Search Publications
Low Radiative Efficiency Accretion at Work in Active Galactic Nuclei: The Nuclear Spectral Energy Distribution of NGC 4565
Macchetto, F. D.; Gilli, R.; Sparks, William B. +1 more
We derive the spectral energy distribution (SED) of the nucleus of the Seyfert galaxy NGC 4565. Despite its classification as a Seyfert 2, the nuclear source is substantially unabsorbed. The absorption we find from Chandra data (NH=2.5×1021 cm-2) is consistent with that produced by material in the galactic disk of …
High-Energy Particles in the Wind Nebula of Pulsar B1509-58 as Seen by INTEGRAL
Goret, P.; Laurent, P.; Kuiper, L. +5 more
We present observations with the INTEGRAL IBIS telescope of the wind nebula powered by the young pulsar B1509-58, and we discuss the spatial and spectral properties of the unpulsed emission in the 20-200 keV energy band. The source extension and orientation along the northwest-southeast axis correspond to the jet emission seen at keV and TeV energ…
Far-Ultraviolet and X-Ray Observations of the Reverse Shock in the Small Magellanic Cloud Supernova Remnant 1E 0102.2-7219
Blair, William P.; Sasaki, Manami; Smith, Randall K. +4 more
We present Far Ultraviolet Spectroscopic Explorer (FUSE) and X-Ray Multi-Mirror Mission (XMM-Newton) data for the reverse shock of the O-rich supernova remnant (SNR) 1E 0102.2-7219 in the Small Magellanic Cloud (SMC). The FUSE observations cover three regions with significantly different optical [O III] intensities, all associated with the relativ…
The Influence of Mass and Environment on the Evolution of Early-Type Galaxies
Lanzoni, Barbara; Jørgensen, Inger; di Serego Alighieri, Sperello
We report on a uniform comparative analysis of the fundamental parameters of early-type galaxies at z~1 down to MB<=-20, both in the field and in clusters. The changes in the M/LB ratio from z~1 to today are larger for lower mass galaxies in all environments, and are larger in the field than in clusters for galaxies with t…
The Spatial Distribution of Faint Fuzzy Star Clusters in NGC 5195
Hwang, Narae; Lee, Myung Gyoon
We present a study of a faint fuzzy star cluster system in the nearby SB0 galaxy NGC 5195 interacting with the famous spiral galaxy NGC 5194 (M51), based on HST ACS BVI mosaic images taken by the Hubble Heritage Team. We have found about 50 faint fuzzy star clusters around NGC 5195 that are larger than typical globular clusters with effective radi…
FUSE Spectroscopy of the White Dwarf in U Geminorum
Brammer, Gabriel; Long, Knox S.; Froning, Cynthia S.
Observations of U Gem with FUSE confirm that the WD is heated by the outburst and cools during quiescence. At the end of an outburst, the best uniform-temperature WD model fits to the data indicate a temperature of 41,000-47,000 K, while in midquiescence, the temperature is 28,000-31,000 K, depending on the gravity assumed for the WD. Photospheric…
Challenging the Carbon Star Dust Condensation Sequence: Anarchist C Stars
Speck, Angela K.; Corman, Adrian B.; Thompson, Grant D. +1 more
There have been several investigations of the evolution of the mid-infrared (IR) dust features in carbon star spectra based on IRAS LRS data, but these studies are somewhat contradictory. In order to understand these differences in interpretations and to develop an understanding of the carbon star dust sequence, we have reexamined 26 IRAS LRS spec…
Luminosity Function of Faint Globular Clusters in M87
Zepf, Stephen E.; Lauer, Tod R.; Waters, Christopher Z. +2 more
We present the luminosity function to very faint magnitudes for the globular clusters in M87, based on a 30 orbit Hubble Space Telescope (HST) WFPC2 imaging program. The very deep images and corresponding improved false source rejection allow us to probe the mass function further beyond the turnover than has been done before. We compare our lumino…
An Estimation of the Acoustic Cutoff Frequency of the Sun Based on the Properties of the Low-Degree Pseudomodes
Jiménez, A.
The acoustic cutoff frequency (νac) is an important atmospheric parameter whose estimation has in the past been based on the study of power spectra that have yielded a wide range of values between 5300 and 5700 µHz. The discovery of a solar signal well beyond the acoustic cutoff frequency (pseudomodes) might lead one to think that…
Variations in D/H and D/O from New Far Ultraviolet Spectroscopic Explorer Observations
Chayer, Pierre; Kruk, Jeffrey W.; Oliveira, Cristina M. +1 more
We use data obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) to determine the interstellar abundances of D I, N I, O I, Fe II, and H2 along the sight lines to WD 1034+001, BD +39 3226, and TD1 32709. Our main focus is on determining the D/H, N/H, O/H, and D/O ratios along these sight lines, with logN(H)>20.0, that prob…