scholarly journals Discovery of Likely Globular Clusters in Maffei 1

2002 ◽  
Vol 207 ◽  
pp. 306-308
Author(s):  
R. Buta ◽  
M. L. McCall
Keyword(s):  
High Resolution ◽  
Preliminary Data ◽  
Globular Clusters ◽  
Hubble Space Telescope ◽  
Elliptical Galaxy ◽  
Core Region ◽  
Wide Field ◽  
Space Telescope ◽  
The Core

The Hubble Space Telescope Wide Field and Planetary Camera 2 was used to image at high resolution the core region of the nearby, heavily obscured massive elliptical galaxy Maffei 1. We report on the discovery of 19 diffuse objects in the WFPC2 field that are likely to be globular clusters associated with Maffei 1. We present some preliminary data on the luminosities, colors, and sizes of these candidates.

scholarly journals New “Einstein Cross” Gravitational Lens Candidates In HST WFPC2 Survey Images

1996 ◽  
Vol 173 ◽  
pp. 323-328 ◽  
Author(s):  
K.U. Ratnatunga ◽  
E.J. Ostrander ◽  
R.E. Griffiths ◽  
M. Im
Keyword(s):  
High Resolution ◽  
Hubble Space Telescope ◽  
Elliptical Galaxy ◽  
Broad Band ◽  
Gravitational Lens ◽  
Space Telescope ◽  
Symmetric Configuration ◽  
Band Filter ◽  
Deep Survey ◽  
Random Survey

We report the serendipitous discovery of quadruple gravitational lens candidates using the Hubble Space Telescope. We have so far discovered two good examples of such lenses, each in the form of four faint blue images located in a symmetric configuration around a red elliptical galaxy. The high resolution of HST has facilitated the discovery of this optically selected sample of faint lenses with small (∼1″) separations between the (I∼ 25–27) lensed components and the much brighter (I∼ 19–22) lensing galaxies. The sample has been discovered in the routine processing of HST fields through the Medium Deep Survey pipeline, which fits simple galaxy models to broad band filter images of all objects detected in random survey fields using WFPC2.

scholarly journals Star Clusters in Galactic Resonance Rings

2002 ◽  
Vol 207 ◽  
pp. 447-449
Author(s):  
R. Buta
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Hubble Space Telescope ◽  
Star Clusters ◽  
Disk Galaxies ◽  
Wide Field ◽  
Space Telescope ◽  
Lindblad Resonance ◽  
Inner Lindblad Resonance

Resonance rings are intriguing sites of organized star formation in some galaxies. The Hubble Space Telescope Wide Field and Planetary Camera 2 has been used to image several resonance rings at high resolution in order to study the star clusters in the rings. Here I summarize results on inner Lindblad resonance rings in ESO 565–11 and NGC 1326, and on an inner 4:1 resonance ring in the Seyfert 2 galaxy NGC 3081. The latter ring provides one of the strongest cases illustrating the connection between star formation and dynamics in disk galaxies.

scholarly journals The grey extinction curve in NGC 3603

2014 ◽  
Vol 10 (S312) ◽  
pp. 243-244
Author(s):  
Xiaoying Pang ◽  
Anna Pasquali ◽  
Eva K. Grebel
Keyword(s):  
Standard Deviation ◽  
High Resolution ◽  
Hubble Space Telescope ◽  
Starburst Galaxies ◽  
Extinction Curve ◽  
Wide Field ◽  
Space Telescope ◽  
Advanced Camera For Surveys

AbstractWe use photometry in the F220W, F250W, F330W, F435W filters from the High Resolution Channel of the Advanced Camera for Surveys and photometry in the F555W, F675W, and F814W filters from the Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope to derive individual stellar reddenings and extinctions for member stars in the HD 97950 cluster in the giant H ii region NGC 3603. Within the standard deviation associated with E(λ−F555W)/E(F435W−F555W) in each filter, the cluster extinction curve at ultraviolet wavelengths tends to be greyer than the average Galactic extinction laws from Cardelli et al. (1989) and Fitzpatrick et al. (1999). It is closer to the extinction law derived by Calzetti et al. (2000) for starburst galaxies, where the 0.2175 μm bump is absent.

scholarly journals Multiple Sequences of M-dwarfs in NGC 2808 and ω Centauri.

