... just to inform you that the review on coronal loops has just been officially published:
http://www.livingreviews.org/lrsp-2010-5
Best regards Fabio
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
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"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.
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"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.
Hi All,
A new AIA loop paper has just been accepted for publication in ApJ:
https://umdrive.memphis.edu/jschmelz/public/Loops/AIA_SchmelzEtAl.pdf
Isothermal and Multithermal Analysis of Coronal Loops Observed with AIA by Schmelz et al.
Abstract: The coronal filters in the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory peak at different temperatures; the series covers the entire active region temperature range, making AIA ideal for multi-thermal analysis. Here we analyze coronal loops from several active regions that have been observed by AIA. We have specifically targeted cool loops (or at least loops with a cool component) that were chosen in the 171\AA\ channel of AIA, which has a peak response temperature of Log T $=$ 5.8. We wanted to determine if the loops could be described as isothermal or multithermal. We find that several of our 12 loops have narrow temperature distributions, which may be consistent with isothermal plasma; these can be modeled with a single flux tube. Other loops have intermediate-width temperature distributions, appear well-constrained, and should be multi-stranded. The remaining loops, however, have unrealistically broad DEMs. We find that this problem is the result of missing low-temperature lines in the AIA 131\AA\ channel. If we repeat the analysis without the 131\AA\ data, these loops also appear to be well-constrained and multi-stranded.
Regards, Joan
Another nice result. So we're all right/wrong. Interesting...
Piet
On 2/14/11 9:26 AM, Joan T Schmelz (jschmelz) wrote:
Hi All,
A new AIA loop paper has just been accepted for publication in ApJ:
https://umdrive.memphis.edu/jschmelz/public/Loops/AIA_SchmelzEtAl.pdf
Isothermal and Multithermal Analysis of Coronal Loops Observed with AIA by Schmelz et al.
Abstract: The coronal filters in the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory peak at different temperatures; the series covers the entire active region temperature range, making AIA ideal for multi-thermal analysis. Here we analyze coronal loops from several active regions that have been observed by AIA. We have specifically targeted cool loops (or at least loops with a cool component) that were chosen in the 171\AA\ channel of AIA, which has a peak response temperature of Log T $=$ 5.8. We wanted to determine if the loops could be described as isothermal or multithermal. We find that several of our 12 loops have narrow temperature distributions, which may be consistent with isothermal plasma; these can be modeled with a single flux tube. Other loops have intermediate-width temperature distributions, appear well-constrained, and should be multi-stranded. The remaining loops, however, have unrealistically broad DEMs. We find that this problem
i
s the result of missing low-temperature lines in the AIA 131\AA\ channel. If we repeat the analysis without the 131\AA\ data, these loops also appear to be well-constrained and multi-stranded.
Regards, Joan _______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Dear coronal loop experts,
You might be interested what AIA reveals to us about the thermal structure of coronal loops. The paper contains also an empirical correction of the A 94 response function.
Looking forward to a fruitful discussion in Palma de Mallorca! Cheers,
Markus
Aschwanden,M.J. and Boerner,P. 2011, The Astrophysical Journal, ... (accepted, March 1, 2011; in press) URL1="http://www.lmsal.com/~aschwand/eprints/2011_boerner.pdf" Solar corona loop studies with AIA: I. Cross-sectional temperature structure
_______________________________________ Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center Org. ADBS, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.com _______________________________________
Dear loop scientists,
If you are interested in modeling the magnetic field of loops, here is a paper of (my freshly-minted PhD) Anne Sandman with a new method to find a potential magnetic field that follows EUV loop tracings closely.
Share & enjoy, Markus & Anne
Sandman,A.W. and Aschwanden,M.J. 2011, Solar Physics, online-first, (DOI 10.1007/s11207-011-9782-x) URL1="http://www.lmsal.com/~aschwand/eprints/2010_sandman.pdf" A new method for modeling the coronal magnetic field with STEREO and submerged dipoles
____________________________________________ Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center Org. ADBS, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.com _______________________________________
loops@solar.physics.montana.edu