≈ 4μas(microarcsec) after a 5 year mission. For narrow angle astrometry (≈ 1000 s integration over a 1° radius field) SIM is designed for 1μas precision. The technology program was completed in 2005 and based on laboratory results, the current best estimate of SIM's performance would be 0.6 μas for narrow angle precision and 2.4 μas for global accuracy. This paper describes a variety of science programs that the SIM science team have proposed to conduct from a search for one Earth mass planets in the habitable zone of (≈130) nearby stars to the study of dark matter in the galactic disk, the galactic halo and the local group.
Measuring proper motions of galactic dwarf galaxies with Hubble Space Telescope
Authors: Piatek S. , Pryor C.
Published: July 2008

Over the past several years, our research group has been measuring proper motions for nearby dwarf satellite galaxies using data taken with the Hubble Space Telescope. In order to measure proper motions with an expected size of several tens of milliarcseconds per century using a time baseline of 2-4 years, our work required that positions of stars and QSOs be measured to an accuracy of ~0.25 mas (~0.005 pixel). This contribution reviews the scientific justification of this work and our methodology. It concludes with a few general results and future directions.
CTE in Space Astrometry
Authors: Kozhurina-Platais V. , Sirianni M. , Chiaberge M.
Published: July 2008

An imperfect CTE in CCD detectors is one of the most important instrumental issues affecting both photometry and astrometry, especially in space-based observations. We discuss the CTE effect in the images taken with the Hubble Space Telescope's, Advanced Camera for Surveys in Wide Field Channel (ACS/WFC). ACS is the only imaging instrument capable of delivering sub-mas astrometry from a single observation, and it is important to take into account any instrumental systematic in positions such as the CTE effect.
A Star Image Extractor for the Nano-JASMINE satellite
Authors: Yamauchi M. , Gouda N. , Kobayashi Y. , Tsujimoto T. , Yano T. , Suganuma M. , Yamada Y. , Nakasuka S. , Sako N.
Published: July 2008

We have developped a software of Star-Image-Extractor (SIE) which works as the on-board real-time image processor. It detects and extracts only the object data from raw image data. SIE has two functions: reducing image data and providing data for the satellite's high accuracy attitude control system.
Astrometric microlensing with the RadioAstron space mission
Authors: Zakharov A. F.
Published: July 2008

According to a revised schedule of the Russian Space Agency, in October 2008 the 10 m space telescope RadioAstron will be launched in a high eccentric orbit around the Earth. Acting together with ground based radio telescopes, the VLBI interferometer with a ground-space arm will operate. The interferometer will have extraordinary angular resolution of a few microarcsecond (μas) at the shortest wavelength (1.35 cm). Since typical angular scales for gravitational microlensing are at the μas level for cosmological locations of sources and microlenses, in principle there is a chance to resolve microimages and (or) at least, detect astrometrical shift of bright point like images. In particular, gravitationally lensed systems, such as B1600+434, where in radio band a signature of microlensing is found, look suitable for direct observations of microlensing, since microlensing with the RadioAstron interferometer may be detected in the future (considering its high angular resolution and a relatively high sensitivity and assuming a ground support by the advanced radio telescopes).
The luminosity function of nearby thick-disk sub-dwarfs
Authors: Arifyanto M. I.
Published: July 2008

We derived the luminosity function of thick disk using V/Vmax method for nearby sub-dwarf stars based on the sample stars of Carney et al. (1994). Hipparcos parallaxes and proper motions and Tycho2 proper motions were combined with radial velocities and metallicities from CLLA. We found that the luminosity function in the absolute magnitude range MV = 4–6 mag agree well with the luminosity function derived from the initial mass function (Reyle & Robin 2001).
Age-Metallicity Relation, [Fe/H] and [α/Fe] vertical gradients in the Milky Way from the SDSS–DR5 spectroscopic database
Authors: Morossi C. , Franchini M. , Di Marcantonio P. , Malagnini M. L.
Published: July 2008

Spectra of FGK stars were selected from the SDSS–DR5 spectroscopic database to investigate the Age-Metallicity relation and the [Fe/H] and [α/Fe] vertical gradients in the Milky Way. Atmospheric parameters and [α/Fe] were derived by comparing synthetic and measured Lick/SDSS spectral indices. Results were checked and complemented by analyzing solar neighbourhood stars. Spectroscopic distances and ages were obtained for a subsample of ~2000 stars using theoretical isochrones via a Bayesian approach. The resulting Age-Metallicity diagram and the [Fe/H] and [α/Fe] vertical gradients are presented.
TW Hydrae astrometric parameters measurement
Authors: Teixeira R. , Ducourant C. , Chauvin G. , Krone-Martins A. G. O. , le Campion J.-F. , Song I. , Zuckerman B.
Published: July 2008

