Search Publications
Chandra X-Ray Observation of a Mature Cloud-Shock Interaction in the Bright Eastern Knot Region of Puppis A
Petre, Robert; Hwang, Una; Flanagan, Kathryn A.
We present Chandra X-ray images and spectra of the most prominent cloud-shock interaction region in the Puppis A supernova remnant. The bright eastern knot (BEK) has two main morphological components: (1) a bright compact knot that lies directly behind the apex of an indentation in the eastern X-ray boundary; and (2) lying 1' westward behind the s…
Detection of γ-ray lines from interstellar 60Fe by the high resolution spectrometer SPI
Knödlseder, J.; Schanne, S.; Diehl, R. +6 more
It is believed that core-collapse supernovae (CCSN), occurring at a rate ~once per century, have seeded the interstellar medium with long-lived radioisotopes such as 60Fe (half-life 1.5 Myr), which can be detected by the γ-rays emitted when they β-decay. Here we report the detection of the 60Fe decay lines at 1173 keV and 133…
The Chandra deep field South/GOODS survey. Optically faint X-ray sources
Alexander, D. M.; Zheng, W.; Gilli, R. +11 more
We provide important new constraints on the nature and redshift distribution of optically faint (R≥ 25) X-ray sources in the Chandra Deep Field South Survey. We use a large multi-wavelength data set, including the GOODS/ACS survey, the recently released Hubble Ultra Deep Field (UDF) data, and the new public VLT/ISAAC imaging. We show that we can d…
XMM-Newton View of PKS 2155-304: Characterizing the X-Ray Variability Properties with EPIC pn
Treves, A.; Celotti, A.; Zhang, Y. H. +2 more
Starting from XMM-Newton EPIC pn data, we present the X-ray variability characteristics of PKS 2155-304 using a simple analysis of the excess variance, σ2XS, and of the fractional rms variability amplitude, Fvar. The scatter in σ2XS and Fvar, calculated using 500 s long segments of …
Cassini UVIS observations of Europa's oxygen atmosphere and torus
Hendrix, A. R.; Shemansky, Donald E.; Hansen, Candice J.
Observations of the Europa environment using the Cassini UltraViolet Imaging Spectrograph (UVIS) show the presence of an extended atomic oxygen atmosphere in addition to the bound molecular oxygen atmosphere first detected by Hubble Space Telescope in 1994 [D.T. Hall, D.F. Strobel, P.D. Feldman, M.A. McGrath, H.A. Weaver, 1995, Detection of an oxy…
A Solar Minimum Irradiance Spectrum for Wavelengths below 1200 Å
Warren, Harry P.
NRLEUV represents an independent approach to modeling the Sun's EUV irradiance and its variability. Our model utilizes differential emission measure distributions derived from spatially and spectrally resolved solar observations, full-disk solar images, and a database of atomic physics parameters to calculate the solar EUV irradiance. In this pape…
Ejection of nitrogen from Titan's atmosphere by magnetospheric ions and pick-up ions
Luhmann, J. G.; Johnson, R. E.; Leblanc, F. +3 more
A 3-D Monte Carlo model is used to describe the ejection of N and N 2 from Titan due to the interaction of Saturn's magnetospheric N + ions and molecular pick-up ions with its N 2 atmosphere. Based on estimates of the ion flux into Titan's corona, atmospheric sputtering is an important source of both atomic and mol…
Proton and helium release times in SEP events observed with SOHO/ERNE
Laitinen, T.; Valtonen, E.; Huttunen-Heikinmaa, K.
We determine the proton and helium nuclei release times at the Sun for 25 SEP events within the time period May 8, 1996-June 20, 2001, and compare them to each other. The event onset times at 1 AU are determined with a Poisson-CUSUM method, and the solar release times are obtained by the velocity dispersion analysis. Velocity dispersions were deri…
XMM-Newton and Gemini Observations of Eight RASSCALS Galaxy Groups
Geller, Margaret J.; Mahdavi, Andisheh; Finoguenov, Alexis +2 more
We study the distribution of gas pressure and entropy in eight groups of galaxies belonging to the ROSAT All-Sky Survey/Center for Astrophysics Loose Systems (RASSCALS). We use archival and proprietary XMM-Newton observations, supplementing the X-ray data with redshifts derived from the literature; we also list 127 new redshifts measured with the …
The Stellar Content of Nearby Star-forming Galaxies. III. Unravelling the Nature of the Diffuse Ultraviolet Light
de Mello, Duilia; Aloisi, Alessandra; Meurer, Gerhardt R. +4 more
We investigate the nature of the diffuse intracluster ultraviolet light seen in 12 local starburst galaxies, using long-slit ultraviolet spectroscopy obtained with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST). We take this faint intracluster light to be the field in each galaxy and compare its spectroscop…