Oscillations in the 45 – 5000 MHz Radio Spectrum of the 18 April 2014 Flare

Using a new type of oscillation map, made from the radio spectra by the wavelet technique, we study the 18 April 2014 M7.3 flare (SOL2014-04-18T13:03:00L245C017). We find a quasi-periodic character of this flare with periods in the range 65?–?115 seconds. At the very beginning of this flare, in connection with the drifting pulsation structure (plasmoid ejection), we find that the 65?–?115 s oscillation phase slowly drifts towards lower frequencies, which indicates an upward propagating wave initiated at the start of the magnetic reconnection. Many periods (1?–?200 seconds) are found in the drifting pulsation structure, which documents multi-scale and multi-periodic processes. On this drifting structure, fiber bursts with a characteristic period of about one second are superimposed, whose frequency drift is similar to that of the drifting 65?–?115 s oscillation phase. We also checked periods found in this flare by the EUV Imaging Spectrometer (EIS)/Hinode and Interface Region Imaging Spectrograph (IRIS) observations. We recognize the type III bursts (electron beams) as proposed, but their time coincidence with the EIS and IRIS peaks is not very good. The reason probably is that the radio spectrum is a whole-disk record consisting of all bursts from any location, while the EIS and IRIS peaks are emitted only from locations of slits in the EIS and IRIS observations.     

Solar System Capabilities of the Thirty Meter Telescope

The TMT Project is completing the design of a telescope with a primary mirror diameter of 30 m, yielding ten times more light gathering power than the largest current telescopes. It is being designed from the outset as a system that will deliver diffraction-limited resolution (8, 15 and 70 milliarcsec at 1.2, 2.2 and 10 microns, respectively) and high Strehl ratios over a 30 arcsecond science field with good performance over a 2 arcmin field. Studies of a representative suite of instruments that span a very large discovery space in wavelength (0.3–30 microns), spatial resolution, spectral resolution and field-of-view demonstrate their feasibility and their tremendous scientific potential. Of particular interest for solar system research, one of these will be IRIS (Infrared Imaging Spectrometer), a NIR instrument consisting of a diffraction-limited imager and an integral-field spectrometer. IRIS will be able to investigate structures with dimensions of only a few tens of kilometers at the distance of Jupiter. Two other instruments, NIRES and MIRES (Near- and Mid IR Echelle Spectrographs) will enable high angular, high spectral resolution observations of solar system objects from the ground with sensitivities comparable to space-based missions. The TMT system is being designed for extremely efficient operation including the ability to rapidly switch to observations with different instruments to take advantage of “targets-of-opportunity” or changing conditions. Thus TMT will provide capabilities that will enable very significant solar system science and be highly synergistic with JWST, ALMA and other planned astronomy missions.     

Astronomy with new nuclei

I present scientific impressions of the workshop ‘Astronomy with Radioactivities’. After a review of the origins of this series of conferences, highlights of this workshop are selected. The theme, ‘new nuclei’, is suggested as an organizing principle for this series of workshops. Six observational domains that drive these themes are recapitulated.     

Instrument Calibration of the <Emphasis Type="Italic">Interface Region Imaging Spectrograph</Emphasis> (IRIS) Mission

The Interface Region Imaging Spectrograph (IRIS) is a NASA small explorer mission that provides high-resolution spectra and images of the Sun in the 133?–?141 nm and 278?–?283 nm wavelength bands. The IRIS data are archived in calibrated form and made available to the public within seven days of observing. The calibrations applied to the data include dark correction, scattered light and background correction, flat fielding, geometric distortion correction, and wavelength calibration. In addition, the IRIS team has calibrated the IRIS absolute throughput as a function of wavelength and has been tracking throughput changes over the course of the mission. As a resource for the IRIS data user, this article describes the details of these calibrations as they have evolved over the first few years of the mission. References to online documentation provide access to additional information and future updates.     

Diurnal Atmospheric Extinction Over Oukaïmeden Observatory using IRIS Database: 1989–1997. Comparison With The Other IRIS Sites

In this work, we use data of nine years (1989 to 1997) at all IRIS sites (Culgoora, Kumbel, Oukaïmeden, Izaña, La Silla and Stanford, devoted to the study of the solar velocity oscillation) to study of diurnal atmospheric extinction coefficient behaviour at Oukaïmeden observatory and to compare it to the others. By this study, we can conclude that the mean extinction coefficient at Oukaimeden is around 0.120 mag airmass^-1. Besides, we show that the daily extinction coefficient varies under the influence of the seasonal effect. By the comparison of Oukaïmeden to the other sites, we showed that Oukaïmeden has a good photometric sky quality and constitutes a potential site for astronomical observations in the north hemisphere.     

