Search Publications
A deeper look at the colors of the saturnian irregular satellites
Bauer, James; Grav, Tommy
We have performed broadband color photometry of the twelve brightest irregular satellites of Saturn with the goal of understanding their surface composition, as well as their physical relationship. We find that the satellites have a wide variety of different surface colors, from the negative spectral slopes of the two retrograde satellites S IX Ph…
Diagnostics of Suprathermal Electrons in Active-Region Plasmas Using He-like UV Lines
Landi, E.; Doschek, G. A.; Feldman, U.
In the present paper we use UV lines emitted by He-like ions as a tool to test the presence of nonthermal high-energy electrons and to quantify their number and energy. The He-like lines we consider are the He-like 1s2s3S-1s2p3P lines observed in the UV, and their use capitalizes on the high excitation energies for the 1s2p
The Abundance of Deuterium in the Warm Neutral Medium of the Lower Galactic Halo
Savage, Blair D.; Lehner, Nicolas; Fox, Andrew +2 more
We use high-resolution ultraviolet spectra to obtain Milky Way interstellar column densities of H I, D I, O I, S II, Fe II, and P II toward the QSO HE 0226-4110 in the Galactic direction l=253.4deg and b=-65.77deg. We obtain D/H=21+8-6 ppm from an analysis of the strong damped Lyα line of H I and the wea…
Geometry of the high-latitude magnetopause as observed by Cluster
Balogh, A.; Zhang, H.; Zong, Q. -G. +3 more
This investigation reveals the geometrical properties of the high-latitude boundaries surrounding the high-altitude cusp. These have been shown by recent studies to include the outer boundary between the magnetosheath and the cusp; the outer boundary between the magnetosheath and the high-latitude, closed field-line region of the dayside magnetosp…
Outflow velocity of the O+5 ions in polar coronal holes out to 5 R⊙
Antonucci, E.; Telloni, D.; Dodero, M. A.
The purpose of the paper is to extend the measurement of the kinetic temperature and outflow velocity of the oxygen ions in the outer corona above polar holes out to 5 R_⊙. An analytical model of the solar corona at the minimum of activity has been employed in order to synthesize the spectral line profiles to be fitted with the data: the kinetic t…
A Compact Cluster of Massive Red Galaxies at a Redshift of 1.5
Glazebrook, Karl; McCarthy, Patrick J.; Yan, Haojing +15 more
We describe a compact cluster or group of massive red galaxies at z=1.5 discovered in one of the Gemini Deep Deep Survey (GDDS) fields. Deep H-band imaging from the Hubble Space Telescope (HST) reveals a high density of red galaxies associated with a galaxy with a spectroscopic redshift of 1.51. These galaxies have spectral energy distributions (S…
Black Hole Masses and Eddington Ratios of AGNs at z < 1: Evidence of Retriggering for a Representative Sample of X-Ray-selected AGNs
Danese, L.; Ballo, L.; Tozzi, P. +10 more
We estimated black hole masses and Eddington ratios for a sample of X-ray-selected active galactic nuclei (AGNs) in the fields covered by the Great Observatory Origins Deep Survey (GOODS). The spanned ranges in redshift (0.4<z<1) and hard X-ray luminosity (1042<~LX<~4×1043 ergs s-1) allow us …
Discharge experiments simulating chemical evolution on the surface of Titan
Fischer, Georg; Rucker, Helmut O.; Lammer, Helmut +7 more
Saturn's moon Titan has been considered as one of the few places in our Solar System, where atmospheric and surface conditions could have produced organic compounds essential as precursors for an evolution of life. The Cassini-Huygens mission has provided new data on Titan's atmosphere and surface, which enabled us to simulate the chemical process…
The sizes of disc galaxies in intermediate-redshift clusters
Milvang-Jensen, B.; Aragón-Salamanca, A.; Bamford, S. P.
We examine how the location of star formation within disc galaxies depends on environment at intermediate redshift. This is achieved by comparing emission-line (rem) and rest-frame B-band (rB) scalelengths for matched samples of 50 field and 19 cluster, star-forming, disc galaxies, with 0.25 <= z <= 1.0 and MB
The XMM-Newton RGS spectrum of the high luminosity Seyfert 1 galaxy Markarian 509
Page, M. J.; Branduardi-Raymont, G.; Smith, R. A. N.
We present a detailed analysis of the soft X-ray spectrum of the Seyfert 1 galaxy Markarian 509 taken with the XMM-Newton Reflection Grating Spectrometer. An underlying power-law continuum and three warm absorber phases provide a good fit to the data along with a number of broad and narrow emission lines. Our three warm absorber phases each have d…