The formation of IRIS diagnostics. III. Near-ultraviolet Spectra and Images

Abstract

The Mg II h&k lines are the prime chromospheric diagnostics of NASA's Interface Region Imaging Spectrograph (IRIS). In the previous papers of this series we used a realistic three-dimensional radiative magnetohydrodynamics model to calculate the h&k lines in detail and investigated how their spectral features relate to the underlying atmosphere. In this work, we employ the same approach to investigate how the h&k diagnostics fare when taking into account the finite resolution of IRIS and different noise levels. In addition, we investigate the diagnostic potential of several other photospheric lines and near-continuum regions present in the near-ultraviolet (NUV) window of IRIS and study the formation of the NUV slit-jaw images. We find that the instrumental resolution of IRIS has a small effect on the quality of the h&k diagnostics; the relations between the spectral features and atmospheric properties are mostly unchanged. The peak separation is the most affected diagnostic, but mainly due to limitations of the simulation. The effects of noise start to be noticeable at a signal-to-noise ratio (S/N) of 20, but we show that with noise filtering one can obtain reliable diagnostics at least down to a S/N of 5. The many photospheric lines present in the NUV window provide velocity information for at least eight distinct photospheric heights. Using line-free regions in the h&k far wings we derive good estimates of photospheric temperature for at least three heights. Both of these diagnostics, in particular the latter, can be obtained even at S/Ns as low as 5.

16 pages, 13 figures. Accepted for publication in ApJ. Updated version with fixed typos in line list and language edits

References in corpus (5)

• Non-equilibrium hydrogen ionization in 2D simulations of the solar atmosphere
• 3D Temperature Mapping of Solar Photospheric Fine Structure Using Ca II H Filtergrams
• Point spread functions for the Solar Optical Telescope onboard Hinode
• Relation between photospheric magnetic field and chromospheric emission
• The energy of waves in the photosphere and lower chromosphere: III. Inversion setup for Ca II H spectra in local thermal equilibrium

Cited by in corpus (77)

