Search Publications
The Host Galaxies of Radio-loud Active Galactic Nuclei: The Black Hole-Galaxy Connection
Urry, C. Megan; O'Dowd, Matthew; Scarpa, Riccardo
We have studied the host galaxies of a sample of radio-loud active galactic nuclei (AGNs) spanning more than 4 decades in the energy output of the nucleus. The core sample includes 40 low-power sources (BL Lac objects) and 22 high-power sources (radio-loud quasars) spanning the redshift range 0.15<~z<~0.5, all imaged with the high spatial re…
Analysis of H2 Emission from Mira B in Ultraviolet Spectra from the Hubble Space Telescope
Wood, Brian E.; Raymond, John C.; Karovska, Margarita
We analyze Lyα fluoresced H2 lines observed in the UV spectrum of Mira B. We identify 13 different sequences fluoresced by 13 different H2 transitions within the Lyα line. The observed H2 line ratios within these sequences imply significant line opacity, so we use a Monte Carlo radiative transfer code to model the …
Very Large Telescope Spectra of Carbon Stars in the Large Magellanic Cloud and Their Metallicity Dependence
Waters, L. B. F. M.; van Loon, J. Th.; Yamamura, I. +4 more
Very Large Telescope (VLT) L-band spectra of six carbon stars in the Large Magellanic Cloud are presented. The stars show absorption bands at 3.1 µm (HCN and C2H2), and 3.8 µm, which is probably due to C2H2. Two LMC stars show strong 3.5 µm HCN absorption. The equivalent widths of the 3…
Cosmic shear from STIS pure parallels. II. Analysis
White, S. D. M.; Fosbury, R. A. E.; Schneider, P. +6 more
We report on the marginal detection of cosmic shear on sub-arcmin scales with archive data from the STIS camera on board HST. For the measurement 121 galaxy fields with a field of view of 51'' x 51'' are used to obtain an rms cosmic shear of ~ 4% with 1.5sigma significance. This value is consistent with groundbased results obtained by other groups…
Survey of the ISM in early-type galaxies. IV. The hot dust component
Panagia, N.; Macchetto, F. D.; Pastoriza, M. G. +3 more
We present mid-IR photometric properties for a sample of 28 early-type galaxies observed at 6.75, 9.63 and 15 mu m with the ISOCAM instrument on board the ISO satellite. We find total mid-IR luminosities in the range (3-42) x 108 Lsun. The spectral energy distributions (SED) of the galaxies were derived using the mid-IR data …
Keck Spectroscopy of Young and Old Star Clusters in NGC 1023
Brodie, Jean P.; Larsen, Søren S.
We present Keck/LRIS spectra for 11 old globular clusters in the S0-type galaxy NGC 1023 and two young blue clusters in the nearby companion NGC 1023A. Analysis of the spectra of seven old clusters with sufficient signal-to-noise ratio shows generally good agreement between spectroscopic and previous photometric metallicity estimates, but the inte…
Polaris: Amplitude, Period Change, and Companions
Evans, Nancy Remage; Short, C. Ian; Sasselov, Dimitar D.
Polaris has presented us with the rare phenomenon of a Cepheid with a pulsation amplitude that has decreased over the last 50 yr. In this study we have used this property to see whether the amplitude decrease during the last 15 yr has had any effect on upper atmosphere heating. We obtained IUE high- and low-resolution spectra but found no change i…
Magnetospheric responses to sudden and quasiperiodic solar wind variations
Kim, K. -H.; Andre, M.; Mozer, F. S. +5 more
On April 13 (day 103), 2001, 0700-1400 UT, the Polar satellite experienced different plasma regimes (i.e., magnetosphere, magnetosheath, and solar wind) because of the solar wind dynamic pressure variations and its high orbital inclination near the subsolar magnetopause meridian. When Polar was in the magnetosheath, quasiperiodic spacecraft potent…
Multiple Collimated Outflows in the Proto-Planetary Nebula GL 618
Trammell, Susan R.; Goodrich, Robert W.
We present narrowband Hα, [S II], and [O I] Hubble Space Telescope images of the young planetary nebula GL 618. This object is a compact, bipolar nebula that is currently undergoing the transition from asymptotic giant branch star to planetary nebula. Our images confirm the presence of at least three highly collimated outflows emanating from the c…
A chromospheric scenario for the activity of beta Pictoris, as revealed by FUSE
Deleuil, M.; Bouret, J. -C.; Roberge, A. +3 more
We investigate a chromospheric scenario to explain the characteristics of the far-UV emission lines of beta Pictoris, revealed by FUSE spectra of this famous circumstellar disk system. The model assumes a thin region heated up to a few 105 K located close to the stellar photosphere. The resonance lines of C III at 977 Å and O VI at 1032…