Mapping the three-dimensional density of the galactic bulge with VVV red clump stars
Christopher Wegg,Ortwin Gerhard +1 more
Reads0
Chats0
TLDR
In this paper, the authors measured the angle of the bar-bulge to the line-of-sight to be (27+-2)deg, where the dominant error is systematic arising from the details of the deconvolution process.Abstract:
The inner Milky Way is dominated by a boxy, triaxial bulge which is believed to have formed through disk instability processes. Despite its proximity, its large-scale properties are still not very well known, due to our position in the obscuring Galactic disk. Here we make a measurement of the three-dimensional density distribution of the Galactic bulge using red clump giants identified in DR1 of the VVV survey. Our density map covers the inner (2.2x1.4x1.1)kpc of the bulge/bar. Line-of-sight density distributions are estimated by deconvolving extinction and completeness corrected K-band magnitude distributions. In constructing our measurement, we assume that the three-dimensional bulge is 8-fold mirror triaxially symmetric. In doing so we measure the angle of the bar-bulge to the line-of-sight to be (27+- 2)deg, where the dominant error is systematic arising from the details of the deconvolution process. The resulting density distribution shows a highly elongated bar with projected axis ratios ~(1:2.1) for isophotes reaching ~2kpc along the major axis. Along the bar axes the density falls off roughly exponentially, with axis ratios (10:6.3:2.6) and exponential scale-lengths (0.70:0.44:0.18)kpc. From about 400pc above the Galactic plane, the bulge density distribution displays a prominent X-structure. Overall, the density distribution of the Galactic bulge is characteristic for a strongly boxy/peanut shaped bulge within a barred galaxy.read more
Citations
More filters
Journal ArticleDOI
Effect of orbital trapping by bar resonances in the local U–V velocity field
Edmundo Moreno,J. G. Fernandez-Trincado,J. G. Fernandez-Trincado,William J. Schuster,Angeles Pérez-Villegas,L. Chaves-Velasquez,L. Chaves-Velasquez +6 more
TL;DR: In this article, the effects of orbital trapping on the local U-V velocity field due to bar resonances have been studied computing fifteen resonant families in a non-axisymmetric Galactic potential, considering the bar's angular velocity between 35 and 57.5.
Journal ArticleDOI
Measuring the Orbits of the Arches and Quintuplet Clusters Using HST and Gaia: Exploring Scenarios for Star Formation near the Galactic Center
Matthew W. Hosek,Tuan Do,Jessica R. Lu,Mark Morris,Andrea M. Ghez,Gregory D. Martinez,Jay Anderson +6 more
TL;DR: In this article , the authors used multiepoch HST observations to construct proper-motion catalogs for the Arches and Quintuplet fields in ICRF coordinates established using stars in common with the Gaia EDR3 catalog.
Journal ArticleDOI
A new look at the kinematics of the bulge from an N-body model
A. E. Gomez,P. Di Matteo,Nicolas Stefanovitch,Misha Haywood,Francoise Combes,D. Katz,C. Babusiaux +6 more
TL;DR: In this article, the imprints of the initial location of stars on the bulge kinematics, in particular on the heliocentric radial velocity distribution of bulge stars, were analyzed using an N-body simulation of a bulge that was formed via a bar instability mechanism.
Journal ArticleDOI
The WFC3 Galactic Bulge Treasury Program: Relative Ages of Bulge Stars of High and Low Metallicity
Alvio Renzini,Mario Gennaro,Manuela Zoccali,Manuela Zoccali,Thomas M. Brown,Jay Anderson,Dante Minniti,Kailash C. Sahu,Elena Valenti,Don A. VandenBerg +9 more
TL;DR: The HST/WFC3 multiband photometry spanning from the UV to the near-IR of four fields in the Galactic bulge, together with that for six template globular and open clusters, is used to photometrically tag the metallicity [Fe/H] of stars in these fields after proper-motion rejecting most foreground disk contaminants as discussed by the authors.
Journal ArticleDOI
Hunting for C-rich long-period variable stars in the Milky Way’s bar-bulge using unsupervised classification of Gaia BP/RP spectra
TL;DR: In this article , the authors investigated the use of unsupervised learning algorithms for classifying the chemistry of long-period variables from Gaia DR3's BP/RP spectra and showed that the combination of the observed number, the spatial alignment, the kinematics and the period distribution disfavour young metalpoor star formation scenarios either in situ or in an accreted host.
References
More filters
Journal ArticleDOI
The relationship between infrared, optical, and ultraviolet extinction
TL;DR: In this article, the average extinction law over the 3.5 micron to 0.125 wavelength range was derived for both diffuse and dense regions of the interstellar medium. And the validity of the law over a large wavelength interval suggests that the processes which modify the sizes and compositions of grains are stochastic in nature.
Journal ArticleDOI
On the variation of the initial mass function
TL;DR: In this paper, the uncertainty inherent in any observational estimate of the IMF is investigated by studying the scatter introduced by Poisson noise and the dynamical evolution of star clusters, and it is found that this apparent scatter reproduces quite well the observed scatter in power-law index determinations, thus defining the fundamental limit within which any true variation becomes undetectable.
Journal ArticleDOI
A Catalog of Parameters for Globular Clusters in the Milky Way
TL;DR: A database of parameters for globular star clusters in the Milky Way is described which is available in electronic form through the WorldWideWeb as discussed by the authors. The information in the catalog includes up-to-date measurements for cluster distance, reddening, luminosity, colors and spectral types, velocity, structural and dynamical parameters, horizontal branch morphology, metallicity, and other quantities.
Journal ArticleDOI
Maximum Likelihood Reconstruction for Emission Tomography
L. A. Shepp,Y. Vardi +1 more
TL;DR: In this paper, the authors proposed a more accurate general mathematical model for ET where an unknown emission density generates, and is to be reconstructed from, the number of counts n*(d) in each of D detector units d. Within the model, they gave an algorithm for determining an estimate? of? which maximizes the probability p(n*|?) of observing the actual detector count data n* over all possible densities?.
Journal ArticleDOI
Bayesian-Based Iterative Method of Image Restoration
TL;DR: An iterative method of restoring degraded images was developed by treating images, point spread functions, and degraded images as probability-frequency functions and by applying Bayes’s theorem.