Search Publications
Intergalactic Hydrogen Clouds OT Low Redshift: Connections to Voids and Dwarf Galaxies
Shull, J. Michael; Stocke, John T.; Penton, Steve
We provide new post-COSTAR data on one sightline (Mrk 421) and updated data from another (I Zw 1) from our Hubble Space Telescope (HST) survey of intergalactic Lyα clouds located along sightlines to four bright quasars passing through well-mapped galaxy voids (16000 km s^-1^ pathlength) and superclusters (18000 km s^-1^) We report two more definit…
The UV-brightest Stars of M33 and Its Nucleus: Discovery, Photometry, and Optical Spectroscopy
Massey, Philip; Bianchi, Luciana; Hutchings, John B. +1 more
We investigate the UV-brightest sources in the nearby galaxy M33. Our catalog of 356 sources is constructed from far-ultraviolet (FUV; 1500 A) and near-ultraviolet (NUV; 2400 A) images obtained with the Ultraviolet Imaging Telescope (UIT) matched with ground-based UBV data. We find that our survey is limited by the FUV flux and is complete to F
The X-ray source in non-magnetic cataclysmic variables.
Beuermann, K.; Verbunt, F.; van Teeseling, A.
We have analysed all available rosat pspc observations of non-magnetic cataclysmic variables. The VY Scl and non-SU UMa systems have harder X-ray spectra than the SU UMa and UX UMa systems. The old nova RR Pic has a very soft X-ray spectrum and might not be an ordinary non-magnetic cataclysmic variable. There appears to be no clear correlation of …
The Speedy Magnetic Propeller in the Cataclysmic Variable AE Aquarii
Eracleous, Michael; Horne, Keith
We present a spectroscopic study of the unusual flaring activity of the cataclysmic variable AE Aqr, which makes use of time-resolved, ultraviolet spectra obtained with the Hubble Space Telescope in November of 1992. This study complements our earlier investigation of the coherent, 33 s oscillations of AE Aqr using the same data. Its scientific ob…
Mid-Infrared Imaging Spectroscopy in Ophiuchus.
Rouan, D.; Perault, M.; Boulanger, F. +13 more
The dust emission spectrum between 5 and 16µm has been measured at the northern edge of the dense cloud in Ophiuchus at a position where the radiation field intensity is estimated to be 10-20 times the mean Solar neighborhood value. The spectrum shows the well known emission bands at 6.2, 7.7, 8.6, 11.3 and 12.7µm. ISO allows to detect…
Statistical properties of mirror mode structures observed by Ulysses in the magnetosheath of Jupiter
Balogh, A.; Erdős, G.
During the outbound pass of the Jovian magnetosheath in February 1992, a large number of magnetic depressions, without a significant change in the direction of the magnetic field vector, were observed by the Ulysses magnetometer. These low-frequency fluctuations, identified earlier as mirror mode waves, lasted about 1 day. The largest amplitude fl…
The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda I
Da Costa, G. S.; Armandroff, T. E.; Caldwell, Nelson +1 more
Images have been obtained with the Hubble Space Telescope WFPC2 camera of Andromeda I, a dwarf spheroidal (dSph) galaxy that lies in the outer halo of M31. The resulting color-magnitude diagrams reveal for the first time the morphology of the horizontal branch in this system. We find that, in a similar fashion to many of the galactic dSph companio…
On the Balmer Line Problem
Werner, K.
The so-called Balmer line problem describes the failure to achieve a consistent fit to the Balmer line spectrum of any hot sdO star whose effective temperature exceeds ~70,000 K. Results of Teff determinations drastically deviate, up to a factor of 2, depending on which Balmer line is examined. This problem was uncovered a few years ago during non…
Infrared absorption of H_2_O toward massive young stars.
van Dishoeck, E. F.; Helmich, F. P.
We present ISO-SWS observations of absorption lines of gas-phase water within its bending vibrational mode at 6µm toward four massive young stars, which cover a range in physical parameters. Hot water with an excitation temperature >200K is detected toward GL 2136 and GL 4176, in addition to GL 2591 discussed by Helmich et al. (1996A&…
Star Clusters in Interacting and Cooling Flow Galaxies
Watson, A. M.; Holtzman, J. A.; Stapelfeldt, K. R. +13 more
Two interacting galaxies and four central galaxies in cooling flow clusters were observed with the Hubble Space Telescope to look for young compact massive star clusters. The two interacting galaxies, NGC 3597 and NGC 6052, show clear evidence for resolved bright blue clusters that are likely to be comparable in mass to Galactic globulars based on…