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We present observations of the dwarf galaxies GALFA Dw3 and GALFA Dw4 with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST). These galaxies were initially discovered as optical counterparts to compact HI clouds in the GALFA survey. Both objects resolve into stellar populations which display an old red giant branch, younger helium burning, and massive main sequence stars. We use the tip of the red giant branch method to determine the distance to each galaxy, finding distances of 7.61$_{-0.29}^{+0.28}$ Mpc and 3.10$_{-0.17}^{+0.16}$ Mpc, respectively. With these distances we show that both galaxies are extremely isolated, with no other confirmed objects within ~1.5 Mpc of either dwarf. GALFA Dw4 is also found to be unusually compact for a galaxy of its luminosity. GALFA Dw3 and Dw4 contain HII regions with young star clusters and an overall irregular morphology; they show evidence of ongoing star formation through both ultraviolet and H$alpha$ observations and are therefore classified as dwarf irregulars (dIrrs). The star formation histories of these two dwarfs show distinct differences: Dw3 shows signs of a recently ceased episode of active star formation across the entire dwarf, while Dw4 shows some evidence for current star formation in spatially limited HII regions. Compact HI sources offer a promising method for identifying isolated field dwarfs in the Local Volume, including GALFA Dw3 & Dw4, with the potential to shed light on the driving mechanisms of dwarf galaxy formation and evolution.
We present images of 29 post-starburst quasars (PSQs) from a Hubble Space Telescope (emph{HST}) Advanced Camera for Surveys (ACS) Wide Field Channel Snapshot program. These broad-lined active galactic nuclei (AGN) possess the spectral signatures of m
We present a sample of 17 newly discovered ultracool dwarf candidates later than ~M8, drawn from 231.90 arcmin2 of {it Hubble Space Telescope} Wide Field Camera 3 infrared imaging. By comparing the observed number counts for 17.5<J_125<25.5 AB mag to
We present deep Hubble Space Telescope imaging at the locations of four, potentially hostless, long-faded Type Ia supernovae (SNe Ia) in low-redshift, rich galaxy clusters that were identified in the Multi-Epoch Nearby Cluster Survey. Assuming a stee
RGG 118 (SDSS 1523+1145) is a nearby ($z=0.0243$), dwarf disk galaxy ($M_{ast}approx2times10^{9} M_{odot}$) found to host an active $sim50,000$ solar mass black hole at its core (Baldassare et al. 2015). RGG 118 is one of a growing collective sample
We present initial results from a Hubble Space Telescope snapshot imaging survey of the host galaxies of Swift-BAT active galactic nuclei (AGN) at z<0.1. The hard X-ray selection makes this sample sample relatively unbiased in terms of obscuration co