Search Publications
The Centers of Early-Type Galaxies with HST. IV. Central Parameter Relations.
Gebhardt, Karl; Richstone, Douglas; Kormendy, John +7 more
We analyze Hubble Space Telescope surface-brightness profiles of 61 elliptical galaxies and spiral bulges (hereafter "hot" galaxies). The profiles are parameterized by break radius rβand break surface brightness 1β These are combined with central velocity dispersions, total luminosities, rotation velocities, and isophote shap…
The Panchromatic Starburst Intensity Limit at Low and High Redshift
Lehnert, Matthew D.; Heckman, Timothy M.; Meurer, Gerhardt R. +2 more
The integrated bolometric effective surface brightness S_e distributions of starburst are investigated for samples observed in 1. the rest frame ultraviolet (UV), 2. the far-infrared and \Hα, and 3. 21cm radio continuum emission. For the UV sample we exploit a tight empirical relationship between UV reddening and extinction to recover the bolometr…
M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale
Gizis, John E.
We present a spectroscopic classification system for M-dwarfs and M-subdwarfs based on quantitative measures of TiO and CaH features in the region lambda lambda 6200 - 7400 Angstroms. Our sample of cool stars covers the range from solar metallicity stars to the most extreme subdwarfs known. Using synthetic spectra computed by Allard and Hauschildt…
Low-Mass Binaries and the Stellar Luminosity Function
Gizis, John E.; Reid, I. Neill
We present a new investigation of the influence of unresolved binaries on the form deduced for the stellar luminosity function from photometric parallax surveys. We have compiled a catalogue of photometry and binary statistics for stars known to be north of -30° declination and within 8 parsecs of the Sun, and have used these stars as a reference …
Evolution of the Galaxy Population Based on Photometric Redshifts in the Hubble Deep Field
Yee, H. K. C.; Lin, H.; Sawicki, M. J.
This paper presents the results of a photometric redshift study of galaxies in the Hubble Deep Field (HDF). The method of determining redshifts from broadband colors is described, and the dangers inherent in using it to estimate redshifts, particularly at very high z, are discussed. In particular, the need for accurate high-z spectral energy distr…
The Star Cluster System of the Merger Remnant NGC 7252
Whitmore, Bradley C.; Fall, S. Michael; Miller, Bryan W. +1 more
We present new U, B, V, and I images of the prototypical merger remnant NGC 7252 obtained with the WFPC2 instrument of the Hubble Space Telescope. The photometry reaches about 3 mag deeper than the previous observations with WF/PC1 and we detect 499 cluster candidates, most of them previously undiscovered. We can distinguish three populations of s…
Spiral Galaxies with WFPC2.I.Nuclear Morphology, Bulges, Star Clusters, and Surface Brightness Profiles
Carollo, C. M.; Stiavelli, M.; de Zeeuw, P. T. +1 more
We report the analysis of HST WFPC2 F606W images of a sample of 35 spiral galaxies. We describe the optical morphological properties of the galaxies on scales of a few tens of parsecs, derive the surface brightness profiles for 18 of them, and present the results of analytical fits to these profiles. We find that: (I) Several galaxies, despite the…
Dust and Recent Star Formation in the Core of NGC 5253
Meurer, Gerhardt R.; Calzetti, Daniela; Leitherer, Claus +4 more
Ultraviolet and optical narrow and broad band images of NGC 5253 obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 are used to derive the properties of the dust distribution and the recent star formation history of this metal-poor dwarf galaxy. Corrections for the effects of dust are important in the center of NGC 5253: du…
The Dwarf Irregular Galaxy Sextans A. II. Recent Star Formation History
Skillman, Evan D.; Saha, A.; Gallagher, J. +6 more
We have used the Hubble Space Telescope to obtain photometric data of the resolved stars in the nearby (D = 1.4 Mpc) dwarf irregular galaxy Sextans A (DDO 75, A 1008-04). The data consist of WFPC2 images in 3 bands: F439W (1 hour), F555W (30 minutes), and F814W (30 minutes). We constructed very accurate color-magnitude diagrams (CMDs) in V and I d…
Extraplanar Dust in the Edge-On Spiral NGC 891
Savage, Blair D.; Howk, J. Christopher
We present high-resolution (0.6"-0.65") optical broad-band images of the edge-on Sb galaxy NGC 891 obtained with the WIYN 3.5-m telescope. These BVR images reveal a complex network of hundreds of dust absorbing structures far from the mid-plane of the galaxy. The dust structures have a wide range of morphologies and are clearly visible to [ζ]≤1.5 …