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On the Size of Structures in the Solar Corona
DeForest, C. E.
Fine-scale structure in the corona appears not to be well resolved by current imaging instruments. Assuming this to be true offers a simple geometric explanation for several current puzzles in coronal physics, including the apparent uniform cross section of bright threadlike structures in the corona, the low EUV contrast (long apparent scale heigh…
Feedback in the Antennae Galaxies (NGC 4038/9). I. High-Resolution Infrared Spectroscopy of Winds from Super Star Clusters
Graham, James R.; Gilbert, Andrea M.
We present high-resolution (R~24,600) near-IR spectroscopy of the youngest super star clusters (SSCs) in the prototypical starburst merger, the Antennae galaxies. These SSCs are young (3-7 Myr old) and massive (105-107 Msolar for a Kroupa initial mass function), and their spectra are characterized by broad, extende…
Measuring PAH Emission in Ultradeep Spitzer IRS Spectroscopy of High-Redshift IR-Luminous Galaxies
Frayer, D. T.; Scott, D.; Chary, R. +9 more
The study of the dominant population of high-redshift IR-luminous galaxies (1011-1012 Lsolar at 1<z<3), requires observation of sources at the ~0.1 mJy level in the mid-IR. We present the deepest spectra taken to date with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. We targeted two faint (…
The Chemical Distribution in a Subluminous Type Ia Supernova: Hubble Space Telescope Images of the SN 1885 Remnant
Wheeler, J. Craig; Fesen, Robert A.; Hamilton, Andrew J. S. +4 more
SN 1885 was a probable subluminous SN Ia that occurred in the bulge of the Andromeda galaxy, M31, at a projected location 16" from the nucleus. Here we present and analyze Hubble Space Telescope images of the SN 1885 remnant seen in absorption against the M31 bulge via the resonance lines of Ca I, Ca II, Fe I, and Fe II. Viewed in Ca II H and K li…
Divergence and Vorticity of Solar Subsurface Flows Derived from Ring-Diagram Analysis of MDI and GONG Data
Howe, R.; Komm, R.; Hill, F. +3 more
We measure the relation between divergence and vorticity of subsurface horizontal flows as a function of unsigned surface magnetic flux. Observations from the Michelson Doppler Imager (MDI) Dynamics Program and Global Oscillation Network Group (GONG) have been analyzed with a standard ring-diagram technique to measure subsurface horizontal flows f…
XMM-Newton Discovery of 7 s Pulsations in the Isolated Neutron Star RX J1856.5-3754
Mereghetti, Sandro; Tiengo, Andrea
Thanks to the high counting statistics provided by a recent XMM-Newton observation of RX J1856.5-3754, we have discovered that this isolated neutron star pulsates at a period of 7.055 s. This confirms that RX J1856.5-3754 is similar in nature to the other six thermally emitting, nearby neutron stars discovered in soft X-rays with ROSAT. The pulsat…
ACS Photometry of Newly Discovered Globular Clusters in the Outer Halo of M31
Mackey, A. D.; Tanvir, N. R.; Ferguson, A. M. N. +6 more
We report the first results from deep ACS imaging of 10 classical globular clusters in the far outer regions (15 kpc<~Rp<~100 kpc) of M31. Eight of the clusters, including two of the most remote M31 globular clusters presently known, are described for the first time. Our F606W, F814W color-magnitude diagrams extend ~3 mag below th…
Star Counts in the Globular Cluster ω Centauri. I. Bright Stellar Components
Degl'Innocenti, S.; Castellani, M.; Piersimoni, A. M. +17 more
We present a photometric investigation on HB, RGB, and MSTO stars in ω Cen=NGC 5139. The center of the cluster was covered with a mosaic of F435W, F625W, and F658N band data collected with HST ACS. The outer reaches were covered with a mosaic of U-, B-, V-, and I-band data collected with the 2.2 m ESO/MPI telescope. The final catalog includes ~1.7…
Low-Energy Cutoffs and Hard X-Ray Spectra in High-z Radio-loud Quasars: The Suzaku View of RBS 315
Maraschi, L.; Tagliaferri, G.; Ghisellini, G. +4 more
We present the results from the Suzaku observation of the powerful radio-loud quasar RBS 315 (z=2.69), for which a previous XMM-Newton observation showed an extremely flat X-ray continuum up to 10 keV (photon index Γ=1.26) and indications of strong intrinsic absorption (NH~1022 cm-2, assuming neutral gas). The inst…
Electrons and Protons in Solar Energetic Particle Events
Ling, A. G.; Cliver, E. W.
A plot of 0.5 MeV peak electron intensity versus >10 MeV peak proton intensity for well-connected solar energetic particle (SEP) events from 1997 to 2003 reveals two distinct populations: (1) a group of events with peak proton intensities <3 protons cm-2 s-1 sr-1 that have electron-to-proton (e/p) ratios rang…