Variable and broad iron lines around black holes

“Variable and Broad Iron Lines around Black Holes” was the topic of the first scientific workshop organized by the XMMNewton Science Operations Centre. This foreword gives a brief introduction to the history of black hole research, which motivated the workshop's scientific topic. The organizing committees are listed and the meeting is shortly outlined. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Discovery of a companion at the brown dwarf limit to the solar‐type star Gliese 29

Gliese 29 is a 7 to 8 Gyr old, southern Population I turnoff star with a large proper motion of 1″/yr. Using recent direct imaging observations with the 0.8 m Infrared Imaging System (IRIS) of the Universitätssternwarte Bochum near Cerro Armazones in Chile, we demonstrate that the faint source 2MASS J00402651–5927168 at a projected angular separation ρ = 6.″35 is a common‐proper‐motion companion to Gl 29. Provided this source is not part of a further subsystem, the IRIS J ‐ and K_s‐band photometry either implies a spectral type of about L2, based on its absolute magnitude, or an approximate mass M_B ≃ 0.077 M_⊙, suggesting that it may even be a brown dwarf. Assuming a face‐on circular orbit this faint companion orbits Gl 29 in 1880 years. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The IRIS sodium cell instrument

In the framework of the IRIS programme, full-disk solar Doppler-shift measurements are made with an optical resonance sodium cell spectrophotometer, a new pattern of the instrument successfully used at the geographic South Pole 10 years ago. After many successive improvements, the IRIS version has now become a precise and reliable device, being limited only by the solar and/or by the atmospheric noise in all the frequency ranges of interest for the p-mode and the g-mode investigation. This instrument is described here in some detail, with the technical specification for each individual component being defined by comparison to the photon and the solar noise.     

On the latitudinal distribution of Titan's haze at the Voyager epoch

We have analysed all the available high phase angle images of Titan limb taken by Voyager 1 and 2, in early 1980. For several different phase angles and wavelengths, we seek for a consistent set of haze parameters able to fit all data simultaneously. Our main purpose is to obtain an accurate estimate of the latitudinal variation of haze opacity at 200 km altitude at the time of the Voyager flyby's. We find that haze opacity at 200 km is about constant in the southern hemisphere and drops between equator and 60^°N by about 30-50%, sharply increasing again beyond 60^°N. The latter feature is clearly due to the north polarhood.This behaviour is opposite to total optical depth variations retrieved from IRIS observation, at the same epoch. The IRIS data refer to levels below 100 km altitude. A comparison of our results with calculations from a general circulation model, shows that (1) our results are realistic and can be considered as robust (2) the opacity variations at 200 km (this work) and at ground (IRIS data), although opposite, are not inconsistent with each other.     

General presentation of a single IRIS site raw data analysis problem

A complete software package has been built for the calibration in m s ^–1 of the velocity residuals due to solar oscillations in the raw IRIS (International Research on the Interior of the Sun) data. It takes into account all known astronomical components contributing to the line-of-sight velocity between the instrument and the solar surface, and also the apparent velocity due to the non-uniform integration of the solar rotation as seen through an inhomogeneous Earth atmosphere. The IRIS data itself is used for the estimation of the nonlinear instrumental response to the velocity, and the residual can be directly obtained in velocity units, without low frequency filtering. On a day of typical photometric sky quality, the power spectrum obtained appears to be solar noise limited.     

The Teide Observatory

The Teide Observatory in the Canary Islands is, at present, a well-known nucleus for solar physics research. In this contribution, the facilities at the Observatory, which now houses one of the IRIS network instruments, are presented.     

A scientific case for XMM‐Newton continuation

The presentations made at the workshop “XMM‐Newton: The Next Decade”, held at ESAC from 4th to the 6th of July 2007, contained an overwhelming amount of new results and well justified scientific questions that can be addressed by observations with XMM‐Newton. XMM‐Newton has over the next decade a solid scientific case. Given the high impact of X‐ray observations, XMM‐Newton operations are not only a matter for “X‐ray astrophysics”, but also of fundamental importance for astrophysics in general. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Magnetic Contamination and Correction in Sodium Dopplergrams

Recently a new version of a sodium double-band magneto-optical filter has been built in order to provide simultaneous Doppler and magnetograms using the same optical path (Cacciani, Moretti, and Rodgers, 1997; Cacciani et al., 1988, 1994). Two observing stations based on this instrument are being installed as part of the French network IRIS. One is already operational in Apple Valley, California, and the other one will be delivered shortly to Tashkent, Uzbekistan. The performance of the instrument is such as to detect the l = 0 mode of solar oscillations from resolved images with a signal-to-noise ratio that has never been achieved before (Cacciani and Moretti, 1994). The magnetic and velocity signals are corrected for the changes that occur in the solar D-line profile in active versus non-active regions. This kind of analysis will be performed by our group in conjunction with parallel analysis of GOLF and IRIS integrated data which use the same sodium lines.     

Compact Two-Dimensional Array of Stressed GE:GA Detectors

We have developed a 4 × 8 array of stressed Ge:Ga detectors. This array detector has a high density format ofentrance pupils so that we can minimize the size of the cameraoptics. The cutoff wavelength of the detector is about 170 m, and the detector's NEP is better than 10¹⁶ WHz^-1/2. We are going apply this array detector toballoon-borne astronomical observations. Furthermore, we aredeveloping this detector into a 5 × 15 array detector that will be placed onboard the IRIS satellite to be launched in 2003.     

