Physics 202: Introduction to Astronomy – Lecture 13

Physics 202: Introduction to Astronomy – Lecture 13

Carsten Denker

Physics DepartmentCenter for Solar–Terrestrial

Research

March 10, 2006 Center for Solar-Terrestrial Research

The SunThe Solar Interior

Mass Luminosity Radius Effective Temperature Surface Composition

The Solar AtmosphereThe Solar Cycle


Sun – OverviewMass (kg)

1.989e+30

Mass (Earth = 1) 332,830

Equatorial radius (km) 695,000

Equatorial radius (Earth = 1) 108.97

Mean density (gm/cm3) 1.410

Rotational period (days) 25-36

Escape velocity (km/sec) 618.02

Luminosity (ergs/sec) 3.827e33

Magnitude (Vo) -26.8

Mean surface temperature 6,000°C

Age (billion years) 4.5

Principal chemistry

Hydrogen Helium Oxygen Carbon Nitrogen Neon Iron Silicon Magnesium All others

92.1%7.8%

0.061%0.030%

0.0084%0.0076%0.0037%0.0031%0.0024%0.0030%


Evolution of the Sun and its Interior

Standard Solar Model:

X: 0.71 0.34

Y: 0.27 0.64


pp–Chain

Solar Neutrino Problem!


Interior Structure


Convection Condition

ln2.5

ln

d P

d T

The Sun is purely radiative below r/R = 0.71 and becomes convective above that point. Physically this occurs because the opacity in the outer layers of the Sun becomes large enough to inhibit the transport of energy.


Differential Rotation and Magnetic Fields


Helioseismology


Photosphere


Sunspots – Umbra and Penumbra


Active Regions

Active region 9169 was the host of the largest sunspot group observed so far during the current solar cycle. On 20 September 2000, the sunspot area within the group spanned 2,140 millionths of the visible solar surface, an area a dozen times larger than the entire surface of the Earth!


Spectrum of Granulation

“Wiggly” spectral lines in the solar photosphere inside and outside a region of activity, reflecting rising and sinking motions in granulation. Over the central one third of the spectrogram height, the slit crossed a magnetically active region. Here, the velocity amplitudes are much reduced, demonstrating how convection is disturbed in magnetic areas.


Supergranulation


Photospheric Magnetic Fields


Sunspots – Pores & Filigree


Thin Flux Tube Model


Magnetic Carpet


Chromosphere


Mercury Transit November 15th, 1999

The images were taken 20 seconds apart from 21:11 (first contact) to 22:10 UT (last contact). The image were captured with a Kodak MegaPlus 4.2 CCD camera. The spatial resolution is about 1 per pixel. Here, we show only a small portion of the full disk images near the solar north pole. The field of view is approximately 470 170 or 340,000 km 125,000 km on the Sun.


Prominences

The SoHO EIT full sun image, taken on 14 September 1999 in the He II line at 304 Å shows the upper chromosphere/lower transition region at a temperature of about 60,000 K. The bright features are called active regions. A huge erupting prominence escaping the Sun can be seen in the upper right part of the image. Prominences are “cool” 60,000 K plasma embedded in the much hotter surrounding corona, which is typically at temperatures above 1 million K.


Filament Evolution

Temporal evolution in H center line of a sigmoidal filament in active region NOAA 8668 during August 2000.

(a) Videomagnetogram , (b) CaI line wing filtergram, (c) H – 0.6 Å filtergram, and (d) Ha center line filtergram.


Filament Eruption HSinger telescope Flat-field and limb

darkening corrected Associated CME 28 June 2000 18:00 – 20:07 UT 120 frames 1 minute cadence 1 arcsec pixel-1 300” x 350” FOV


Sympathetic Flares


Transition Region & Corona


Corona – EIT 304 Å


Corona – EIT 171 Å


Corona – LASCO C2


Corona – LASCO C3


Corona and Planets


Coronal Mass Ejection – LASCO


Coronal Mass Ejection & Comet


Coronal Mass Ejection – TRACE


Space Weather


Space Weather – Sun Earth Connection


Space Weather – Bow Shock


Space Weather Effects on Earth


Solar Cycle – Butterfly Diagram


Solar Cycle


Solar Cycle – Synoptic Map

Physics 202: Introduction to Astronomy – Lecture 13

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