2009/01/20 by J. T. Schmelz, Steven H. Saar, S. H. Saar +7 · 96 citations
Physics and Astronomy · #Astronomy #Astrophysics #Emission spectrum #Imaging spectrometer #Measure (data warehouse) #Optics #Physics #Solar and Space Plasma Dynamics #Spectral line #Spectrometer #Stellar, planetary, and galactic studies #Telescope #X-ray Spectroscopy and Fluorescence Analysis #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/693/2/l131
published in The Astrophysical Journal 693(2), L131-L135 (IOP Publishing) · Submitted to ApJ Letters
arxiv created 2009/01/20 · openalex publication_date 2009/02/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The X-Ray Telescope (XRT) on the Japanese/USA/UK Hinode (Solar-B) spacecraft has detected emission from a quiescent active region core that is consistent with nanoflare heating. The fluxes from 10 broadband X-ray filters and filter combinations were used to construct differential emission measure (DEM) curves. In addition to the expected active region peak at log T = 6.3–6.5, we find a high-temperature component with significant emission measure at log T > 7.0. This emission measure is weak compared to the main peak—the DEM is down by almost three orders of magnitude—which accounts of the fact that it has not been observed with earlier instruments. It is also consistent with spectra of quiescent active regions: no Fe xix lines are observed in a CHIANTI synthetic spectrum generated using the XRT DEM distribution. The DEM result is successfully reproduced with a simple two-component nanoflare model.