Search Publications
Star Clusters in Virgo and Fornax Dwarf Irregular Galaxies
Olsen, Knut; Seth, Anil; Lotz, Jennifer +2 more
We present the results of a search for clusters in dwarf irregular galaxies in the Virgo and Fornax Clusters using Hubble Space Telescope (HST) WFPC2 snapshot data. The galaxy sample includes 28 galaxies, 11 of which are confirmed members of the Virgo and Fornax Clusters. In the 11 confirmed members, we detect 237 cluster candidates and determine …
Dust in Comet 67P/Churyumov-Gerasimenko
Lara, L. M.; López-Moreno, J. J.; Moreno, F. +2 more
Comet 67P/Churyumov-Gerasimenko has been designated the new target for the ESA Rosetta mission, launched successfully on 2004 March 2. We have analyzed an image set taken in 2003 March, in which the comet appeared to have a conspicuous dust antitail. We employed a Monte Carlo code, similar to that by Fulle (1989), by which we have computed the dus…
Abundance constraints and direct redshift measurement of the diffuse X-ray emission from a distant cluster of galaxies
Böhringer, H.; Barcons, X.; Fabian, A. C. +4 more
We report on the XMM-Newton (XMM) observation of RX J1053.7+5735, one of the most distant X-ray selected clusters of galaxies, which also shows an unusual double-lobed X-ray morphology, indicative of a possible equal-mass cluster merger. The cluster was discovered during the ROSAT deep pointings in the direction of the Lockman Hole. All XMM Lockma…
Intermittent Heating of the Solar Corona by Heat Flux-generated Ion Cyclotron Waves
Hollweg, Joseph V.; Markovskii, S. A.
Recently, we suggested that the source of ion heating in solar coronal holes is small-scale reconnection events (microflares) at the coronal base. The microflares launch intermittent heat flux up into the corona exciting ion cyclotron waves through a plasma microinstability. The ions are heated by these waves during the microflare bursts and then …
The Irradiated Herbig-Haro Jets Near σ Orionis
Bally, John; Andrews, Sean M.; Reipurth, Bo +1 more
We present high-resolution echelle spectra of the irradiated Herbig-Haro jets HH 444, 445, 446, and 447 from the Keck I telescope. The structural, kinematic, and physical properties of the jets near their sources are analyzed in detail. In particular, spatio-kinematic electron density variations and evidence for excited, low-velocity entrained mat…
XMM-Newton Spectra of Intermediate-Mass Black Hole Candidates: Application of a Monte Carlo Simulated Model
Wang, Q. Daniel; Yao, Yangsen; Fukui, Wakako +2 more
We present a systematic spectral analysis of six ultraluminous X-ray sources (NGC 1313 X-1 and X-2, IC 342 X-1, Ho IX X-1, NGC 5408 X-1, and NGC 3628 X-1) observed with the XMM-Newton observatory. These extranuclear X-ray sources in nearby late-type galaxies have been considered as intermediate-mass black hole candidates. We have performed Monte C…
The Slowly Expanding Envelope of CRL 618 Probed with HC3N Rotational Ladders
Phillips, T. G.; Cernicharo, J.; Goicoechea, J. R. +1 more
Lines from HC3N and isotopic substituted species in ground and vibrationally excited states produce crowded millimeter and submillimeter wave spectra in the C-rich protoplanetary nebula CRL 618. The complete sequence of HC3N rotational lines from J=9-8 to J=30-29 has been observed with the IRAM 30 m telescope toward this obje…
Solar cycle dependence of the apparent radius of the Sun
Noël, F.
Visual astrometric observations of the Sun covering the second and first part of solar cycles 22 and 23 respectively, have been carried out during the last 13 years with the Danjon astrolabe of Santiago, Chile. These observations give, among other solar parameters, an absolute value of the Sun's apparent radius. We report here the results obtained…
On the Temporal Relationship between Hα Filament Eruptions and Soft X-Ray Emissions
Schuck, P. W.; Chen, J.; Schwartz, I. B. +1 more
A technique for investigating the temporal relationship between Hα filament eruptions and soft X-ray flux is presented. The method is fast, simple, based on statistical measures, and requires no a priori knowledge regarding the location of the filaments on the solar disk. The method is used to study the filament eruption associated with a coronal …
A High-Speed Erupting-Prominence CME: A Bridge Between Types
Feynman, Joan; Ruzmaikin, Alexander
Several studies have indicated that there may be two distinct types of coronal mass ejections (CMEs); a high-velocity bright energetic type associated with flares, and a smaller slower less impressive type associated with erupting prominences. How valid is this distinction? We analyze a CME combining attributes of both types, a high-velocity brigh…