Search Publications
The Very Highly Ionized Broad Absorption Line System of the QSO SBS 1542+541
Green, Richard F.; Kriss, Gerard A.; Zheng, Wei +2 more
We have analyzed the broad absorption line system of the bright (V ~ 16.5) high-redshift (z = 2.361) QSO SBS 1542+541 using UV spectra from the Hubble Space Telescope Faint Object Spectrograph, along with optical data from the Multiple Mirror Telescope and the Steward Observatory 2.3 m telescope. These spectra offer continuous wavelength coverage …
Hubble Space Telescope Imaging of the Optical Transient Associated with GRB 970508
Piro, L.; Pian, E.; Palazzi, E. +15 more
We report on Hubble Space Telescope observations of the optical transient (OT) discovered in the error box of the gamma-ray burst GRB 970508. The object was imaged on 1997 June 2 with the Space Telescope Imaging Spectrograph and Near-Infrared Camera and Multiobject Spectrometer. The observations reveal a pointlike source with R = 23.1+/-0.2 and H …
Is There a Deficit of S0 Galaxies at Intermediate Redshift?
Andreon, S.
Two contradictory results on the evolution of SO galaxies now exist in the recent literature: either S0's are old (zformation > 2) and are evolving passively or most of them form at z < 0.5, as implied by the deficit of S0's in intermediate-redshift (z ~ 0.5) clusters. The resolution of this controversy may be that the apparent de…
The Hubble Space Telescope Extragalactic Distance Scale Key Project. X. The Cepheid Distance to NGC 7331
Illingworth, Garth D.; Madore, Barry F.; Freedman, Wendy L. +17 more
The distance to NGC 7331 has been derived from Cepheid variables observed with the Hubble Space Telescope (HST) WFPC2, as part of the Extragalactic Distance Scale Key Project. Multiepoch exposures in F555W (~V) and F814W (~I), with photometry derived independently from DoPHOT and DAOPHOT/ALLFRAME programs, were used to detect a total of 13 reliabl…
Molecular Gas and Star Formation in the Host Galaxy of the QSO I ZW 1
Tacconi, L. J.; Schinnerer, E.; Eckart, A.
We have investigated the ISM of the I Zw 1 QSO host galaxy with Plateau de Bure millimeter interferometry and high angular resolution near-infrared imaging spectroscopy. We have detected a circumnuclear gas ring of diameter ~1.5" (1.8 kpc) in its millimetric CO line emission and have mapped the disk and the spiral arms of the host galaxy in the
Chromospheric Upflow Events Associated with Transition Region Explosive Events
Wang, Haimin; Chae, Jongchul; Schühle, Udo +2 more
Transition region explosive events are considered to be a manifestation of small-scale magnetic reconnection ubiquitously occurring--even in the quiet Sun. In this paper, we report a close association between transition region explosive events and chromospheric upflow events seen in Hα. From a comparison of the Big Bear Solar Observatory (BBSO) Hα…
HST Images of the Extremely Clumpy Radio Galaxy 1138-262 at z = 2.2
Pentericci, L.; Macchetto, F.; Spinrad, H. +4 more
We present and discuss optical continuum images made with the Hubble Space Telescope of the radio galaxy 1138-262 at z = 2.2. This object possesses one of the clumpiest optical morphologies of all known high-redshift radio galaxies, consisting of a bright nucleus aligned along the radio axis and a number of smaller components distributed over a re…
Searching for Wolf-Rayet Stars in I ZW 18: the Origin of He II Emission
Schaerer, Daniel; Leitherer, Claus; de Mello, Duília F. +1 more
I Zw 18 is the most metal-poor star-forming galaxy known and is an ideal laboratory to probe stellar evolution theory at low metallicities. Using archival Hubble Space Telescope WFPC2 imaging and Faint Object Spectrograph spectroscopy, we were able to improve previous studies. We constructed a continuum-free He II λ4686 map, which was used to iden…
The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XI. The Cepheids in NGC 4414
Kelson, Daniel D.; Illingworth, Garth D.; Huchra, John P. +21 more
We report the discovery of Cepheid variable stars in the galaxy NGC 4414, as part of the Hubble Space Telescope (HST) Key Project on the Extragalactic Distance Scale. Observations were obtained with the HST Wide-Field and Planetary Camera 2 (WFPC2) for 13 epochs at V (F555W) and 4 at I (F814W). Photometry was performed using two independent progra…
A New Look at Carbon Abundances in Planetary Nebulae. III. DDDM1, IC 3568, IC 4593, NGC 6210, NGC 6720, NGC 6826, and NGC 7009
Henry, R. B. C.; Kwitter, K. B.
This paper is the third in a series reporting on a study of carbon abundances in a carefully chosen sample of planetary nebulae representing a large range in progenitor mass and metallicity. We make use of the IUE Final Archive database containing consistently reduced spectra to measure line strengths of C III] λ1909 along with numerous other UV l…