We present echelle observations of the intrinsic UV absorption lines in the Seyfert galaxy NGC 4151, which were obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) on 1999 July 19. The UV continuum flux at 1450Å decreased by factor of about four over the previous two years and there was a corresponding dramatic increase in the column densities of th...

We observe with Keck/HIRES the z ≈ 2.5 QSO triplet 1623+27 in order to explore on the scale of a Megaparsec the spatial clustering of C IV absorbers between adjacent sightlines. We find this signal to be significantly weaker than the clustering in velocity on corresponding scales along single sightlines, assuming that the relative velocity of absorbers is dominated by the Hubble flow. This indi...

The excited states of UV-B absorbers, ethylhexyl triazone (EHT) and diethylhexylbutamido triazone (DBT), have been studied through measurements of UV absorption, fluorescence, phosphorescence, triplet-triplet absorption and electron paramagnetic resonance spectra in ethanol. The energy levels of the lowest excited singlet (S1) and triplet (T1) states and quantum yields of fluorescence and phosp...

We present an imaging and spectroscopic survey of galaxies in fields around QSOs HE 0226−4110, PKS 0405−123, and PG 1216+069. The fields are selected to have ultraviolet echelle spectra available, which uncover 195 Lyα absorbers and 13 OVI absorbers along the three sightlines. We obtain robust redshifts for 1104 galaxies of rest-frame absolute magnitude MR −5log h . −16 and at projected physica...

We use a halo occupation approach to connect Mg II absorbers to dark matter halos as a function of redshift. Using the model constructed in Tinker & Chen (2008), we parameterize the conditional probability of an absorber of equivalent width Wr being produced by a halo of mass Mh at a given redshift, P(Wr|Mh,z). We constrain the free parameters of the model by matching the observed statistics of...

This paper investigates the use of order-tuned absorbers to attenuate vibrations of flexible blades in a bladed disk assembly subjected to engine order excitation. The blades are modeled by a cyclic chain of N oscillators, and a single vibration absorber is fitted to each blade. These absorbers exploit the centrifugal field arising from rotation so that they are tuned to a given order of rotati...

We present a study of the nature of warm absorbers on the basis of ROSAT X-ray observations and photoionization calculations carried out with the code Cloudy. We focus on ‘non-standard’ warm absorbers: (i) the proposed dusty warm absorbers in IRAS 13349+2438 and IRAS 17020+4544, and possibly in 4C+74.26, (ii) we explore several scenarios to account for the recently observed peculiar absorption ...

A method for measuring the vapor pressures of a wide range of materials using a conventional thermobalance and standard sample holders is described. The equipment is calibrated using pure reference materials of known vapor pressure and exploiting the relationship between volatilization rate and vapor pressure based on the Langmuir equation for free evaporation. Enthalpies of vaporization and su...