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A Far-Ultraviolet Spectroscopic Survey of Luminous Cool Stars
Young, P. R.; Linsky, J. L.; Lobel, A. +3 more
The Far Ultraviolet Spectroscopic Explorer (FUSE) ultraviolet spectra of eight giant and supergiant stars reveal that high-temperature (3×105 K) atmospheres are common in luminous cool stars and extend across the color-magnitude diagram from α Car (F0 II) to the cool giant α Tau (K5 III). Emission present in these spectra includes chrom…
Elemental Abundances in Two High Column Density Damped Lyα Systems at z < 1.5
Rao, Sandhya M.; Howk, J. Christopher; Wolfe, Arthur M. +1 more
We present Keck HIRES abundance measurements and metal-line kinematic profiles of the damped Lyα systems (DLAs) toward the quasars Q0933+733 (zabs=1.479) and Q0948+433 (zabs=1.233). These two DLAs have among the five highest H I column densities at any redshift: N(HI)=4.2×1021 cm-2. The metal-line data, …
AWM 4 - an isothermal cluster observed with XMM-Newton
O'Sullivan, E.; Vrtilek, J. M.; David, L. P. +2 more
We present an analysis of an XMM-Newton observation of the poor cluster AWM 4. The cluster is relaxed and its X-ray halo is regular with no apparent substructure. Azimuthally averaged radial spectral profiles suggest that the cluster is isothermal to a radius of at least 160 kpc, with no evidence of a central cooling region. Spectral mapping shows…
XMM-Newton detection of hot gas in the Eskimo Nebula: Shocked stellar wind or collimated outflows?
Gruendl, R. A.; Chu, Y. -H.; Guerrero, M. A. +1 more
The Eskimo Nebula (NGC 2392) is a double-shell planetary nebula (PN) known for the exceptionally large expansion velocity of its inner shell, ∼90 km s-1, and the existence of a fast bipolar outflow with a line-of-sight expansion velocity approaching 200 km s-1. We have obtained XMM-Newton observations of the Eskimo and detect…
Time-Distance Helioseismology: Inversion of Noisy Correlated Data
Kosovichev, A. G.; Birch, A. C.; Gizon, L. +2 more
In time-distance helioseismology most inversion procedures ignore the correlations in the data errors. Here we simulate the travel-time perturbations of wavepackets that result from known distributions of sound speed inhomogeneities. The forward and inverse problems are carried out using recently developed Born approximation sensitivity kernels. A…
Dispersion analysis of low-frequency waves through the terrestrial bow shock
Glassmeier, K. -H.; Narita, Y.
We present dispersion relations of low-frequency waves observed upstream and downstream of the Earth's bow shock analyzing Cluster magnetometer measurements along an outbound orbit covering four regions: the foreshock, the outer, the middle, and the inner magnetosheath. The aim of our study is to better understand wave transmission, mode conversio…
Intergalactic HeII absorption towards QSO 1157+3143
Reimers, D.; Hagen, H. -J.; Jakobsen, P. +3 more
We report the discovery of a further line of sight allowing detection of He II Lyα absorption by the intergalactic medium. A HST/STIS survey of 32 bright z ∼ 3 quasars selected from the Hamburg Quasar Surveys yielded one detection toward QSO 1157+3143 (z ∼ 3, B ≃ 17). A 10 orbit follow-up spectrum reveals a UV spectrum significantly suppressed by …
Identification of 8 INTEGRAL hard X-ray sources with Chandra
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +2 more
We report the results of identification of 8 hard X-ray sources discovered by the INTEGRAL observatory during the ongoing all-sky survey. These sources have been observed by Chandra. In 6 cases a bright X-ray source was found within the INTEGRAL localization region, which permitted to unambiguously identify 5 of the objects with nearby galaxies, i…
The Araucaria Project: The Effect of Blending on the Cepheid Distance to NGC 300 from Advanced Camera for Surveys Images
Bresolin, Fabio; Kudritzki, Rolf-Peter; Gieren, Wolfgang +1 more
We have used the Advanced Camera for Surveys aboard the Hubble Space Telescope (HST) to obtain F435W, F555W, and F814W single-epoch images of six fields in the spiral galaxy NGC 300. Taking advantage of the superb spatial resolution of these images, we have tested the effect that blending of the Cepheid variables studied from the ground with close…
Hubble Space Telescope NICMOS Imaging of W3 IRS 5: A Trapezium in the Making?
Megeath, S. T.; Wilson, T. L.; Corbin, M. R.
We present Hubble Space Telescope NICMOS imaging of W3 IRS 5, a binary high-mass protostar. In addition to the two protostars, NICMOS images taken in the F222M and F160W filters show three new 2.22 µm sources with very red colors; these sources fall within a region 5600 AU in diameter and are coincident with an ~100 Msolar, dense …