A Publicly Available Multiobservatory Data Set of an Enhanced Network Patch from the Photosphere to the Corona

Abstract

New instruments sensitive to chromospheric radiation at X-ray, UV, visible, IR, and submillimeter wavelengths have become available that significantly enhance our ability to understand the bidirectional flow of energy through the chromosphere. We describe the calibration, coalignment, initial results, and public release of a new data set combining a large number of these instruments to obtain multiwavelength photospheric, chromospheric, and coronal observations capable of improving our understanding of the connectivity between the photosphere and the corona via transient brightenings and wave signatures. The observations center on a bipolar region of enhanced-network magnetic flux near disk center on SOL2017-03-17T14:00–17:00. The comprehensive data set provides one of the most complete views to date of chromospheric activity related to small-scale brightenings in the corona and chromosphere. Our initial analysis shows a strong spatial correspondence between the areas of broadest width of the hydrogen-α spectral line and the hottest temperatures observed in Atacama Large Millimeter/submillimeter Array (ALMA) Band 3 radio data, with a linear coefficient of 6.12 × 10−5Å/K. The correspondence persists for the duration of cotemporal observations (≈60 m). Numerous transient brightenings were observed in multiple data series. We highlight a single, well-observed transient brightening in a set of thin filamentary features with a duration of 20 minutes. The timing of the peak intensity transitions from the cooler (ALMA, 7000 K) to the hotter (XRT, 3 MK) data series.

Spatio-temporal comparisons of the hydrogen-alpha line width and ALMA 3 mm brightness temperature in the weak solar network

“…A linear fit to the trend gave a slope of 6.12 × 10 −5 Å/K. Kobelski et al (2022) confirmed this strong correlation between the two quantities for a region of weakly enhanced network magnetic field in the quiet Sun. They reported a steeper slope of 1.1 × 10 −4 Å/K over a narrower range of observed temperatures, due to their more quiet target region.…”

“…The present work uses two data series taken from the more extensive coordinated data set described in Kobelski et al (2022) 1 . The full data set includes coordinated observations between ALMA and multiple instruments at each of the Dunn Solar Telescope (DST), IRIS, Hinode spacecraft, and SDO facilites; the Nuclear Spectroscopic Telescope Array (NuSTAR) also observed the same solar target within several hours of our observations.…”

“…The calibration of each data series, the coalignment of all series to each other, and the solar target are fully described in that paper, so here we only provide a short overview of the details relevant to the present work. Kobelski et al (2022) have made the full data set publicly available at https://share.nso.edu/ shared/dkist/ltarr/kolsch/.…”

“…The time series includes five ≈10 minute acquisitions, each separated by 3 min of calibration data. Given the quiet Sun target and its proximity to disk center, we use the mean temperature of 7300 K reported in White et al (2017) for quiet Sun disk center ALMA 100 GHz observations to define the zero point of these observations, i.e., T B = ΔT B + 7300 K. The details of the ALMA data set are described further in Kobelski et al (2022). The spatial maps show features over approximately a 60′′ diameter field of view, see Figure 1A.…”

“…We present here analysis of a combined data set described in Kobelski et al (2022) that includes 3 mm (or 100 GHz; Band 3) interferometric observations from the ALMA, sensitive to the chromospheric temperature, and spectral-imaging observations of the hydrogen Hα line at 656.3 nm from the Interferometric Bidimensional Spectropolarimeter [IBIS; (Cavallini, 2006)]; at the Dunn Solar Telescope. The combined data set covers ∼60 min of observations of a small, bipolar region of network flux located near disk center on 2017-03-21.…”