J.t. Ii Olivar, Maed Faculty Of Arts And Letters University Of Santo Tomas

SUN J.T. II Olivar, MAEd Faculty of Arts and Letters University of Santo Tomas

Outline of the Lecture  Properties

of the [our] Sun  Sun and the concept of Temperature  Energy transport mechanisms of the Sun  Parts of the Sun

Properties of the Sun      

Spectral Type of Star – G2 V Age – 4,600 million years Mean Distance to Earth – 150 Million Kilometers (1 AU) Rotation Period (equator) – 26.8 days Radius – 695,000 Kilometers Composition – 71% Hydrogen [H], 26.5% Helium [He], 2.5% Other

     

Mass – 1.99 x 1030 Kilograms Effective Surface Temperature – 6,000 oC Core Temperature – 15 million oC Luminosity [Energy Output] – 3.83 x 1033 ergs / second Solar Constant – 0.137 Watts / cm2 Inclination of Solar Equator to Ecliptic – 7.25o

Absolute Zero  Lowest

temperature theoretically possible, characterized by complete absence of heat. Absolute zero is -273.15°C (-459.67°F), or zero degrees on the Kelvin scale (0 K).

Energy Transport Mechanisms of the Sun Radiation – Energy is carried by photons of all wavelengths. 2. Convection – Energy is transported by the bulk motion of materials. 3. Conduction – No bulk transport of matter or radiation takes place. 1.

Corona  2,000,000

K  Outermost part of the solar atmosphere  Faint white halo around the sun  Coronal holes – emanation of solar winds  Coronagraph

– invented by Bernard Lyot

Chromosphere  Chromos

(color)

 15,000

K  Not seen as spherical shell  Spicules – visualized as cylinders about 700 kms across and 7000 kms tall

Photosphere  Photos

(light)  Limb darkening  Granulation  Granule – 1,000 kilometers across  Convective

zone

– 5 minute oscillation

Sunspots  3,800

K  Appear dark when seen in white light  Cooler areas of the solar surface  Magnetic Lines of Force (Magnetic Field Lines)  1610 – Galilee, Scheiner, and Harriot  1850 – Sunspot cycle (11 years)  1908 – Hale

 1645-1715

– No Sunspots  Maunder minimum – Walter Maunder  Solar

Plages – Bright areas that surround the sunspot

Solar Flares  5,000,000

K  20 minutes  Solar storms  Aurora borealis  Aurora australis

Solar Prominences  Filaments

on the limb of the sun  3,000 – 7,000 K  10 – 100,000 kilometers high

Solar Flare and Solar Prominence

Solar Winds  10

days to reach the earth

Solar wind

Solar Constant  The

amount of solar energy that passes through each square centimeter of space at the average distance of the earth from the sun every second.