M. Landini

CHIANTI—An Atomic Database for Emission Lines. VII. New Data for X-Rays and Other Improvements

The CHIANTI atomic database contains atomic energy levels, wavelengths, radiative transition probabilities, and collisional excitation data for a large number of ions of astrophysical interest. CHIANTI also includes a suite of IDL routines to calculate synthetic spectra and carry out plasma diagnostics. Version 5 has been released, which includes several new features, as well as new data for many ions. The new features in CHIANTI are as follows: the inclusion of ionization and recombination rates to individual excited levels as a means to populate atomic levels; data for Kα and Kβ emission from Fe II to Fe XXIV; new data for high-energy configurations in Fe XVII to Fe XXIII; and a complete reassessment of level energies and line identifications in the X-ray range, multitemperature particle distributions, and photoexcitation from any user-defined radiation field. New data for ions already in the database, as well as data for ions not present in earlier versions of the database, are also included. Version 5 of CHIANTI represents a major improvement in the calculation of line emissivities and synthetic spectra in the X-ray range and expands and improves theoretical spectra calculations in all other wavelength ranges.

CHIANTI?An Atomic Database for Emission Lines. VI. Proton Rates and Other Improvements

The CHIANTI atomic database contains atomic energy levels, wavelengths, radiative transition probabilities, and electron excitation data for a large number of ions of astrophysical interest. Version 4 has been released, and proton excitation data are now included, principally for ground configuration levels that are close in energy. The fitting procedure for excitation data, both electrons and protons, has been extended to allow nine-point spline fits in addition to the previous five-point spline fits. This allows higher quality fits to data from close-coupling calculations where resonances can lead to significant structure in the Maxwellian-averaged collision strengths. The effects of photoexcitation and stimulated emission by a blackbody radiation field in a spherical geometry on the level balance equations of the CHIANTI ions can now be studied following modifications to the CHIANTI software. With the addition of H I, He I, and N I, the first neutral species have been added to CHIANTI. Many updates to existing ion data sets are described, while several new ions have been added to the database, including Ar IV, Fe VI, and Ni XXI. The two-photon continuum is now included in the spectral synthesis routines, and a new code for calculating the relativistic free-free continuum has been added. The treatment of the free-bound continuum has also been updated.

EUV Emission Lines and Diagnostics Observed with Hinode/EIS

Quiet Sun and active region spectra from the Hinode/EIS instrument are presented, and the strongest lines from different temperature regions discussed. A list of emission lines recommended to be included in EIS observation studies is presented based on analysis of blending and diagnostic potential using the CHIANTI atomic database. In addition we identify the most useful density diagnostics from the ions covered by EIS.

Spectroscopic diagnostics of stellar transition regions and coronae in the XUV: AU Mic in quiescence

In this paper we review the spectroscopic diagnostic techniques that can be applied to XUV observations of active stars. In particular, we discuss methods for the determination of electron densities, emission measures and the chemical composition of the stellar transition regions and coronae. We pay particular attention to the atomic data used and we revise several previous analyses with the most recent atomic data (from CHIANTI). We nd severe limitations to some of the commonly used methods and atomic data and we obtain results which are signicantly dierent from other authors. We illustrate this with a number of examples. We analyse a combined set of multi-wavelength observations (EUVE, HST/STIS, FUSE) for the quiescent phase of the dMe star AU Mic. A major conclusion of this paper is that the use of spectral lines from the Li and Na isoelectronic sequences, common in previous literature, produces erroneous results in the determination of emission measures, elemental abundances and transition region densities.

Models for Solar Magnetic Loops. III. Dynamic Models and Coronal Diagnostic Spectrometer Observations

In the present work SOHO Coronal Diagnostic Spectrometer (CDS) observations of a quiescent active region loop are compared to a steady state, dynamic loop model. Three different heating functions are adopted: uniform, concentrated at the top, and concentrated at the footpoints. Predicted temperature and density profiles of the selected loop are compared with those obtained from CDS observations using line ratios and an emission measure analysis. The latter method also allows us to measure the loop filling factor. The space of parameters of the model is investigated in an effort to achieve agreement with observations. The effects of uncertainties and of CDS instrumental limitations on the results are assessed. We find that no agreement can be found between model predictions and observations. Possible causes of the disagreement and areas of further investigation are discussed. This work also demonstrates the potential of high-resolution spectroscopy in loop studies, even in the presence of moderate spatial resolution.

