اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدآلما كمستجيب المثالي للكروموسفير الشمسي
ALMA as the ideal probe of the solar chromosphere
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الطبيعة الحقيقية لشريحة الشمس، وتركيبها وديناميكاها، لا تزال بعيدة عن الفهم الصحيح، على الرغم من البحث المكثف. هنا نشير إلى الإمكانية التي تحملها ملاحظات شريحة الشمس على الطول الموجي الميليمتري لحل هذه المشكلة المستمرة. وأظهرت الحسابات التي تم إجراؤها باستخدام نموذج ديناميكي متقدم لشريحة الشمس بسبب كارلسون وستاين أن الانبعاثات الميليمترية حساسة للغاية للعمليات الديناميكية في شريحة الشمس وأن الطول الموجي المناسب للبحث عن العلامات الديناميكية في النطاق 0.8-5.0 ملم. وأشار النموذج أيضًا إلى أن الملاحظات التي توفرها ALMA بدقة عالية ستمتلك الخاصية الفريدة من نوعها من الرد على الغاز الساخن والبارد، وبالتالي ستمتلك الإمكانية الحاسمة للتمييز بين النماذج المنافسة لجو الشمس. وبالتالي، أظهرت النتائج الأولية التي تم الحصول عليها من ملاحظات الشمس الهادئة على 3.5 ملم مع مجموعة BIMA (دقة 12 أرضية) وجود تزامن معظم بمقادير 50-150 كيلو، وترددات 1.5-8 ميغاهرتز، مع اتجاه نحو التزامن القصير الأجل في المنطقة غير الشبكية والأجل الأطول في المناطق الشبكية. ومع ذلك، يتطلب الدقة العالية التي توفرها ALMA للفصل النظيف بين الميزات الموجودة داخل جو الشمس ولمقارنة مناسبة مع الخرج الذي يوفره الحسابات الديناميكية الشاملة.
The very nature of the solar chromosphere, its structuring and dynamics, remains far from being properly understood, in spite of intensive research. Here we point out the potential of chromospheric observations at millimeter wavelengths to resolve this long-standing problem. Computations carried out with a sophisticated dynamic model of the solar chromosphere due to Carlsson and Stein demonstrate that millimeter emission is extremely sensitive to dynamic processes in the chromosphere and the appropriate wavelengths to look for dynamic signatures are in the range 0.8-5.0 mm. The model also suggests that high resolution observations at mm wavelengths, as will be provided by ALMA, will have the unique property of reacting to both the hot and the cool gas, and thus will have the potential of distinguishing between rival models of the solar atmosphere. Thus, initial results obtained from the observations of the quiet Sun at 3.5 mm with the BIMA array (resolution of 12 arcsec) reveal significant oscillations with amplitudes of 50-150 K and frequencies of 1.5-8 mHz with a tendency toward short-period oscillations in internetwork and longer periods in network regions. However higher spatial resolution, such as that provided by ALMA, is required for a clean separation between the features within the solar atmosphere and for an adequate comparison with the output of the comprehensive dynamic simulations.
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