Search Publications
Nitrogen Overabundance: Globular Cluster and Halo Formation
Burstein, David; Li, Yong
Halo globular clusters pose four succinct issues that must be solved in any scenario of their formation: single-age, single-metallicity stellar populations; a lower limit ([Fe/H]~-2.5) to their average metallicity; comprising only 1% of the stellar halo mass; and being among the oldest stars in our Galaxy. New spectra are presented of Galactic sta…
NGC 2264 IRS 1: The Central Engine and Its Cavity
Stecklum, B.; Henning, Th.; Linz, H. +1 more
We present a high-resolution study of NGC 2264 IRS 1 in CS 2-->1 and in the 3 mm continuum using the IRAM Plateau de Bure interferometer. We complement these radio data with images taken at 2.2, 4.6, and 11.9 µm. The combined information allows a new interpretation of the closest environment of NGC 2264 IRS 1. No disk around the B-type st…
Smaug: A New Technique for the Deprojection of Galaxy Clusters
Molendi, Silvano; Ghizzardi, Simona; De Grandi, Sabrina +1 more
This paper presents a new technique for reconstructing the spatial distributions of hydrogen, temperature, and metal abundance of a galaxy cluster. These quantities are worked out from the X-ray spectrum, modeled starting from few analytical functions describing their spatial distributions. These functions depend on some parameters, determined by …
Mid-Infrared Imaging of the Protostellar Binary L1448N IRS 3(A,B)
Ciardi, David R.; Williams, Jonathan P.; Telesco, Charles M. +4 more
Mid-infrared (10-25 µm) imaging of the protostellar binary system L1448N IRS 3(A,B) is presented. Only one source, IRS 3(A), was detected at mid-infrared wavelengths-all of the mid-infrared emission from IRS 3(A,B) emanates from IRS 3(A). The mid-infrared luminosity of IRS 3(A) is Lmidir=1.3[d/(300pc)]2Lsolar…
FUSE Measurements of Rydberg Bands of Interstellar CO between 925 and 1150 Å
Andersson, B. -G.; Federman, S. R.; Sheffer, Y.
We report the detection of 11 Rydberg bands of CO in FUSE spectra of the sight line toward HD 203374A. Eight of these electronic bands are seen in the interstellar medium for the first time. Our simultaneous fit of five non-Rydberg A-X bands together with the strongest Rydberg band of CO, C-X (0-0), yields a four-component cloud structure toward t…
Calcium Abundance in the Solar Wind
Wurz, P.; Bochsler, P.; Ipavich, F. M. +1 more
We report on the calcium abundance in the solar wind for an extended time period around the 1996 solar minimum. Data were recorded with the Mass Time-of-Flight (MTOF) sensor of the Charge, Element, and Isotope Analysis System (CELIAS) instrument on the SOHO spacecraft. The Ca/O abundance is 0.017+/-0.003 for slow solar wind (VSW<400 …
High-Resolution Continuum Imaging at 1.3 and 0.7 Centimeters of the W3 IRS 5 Region
Megeath, S. T.; Wilson, T. L.; Boboltz, D. A. +1 more
High-resolution images of the hypercompact H II (HC H II) regions in W3 IRS 5 taken with the Very Large Array (VLA) at 1.3 and 0.7 cm are presented. Four HC H II regions were detected with sufficient signal-to-noise ratios to allow the determination of relevant parameters, such as source position, size, and flux density. The sources are slightly e…
Search for the Optical Counterpart of the Vela Pulsar X-Ray Nebula
Caraveo, P. A.; De Luca, A.; Zaggia, S. +4 more
Observations of the Vela pulsar region with the Chandra X-Ray Observatory have revealed the fine structure of its synchrotron pulsar-wind nebula (PWN), which showed an overall similarity with the Crab PWN. However, contrary to the Crab, no firm detection of the Vela PWN in optical has been reported yet. To search for the optical counterpart of the…
The Origin of High-Energy 3He-rich Solar Particle Events
Torsti, J.; Kocharov, L.
Observed isotope abundances in the energy range >15 MeV nucleon-1 by the ERNE instrument on board Solar and Heliospheric Observatory show a group of high-energy 3He-rich solar particle events that apparently has not been identified in earlier observations. Those events are observed to start well after the flare, when the a…
On the Extreme-Ultraviolet/Ultraviolet Plasma Diagnostics for Nitrogen-like Ions from Spectra Obtained By SOHO/SUMER
Dwivedi, B. N.; Mohan, A.; Landi, E.
In this work we discuss the potential for plasma diagnostics of forbidden transitions from the ground levels in the nitrogen-like ions: Al VII, Si VIII, P IX, S X, Ar XII, K XIII, and Ca XIV. We also study the lines emitted by n=3 levels of Si VIII. These transitions fall in the UV spectral range and have been recently observed by the SOHO/SUMER i…