Proxima Centauri

Space Documentary | The secret of the stars HD | Star science facts

• Report rights infringement
• published: 30 Nov 2015
• views: 934

Each star in the sky is an enormous glowing ball of gas. Our sun is a medium-sized star. Stars can live for billions of years. A star is born when an enormous cloud of hydrogen gas collapses until it is hot enough to burn nuclear fuel (producing tremendous amounts heat and radiation). As the nuclear fuel runs out (in about 5 billion years), the star expands and the core contracts, becoming a giant star which eventually explodes and turns into a dim, cool object (a black dwarf, neutron star, or black hole, depending on its initial mass). The largest stars have the shortest life span (still billions of years); more massive stars burn hotter and faster than their smaller counterparts (like the Sun). The composition of stars is studied using spectroscopy in which their visible light (the spectrum) is studied. GROUPS OF STARS In the universe, most stars occur in groups of at least two stars. Two stars that are locked in elliptical orbit around their center of mass (their barycenter) are called a binary star system. About half of all stars are in a binary star system. There are larger groups of stars, called clusters. These are relatively unorganized collections of stars. An open cluster is a loose collection of up to about 1,000 stars. Examples of open clusters include the Pleiades and Hyades. All groups of stars are held together by gravitational forces. WHY ARE STARS HOT AND BRIGHT? Nuclear Fusion and Nucleosynthesis Stars are giant nuclear reactors. In the center of stars, atoms are taken apart by tremendous atomic collisions that alter the atomic structure and release an enormous amount of energy. This makes stars hot and bright. In most stars, the primary reaction converts hydrogen atoms into helium atoms, releasing an enormous amount of energy. This reaction is called nuclear fusion because it fused the nuclei (center) of atoms together, forming a new nucleus. The process of forming a new nucleus (and element) is nucleosynthesis. WHAT IS THE CLOSEST STAR? The closest star to us is the sun! Other than that, the closest star is Proxima Centauri, aka Alpha Centauri C (the dimmest star in the Alpha Centauri system). Proxima Centauri is 4.3 light-years from the Sun. It has an absolute magnitude of 15.5.