• The Interface Region Imaging Spectrograph (IRIS)
• A publicly available simulation of an enhanced network region of the Sun
• An Open Source, Massively Parallel Code for Non-LTE Synthesis and Inversion of Spectral Lines and Zeeman-induced Stokes Profiles
• On the generation of solar spicules and Alfvénic waves
• STiC -- A multi-atom non-LTE PRD inversion code for full-Stokes solar observations
• An Interface Region Imaging Spectrograph first view on Solar Spicules
• Solar science with the Atacama Large Millimeter/submillimeter Array - A new view of our Sun
• On the prevalence of small-scale twist in the solar chromosphere and transition region
• Bombs and flares at the surface and lower atmosphere of the Sun
• Ellerman bombs at high resolution III. Simultaneous observations with IRIS and SST
• RH 1.5D: a massively parallel code for multi-level radiative transfer with partial frequency redistribution and Zeeman polarisation
• The Formation of IRIS diagnostics. IV. The Mg II triplet lines as a new diagnostic for lower chromospheric heating
• Radiative diagnostics in the solar photosphere and chromosphere
• Why Is Non-thermal Line Broadening of Spectral Lines in The Lower Transition Region of the Sun Independent of Spatial Resolution?
• On fibrils and field lines: The nature of H$\alpha$ fibrils in the solar chromosphere
• Three-dimensional modeling of the Ca II H&K lines in the solar atmosphere
• The formation of IRIS diagnostics V. A quintessential model atom of C II and general formation properties of the C II lines at 133.5 nm
• Investigating the response of loop plasma to nanoflare heating using RADYN simulations
• Millimeter radiation from a 3D model of the solar atmosphere I. Diagnosing chromospheric thermal structure
• IRIS Observations of the Mg II h & k Lines During a Solar Flare
• Partial redistribution in 3D non-LTE radiative transfer in solar atmosphere models
• Explosive events on sub-arcsecond scale in IRIS observations: a case study
• The formation of IRIS diagnostics VI. The Diagnostic Potential of the C II Lines at 133.5 nm in the Solar Atmosphere
• Internetwork chromospheric bright grains observed with IRIS
• Transition Region and Chromospheric Signatures of Impulsive Heating Events. I. Observations
• The Formation of IRIS Diagnostics. VII. The Formation of the OI 135.56 nm Line in the Solar Atmosphere
• Vertical Propagation of Acoustic Waves in the Solar Inter-Network as Observed by IRIS
• A First Comparison of Millimeter Continuum and Mg II Ultraviolet Line Emission from the Solar Chromosphere
• Observed Variability of the Solar Mg II h Spectral Line
• Casting the Coronal Magnetic Field Reconstruction Tools in 3D Using MHD Bifrost Model
• The solar chromosphere at millimetre and ultraviolet wavelengths. I. Radiation temperatures and a detailed comparison
• Temperature constraints from inversions of synthetic solar optical, UV and radio spectra
• Millimeter radiation from a 3D model of the solar atmosphere II. Chromospheric magnetic field
• Hinode and IRIS observations of the magnetohydrodynamic waves propagating from the photosphere to the chromosphere in a sunspot
• Chromospheric heating due to cancellation of quiet Sun internetwork fields
• Mg II Lines Observed during the X-class Flare on 29 March 2014 by the Interface Region Imaging Spectrograph
• First High-resolution Spectroscopic Observations of an Erupting Prominence Within a Coronal Mass Ejection by the Interface Region Imaging Spectrograph (IRIS)
• Helical motions of fine-structure prominence threads observed by Hinode and IRIS
• Solar Flare Ribbon Fronts I: Constraining flare energy deposition with IRIS spectroscopy
• The effects of three-dimensional radiative transfer on the resonance polarization of the Ca I 4227 $\mathring{\mathrm{A}}$ line
• Semi-empirical model atmospheres for the chromosphere of the sunspot penumbra and umbral flashes
• Multi thermal atmosphere of a mini solar flare during magnetic reconnection observed with IRIS
• Emission of solar chromospheric and transition region features related to the underlying magnetic field
• Emergence of granular-sized magnetic bubbles through the solar atmosphere. III. The path to the transition region
• Force-Free Field Reconstructions Enhanced by Chromospheric Magnetic Field Data
• High-resolution observations of the solar photosphere, chromosphere and transition region. A database of coordinated IRIS and SST observations
• Quiet-Sun and Coronal Hole in \ion{Mg}{2}~k line as observed by IRIS
• On the formation of solar wind & switchbacks, and quiet Sun heating
• Spectro-imagery of an active tornado-like prominence: formation and evolution
• The Formation of IRIS Diagnostics. IX. The Formation of the C I 135.58 Line in the Solar Atmosphere
• Mg ii h&k spectra of an enhanced network region simulated with the MURaM-ChE code. Results using 1.5D synthesis
• A multiple spacecraft detection of the 2 April 2022 M-class flare and filament eruption during the first close Solar Orbiter perihelion
• A comparison of the active region upflow and core properties using simultaneous spectroscopic observations from IRIS and Hinode
• Comparing UV/EUV line parameters and magnetic field in a quiescent prominence with tornadoes
• Chromospheric Heating from Local Magnetic Growth and Ambipolar Diffusion Under Non-Equilibrium Conditions
• $IRI{S}^{2+}$: A comprehensive database of stratified thermodynamic models in the low solar atmosphere
• The dynamic chromosphere: pushing the boundaries of observations and models
• Far beyond the Sun: II. Probing the stellar magnetism of the young Sun ι Horologii from the photosphere to its corona
• Shape-based clustering of synthetic Stokes profiles using k-means and k-Shape
• Evolution of exploding granules from coordinated observations by THEMIS, IRIS, SDO/HMI, and HINODE, and a simulation
• Constraining the systematics of (acoustic) wave heating estimates in the solar chromosphere
• SunnyNet: A neural network approach to 3D non-LTE radiative transfer
• Spectroscopic observation of a transition region network jet
• Chromospheric impact of an exploding solar granule
• Effects of spectral resolution on simple magnetic field diagnostics of the Mg II h & k lines
• A multi-diagnostic spectral analysis of penumbral microjets
• Using Multiple Instance Learning for Explainable Solar Flare Prediction
• Dynamics in the transition region beneath active region upflows viewed by IRIS
• Observations of umbral flashes in the resonant sunspot chromosphere
• Temperature diagnostics of chromospheric fibrils
• Recovering thermodynamics from spectral profiles observed by IRIS (II): improved calculation of the uncertainties based on Monte Carlo experiments
• Solar Atmosphere Radiative Transfer Model Comparison based on 3D MHD simulations
• Magnetic Imaging of the Outer Solar Atmosphere (MImOSA): Unlocking the driver of the dynamics in the upper solar atmosphere
• A new view of the solar interface region from the Interface Region Imaging Spectrograph (IRIS)
• On the formation of Lyman $\beta$ and the O I 1027 and 1028 Å spectral lines
• Evolution of the Ratio of Mg II Intensities During Solar Flares
• Small-scale energetic phenomena in Hε: Ellerman bombs, UV bursts, and small flares