Search Publications
Young Planetary Nebulae: Hubble Space Telescope Imaging and a New Morphological Classification System
Morris, Mark R.; Sahai, Raghvendra; Villar, Gregory G.
Using Hubble Space Telescope images of 119 young planetary nebulae (PNs), most of which have not previously been published, we have devised a comprehensive morphological classification system for these objects. This system generalizes a recently devised system for pre-planetary nebulae, which are the immediate progenitors of PNs. Unlike previous c…
The Relationships among Compact Stellar Systems: A Fresh View of Ultracompact Dwarfs
Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P. +1 more
We use a combined imaging and spectroscopic survey of the nearby central cluster galaxy, M87, to assemble a sample of 34 confirmed ultracompact dwarfs (UCDs) with half-light radii of gsim10 pc measured from Hubble Space Telescope images. This doubles the existing sample in M87, making it the largest such sample for any galaxy, while extending the …
Star Clusters in M31. II. Old Cluster Metallicities and Ages from Hectospec Data
Caldwell, Nelson; Harding, Paul; Rose, James A. +2 more
We present new high signal-to-noise spectroscopic data on the M31 globular cluster (GC) system, obtained with the Hectospec multifiber spectrograph on the 6.5 m MMT. More than 300 clusters have been observed at a resolution of 5 Å and with a median S/N of 75 per Å, providing velocities with a median uncertainty of 6 km s-1. The primary …
Distance Scale Zero Points from Galactic RR Lyrae Star Parallaxes
Kochukhov, Oleg; Nelan, Edmund P.; Freedman, Wendy L. +15 more
We present new absolute trigonometric parallaxes and proper motions for seven Population II variable stars—five RR Lyr variables: RZ Cep, XZ Cyg, SU Dra, RR Lyr, and UV Oct; and two type 2 Cepheids: VY Pyx and κ Pav. We obtained these results with astrometric data from Fine Guidance Sensors, white-light interferometers on Hubble Space Telescope. W…
Star Clusters in M31. V. Internal Dynamical Trends: Some Troublesome, Some Reassuring
Caldwell, Nelson; Strader, Jay; Seth, Anil C.
We present internal velocity dispersions and precise radial velocities for 200 globular clusters (GCs) in M31 that are derived using new high-resolution spectra from MMT/Hectochelle. Of these, 163 also have King model structural parameters that allow us to estimate their mass-to-light ratios. This is, by far, the largest such data set available fo…
The Nuclear Structure in Nearby Luminous Infrared Galaxies: Hubble Space Telescope NICMOS Imaging of the GOALS Sample
Sanders, D. B.; Surace, J. A.; Inami, H. +16 more
We present results of Hubble Space Telescope (HST) NICMOS H-band imaging of 73 of the most luminous (i.e., log[L IR/L sun]>11.4) infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey. This data set combines multi-wavelength imaging and spectroscopic data from space-based (Spitzer, HST, GALEX, and Chandra…
An Ultraviolet Spectroscopic Atlas of Local Starbursts and Star-forming Galaxies: The Legacy of FOS and GHRS
Heckman, Timothy M.; Calzetti, Daniela; Leitherer, Claus +1 more
We present 46 rest-frame ultraviolet (UV) spectra of 28 local starburst and star-forming galaxies which were observed with the Faint Object Spectrograph (FOS) and the Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) at a spectral resolution of a few 100 km s-1. We compare the HST spectra with lower resolut…
Stellar Activity in the Broadband Ultraviolet
Findeisen, K.; Hillenbrand, L.; Soderblom, D.
The completion of the GALEX All-Sky Survey in the ultraviolet allows activity measurements to be acquired for many more stars than is possible with the limited sensitivity of ROSAT or the limited sky coverage of Chandra, XMM, or spectroscopic surveys for line emission in the optical or ultraviolet. We have explored the use of GALEX photometry as a…
Spitzer Infrared Spectrometer 16 µm Observations of the Goods Fields
Papovich, Casey; Dickinson, Mark; Teplitz, Harry I. +13 more
We present Spitzer 16 µm imaging of the Great Observatories Origins Deep Survey (GOODS) fields. We survey 150 arcmin2 in each of the two GOODS fields (North and South), to an average 3σ depth of 40 and 65 µJy, respectively. We detect ~1300 sources in both fields combined. We validate the photometry using the 3-24 µm sp…
Evolution of X-ray and Far-ultraviolet Disk-dispersing Radiation Fields
Briceño, Cesar; Hartmann, Lee; Calvet, Nuria +5 more
We present new X-ray and far-ultraviolet (FUV) observations of T Tauri stars covering the age range 1-10 Myr. Our goals are to observationally constrain the intensity of radiation fields responsible for evaporating gas from the circumstellar disk and to assess the feasibility of current photoevaporation models, focusing on X-ray and UV radiation. …