Publication Search Results

ID: 158885
Type: article
Authors: Albert, Damien; Antony, Bobby K.; Ba, Yaye Awa; Babikov, Yuri L.; Bollard, Philippe; Boudon, Vincent; Delahaye, Franck; Del Zanna, Giulio; Dimitrijevic, Milan S.; Drouin, Brian J.; Dubernet, Marie-Lise; Duensing, Felix; Emoto, Masahiko; Endres, Christian P.; Fazliev, Alexandr Z.; Glorian, Jean-Michel; Gordon, Iouli E.; Gratier, Pierre; Hill, Christian; Jevremovic, Darko; Joblin, Christine; Kwon, Duck-Hee; Kochanov, Roman V.; Krishnakumar, Erumathadathil; Leto, Giuseppe; Loboda, Petr A.; Lukashevskaya, Anastasiya A.; Lyulin, Oleg M.; Marinkovic, Bratislav P.; Markwick, Andrew; Marquart, Thomas; Mason, Nigel J.; Mendoza, Claudio; Millar, Tom J.; Moreau, Nicolas; Morozov, Serguei V.; Möller, Thomas; Müller, Holger S. P.; Mulas, Giacomo; Murakami, Izumi; Pakhomov, Yury; Palmeri, Patrick; Penguen, Julien; Perevalov, Valery I.; Piskunov, Nikolai; Postler, Johannes; Privezentsev, Alexei I.; Quinet, Pascal; Ralchenko, Yuri; Rhee, Yong-Joo; Richard, Cyril; Rixon, Guy; Rothman, Laurence S.; Roueff, Evelyne; Ryabchikova, Tatiana; Sahal-Bréchot, Sylvie; Scheier, Paul; Schilke, Peter; Schlemmer, Stephan; Smith, Ken W.; Schmitt, Bernard; Skobelev, Igor Yu; Sreckovic, Vladimir A.; Stempels, Eric; Tashkun, Serguey A.; Tennyson, Jonathan; Tyuterev, Vladimir G.; Vastel, Charlotte; Vujcic, Veljko; Wakelam, Valentine; Walton, Nicholas A.; Zeippen, Claude; Zwölf, Carlo Maria

ID: 157649
Type: article
Authors: Smith, Randall; Hahn, Michael; Raymond, John; Kallman, T.; Ballance, C. P.; Polito, Vanessa; Del Zanna, Giulio; Gu, Liyi; Hell, Natalie; Cumbee, Renata; Betancourt-Martinez, Gabriele; Costantini, Elisa; Corrales, Lia
Abstract: Cosmic EUV/x-ray spectroscopists, including both solar and astrophysical analysts, have a wide range of high-resolution and high-sensitivity tools in use and a number of new facilities in development for launch. As this bandpass requires placing the spectrometer beyond the Earth's atmosphere, each mission represents a major investment by a national space agency such as NASA, ESA, or JAXA, and more typically a collaboration between two or three. In general justifying new mission requires an improvement in capabilities of at least an order of magnitude, but the sensitivity of these existing missions are already taxing existing atomic data quantity and accuracy. This roadmap reviews the existing missions, showing how in a number of areas atomic data limits the science that can be performed. The missions that will be launched in the coming Decade will without doubt require both more and improved measurements of wavelengths and rates, along with theoretical calculations of collisional and radiative cross sections for a wide range of processes.

ID: 152900
Type: article
Authors: Dudík, Jaroslav; Dzifčáková, Elena; Del Zanna, Giulio; Mason, Helen E.; Golub, Leon L.; Winebarger, Amy R.; Savage, Sabrina L.
Abstract: Aims: We investigated the possibility of diagnosing the degree of departure from the Maxwellian distribution using the Fe XVII-Fe XVIII spectra originating in plasmas in collisional ionization equilibrium, such as in the cores of solar active regions or microflares. Methods: The original collision strengths for excitation are integrated over the non-Maxwellian electron κ-distributions characterized by a high-energy tail. Synthetic X-ray emission line spectra were calculated for a range of temperatures and κ. We focus on the 6-24 Å spectral range to be observed by the upcoming Marshall Grazing-Incidence X-ray Spectrometer MaGIXS. Results: We find that many line intensity ratios are sensitive to both T and κ. Best diagnostic options are provided if a ratio involving both Fe XVII and Fe XVIII is combined with another ratio involving lines formed within a single ion. The sensitivity of such diagnostics to κ is typically a few tens of per cent. Much larger sensitivity, of about a factor of two to three, can be obtained if the Fe XVIII 93.93 Å line observed by SDO/AIA is used in conjuction with the X-ray lines. Conclusions: We conclude that the MaGIXS instrument is well-suited for detection of departures from the Maxwellian distribution, especially in active region cores.

