Search Publications
Evidence for explosive event activity originating in the chromosphere
Doyle, J. G.; Bryans, P.; Summers, H. P. +2 more
We report on a joint SUMER, CDS, TRACE study, concentrating on a region which shows prolonged EUV explosive event (EE) activity in the transition region line N v 1238 Å, yet little evidence of such activity in another transition region line O v 629 Å (formed at a similar temperature) which was observed simultaneously. A possible explanation for th…
The field Am and ρ Puppis-like stars: Lithium and heavier elements
Gerbaldi, M.; Burkhart, C.; Coupry, M. F. +1 more
With observations at the Canada-France-Hawaii telescope, photospheric abundances of two evolved field Am stars,
The XMM-Newton spectrum of the high-z optically-obscured QSO RX J1343.4+0001: a classic radio quiet QSO
Cappi, M.; Guainazzi, M.; Schartel, N. +2 more
We present a 30 ks XMM-Newton observation of the z = 2.35 type II radio quiet quasar RX J1343.4+0001. These data provide the first good quality X-ray spectrum for this object. We measured a continuum slope Γ = 1.85±0.10 with only an upper limit on the column density of the absorbing material of NHz ⪉ 1022 cm-2…
Re-determination of Phoebe's orbit
Qiao, R. C.; Shen, K. X.; Dourneau, G. +2 more
In order to improve the orbit of Phoebe, the ninth satellite of the Saturnian system, 101 new observations were made by our research team in 2003, using a CCD detector of large size (2048×2048 pixels) mounted on the 1.56 m astrometric reflector at the Sheshan Station of Shanghai Astronomical Observatory. We fitted a numerical integration of its or…
High-Resolution Spectroscopy of X-Ray Quasars: Searching for the X-Ray Absorption from the Warm-Hot Intergalactic Medium
Canizares, Claude R.; Marshall, Herman L.; Fang, Taotao
We present a survey of six low- to moderate-redshift quasars with Chandra and XMM-Newton. The primary goal is to search for the narrow X-ray absorption lines produced by highly ionized metals in the warm-hot intergalactic medium. All the X-ray spectra can be fitted by a power law with the neutral hydrogen absorption method. The residuals that may …
Visible albedo of Mars' south polar cap: 2003 HST observations
Wolff, Michael J.; James, Philip B.; Bonev, Boncho P.
The martian south polar cap was observed with the High Resolution Camera on Hubble Space Telescope near the very favorable 2003 opposition. Well calibrated images taken at a number of wavelengths in visible and UV were used to measure the apparent Lambert albedos of two bright polar areas. These were corrected for the effects of atmospheric dust t…
Far-Infrared and Millimeter Continuum Studies of K Giants: α Bootis and α Tauri
McMurry, A. D.; Lim, Tanya; Schulz, Bernhard +5 more
We have imaged two normal, noncoronal, infrared-bright K giants, α Tau and α Boo, in the 1.4 and 2.8 mm continua using BIMA. These stars have been used as important absolute calibrators for several infrared satellites. Our goals are (1) to establish whether these stars radiate as simple photospheres or possess long-wavelength chromospheres and (2)…
Measured cosmological mass density in the WHIM: The solution to the ‘Missing Baryons’ problem
Elvis, Martin; Nicastro, Fabrizio; Fiore, Fabrizio +1 more
We review the current high-significance X-ray detections of Warm-Hot Intergalactic Medium (WHIM) filaments at z > 0 along the lines of sight to the two blazars Mrk 421 ( z = 0.03) and 1ES 1028 + 511 ( z = 0.361). For these WHIM filaments, we derive ionization corrections and, when possible, metallicity estimates. This allows us to obtain refine…
Mg II chromospheric radiative loss rates in cool active and quiet stars
Cardini, D.
The Mg II k emission line is a good indicator of the level of chromospheric activity in late-type stars. We investigate the dependence of this activity indicator on fundamental stellar parameters. To this purpose we use IUE observations of the Mg II k line in 225 late-type stars of luminosity classes I-V, with different levels of chromospheric act…
Prospects in space-based gamma-ray astronomy
Knödlseder, J.
Observations of the gamma-ray sky reveal the most powerful sources and the most violent events in the Universe. While at lower wavebands the observed emission is generally dominated by thermal processes, the gamma-ray sky provides us with a view on the non-thermal Universe. Here particles are accelerated to extreme relativistic energies by mechani…