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Tip of the Red Giant Branch Distances. I. Optimization of a Maximum Likelihood Algorithm
Dolphin, Andrew E.; Shaya, Edward J.; Tully, R. Brent +4 more
Accurate distances to galaxies can be determined from the luminosities of stars at the tip of the red giant branch (TRGB). We use a maximum likelihood algorithm to locate the TRGB in galaxy color-magnitude diagrams. The algorithm is optimized by introducing reliable photometric errors and a completeness characterization determined with artificial …
The Extrasolar Planet ɛ Eridani b: Orbit and Mass
Kürster, Martin; Gatewood, George; Cochran, William D. +11 more
Hubble Space Telescope (HST) observations of the nearby (3.22 pc) K2 V star ɛ Eridani have been combined with ground-based astrometric and radial velocity data to determine the mass of its known companion. We model the astrometric and radial velocity measurements simultaneously to obtain the parallax, proper motion, perturbation period, perturbati…
Globular Clusters in Virgo Ellipticals: Unexpected Results for Giants and Dwarfs from Advanced Camera for Surveys Imaging
Brodie, Jean P.; Beasley, Michael A.; Strader, Jay +1 more
We have analyzed archival Hubble Space Telescope Advanced Camera for Surveys images in g and z of the globular cluster (GC) systems of 53 ellipticals in the Virgo Cluster, spanning massive galaxies to dwarf ellipticals (dEs). Several new results emerged. (1) In the giant ellipticals (gEs) M87 and NGC 4649, there is a correlation between luminosity…
Ca II Triplet Spectroscopy of Large Magellanic Cloud Red Giants. I. Abundances and Velocities for a Sample of Populous Clusters
Smith, Verne V.; Cole, Andrew A.; Sarajedini, Ata +2 more
Using the FORS2 instrument on the Very Large Telescope, we have obtained near-infrared spectra for more than 200 stars in 28 populous LMC clusters. This cluster sample spans a large range of ages (~1-13 Gyr) and metallicities (-0.3>~[Fe/H]>~-2.0) and has good areal coverage of the LMC disk. The strong absorption lines of the Ca II triplet ar…
Clues to Nuclear Star Cluster Formation from Edge-on Spirals
Seth, Anil C.; Dalcanton, Julianne J.; Hodge, Paul W. +1 more
We find nine nuclear cluster candidates in a sample of 14 edge-on, late-type galaxies observed with the Hubble Space Telescope Advanced Camera for Surveys. These clusters have magnitudes (MI~-11) and sizes (reff~3 pc) similar to those found in previous studies of face-on, late-type spirals and dE galaxies. However, three of t…
A Recalibration of Optical Photometry: Tycho-2, Strömgren, and Johnson Systems
Maíz Apellániz, J.
I use high-quality Hubble Space Telescope (HST) spectrophotometry to analyze the calibration of three popular optical photometry systems: Tycho-2 BT and VT, Strömgren uvby, and Johnson UBV. For Tycho-2, I revisit the analysis of an earlier paper to include the new recalibration of grating/aperture corrections, vignetting, and charge transfer ineff…
Surface Brightness Profiles of Galactic Globular Clusters from Hubble Space Telescope Images
Gebhardt, Karl; Noyola, Eva
The Hubble Space Telescope (HST) allows us to study the central surface brightness profiles of globular clusters at unprecedented detail. We have mined the HST archives to obtain 38 WFPC2 images of Galactic globular clusters with adequate exposure times and filters, which we use to measure their central structure. We outline a reliable method to o…
Type II Quasars from the Sloan Digital Sky Survey. V. Imaging Host Galaxies with the Hubble Space Telescope
Strauss, Michael A.; Brinkmann, J.; Schneider, Donald P. +7 more
Type II quasars are luminous active galactic nuclei (AGNs) whose centers are obscured by large amounts of gas and dust. In this paper we present three-band Hubble Space Telescope images of nine type II quasars with redshifts 0.2<z<0.4 selected from the Sloan Digital Sky Survey based on their emission-line properties. The intrinsic luminositi…
Advanced Camera for Surveys Imaging of 25 Galaxies in Nearby Groups and in the Field
Dolphin, Andrew; Shaya, Edward J.; Tully, R. Brent +6 more
We present Hubble Space Telescope Advanced Camera for Surveys images and color-magnitude diagrams for 25 nearby galaxies with radial velocities VLG<500 km s-1. Distances are determined based on the luminosities of stars at the tip of the red giant branch that range from 2 to 12 Mpc. Two of the galaxies, NGC 4163 and IC 466…
Kinematics of the Narrow-Line Region in the Seyfert 2 Galaxy NGC 1068: Dynamical Effects of the Radio Jet
Kraemer, S. B.; Crenshaw, D. M.; Das, V. +1 more
We present a study of high-resolution long-slit spectra of the narrow-line region (NLR) in NGC 1068 obtained with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope (HST). The spectra were retrieved from the Multimission Archive at the Space Telescope Science Institute obtained from two visits and seven orbits of HST time. …