In the early moments of the universe, hydrogen and helium were formed through a process known as baryogenesis. Trace amounts of other elements such as lithium were also produced, but none of the heavier elements. This means that the first generation of stars were composed of hydrogen and helium, and it is only through fusion in their cores that the heavier elements we see today were created. The carbon, oxygen and iron in our bodies was produced through that process, which is why it is often said that we are star stuff.
Seven Sisters
The seven sisters, also known as the Pleiades, is an open cluster of stars, meaning it is a loosely bound star cluster. It is distinctive in the sky because its brightest stars are brilliant blue stars. At least six stars in the cluster are easily seen with the naked eye. With a pair of binoculars or a small telescope, you can see hundreds of stars in the cluster, which makes it an excellent object for amateur viewing.
Cosmic Rainbow
Recently I wrote about the average color of the universe, as determined by a survey of more than 230,000 galaxies. While knowing the overall color of these galaxies is a fun little factoid, it isn’t particularly useful from a scientific standpoint. However the color was determined by the average spectrum of the galaxies, which is quite scientifically useful. This “cosmic rainbow” tells us about the history of star formation in the universe.
Three is a Magic Number
Yesterday I talked about the star T Tauri, a red star that is transitioning into a main sequence star. The image yesterday was a composite of visible and near infrared images. The image below is a high resolution image at an infrared wavelength known as the K-band. You can see the visible star labeled as T Tau N (T Tauri North). You can also see two smaller stars, labeled Sa and Sb. These two stars don’t emit much light in the visible, so they can only be observed in the infrared. Earlier images didn’t resolve the binary pair, and instead only saw it as a single star (T Tauri South). It has only been in the past few years that we’ve seen them as a binary.
Winds of Change
The image above is of a star known as T Tauri. T Tauri is the prototype (primary example) of T Tauri type stars. In many ways T Tauri is a star in the making. Not quite a main sequence star, but more than a protostar.
Brown Dwarf Desert
A brown dwarf is larger than a planet, but not large enough to be considered a star. Stars undergo fusion in their cores, but a brown dwarf lacks the mass necessary to initiate fusion. At the same time, they are more like stars than planets, and can have at atmospheric temperature of 2000 K. So these objects occupy a middle ground between star and planet.
Wondrous Star
Mira is a red star in the constellation Cetus. It is a variable star, meaning that its brightness changes over time. The name Mira is Latin for “wondrous”, and so Mira is indeed a wondrous star.
Dark Star
So it is tempting to wonder what effect dark matter might have on the formation and evolution of stars themselves. The problem is we can’t be sure without an understanding of type of dark matter which exists. That hasn’t stopped some astronomers from speculating, however.
Destiny
The evolution of a star depends mainly upon its mass. There are other factors such as metallicity that can affect a star’s evolution, but the main factor is mass. It is the mass of a star that determines its destiny.
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