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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 …
The Evolution of the Final Helium Shell Flash Star V605 Aquilae From 1917 to 1997
De Marco, Orsola; Clayton, Geoffrey C.
Only three stars have been observed going through a final helium shell flash since the advent of modem instrumentation, FG Sagittae (in 1894), V605 Aquilae (in 1919), and Sakurai's Object (in 1996). In this paper, we present for the first time a spectrum taken of V605 Aql, while it was in its cool giant phase in 1921. This spectrum is identical to…
Absorption by Highly Ionized Interstellar Gas Along Extragalactic and Galactic Sight Lines
Sembach, Kenneth R.; Savage, Blair D.; Lu, Limin
We present intermediate resolution (FWHM ∼10-20 km s-1) Goddard High Resolution Spectrograph observations of Galactic C IV and N V absorption along the sight lines to Fairall 9, Mrk 509, PKS 2155-304, and NGC 5548. These observations also provide measures of Si II and S II along the sight lines. Recent measurements of Si IV absorption f…
Planetary Nebulae in the Globular Cluster PAL 6 and NGC 6441
Henry, R. B. C.; Kwitter, K. B.; Morse, Jon A. +2 more
Jacoby & Fullton (1998, in preparation) recently surveyed the Galactic globular cluster system for planetary nebulae and identified excellent candidates in the disk clusters Pal 6 and NGC 6441. Velocities, abundances, and central star properties for these two nebulae are derived. There is a 0.5% probability that the nebula in Pal 6 is a chance…
Hubble Space Telescope Images of the HH 111 Jet.
Hartigan, Patrick; Bally, John; Reipurth, Bo +2 more
We have observed the classic Herbig-Haro jet HH 111 with the Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope (\HST) through narrow-band filters isolating Hα and [S II]lambda lambda6716 ,6731 emission. The new images fully resolve the body of the jet into a series of small bow shocks, which we conclude form as fast jet material …
Resolving the Helium Lyman-alpha Forest: Mapping Intergalactic Gas and Ionizing Radiation at z~3
Anderson, Scott F.; Hogan, Craig J.; Rugers, Martin H.
We present a new, high resolution HST/GHRS spectrum of quasar Q0302-003, and use the He(+) Lyman-alpha absorption, together with a high resolution Keck spectrum of the HI Lyman-alpha forest, to probe the distribution and ionization state of foreground gas just below the quasar redshift z~ 3.3. Within ~ 4000 km/sec of the quasar redshift the spectr…
NGC 2419, M92, and the age gradient in the galactic halo
Bond, Howard E.; Stetson, Peter B.; Richer, Harvey B. +7 more
The WFPC2 camera on HST has been used to obtain photometry of the low-metallicity ([Fe/H] =-2.14), outer-halo globular cluster NGC 2419. Our color-magnitude diagram in (V, V-I) reaches Vlim =~ 27.8, clearly delineating the subgiant and turnoff region and about three magnitudes of the unevolved main sequence. A differential fit of the NG…
WFPC2 Observations of the Carina Dwarf Spheroidal Galaxy.
Mighell, Kenneth J.
We present our analysis of Hubble Space Telescope Wide Field Planetary Camera 2 observations in F555W (∼V) and F814W (∼I) of the Carina dwarf spheroidal galaxy. The resulting V vs V-I color-magnitude diagrams reach V≈27.1 mag. The reddening of Carina is estimated to be E(V-I)=0.08±0.02 mag. A new estimate of the distance modulus of Carina, (m - M)…
HST/GHRS Observations of the Compact Slow Ejecta of Eta Carinae
Humphreys, R. M.; Balick, B.; Davidson, Kris +6 more
We report spectroscopic observations of eta Car and adjacent gas with an unprecedented combination of spatial and spectral resolution, 0.1 arcsec x 0.1 Angstroms. Radial velocities show that the bright objects C and D, 0.2 arcsec from the star, are slow equatorial ejecta. The narrow emission lines which fluctuate in the spectrum of the core region…