The high altitude observatory of the national center for atmospheric research Boulder,Colorado

Summary The High Altitude Observatory attempts to carry out a balanced program of theoretical and experimental research in solar, solar-terrestrial, and stellar-related physics. The scientific efforts are carried out within a sectional structure including the major areas of Solar Atmosphere and Magnetic Fields, Coronal/Interplanetary Physics, and Solar Variability. As one division of a National Center, the Observatory attempts to provide leadership through operation and sponsorship of seminars on specialized topics and organization of workshops to exploit data collections. In addition to the examples given, the Observatory, under NASA sponsorship, has organized a workshop series on solar flares, a central theme of which was the interpretation of Skylab results. This effort has resulted in the publication of a volume Solar Flares, edited by P. Sturrock, Colorado Associated University Press, 1979. Through these efforts, and the participation of individual staff members on advisory committees and working groups within the national and international framework, the Observatory continues to play a role in the guidance of research in solar and related physics.     

Amalthea: Implications of the temperature observed by Voyager

Voyager 1 IRIS observations of Amalthea, although initially indicating an unusually high temperature, now give a temperature of only 164 ± 5°K, a value consistent with the Earth-based measurement by G. H. Rieke [Icarus25, 333–334 (1975)] of 155 ± 15°K. We numerically modeled the temperature profile in the satellite's surface layer as a function of location and time of day, assuming a triaxial ellipsoid shape and thermal properties similar to those of the lunar soil. The major heat source is direct insolation, but temperatures are increased slightly by thermal radiation from Jupiter (?9°K), by sunlight reflected from the planet (?5°K), and by charged particle bombardment (?2°K). Maximum calculated temperatures reach 166°K, and we estimate that the temperature that Voyager would have measured under these circumstances is ≈160°K, in agreement with the observed temperature. Possible sources of error in the model are discussed in detail, including satellite shape effects, unusually low emissivity, uncommonly rough surface, abnormal thermal intertia, variability of the charged particle flux, and Joule heating. The IRIS observation strongly suggests that (i) the Amalthean surface has an emissivity near unity; (ii) the charged particle flux on the satellite at the time of observation was no more than 20 times larger than the flux indicated by Pioneer observations; and (iii) Joule heating of the satellite is insignificant (a conclusion also supported by rough calculations). The IRIS observation cannot, however, put any useful limits on the thermal inertia of the Amalthean surface layer.     

Solar flares registered by the IRIS spectrometer onboard the CORONAS-F satellite: Peculiarities of the X-ray emission

The X-ray spectrometer IRIS was designed to register the fluxes of quanta with energies ranging from 2 to 250 keV in various time-resolution modes: 0.01, 1.0, and 2.5 s in 4, 64, and 12 channels, respectively. Owing to the high instrument sensitivity, individual spikes of tens of milliseconds can be distinguished in the time structure of the X-ray flare emission. The time spectral analysis carried out for the X-ray emission of a number of registered flares points to the presence of a quasiperiodic structure with characteristic times of the same order. For the flares of December 19, 2001, and August 10, 2002, the process of energy release has been considered with a 1-s time resolution, and its periodic character has been revealed. For the flare of December 19, 2001, the energy spectra of the hard X-ray emission have been simulated by thermal and nonthermal models. It has been shown that the both models can describe this emission.     

Planetary-scale wave structure in the Martian atmosphere

Wave-like perturbations are found in the Mariner 9 IRIS atmospheric temperature data during late Northern Hemisphere winter in a latitude band between 45°N and 65°N. The nature of the data base prevents a unique separation of spatial and temporal behavior, but Fourier analysis of the data constrains the waves to discrete combinations of planetary wavenumber and period. One major spectral component possesses a meridional amplitude cross section with a maximum near the 1-mbar level at 60°N and is strongly correlated with the circumpolar jet observed in thermal winds calculated from the mean meridional temperature cross section. This feature is consistent with the low-wavenumber baroclinic waves observed in Viking Lander data, and the vertical structure reflects the behavior anticipated for a vertically penetrating quasi-geostrophic disturbance. Other possible origins for the wave cannotbe ruled out, however. Among these is a stationary wave forced by wavenumber-2 topographic relief.     

A protocol standard for heterogeneous telescope networks

The scientific need for a standard protocol permitting the exchange of generic observing services is rapidly escalating as more observatories adopt service observing as a standard operating mode and as more remote or robotic telescopes are brought on‐line. To respond to this need, we present the results of the first interoperability workshop for Heterogeneous Telescope Networks (HTN) held in Exeter. We present a draft protocol, designed to be independent of the specific instrumentation and software that controls the remote and/or robotic telescopes, allowing these telescopes to appear to the user with a unified interface despite any underlying architectural differences. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)