Soft X-ray and gyroresonance emission above sunspots
Φόρτωση...
Ημερομηνία
Συγγραφείς
Nindos, A.
Kundu, M. R.
White, S. M.
Shibasaki, K.
Gopalswamy, N.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Astrophysical Journal Supplement Series
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
Using Yohkoh SXT and Nobeyama 17 GHz data, we have studied the soft X-ray and microwave emission above several stable, large sunspots near central meridian passage. Our study confirms the well-known fact that soft X-ray emission is depressed above sunspots. It also shows that the distribution of their soft X-ray intensity is not uniform; usually the darkest pixels are associated with the umbra or the far edges of the leading part of the penumbra while the following part of the penumbra may contain higher intensity pixels associated with brighter loops. For the first time, we present a systematic survey of the temperatures and emission measures of the soft X-ray material above sunspots. Sunspots always contain the lowest temperatures and emission measures in the active regions. The mean umbral temperature is 1.8 x 10(6) K, and the mean penumbral temperature is 2.4 x 106 K. The mean umbral and penumbral emission measures are log EM = 26.60 cm(-5) and log EM = 27.00 cm(-5), respectively. The differences between the umbral and penumbral plasma temperatures are physically significant. The higher penumbral values imply that the loops associated with the penumbrae are generally hotter and denser than the loops associated with the umbrae. The highest sunspot temperatures and emission measures are still lower than the average active region parameters but higher than the quiet-Sun plasma parameters. The coronal radiative energy loss rate above the umbrae is 15% higher than the radiative loss rate of the quiet-Sun plasma but a factor of 8.3 lower than the typical active region radiative loss rate. The radio emission comes from the gyroresonance mechanism, and, as expected, it is sensitive to the magnetic field rather than the soft X-ray-emitting plasma.
Περιγραφή
Λέξεις-κλειδιά
sun : corona, sun : radio radiation, sun : x-rays, gamma rays, solar active-region, magnetic-fields, extreme-ultraviolet, coronal currents, radio-emission, quiet-sun, microwave, yohkoh, model, telescope
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://000165579900009
http://iopscience.iop.org/0067-0049/130/2/485/pdf/0067-0049_130_2_485.pdf
http://iopscience.iop.org/0067-0049/130/2/485/pdf/0067-0049_130_2_485.pdf
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών