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Posts
- Get Lost in Space! (9/14/2018) - Way back in August, in anticipation of the start of a new school year, I set out to update the pages on this site related to space. Those pages tend to be popular among the teachers and students who use Cosma, and I happen to enjoy updating them, too. It sounded like a short, fun … Continue reading Get Lost in Space!
- Milky Way Lost & Found (8/15/2018) - Have you seen the Milky Way? You may think that you have, but are you sure? Unless you live in an extremely remote area, or you’ve visited one, then you probably haven’t seen our own galaxy, the Milky Way, very well, or at all. Worse yet, you may not even realize that it’s missing. The … Continue reading Milky Way Lost & Found
- Umbraphiles (8/20/2017) - umbraphile : One who loves eclipses, often travelling to see them. — Wiktionary Yes, this is that obligatory post about “The Solar Eclipse” (NASA, Wikipedia). Of course, there had to be one — eclipses really are just too cool to ignore. You’ve already been bombarded with explanations of the science and history of eclipses, but … Continue reading Umbraphiles
- To touch the Sun (6/1/2017) - The big “space” news this week is that NASA has announced that they renamed the Solar Probe Plus spacecraft the “Parker Solar Probe” in honor of Eugene N. Parker, the astrophysicist from the University of Chicago who predicted the solar wind. The probe is scheduled to launch next summer and become the first mission to … Continue reading To touch the Sun
- TRAPPIST-1 (2/23/2017) - You’ve probably heard that NASA has found a trove of “Earth-like” planets circling the TRAPPIST-1 system roughly 40 light years away, but just in case you haven’t, here’s a short 2 minute AP video about the discovery. Here’s another video from NASA/JPL with more explanation. Most entertainingly, here’s a 360° YouTube Video published by NASA/JPL … Continue reading TRAPPIST-1
Resources
These are organized by a classification scheme developed exclusively for Cosma. More…
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star : a self-luminous gaseous spheroidal celestial body of great mass which produces energy by means of nuclear fusion reactions — Webster
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Encyclopedia
Star is a luminous sphere of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. However, most of the stars in the Universe, including all stars outside our galaxy, the Milky Way, are invisible to the naked eye from Earth. Indeed, most are invisible from Earth even through the most powerful telescopes.
For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star’s interior and then radiates into outer space. Almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the star’s lifetime, and for some stars by supernova nucleosynthesis when it explodes. Near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, its luminosity, and spectrum respectively. The total mass of a star is the main factor that determines its evolution and eventual fate. Other characteristics of a star, including diameter and temperature, change over its life, while the star’s environment affects its rotation and movement. A plot of the temperature of many stars against their luminosities produces a plot known as a Hertzsprung–Russell diagram (H–R diagram). Plotting a particular star on that diagram allows the age and evolutionary state of that star to be determined.
A star’s life begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. When the stellar core is sufficiently dense, hydrogen becomes steadily converted into helium through nuclear fusion, releasing energy in the process. The remainder of the star’s interior carries energy away from the core through a combination of radiative and convective heat transfer processes. The star’s internal pressure prevents it from collapsing further under its own gravity. A star with mass greater than 0.4 times the Sun’s will expand to become a red giant when the hydrogen fuel in its core is exhausted. In some cases, it will fuse heavier elements at the core or in shells around the core. As the star expands it throws a part of its mass, enriched with those heavier elements, into the interstellar environment, to be recycled later as new stars. Meanwhile, the core becomes a stellar remnant: a white dwarf, a neutron star, or if it is sufficiently massive a black hole.
