دوران الشمس
دوران الشمس Solar rotation هي حركة الشمس بالنسبة إلى المعيار المحلى للسكون وتبلغ حركة الشمس هذه نحو 20 كيلو مترا في الثانية الواحدة.
The reason why different latitudes rotate at different periods is unknown. The rate of surface rotation is observed to be the fastest at the equator (latitude φ = 0°) and to decrease as latitude increases. The solar rotation period is 24.47 days at the equator and almost 38 days at the poles.
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الدوران السطحي كمعادلة
معدل الدوران التفاضلي عادةً ما يوصف بالمعادلة:
where ω is the angular velocity in degrees per day, φ is the solar latitude and A, B, and C are constants. The values of A, B, and C differ depending on the techniques used to make the measurement, as well as the time period studied.[1] A current set of accepted average values[2] is:
- A= 14.713 ± 0.0491 °/d
- B= -2.396 ± 0.188 °/d
- C= -1.787 ± 0.253 °/d
الدوران السماوي
رقم بارتلز للدوران
Bartels' Rotation Number is a serial count that numbers the apparent rotations of the Sun as viewed from Earth, and is used to track certain recurring or shifting patterns of solar activity. For this purpose, each rotation has a length of exactly 27 days, close to the synodic Carrington rotation rate. Julius Bartels arbitrarily assigned rotation one day one to 8 February 1832. The serial number serves as a kind of calendar to mark the recurrence periods of solar and geophysical parameters.
دوران كارنگتن
The Carrington rotation is a system for comparing locations on the Sun over a period of time, allowing the following of sunspot groups or reappearance of eruptions at a later time.
Bartels "musical diagram" or the Condegram spiral plot are other techniques for expressing the approximate 27-day periodicity of various phenomena originating at the solar surface.
استخدام البقع الشمسية لقياس الدوران
الدوران الشمسي الداخلي
انظر أيضا
الهامش
- ^ Beck, J. (2000). "A comparison of differential rotation measurements". Solar Physics. 191: 47–70. Bibcode:2000SoPh..191...47B. doi:10.1023/A:1005226402796.
- ^ Snodgrass, H.; Ulrich, R. (1990). "Rotation of Doppler features in the solar photosphere". Astrophysical Journal. 351: 309–316. Bibcode:1990ApJ...351..309S. doi:10.1086/168467.
- Cox, Arthur N., Ed. "Allen's Astrophysical Quantities", 4th Ed, Springer, 1999.
- Javaraiah, J., 2003. Long-Term Variations in the Solar Differential Rotation. Solar Phys., 212 (1): 23-49.
- St. John, C., 1918. The present condition of the problem of solar rotation, Publications of the Astronomical Society of the Pacific, V.30, No. 178, 318-325.
المصادر
- مؤمن, عبد الأمير (2006). قاموس دار العلم الفلكي. بيروت، لبنان: دار العلم للملايين.
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