ID: 154644
Type: article
Authors: Hinode Review Team; Al-Janabi, Khalid; Antolin, Patrick; Baker, Deborah; Bellot Rubio, Luis R.; Bradley, Louisa; Brooks, David H.; Centeno, Rebecca; Culhane, J. Leonard; Del Zanna, Giulio; Doschek, George A.; Fletcher, Lyndsay; Hara, Hirohisa; Harra, Louise K.; Hillier, Andrew S.; Imada, Shinsuke; Klimchuk, James A.; Mariska, John T.; Pereira, Tiago M. D.; Reeves, Katharine K.; Sakao, Taro; Sakurai, Takashi; Shimizu, Toshifumi; Shimojo, Masumi; Shiota, Daikou; Solanki, Sami K.; Sterling, Alphonse C.; Su, Yingna; Suematsu, Yoshinori; Tarbell, Theodore D.; Tiwari, Sanjiv K.; Toriumi, Shin; Ugarte-Urra, Ignacio; Warren, Harry P.; Watanabe, Tetsuya; Young, Peter R.
Abstract: Hinode is Japan's third solar mission following Hinotori (1981-1982) and Yohkoh (1991-2001): it was launched on 2006 September 22 and is in operation currently. Hinode carries three instruments: the Solar Optical Telescope, the X-Ray Telescope, and the EUV Imaging Spectrometer. These instruments were built under international collaboration with the National Aeronautics and Space Administration and the UK Science and Technology Facilities Council, and its operation has been contributed to by the European Space Agency and the Norwegian Space Center. After describing the satellite operations and giving a performance evaluation of the three instruments, reviews are presented on major scientific discoveries by Hinode in the first eleven years (one solar cycle long) of its operation. This review article concludes with future prospects for solar physics research based on the achievements of Hinode.

ID: 152607
Type: article
Authors: Madsen, Chad A.; Samra, Jenna E.; Del Zanna, Giulio; DeLuca, Edward E.

ID: 145768
Type: article
Authors: Del Zanna, Giulio; DeLuca, Edward E.
Abstract: We review the coronal visible and infrared lines, collecting previous observations and comparing, whenever available, observed radiances to those predicted by various models: the quiet Sun (QS), a moderately active Sun, and an active region as observed near the limb, around 1.1 R _&sun;. We also model the off-limb radiances for the QS case. We used the most up-to-date atomic data in CHIANTI version 8. The comparison is satisfactory, in that all of the strong visible lines now have a firm identification. We revise several previous identifications and suggest some new ones. We also list the large number of observed lines for which we do not currently have atomic data, and therefore still await firm identifications. We also show that a significant number of coronal lines should be observable in the near-infrared region of the spectrum by the upcoming Daniel K. Inouye Solar Telescope (DKIST) and the AIR-Spec instrument, which observed the corona during the 2017 August 21 solar eclipse. We also briefly discuss the many potential spectroscopic diagnostics available to the visible and infrared, with particular emphasis on measurements of electron densities and chemical abundances. We briefly point out some of the potential diagnostics that could be available with the future infrared instrumentation that is being built for DKIST and planned for the Coronal Solar Magnetism Observatory. Finally, we highlight the need for further improvements in the atomic data.

