[Loops] new paper(s)

[Paola Testa]

Dear all,

please find below the links to a couple of new papers that may be of 
interest to some of you.

The first one is on "Temperature distribution of a non-flaring active 
region from simultaneous Hinode XRT and EIS observations", and it has 
just been accepted to ApJ. We discuss the complementary diagnostics from 
the two instruments, some insights into their cross-calibration, and the 
effects of the assumed abundances on the results. 

The other paper is a short review on "Element abundances in X-ray 
emitting plasmas in stars" that will soon be published on Space Science 
Reviews. I know it's a bit off topic, but I thought some of you might be 
interested in a brief review of recent studies of abundances in stellar 
coronae. Also, in the paper I'm trying to discuss the findings from 
solar and stellar abundance studies in a unified context.

Thanks!

cheers,
Paola


==============================


"Temperature distribution of a non-flaring active region from 
simultaneous Hinode XRT and EIS observations"
Testa P., Reale F., Landi E., DeLuca, E.E., Kashyap V., ApJ, in press

You can download the paper from http://arxiv.org/abs/1012.0346

Abstract:
We analyze coordinated Hinode XRT and EIS observations of a non-flaring 
active region to investigate the thermal properties of coronal plasma 
taking advantage of the complementary diagnostics provided by the two 
instruments. In particular we want to explore the presence of hot plasma 
in non-flaring regions. Independent temperature analyses from the XRT 
multi-filter dataset, and the EIS spectra, including the instrument 
entire wavelength range, provide a cross-check of the different 
temperature diagnostics techniques applicable to broad-band and spectral 
data respectively, and insights into cross-calibration of the two 
instruments. The emission measure distribution, EM(T), we derive from 
the two datasets have similar width and peak temperature, but show a 
systematic shift of the absolute values, the EIS EM(T) being smaller 
than XRT EM(T) by approximately a factor 2. We explore possible causes 
of this discrepancy, and we discuss the influence of the assumptions for 
the plasma element abundances. Specifically, we find that the 
disagreement between the results from the two instruments is 
significantly mitigated by assuming chemical composition closer to the 
solar photospheric composition rather than the often adopted "coronal" 
composition (Feldman 1992). We find that the data do not provide 
conclusive evidence on the high temperature (log T[K] >~ 6.5) tail of 
the plasma temperature distribution, however, suggesting its presence to 
a level in agreement with recent findings for other non-flaring regions.


---------


"Element abundances in X-ray emitting plasmas in stars"
Testa P., Space Science Reviews, in press

http://arxiv.org/abs/1012.0343

Abstract:
Studies of element abundances in stars are of fundamental interest for 
their impact in a wide astrophysical context, from our understanding of 
galactic chemistry and its evolution, to their effect on models of 
stellar interiors, to the influence of the composition of material in 
young stellar environments on the planet formation process. We review 
recent results of studies of abundance properties of X-ray emitting 
plasmas in stars, ranging from the corona of the Sun and other 
solar-like stars, to pre-main sequence low-mass stars, and to early-type 
stars. We discuss the status of our understanding of abundance patterns 
in stellar X-ray plasmas, and recent advances made possible by accurate 
diagnostics now accessible thanks to the high resolution X-ray 
spectroscopy with Chandra and XMM-Newton.