The primary goal of this study was measurement of trigonometric parallaxes and proper motions of a dozen members of the TW Hydrae Association (TWA) that are not present in the Hipparcos catalogue.
Hipparcos data supporting the IB school curriculum
Authors: O'Flaherty K. S. , Brumfitt A. , Lawton C.
Published: July 2008

The Hipparcos and Tycho catalogues are ideal data sources for classwork since they provide real data illustrating fundamental astronomical concepts in a simple and easy to manipulate format. In this poster we describe how some of this data is used as support material within the International Baccalaureate (IB) science curriculum. The preparation and deployment of a series of Teacher Notes, specifically constructed to support the IB but applicable to other curricula, is described. Specific attention is given to the Teacher Notes on Stellar Distances which employs data from the Hipparcos and Tycho catalogues.
The extended solar neighborhood: precision astrometry from the Pan-STARRS 1 3π Survey
Authors: Magnier E. A. , Liu M. , Monet D. G. , Chambers K. C.
Published: July 2008

The Pan-STARRS pathfinding telescope PS1 will begin a major set of surveys starting in 2008, and lasting for 3.5 years. One of these, the PS1 3π Survey, will repeatedly observe the entire sky north of −30 degrees, visiting every position 12 times in each of 5 filters. With single-epoch astrometry of 10 milliarcseconds, these observations will yield parallaxes for stars within 100 pc and proper motions out to several hundred pc. The result will be an unprecedented view on nearby stellar populations and insight into the dynamical structure of the local portions of the Galaxy. One exciting science product will be a volume-limited sample of nearby low-mass objects including thousands of L dwarfs, hundreds of T dwarfs, and perhaps even cooler sub-stellar objects. Another project will use proper-motion measurements to improve the membership of nearby star forming regions.
PMOE planetary/lunar ephemeris framework
Authors: Li G. Y. , Zhao H. B. , Xia Y. , Zeng F. , Luo Y. J.
Published: July 2008

The PMOE planetary/lunar ephemeris framework was established in 2003, and has been improved in recent years. In the framework of the post-Newtonian effects, the figure perturbation effects arising from the a finite size of the Sun, Moon and the Earth, and the effect of the Earth tide were taken into account. The accuracy of using the PMOE ephemeris to predict the positions of the planets in the solar system are the same as that of JPL DE 405. Based on this framework, the orbit optimization for the LISA, ASTROD and ASTROD I missions, and the computation of celestial phenomena and lunar phases in the Xia Shang and Zhou period of ancient China have been completed.
Getting ready for the micro-arcsecond era
Authors: Brown A. G. A.
Published: July 2008

As the title of this symposium implies, one of the aims is to examine the future of astrometry as we move from an era in which thanks to the Hipparcos Catalogue everyone has become familiar with milliarcsecond astrometry to an era in which microarcsecond astrometry will become the norm. I will take this look into the future by first providing an overview of present astrometric programmes and how they fit together and then I will attempt to identify the most promising future directions. In addition I discuss the important conditions for the maximization of the scientific return of future large and highly accurate astrometric catalogues; catalogue access and analysis tools, the availability of sufficient auxiliary data and theoretical knowledge, and the education of the future generation of astrometrists.
The structure of NoRC‐associated RNA is crucial for targeting the chromatin remodelling complex NoRC to the nucleolus
Authors: Mayer Christine , Neubert Melanie , Grummt Ingrid
Published: July 2008

Silencing of ribosomal RNA genes (rDNA) requires binding of the chromatin remodelling complex NoRC to RNA that is complementary to the rDNA promoter. NoRC‐associated RNA (pRNA) folds into a conserved stem–loop structure that is required for nucleolar localization and rDNA silencing. Mutations that disrupt the stem–loop structure impair binding of TIP5, the large subunit of NoRC, to pRNA and abolish targeting of NoRC to nucleoli. Binding to pRNA results in a conformational change of TIP5, as shown by enhanced sensitivity of TIP5 towards trypsin digestion. Our results indicate an RNA‐dependent mechanism that targets NoRC to chromatin and facilitates the interaction with co‐repressors that promote heterochromatin formation and rDNA silencing.
Structural basis for RNA‐silencing suppression by Tomato aspermy virus protein 2b
Authors: Chen Hong‐Ying , Yang Jing , Lin Chengqi , Yuan Y Adam
Published: July 2008

