Search Publications
HST and Infrared Images of the Circumstellar Environment of the Cool Hypergiant IRC + 10420
Smith, Nathan; Humphreys, Roberta M.; Davidson, Kris +6 more
We present HST WFPC2 and ground-based infrared images of the very evolved, luminous OH/IR star IRC+10420. The HST optical images reveal an amazingly complex environment, with one or more distant reflection shells probably ejected during the star's previous red supergiant stage plus numerous features within two arcseconds of the star including cond…
Hubble Space Telescope Observations of Two Dynamically Young Elliptical Galaxies
Whitmore, Bradley C.; Fall, S. Michael; Miller, Bryan W. +1 more
High-resolution images of the candidate dynamically young ellipticals NGC 1700 and NGC 3610 have been obtained with the WFPC2 of the Hubble Space Telescope. NGC 1700 contains approximately a dozen dust clouds arranged in a chaotic distribution near the center of the galaxy, suggestive of a merger or accretion event. NGC 3610 contains a remarkably …
Stellar Populations in the Dwarf Elliptical Galaxy NGC 147
Krist, J.; Stapelfeldt, K.; Gallagher, J. S., III +16 more
Deep V and I CCD images in a central and an outer field of the Local Group dwarf elliptical galaxy NGC 147 have been obtained with the Wide Field and Planetary Camera-2 (WFPC2) on board of the Hubble Space Telescope. The color-magnitude diagram shows a number of interesting features, including a well defined red giant branch (RGB), a red horizonta…
Stellar Populations in the Large Magellanic Cloud:Evidence for a Significant Number of Older Stars or a Steeper IMF?
Stapelfeldt, K. R.; Clarke, J. T.; Grillmair, Carl J. +14 more
We present deep photometry obtained with the HST in an outer LMC field. A well-defined main sequence is seen down to V>26. We derive a luminosity function from the data and use it to constrain the IMF and the star formation history. We derive limits on the IMF slope, alpha (with dN/dM~ M(alpha ) ), from stars on the main sequence which are fain…
A Comparison of Deep HST Luminosity Functions of Four Globular Clusters
Piotto, Giampaolo; Cool, Adrienne M.; King, Ivan R.
From deep color-magnitude arrays made from V and I images taken with Hubble Space Telescope's WFPC2 camera we have determined luminosity functions (LFs) down to a level that corresponds to ~ 0.13 \msun, for the low-metal-abundance globular clusters M15, M30, M92, and NGC 6397. Because of the similarity of the metallicities of these clusters, diffe…
HST Imagery of the Non-Expanding, Clumped "Shell" of the Recurrent Nova T Pyxidis
Williams, Robert E.; Zurek, David R.; Moffat, Anthony F. J. +3 more
The "shell" of the recurrent nova T Pyxidis has been resolved with HST imagery into more than two thousand individual knots. Hydrogen and [N II] emission have very similar spatial distributions. Four epochs of observation allow us to place an upper limit of 40 km/s on the systematic expansion velocity of the knots. This is in contrast to our 1985 …
The Apparent Morphology of Peculiar Galaxies at Intermediate to High Redshifts
Vacca, W. D.; Hibbard, J. E.
To understand the range of morphologies observed in the galaxy population at high redshift, it is instructive to evaluate the appearance of local peculiar galaxies when placed at cosmological distances. To this end, we use rest-frame ultraviolet (UV), B- and V-band images of five nearby (ζ<0.02) interacting and/or starbursting galaxies to simul…
Kinematics of the Interstellar Medium in NGC 1705: Implications for Distant Star-Forming Galaxies
Heckman, Timothy M.; Leitherer, Claus
We report the results of space-ultraviolet (UV) spectroscopy of the super star cluster `1' in the nearby dwarf starburst galaxy NGC 1705, using the Goddard High Resolution Spectrograph on the Hubble Space Telescope. The exceptionally high UV flux and surface brightness of NGC 1705-1 makes it ideal for studying how UV spectral diagnostics can be us…
Low-Mass Binaries in the Hyades: A Scarcity of Brown Dwarfs
Gizis, John E.; Reid, I. Neill
We have obtained HST Planetary Carnera observations of a total of 53 low-mass (M<0.3Msun) members of the Hyades cluster. Nine of these stars are resolved as binaries, with separations between 0.1 and 3.1 arcseconds, while a further three are probably equal-mass systems at smaller separations. Allowing for observational selection effe…
HST Observations and Models of the Gravitational Lens System MG 0414+0534
Falco, Emilio E.; Lehar, Joseph; Shapiro, Irwin I.
Quadruple gravitational lens systems offer the possibility of measuring time delays for image pairs, microlensing effects, and extinction in distant galaxies. Observations of these systems may be used to obtain estimates of H0 and to study the various mass components of lens galaxies at high redshifts. With the Hubble Space Telescope, w…