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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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Stars Reference (National Geographic)
Star Portal (Wikipedia)
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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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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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Astronomers use giant galaxy cluster as X-ray...
on October 14, 2019 at 3:17 pm
Astronomers have used a massive cluster of galaxies as an X-ray magnifying glass to peer back in time, to nearly 9.4 billion years ago. In the process, they spotted a tiny dwarf galaxy in its very first, high-energy stages of star formation.
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Black holes stunt growth of dwarf galaxies
on October 11, 2019 at 8:53 pm
Astronomers have discovered that powerful winds driven by supermassive black holes in the centers of dwarf galaxies have a significant impact on the evolution of these galaxies by suppressing star formation.
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The Milky Way kidnapped several tiny galaxies...
on October 10, 2019 at 3:32 pm
A team of astronomers has discovered that several of the small -- or 'dwarf' -- galaxies orbiting the Milky Way were likely stolen from the Large Magellanic Cloud, including several ultrafaint dwarfs, but also relatively bright and well-known satellite galaxies, such as Carina and Fornax.
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How do the strongest magnets in the universe form?
on October 9, 2019 at 5:17 pm
How do some neutron stars become the strongest magnets in the Universe? Astrophysicists have found a possible answer to the question of how these so-called magnetars form. Researchers have used large computer simulations to demonstrate how the merger of two stars creates strong magnetic fields. If such stars explode in supernovae, magnetars could result.
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Liquifying a rocky exoplanet
on October 9, 2019 at 1:58 pm
A hot, molten Earth would be around 5% larger than its solid counterpart. The difference between molten and solid rocky planets is important for the search of Earth-like worlds beyond our Solar System and the understanding of Earth itself.
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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Open cluster ASCC 123 investigated in detail
on October 14, 2019 at 1:00 pm
Using the Galileo National Telescope, astronomers have conducted a high-resolution spectroscopic study of the open cluster ASCC 123 as part of the Stellar Population Astrophysics (SPA) project. Results of the new research, presented in a paper published October 4 on arXiv.org, provide important information about fundamental parameters of 17 candidate members of ASCC 123, shedding more light on the properties of this little-studied cluster.
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Black holes stunt growth of dwarf galaxies
on October 12, 2019 at 9:16 am
Astronomers at the University of California, Riverside, have discovered that powerful winds driven by supermassive black holes in the centers of dwarf galaxies have a significant impact on the evolution of these galaxies by suppressing star formation.
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Milky Way raids intergalactic 'bank accounts,'...
on October 10, 2019 at 2:20 pm
Our Milky Way is a frugal galaxy. Supernovas and violent stellar winds blow gas out of the galactic disk, but that gas falls back onto the galaxy to form new generations of stars. In an ambitious effort to conduct a full accounting of this recycling process, astronomers were surprised to find a surplus of incoming gas.
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Milky Way's center will be revealed by NASA's...
on October 10, 2019 at 12:31 pm
The center of our galaxy is a crowded place: A black hole weighing 4 million times as much as our sun is surrounded by millions of stars whipping around it at breakneck speeds. This extreme environment is bathed in intense ultraviolet light and X-ray radiation. Yet much of this activity is hidden from our view, obscured by vast swaths of interstellar dust.
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Using velocity-induced acoustic oscillations as a...
on October 7, 2019 at 1:40 pm
Our current understanding of physics suggests that there are two main types of matter in the universe known as dark and baryonic matter. Dark matter is made up of material that scientists cannot directly observe, as it does not emit light or energy. On the other hand, baryonic matter is made up of normal atomic matter, including protons, neutrons and electrons.