2012 ◽  
Vol 10 (H16) ◽  
pp. 241-242
Author(s):  
A. P. Milone
Keyword(s):  
Globular Clusters ◽  
Hubble Space Telescope ◽  
Wide Field ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
Space Telescope ◽  
Low Mass ◽  
Multiple Sequences ◽  
Infrared Channel

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.

scholarly journals Hunting for intermediate-mass black holes in globular clusters: an astrometric study of NGC 6441

2021 ◽  
Vol 503 (1) ◽  
pp. 1490-1506
Author(s):  
Maximilian Häberle ◽  
Mattia Libralato ◽  
Andrea Bellini ◽  
Laura L Watkins ◽  
Jörg-Uwe Pott ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Velocity Dispersion ◽  
Angular Resolution ◽  
Hubble Space Telescope ◽  
High Mass ◽  
High Angular Resolution ◽  
Stellar Kinematics ◽  
Intermediate Mass ◽  
The Core ◽  
Large Telescopes

ABSTRACT We present an astrometric study of the proper motions (PMs) in the core of the globular cluster NGC 6441. The core of this cluster has a high density and observations with current instrumentation are very challenging. We combine ground-based, high-angular-resolution NACO@VLT images with Hubble Space Telescope ACS/HRC data and measure PMs with a temporal baseline of 15 yr for about 1400 stars in the centremost 15 arcsec of the cluster. We reach a PM precision of ∼30 µas yr−1 for bright, well-measured stars. Our results for the velocity dispersion are in good agreement with other studies and extend already existing analyses of the stellar kinematics of NGC 6441 to its centremost region never probed before. In the innermost arcsecond of the cluster, we measure a velocity dispersion of (19.1 ± 2.0) km s−1 for evolved stars. Because of its high mass, NGC 6441 is a promising candidate for harbouring an intermediate-mass black hole (IMBH). We combine our measurements with additional data from the literature and compute dynamical models of the cluster. We find an upper limit of $M_{\rm IMBH} \lt 1.32 \times 10^4\, \textrm{M}_\odot$ but we can neither confirm nor rule out its presence. We also refine the dynamical distance of the cluster to $12.74^{+0.16}_{-0.15}$ kpc. Although the hunt for an IMBH in NGC 6441 is not yet concluded, our results show how future observations with extremely large telescopes will benefit from the long temporal baseline offered by existing high-angular-resolution data.

Reconstruction of the last three millennia South American Monsoon variability over the Amazon basin using speleothem isotope records 

2021 ◽  
Author(s):  
Marcela Eduarda Della Libera de Godoy ◽  
Valdir F. Novello ◽  
Francisco William Cruz
Keyword(s):  
High Resolution ◽  
Amazon Basin ◽  
Rainfall Variability ◽  
Isotope Analysis ◽  
Core Region ◽  
South American ◽  
The South ◽  
Continuous Increase ◽  
South American Monsoon ◽  
The Core

<p>South American Monsoon System (SAMS) and its main feature, the South American Convergence Zone (SACZ) are responsible for the major distribution of moisture in South America. The current work presents a novel high-resolution oxygen isotope record (δ<sup>18</sup>O) based on speleothems from southwest Amazon basin (Brazil), right at SAMS' core region and SACZ onset, where there is still a gap of high resolution paleoclimate records. The novel δ<sup>18</sup>O record presents an average of 3 year-resolution, composed by 1344 stable isotope analysis performed in two speleothems with a well-resolved chronology (37 U/Th ages) with average errors <1%. This work aims to describe the rainfall variability of the core region of the South American monsoon for the last 3k years and to take a broader look at precipitation patterns over Amazon basin. The Rondônia δ18O record shows three main stages throughout this time period. The first is from -1000 to ~400 CE, where it’s in accordance with most of other paleorecords from the Amazon basin. the second segment  is from ~400 to 1200 CE, when there is a continuous increase in the δ18O record until it reaches its highest values around 850 CE during the MCA (800-1200 CE), which is in accordance with western Amazon records, whilst the record in eastern Amazon presents an opposite trend. Thus, a precipitation dipole over Amazon emerges from ~400 CE onwards, majorly triggered by anomalous climate changes such as MCA, where western (eastern) Amazon is drier (wetter). During LIA (1450-1800 CE), on the other hand, Rondônia record presents its lowest values, also agreeing with western records and with records under the influence of SACZ whilst on eastern Amazon a drier period is established. Therefore, with this novel paleoclimate record located at the core region of SAMS, it's possible to evidence the dynamics of the precipitation dipole over the Amazon region, as well as understand the SACZ intensity variations.</p>

[ITAL]Hubble Space Telescope[/ITAL] Imaging of the Globular Clusters in the Fornax Cluster: Color and Luminosity Distributions

1999 ◽  
Vol 117 (1) ◽  
pp. 167-180 ◽  
Author(s):  
Carl J. Grillmair ◽  
Duncan A. Forbes ◽  
Jean P. Brodie ◽  
Rebecca A. W. Elson
Keyword(s):  
Globular Clusters ◽  
Hubble Space Telescope ◽  
Space Telescope ◽  
Fornax Cluster
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