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Free Wallpapers Sky, Galaxies & Space Page 7
All free wallpaper images of space, galaxies, the solar system, stars, planets including Hubble Telescope and NASA pictures. See both Space Wallpaper categories below for all image downloads.
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Free Wallpaper Images - The Sky, Galaxies and Space
Sky, Galaxies & Space Wallpaper Downloads - Viewing Page 7
Huge selection of high resolution desktop wallpapers from NASA, the Hubble Telescope and other invaluable sources. Our night sky, the nine planets in our solar system, the earth, sun, mars, jupiter, venus, uranus, pluto, saturn, mercury, stars, star births, star formaions, distant galaxies, nebula (nebulae) and many more stunningly beautiful pictures of our solar system and beyond. Find high quality wallpaper pictures for your computer desktop and download free.
How to Download Your Free Computer Wallpapers
Right-click on a wallpaper preview pane and choose 'Save Picture As' or 'Save Image As' to save it on your computer in full size. To preview any wallpaper image at full size, click on a wallpaper preview picture or the link describing the wallpaper. All wallpaper images are minimum 1024 x 768 for great viewing on any desktop.
Index of Free Space Wallpaper Downloads
Sky, Outer Space, Galaxies, Solar System, Space, Planets and Stars
Sky, Galaxies & Space Planets, Stars & Solar System
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Protostars - The Formation of Stars - How a Star is Born - Part 2 of 3|
A protostar is a young star that has started its collapse but has not yet gotten clear of its circumstellar envelope. This envelope is opaque to optical light and thus protostars are generally invisible to ordinary telescopes. Most of what we know about protostars comes from observations at infrared and millimeter wavelengths.
Protostars have ages of around 100,000 years and are still accreting material onto the central star. At this stage the protostar consists of a central condensation that will become the star, an accretion disk, and an envelope. Another important property of protostars is their outflows. In addition to matter falling on to the star there is also large amounts of material being ejected from the star in the form of powerful bipolar jets. These jets can be seen in Hubble Space Telescope images and are traveling at hundreds of kilometers a second. Bipolar jets are believed to be important for transporting excess angular momentum away from the star.
Observationally, protostars are Class I infrared objects. This means that the infrared emission from the disk and envelope is dominated by the cooler material in the envelope. A few protostars have also been observed at X-ray wavelengths. X-ray emission may be an important source of ionization, allowing the star, disk and outflow to be coulpled by magnetic fields. Such magnetic fields may also be responsible for squeezing the outflow, producing the narrow jets seen above.
The Classical T Tauri Stars - From Darkness Comes Light A T Tauri star is a young object that has emerged from its opaque dusty envelope and has become visible at optical wavelengths. T Tauri stars are divided into two categories: Classical and Weak-lined.
Classical T Tauri stars were first discovered by the presence of strong chromospheric spectroscopic lines, especially the Hydrogen alpha line. This line is believed to be produced by interaction between the disk and the stellar surface. This disk may be the precursor to planetary systems like our own solar system and many have been detected by their millimeter and infrared emission. Recently there has also been some direct imaging of these disks by the Hubble Space Telescope.
Classical T Tauri stars are about 1-10 million years old, and are Class II infrared objects. This means that most of the infrared emission from the object is from the disk, since the envelope has mostly dissipated. Classical T Tauri stars are strong X-ray emitters and can also produce powerful winds.
Part 1 Part 2 Part 3
Picture of a Protostar Disk with Outflow
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