Binary and multi-star systems consist of two or more stars that are gravitationally bound and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy. — Wikipedia
Stars (Eric Weisstein’s World of Astronomy, Wolfram Research)
David Darling’s Internet Encyclopedia of Science
Encyclopædia Britannica
Introduction
Guide to Stars & Galaxies (Telescope.org)
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Science
Stellar Astronomy is the study of stars and stellar evolution, and it is fundamental to our understanding of the Universe. The astrophysics of stars has been determined through observation and theoretical understanding; and from computer simulations of the interior. Star formation occurs in dense regions of dust and gas, known as giant molecular clouds. When destabilized, cloud fragments can collapse under the influence of gravity, to form a protostar. A sufficiently dense, and hot, core region will trigger nuclear fusion, thus creating a main-sequence star. — Wikipedia
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Stars News -- ScienceDaily News about Stars. Read science articles and see images on the birth of monstrous stars, brown dwarfs and red giants. Consider stellar evolution and more.
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Unknown treasure trove of planets found hiding in...
on December 7, 2018 at 4:27 pm
The first unbiased survey of protoplanetary disks surrounding young stars in the Taurus star-forming region turned up a higher-than-expected number of disks with features suggesting nascent planets, according to a new study. […]
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An exoplanet inflated like a balloon
on December 6, 2018 at 7:12 pm
Although helium is a rare element on Earth, it is ubiquitous in the universe. It is, after hydrogen, the main component of stars and gaseous giant planets. Despite its abundance, helium was only detected recently in the atmosphere of a gaseous giant by an international team. The team has observed for the first time how this gas escapes from the overheated atmosphere of an exoplanet, literally inflated with helium. […]
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Combination of space-based and ground-based...
on December 3, 2018 at 4:16 pm
Astronomers using a combination of ground and space based telescopes have reported more than 100 extrasolar planets (exoplanets) in only three months. These planets are quite diverse and expected to play a large role in developing the research field of exoplanets and life in the Universe. […]
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Newly discovered supernova complicates origin...
on November 30, 2018 at 2:01 pm
A supernova discovered by an international group of astronomers provides an unprecedented look at the first moments of a violent stellar explosion. The light from the explosion's first hours showed an unexpected pattern, which astronomers analyzed to reveal that the genesis of these phenomena is even more mysterious than previously thought. […]
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All of the starlight ever produced by the...
on November 29, 2018 at 7:24 pm
From their laboratories on a rocky planet dwarfed by the vastness of space, scientists have collaborated to measure all of the starlight ever produced throughout the history of the observable universe. […]
Phys.org - latest science and technology news stories Phys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.
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Unknown treasure trove of planets found hiding in...
on December 6, 2018 at 7:33 pm
"Super-Earths" and Neptune-sized planets could be forming around young stars in much greater numbers than scientists thought, new research by an international team of astronomers suggests. […]
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How do stellar binaries form?
on December 3, 2018 at 1:50 pm
Most stars with the mass of the sun or larger have one or more companion stars, but when and how these multiple stars form is one of the controversial central problems of astronomy. Gravity contracts the natal gas and dust in an interstellar cloud until clumps develop that are dense enough to coalesce into stars, but how are multiple stars fashioned? Because the shrinking cloud has a slight spin, a disk (possibly a preplanetary system) eventually forms. In one model of binary star formation, […]
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Newly discovered supernova may rewrite exploding...
on November 30, 2018 at 12:38 pm
A supernova discovered by an international group of astronomers has provided an unprecedented look at the first moments of a violent stellar explosion. The team, led by the University of Hawaiʻi (UH) Institute for Astronomy's (IfA) Ben Shappee and Carnegie Observatories' Tom Holoien, found a mysterious signature in the light from the explosion's first hours. Their findings are published in a trio of papers in the Astrophysical Journal. […]
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Scientists measure all of the starlight ever...
on November 29, 2018 at 7:00 pm
From their laboratories on a rocky planet dwarfed by the vastness of space, Clemson University scientists have managed to measure all of the starlight ever produced throughout the history of the observable universe. […]
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We may soon be able to see the first supergiant...
on November 29, 2018 at 1:40 pm
We need to talk about the dark ages. No, not those dark ages after the fall of the western Roman Empire. The cosmological dark ages. The time in our universe, billions of years ago, before the formation of the first stars. And we need to talk about the cosmic dawn: the birth of those first stars, a tumultuous epoch that completely reshaped the face the cosmos into its modern form. […]