ID: 149395
Type: article
Authors: Del Zanna, Giulio; Raymond, John; Andretta, Vincenzo; Telloni, Daniele; Golub, Leon
Abstract: We present estimates of the signal to be expected in quiescent solar conditions, as would be obtained with the COronal Spectrographic Imager in the EUV in its coronagraphic mode (COSIE-C). COSIE-C has been proposed to routinely observe the relatively unexplored outer corona, where we know that many fundamental processes affecting both the lower corona and the solar wind are taking place. The COSIE-C spectral band, 186–205 Å, is well-known as it has been observed with Hinode EIS. We present Hinode EIS observations that we obtained in 2007 out to 1.5 R _⊙, to show that this spectral band in quiescent streamers is dominated by Fe XII and Fe XI and that the ionization temperature is nearly constant. To estimate the COSIE-C signal in the 1.5–3.1 R _⊙ region we use a model based on CHIANTI atomic data and SoHO UVCS observations in the Si XII and Mg X coronal lines of two quiescent 1996 streamers. We reproduce the observed EUV radiances with a simple density model, photospheric abundances, and a constant temperature of 1.4 MK. We show that other theoretical or semi-empirical models fail to reproduce the observations. We find that the coronal COSIE-C signal at 3 R _⊙ should be about 5 counts/s per 3.″1 pixel in quiescent streamers. This is unprecedented and opens up a significant discovery space. We also briefly discuss stray light and the visibility of other solar features. In particular, we present UVCS observations of an active region streamer, indicating increased signal compared to the quiet Sun cases.

ID: 149378
Type: article
Authors: Yu, Xixi; Del Zanna, Giulio; Stenning, David C.; Cisewski-Kehe, Jessi; Kashyap, Vinay L.; Stein, Nathan; van Dyk, David A.; Warren, Harry P.; Weber, Mark A.
Abstract: Information about the physical properties of astrophysical objects cannot be measured directly but is inferred by interpreting spectroscopic observations in the context of atomic physics calculations. Ratios of emission lines, for example, can be used to infer the electron density of the emitting plasma. Similarly, the relative intensities of emission lines formed over a wide range of temperatures yield information on the temperature structure. A critical component of this analysis is understanding how uncertainties in the underlying atomic physics propagate to the uncertainties in the inferred plasma parameters. At present, however, atomic physics databases do not include uncertainties on the atomic parameters and there is no established methodology for using them even if they did. In this paper we develop simple models for uncertainties in the collision strengths and decay rates for Fe XIII and apply them to the interpretation of density-sensitive lines observed with the EUV (extreme ultraviolet) Imagining spectrometer (EIS) on Hinode. We incorporate these uncertainties in a Bayesian framework. We consider both a pragmatic Bayesian method where the atomic physics information is unaffected by the observed data, and a fully Bayesian method where the data can be used to probe the physics. The former generally increases the uncertainty in the inferred density by about a factor of 5 compared with models that incorporate only statistical uncertainties. The latter reduces the uncertainties on the inferred densities, but identifies areas of possible systematic problems with either the atomic physics or the observed intensities.

ID: 143367
Type: article
Authors: Dudík, Jaroslav; Polito, Vanessa; Dzifcáková, Elena; Del Zanna, Giulio; Testa, Paola
Abstract: We investigate the nature of the spectral line profiles for transition-region (TR) ions observed with the Interface Region Imaging Spectrograph (IRIS). In this context, we analyzed an active-region observation performed by IRIS in its 1400 Å spectral window. The

ID: 144727
Type: article
Authors: Parenti, Susanna; Del Zanna, Giulio; Petralia, Antonino; Reale, Fabio; Teriaca, Luca; Testa, Paola; Mason, Helen E.
Abstract: In this work we investigate the thermal structure of an off-limb active region (AR) in various non-flaring areas, as it provides key information on the way these structures are heated. In particular, we concentrate on the very hot component (> 3 {MK}) as it is a crucial element to distinguish between different heating mechanisms. We present an analysis using Fe and Ca emission lines from both the Solar Ultraviolet Measurement of Emitted Radiation (SUMER) on board the Solar and Heliospheric Observatory (SOHO) and the EUV Imaging Spectrometer (EIS) on board Hinode. A data set covering all ionization stages from Fe x to Fe xix has been used for the thermal analysis (both differential emission measure and emission measure, EM). Ca xiv is used for the SUMER-EIS radiometric cross calibration. We show that the very hot plasma is present and persistent almost everywhere in the core of the limb AR. The off-limb AR is clearly structured in Fe xviii. Almost everywhere, the EM analysis reveals plasma at 10 MK (visible in Fe xix emission), which is down to 0.1% of EM of the main 3 {MK} plasma. We estimate the power-law index of the hot tail of the EM to be between -8.5 and -4.4. However, the question about the possible existence of a small minor peak at around 10 {MK} remains open. The absence in some part of the AR of the Fe xix and Fe xxiii lines (which fall into our spectral range) enables us to determine an upper limit on the EM at these temperatures. Our results include a new Ca xiv 943.59 Å atomic model.