Search Publications
The Post-Coronal Mass Ejection Solar Atmosphere and Radio Noise Storm Activity
Ramesh, R.; Kathiravan, C.; Nataraj, H. S.
We carried out a statistical study of solar radio noise storms whose onset was in the aftermath of coronal mass ejections (CMEs) that occurred during 1997-2004, the first half of present solar cycle 23. The work is an attempt to understand the post-CME corona through observations of noise storms since the latter are considered to be closely relate…
An XMM-Newton observation of the neutron star X-ray transient 2S 1803-245 in quiescence
Wijnands, R.; Homan, J.; Cornelisse, R.
We observed the neutron star X-ray transient 2S 1803-245 in quiescence with the X-ray satellite XMM-Newton, but did not detect it. An analysis of the X-ray bursts observed during the 1998 outburst of 2S 1803-245 gives an upper limit to the distance of <=7.3 kpc, leading to an upper limit on the quiescent 0.5-10 keV X-ray luminosity of <=2.8 …
Hard X-Rays and Fluorescent Iron Emission from the Embedded Infrared Cluster in NGC 2071
Skinner, Stephen L.; Güdel, Manuel; Audard, Marc +1 more
We present first results of XMM-Newton X-ray observations of the infrared cluster lying near the NGC 2071 reflection nebula in the Orion B region. This cluster is of interest because it is one of the closest regions known to harbor embedded high-mass stars. We report the discovery of hard X-ray emission from the dense central NGC 2071-IR subgroup,…
The X-ray spectra of the flaring and quiescent states of YZ CMi observed by XMM-Newton
Raassen, A. J. J.; Güdel, M.; Mitra-Kraev, U.
We analyse the X-ray spectrum of the active late-type star YZ CMi (M4.5V); for quiescent as well as active stages, we derive emission measure (EM) distributions, elemental abundances, and electron temperatures and densities, which are in turn used to estimate flare loop lengths as well as coronal magnetic field strengths.
YZ CMi was observed …Surface roughness and geological mapping at subhectometer scale from the High Resolution Stereo Camera onboard Mars Express
Greeley, Ronald; Mangold, Nicolas; Martin, Patrick +7 more
The quantitative measurement of surface roughness of planetary surfaces at all scales provides insights into geological processes. A characterization of roughness variations at the scale of a few tens of meters is proposed that complements the analysis of local topographic data of the martian surface at kilometer scale, as achieved from the Mars O…
Optical Variability of Infrared Power-Law-Selected Galaxies and X-Ray Sources in the GOODS-South Field
Sarajedini, Vicki; Klesman, Alison
We investigate the use of optical variability to identify and study active galactic nuclei (AGNs) in the GOODS-South field. A sample of 22 mid-IR power-law sources and 102 X-ray sources with optical counterparts in the HST ACS images were selected. Each object is classified with a variability significance value related to the standard deviation of…
A Robust Test of Evolution near the Tip of the Red Giant Branch and Missing Giants in NGC 2808
Martel, André R.; Sandquist, Eric L.
We describe a new method for robustly testing theoretical predictions of red giant evolution near the tip of the giant branch. When theoretical cumulative luminosity functions are shifted to align the tip in the I band and normalized at a luminosity level slightly brighter than the red giant bump, virtually all dependence on age and composition (h…
On the artificial nature of aperiodic variability in XMM-Newton observations of M 31 X-ray sources and the ultraluminous X-ray source NGC 4559 ULX-7
Osborne, J. P.; Barnard, R.; Kolb, U. C. +3 more
Context: Power density spectra (PDS) that are characteristic of low mass X-ray binaries (LMXBs) have been previously reported for M 31 X-ray sources, observed by XMM-Newton. However, we have recently discovered that these PDS result from the improper addition/subtraction of non-simultaneous lightcurves.
Aims: To understand the properties and o…
Orbits and System Masses of 14 Visual Double Stars with Early-Type Components
Docobo, J. A.; Ling, J. F.
This paper presents revised orbits and system masses of 14 visual double stars, in all of which at least one component is of early spectral type: WDS 00546+1911 (STT 20 AB), WDS 01040+3528 (HO 213), WDS 02039+4220 (STT 38 BC), WDS 03503+2535 (STT 65), WDS 06393+4200 (STT 150), WDS 08285-0231 (A551 AB), WDS 15088-4517 (SEE 219 AB), WDS 15416+1940 (…
Star formation history and evolution of gas-rich dwarf galaxies in the Centaurus A group
Freeman, K. C.; Gallagher, J. S.; Disney, M. J. +4 more
We analyse the properties of three unusual dwarf galaxies in the Centaurus A group discovered with the HIPASS survey. From their optical morphology, they appear to be low surface brightness dwarf spheroidals, yet they are gas rich (MHI/LB > 1) with gas-mass-to-stellar light ratios larger than typical dwarf irregular galaxi…