SOHO CDS-NIS in-flight intensity calibration using a plasma diagnostic method

The internal intensity calibration of the Coronal Diagnostic Spectrometer (CDS) – Normal Incidence Spectrometer (NIS) is studied using the Arcetri diagnostic method. A large number of spectral lines observed by the CDS–NIS 1 and NIS 2 windows in a solar active region is analysed in order to determine the intensity calibration curve for both channels.The plasma diagnostic method developed in Arcetri allows the measurement of the correction factors to the preliminary CDS–NIS internal intensity calibration curves and the determination of the relative calibration between NIS 1 and NIS 2. A further correction factor of approximately three is found to be necessary for a correct intercalibration of the two wavelength windows. Also the NIS 2 second-order sensitivity is measured. The Arcetri diagnostic method proves to be a powerful tool for intensity calibration studies.

Models for solar magnetic loops. V. A new diagnostic technique to compare loop models and observations

We present a new diagnostic technique to compare theoretical models with observations of quiescent magnetic loops from high-resolution imaging spectrometers. The diagnostic technique is primarily suited for the analysis of high-resolution, spatially resolved spectra, but it can also be applied to narrowband images. The diagnostic technique is based on a steady state, dynamic loop model and allows us to unambiguously determine whether the model reproduces the observations and to determine the plasma heating, velocities, footpoint conductive flux, and pressure in the loop.

Phase-noise protection in quantum-enhanced differential interferometry

Differential interferometry (DI) with two coupled sensors is a most powerful approach for precision measurements in presence of strong phase noise. However DI has been studied and implemented only with classical resources. Here we generalize the theory of differential interferometry to the case of entangled probe states. We demonstrate that, for perfectly correlated interferometers and in the presence of arbitrary large phase noise, sub-shot noise sensitivities -- up to the Heisenberg limit -- are still possible with a special class of entangled states in the ideal lossless scenario. These states belong to a decoherence free subspace where entanglement is passively protected. Our work pave the way to the full exploitation of entanglement in precision measurements in presence of strong phase noise.

EUV and soft x-ray telescope-spectrometer for imaging spectroscopy on the Solar Orbiter mission: grazing-incidence configuration

The optical design of a stigmatic grazing-incidence telescope-spectrometer for solar imaging spectroscopy is presented. The instrument is designed for the Solar Orbiter mission. It consists of a double telescope and a flat-field spectrometer. The telescope 1 is a single-element telescope: it focuses the radiation on the entrance slit of the spectrometer only in the direction perpendicular to the slit, i.e. the spectral dispersion plane. The telescope 2 is a double-element Wolter telescope: it focuses the radiation on the focal plane in the direction parallel to the slit, i.e. perpendicular to the spectral dispersion plane. Finally, the spectrometer consists of a grazing-incidence variable-line-spaced grating with flat-field properties. The telescope 2 is crossed with respect to the telescope 1 and the grating, i.e. it is mounted with its tangential plane coincident with the grating equatorial plane. The spectrum is acquired by a detector at near normal incidence with respect to the direction of the exit beam. Such unique configuration gives stigmatic monochromatic images of extended regions even in the grazing-incidence domain.

Data bases for diagnostic of high temperature astrophysical plasmas

The spectral region below 2000 A is crowded of lines from the most important elements in the universe and the x-ray and EUV emission of astrophysical plasmas is an extremely powerful tool to investigate temperature and density models of celestial sources. In the last two decades a number of space missions has been devoted to investigate the X-ray and EUV sky, and, even before, space born spectrograph, measured detailed spectra of the solar corona. Two high spectral resolution instruments, CDS and SUMER, on the SOHO mission, are producing a lot of high quality spectra of the solar corona between 150 and 1600 A and high resolution observations are planned for the near future also from stars and galaxies. To properly exploit the huge amount of information supplied by the Observations and to plan new observations, the most updated sets of atomic data are necessary. Models of neutral atoms and ions, details of the most important atomic processes, (rates of collision and radiative ionizations and excitation, ra...