The 2b proteins encoded by cucumovirus act as post‐transcriptional gene silencing suppressors to counter host defence during infection. Here we report the crystal structure of Tomato aspermy virus 2b (TAV2b) protein bound to a 19 bp small interfering RNA (siRNA) duplex. TAV2b adopts an all α‐helix structure and forms a homodimer to measure siRNA duplex in a length‐preference mode. TAV2b has a pair of hook‐like structures to recognize simultaneously two α‐helical turns of A‐form RNA duplex by fitting its α‐helix backbone into two adjacent major grooves of siRNA duplex. The conserved π‐stackings between tryptophan and the 5′‐terminal base of siRNA duplex from both ends enhance the recognition. TAV2b further oligomerizes to form a dimer of dimers through the conserved leucine‐zipper‐like motif at its amino‐terminal α‐helix. Biochemical experiments suggest that TAV2b might interfere with the post‐transcriptional gene silencing pathway by directly binding to siRNA duplex.
The Yku70–Yku80 complex contributes to regulate double‐strand break processing and checkpoint activation during the cell cycle
Authors: Clerici Michela , Mantiero Davide , Guerini Ilaria , Lucchini Giovanna , Longhese Maria Pia
Published: July 2008

DNA double‐strand breaks (DSBs) are repaired by non‐homologous end joining (NHEJ) or homologous recombination (HR). HR requires 5′ DSB end degradation that occurs in the presence of cyclin‐dependent kinase (CDK) activity. Here, we show that a lack of any of the NHEJ proteins Yku (Yku70–Yku80), Lif1 or DNA ligase IV (Dnl4) increases 5′ DSB end degradation in G1 phase, with ykuΔ cells showing the strongest effect. This increase depends on MRX, the recruitment of which at DSBs is enhanced in ykuΔ G1 cells. DSB processing in G2 is not influenced by the absence of Yku, but it is delayed by Yku overproduction, which also decreases MRX loading on DSBs. Moreover, DSB resection in ykuΔ cells occurs independently of CDK activity, suggesting that it might be promoted by CDK‐dependent inhibition of Yku.
Area Postrema
Authors:   Allen Institute for Brain Science, Glattfelder Katie , Ng Lydia , Morris John
Published: July 2008

This report contains a gene expression summary of the area postrema (AP), derived from the "Allen Brain Atlas":http://www.brain-map.org/welcome.do;jsessionid=EDE40ADC940845D169DE378ADC9B71BD (ABA) in-situ hybridization (ISH) mouse data set. The structure’s location and morphological characteristics in the mouse brain are described using the Nissl data found in the "Allen Reference Atlas":http://www.brain-map.org/mouse/atlas/coronal/legend.html. Using an established algorithm, the expression values of the AP were compared to the values of the macro/parent-structure, in this case the medulla, for the purpose of extracting regionally specific gene expression data. The highest ranking ratios were then manually curated and verified. The 50 Select Genes were compiled for expression characterization. The experimental data for each gene may be accessed via the links provided; complementary sagittal data may also be accessed using the "ABA":http://www.brain-map.org/welcome.do. Correlation between gene expression in the AP and the rest of the brain, across all genes in the coronal dataset (~4300 genes), were derived computationally and are presented below. A gene ontology table (derived from DAVID Bioinformatics Resources 2007) is also included, highlighting possible functions of these 50 Select Genes.
Establishment of hapten‐specific monoclonal avian IgY by conversion of antibody fragments obtained from combinatorial libraries
Authors: Deckers Susanne , Braren Ingke , Greunke Kerstin , Meyer Nadine , Rühl Dana , Bredehorst Reinhard , Spillner Edzard
Published: July 2008

Nowadays, recombinant antibody and phage display technology enable the efficient generation of immunotools and a subsequent manipulation for optimized affinity, specificity or overall performance. Such advantages are of particular interest for haptenic target structures, such as TNT (2,4,6‐trinitrotoluene). The toxicity of TNT and its breakdown products makes a reliable and fast detection of low levels in aqueous samples highly important. In the present study, we aimed for the generation of scFvs (single‐chain antibody fragments) specific for the TNT‐surrogate TNP (2,4,6‐trinitrophenyl) and their subsequent production as monoclonal avian IgY immunoglobulins providing improved assay performance. Therefore we subjected a human synthetic scFv library to selection following different strategies. TNP‐specific human antibody fragments could be identified, characterized for their primary structure and evaluated for production as soluble scFv in Escherichia coli. Additionally, a murine TNP‐specific antibody fragment was obtained from the hybridoma 11B3; however, the prokaryotic expression level was found to be limited. To generate and evaluate immunoglobulin formats with superior characteristics, all recombinant antibody fragments then were converted into two different chimaeric bivalent IgY antibody formats. After expression in mammalian cells, the IgY antibodies were assessed for their reactivity towards TNT. The IgY antibodies generated on the basis of the combinatorial library proved to be useful for detection of TNT, thereby emphasizing the high potential of this approach for the development of detection devices for immunoassay‐based techniques.