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The Optical Gravitational Lensing Experiment (OGLE, Udalski et al.~1994a; Paczy\'nski et al.~1994b -- these proceedings; and references therein) is an extensive photometric search for the rare cases of gravitational microlensing of Galactic…

Astrophysics · Physics 2007-05-23 K. Z. Stanek , M. Mateo , A. Udalski , M. Szymanski , J. Kaluzny , M. Kubiak , W. Krzeminski

RR Lyrae stars (RRLS) belong to population II and are generally used as a tracer of the host galaxy halo. The surface as well as vertical distribution of RRLS in the inner Large Magellanic Cloud (LMC) are studied to understand whether these…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Annapurni Subramaniam , Smitha Subramanian

Our study aims to investigate the outer disc structure of the Milky Way galaxy using the red clump (RC) stars. We analysed the distribution of the largest sample of RC stars to date, homogeneously covering the entire Galactic plane in the…

Astrophysics of Galaxies · Physics 2023-11-17 Namita Uppal , Shashikiran Ganesh , Mathias Schultheis

We present a catalogue of variable stars in the near-infrared wavelength detected with overlapping regions of the 2MASS public images, and discuss their properties. The investigated region is in the direction of the Galactic center (-30 < l…

Solar and Stellar Astrophysics · Physics 2014-11-20 Shinjirou Kouzuma , Hitoshi Yamaoka

We have measured the fraction of bars in nearby spiral galaxies using near-infrared J, H, and K_s images of 151 spiral galaxies from 2MASS. This local sample provides an anchor for the study of the evolution of the bar fraction and bar…

Most of the observed and simulated galactic bars are symmetric in the face-on view. However, there are indeed cases of bars that are off-center with respect to the disk or have an asymmetric shape. The only well-known example showing both…

Astrophysics of Galaxies · Physics 2021-12-01 Ewa L. Lokas

We construct a large set of dynamical models of the galactic bulge, bar and inner disk using the Made-to-Measure method. Our models are constrained to match the red clump giant density from a combination of the VVV, UKIDSS and 2MASS…

Astrophysics of Galaxies · Physics 2016-12-21 Matthieu Portail , Ortwin Gerhard , Christopher Wegg , Melissa Ness

We discuss the origin of the LMC stellar bar by comparing the star formation histories (SFH) obtained from deep color-magnitude diagrams (CMDs) in the bar and in a number of fields in different directions within the inner disk. The CMDs,…

Astrophysics of Galaxies · Physics 2017-11-29 L. Monteagudo , C. Gallart , M. Monelli , E. J. Bernard , P. B. Stetson

We extend the work developed in previous papers on microlensing with a selection of variable stars. We use the Pixel Method to select variable stars on a set of 2.5 x 10**6 pixel light curves in the LMC Bar presented elsewhere. The previous…

Astrophysics · Physics 2009-11-06 A. -L. Melchior , S. M. G. Hughes , J. Guibert

(Abridge) Bars are very common in the centre of the disc galaxies, and they drive the evolution of their structure. A volume-limited sample of 2106 disc galaxies extracted from the Sloan Digital Sky Survey Data Release 5 was studied to…

Astrophysics of Galaxies · Physics 2009-11-13 J. A. L. Aguerri , J. Mendez-Abreu , E. M. Corsini

An analysis of the NICMOS Deep Field shows that there is no evidence of a decline in the bar fraction beyond z~0.7, as previously claimed; both bandshifting and spatial resolution must be taken into account when evaluating the evolution of…

This paper describes a framework for studying galaxy morphology, particularly bar strength, in a quantitative manner, and presents applications of this approach that reveal observational evidence for secular evolution in bar morphology. The…

Astrophysics · Physics 2007-05-23 M. R. Merrifield

Both the three-dimensional density of red clump giants and the gas kinematics in the inner Galaxy indicate that the pattern speed of the Galactic bar could be much lower than previously estimated. Here, we show that such slow bar models are…

Astrophysics of Galaxies · Physics 2016-12-21 Giacomo Monari , Benoit Famaey , Arnaud Siebert , Aurore Duchateau , Thibault Lorscheider , Olivier Bienaymé

The analysis of the first two years of OGLE data revealed 9 microlensing events of the galactic bulge stars, with the characteristic time scales in the range $ 8.6 < t_0 < 62 $ days, where $ t_0 = R_E / V $. The optical depth to…

Astrophysics · Physics 2008-12-18 B. Paczynski , K. Z. Stanek , A. Udalski , M. Szymanski , J. Kaluzny , M. Kubiak , M. Mateo , W. Krzeminski

We derive unbiased distance estimates for the Gaia-TGAS dataset by correcting for the bias due to the distance dependence of the selection function, which we measure directly from the data. From these distances and proper motions, we…

Astrophysics of Galaxies · Physics 2018-07-04 Ralph Schönrich , Walter Dehnen

We search OGLE-I photometric database for stars, which, as defined by formal criteria adopted by OGLE-I microlensing search, showed variability during only one out of 3 or 4 observing seasons. The results include 17 previously reported…

Astrophysics · Physics 2007-05-23 Przemyslaw Wozniak , Michal Szymanski

We derive the vertical velocities of disk stars in the range of Galactocentric radii of R=5-16 kpc within 2 kpc in height from the Galactic plane. This kinematic information is connected to dynamical aspects in the formation and evolution…

Astrophysics of Galaxies · Physics 2014-12-10 M. Lopez-Corredoira , H. Abedi , F. Garzon , F. Figueras

We compare stellar orbits in an early (NGC 4314) and a late-type barred galaxy (NGC 1073). We find that these bars are cold in the sense that the majority of stars can be described as being nearby to periodic orbits. We place limits of…

Astrophysics · Physics 2007-05-23 A. C. Quillen

The microlensing probability (optical depth $\tau$) toward the Galactic center carries information about the mass distribution of the Galactic bulge/bar, so can be used to constrain the very uncertain shape parameters of the bar. We find…

Astrophysics · Physics 2015-06-24 HongSheng Zhao , Shude Mao

One third of present-day spirals host optically visible strong bars that drive their dynamical evolution. However, the fundamental question of how bars evolve over cosmological times has yet to be addressed, and even the frequency of bars…

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