On the Cause of Solar Differential Rotation

Ling-Hsiao LyuInstitute of Space Science, National Central Universit

y呂凌霄

中央大學太空科學研究所

太陽差動自轉的成因

Motivation of this study:

To answer the toughest question in lectures of space physics

Example of a lecture in space physics

Solar Cycle andSun-Earth Connection

磁暴時，難得一見之紅綠相間的極光（Ｏ 2→ Ｏ＋Ｏ）

太空梭上所拍攝到的極光

極光什麼時候會出現？• 高緯地區，極光橢圓圈內的地方，每天晚上（尤其

是午夜前），如果天空晴朗，一定可以看到極光。• 非常劇烈的極光活動，通常發生在太陽閃焰之後的

一兩天內，這段時間裡，全球地表的磁場也發生大幅變動，故稱為磁暴！

• 二十世紀初科學家就發現：【極光出現頻率】、【磁暴出現頻率】、與【太陽黑子個數多寡】， 三者之間關係密切。

What is Sunspots?太陽黑子 Sunspots on White Light Solar Image

Close View of Sunspots

11-years Solar Cycle Based on Sunspot Number

Butterfly Diagram of Sunspot Distribution

22-years Solar Cycle Based on Leading Sunspot Magnetic Polarity

Solar Differential Rotation --> Solar Dynamo (-effects, -effects)

-->22-years Magnetic Solar Cycle

T: Differential rotation is the major cause of solar cycle!

S: What is the cause of solar differential rotation?

T: (mmm~~~~~~) It is an observational result!

*@#%!Tough question!

太陽黑子數目與強磁暴之間的相關性太陽外部磁偶極方向朝南期間

二十世紀末二十一世紀初科學家發現：【太陽日冕物質拋射】與【太陽風速大小】

是造成【磁暴】與【絢麗極光】的主因。

太陽日冕物質拋射則與日珥噴發息息相關！

什麼是日冕？什麼是日珥？

什麼是太陽風？

日冕與日冕洞的可見光影像 Corona & Coronal Hole in

White Light Image

White-light solar image during solar maximum

White-light solar image during solar minimum

White-light solar image during solar minimum

Magnetic Field Distribution in Corona and Coronal Hole regions

用不同波長的Ｘ光與紫外光觀測太陽圓盤上的

日冕與日冕洞的分布 CORONAL HOLE DISTRIBUTION

ON SOLAR DISKin Hard X-ray, Soft X-ray, & EUV i

mages

Hard X-ray image

Soft X-ray image

EUV image

Ulysses observation of solar wind speed(1991-1998)

It is believed that …observed large-amplitudeAlfven waves are responsible for solar wind acceleration in the polar coronal hole region.

High speed solar wind can lead to magnetic storm or substorm!

S: What is the energy source of these large-amplitude Alfven waves?T: mm~~~, Let’s move on to next slide. (another tough question!)

日珥 Solar Prominences

日珥Solar Prominen

ces

日珥噴發 Prominence Eruption

日珥噴發 Prominence Eruption

當日珥出現在太陽光盤上時被稱為暗紋

Prominences on the solar disk is called Filaments

Filaments on sloar disk

Filaments&

Prominences

Magnetic field configuration

near a filament

Q: What process leads to formation of filaments?

Q: What cause eruption of a prominence?

A:mm~~, this is an ongoing research subject! There are

many theoretical models trying to explain formation

and eruption of prominence!~~ another tough question!

日珥噴發 Prominence Eruption

太陽閃焰 Solar Flares

日冕物質拋射 Coronal Mass Ejections (CMEs)

太陽閃焰 (solar flare)[ 耀斑 ]閃焰發生前的觀測照片 閃焰發生時的觀測照片

日珥噴發伴隨著太陽閃焰

日冕物質拋射（ CME ）如果噴發方向對著地球，而且攜帶著南向磁場，

可造成地球磁暴

CME (Coronal Mass Ejection)