The Sun & Stars - Notes

Photosphere

Visible surface of the Sun

Chromosphere

Reddish gaseous layer outside the photosphere

Corona

Rarefied gaseous envelope of the Sun, visible during a total solar eclipse

Solar wind

Continuous flow of charged particles from the Sun

Sunspot

Dark spot on the Sun's surface

Solar flare

Sudden flash of increased brightness on the Sun

Prominence

Large, bright, gaseous feature extending into the corona

Fusion

Process by which multiple nuclei join to form a heavier nucleus

Fission

Splitting of a heavy, unstable nucleus into two lighter nuclei

Apparent magnitude

is a measure of the brightness of a celestial object as seen from Earth, taking into account distance and observer's viewing conditions.

Absolute magnitude

The measure of a star's intrinsic brightness as seen from a standard distance of 10 parsecs.

Luminosity

The total amount of energy emitted by a star per unit time, typically expressed in watts. It is an intrinsic property and does not depend on distance from the observer.

Hertzsprung-Russell diagram

A scatter plot of stars showing the relationship between their absolute magnitude and effective temperature; it helps classify stars into different types.

Main sequence

The continuous band of stars on the Hertzsprung-Russell diagram that are in the stable phase of hydrogen burning, including most stars like the Sun.

Nebula

A large cloud of gas and dust in space, often the birthplace of stars and planetary systems.

Protostar

An early stage of star formation where a cloud of gas and dust begins to collapse and heat up, ultimately leading to the formation of a main sequence star.

Neutron star

A type of compact star that is the remnant of a supernova explosion, composed mostly of neutrons and extremely dense.

Pulsar

A highly magnetized rotating neutron star that emits beams of electromagnetic radiation, observed as pulses as it rotates.

Supernova

A powerful explosion marking the death of a massive star, resulting in the ejection of its outer layers and leaving behind a neutron star or black hole.

Black hole

A region of spacetime exhibiting gravitational acceleration so strong that nothing can escape from it, formed when a massive star collapses.