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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)
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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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Rapid destruction of Earth-like atmospheres by...
on April 24, 2019 at 2:22 pm
The discoveries of thousands of planets orbiting stars outside our solar system has made questions about the potential for life to form on these planets. Fundamentally important for the habitability of a planet is whether or not it can hold onto an atmosphere. A new study by has shown that young stars can rapidly destroy the atmospheres of Earth-like planets, which is a significant additional difficulty for the formation of life outside our solar system. […]
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Hubble celebrates its 29th birthday with...
on April 18, 2019 at 5:14 pm
This incredible image of the hourglass-shaped Southern Crab Nebula was taken to mark the NASA/ESA Hubble Space Telescope's 29th anniversary in space. The nebula, created by a binary star system, is one of the many objects that Hubble has demystified throughout its productive life. This new image adds to our understanding of the nebula and demonstrates the telescope's continued capabilities. […]
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Explosion on Jupiter-sized star 10 times more...
on April 17, 2019 at 4:00 pm
A stellar flare 10 times more powerful than anything seen on our Sun has burst from an ultracool star almost the same size as Jupiter. […]
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Powerful particles and tugging tides may affect...
on April 17, 2019 at 2:28 pm
Two new studies, one on high-energy particles and the other on tidal forces, may bring into question the habitability of TRAPPIST-1 exoplanets. […]
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Five planets revealed after 20 years of...
on April 17, 2019 at 2:27 pm
To confirm the presence of a planet, it is necessary to wait until it has made one or more revolutions around its star. This can take from a few days for the closest to the star to decades for the furthest away. Only a telescope dedicated to the search for exoplanets can carry out such measurements over such long periods of time, which is the case of the EULER telescope of UNIGE. […]
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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Research provides insights into molecular gas in...
on April 18, 2019 at 1:00 pm
In a recently published research, which is part of a broader observational campaign focused on studying massive spiral galaxies, astronomers have investigated molecular lines of carbon monoxide and its isotopologues in NGC 5908. The study, detailed in a paper published April 10 on arXiv.org, sheds more light on properties of molecular gas in this galaxy, what could be helpful to better understand the evolution of such massive objects. […]
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Astronomers take first, high-resolution look at...
on April 15, 2019 at 4:43 pm
Astronomers from the United States and South Korea have made the first high-resolution, radio telescope observations of the molecular clouds within a massive star-forming region of the outer Milky Way. […]
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Breezing through the space environment of...
on April 15, 2019 at 11:49 am
The closest exoplanet to us, if we include only single stars like the Sun, is the planet around Barnard's Star, Barnard's Star-b ("BSb"). (The planet Promixa Centauri-b is closer, but Proxima Cen is part of a triple-star system with Alpha and Beta Centauri, and understanding the evolutionary development of the planet is more complicated.) BSb orbits at a distance similar to that of Mercury around the Sun, but Barnard's Star is a cool M-dwarf star and so despite the planet being close to the […]
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Observing the invisible: The long journey to the...
on April 11, 2019 at 12:20 pm
The first picture of a supermassive black hole at the centre of a galaxy shows how we have, in a sense, observed the invisible. […]
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Giant molecular outflow detected from the quasar...
on April 3, 2019 at 1:00 pm
Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, astronomers have detected a galaxy-wide molecular outflow from the quasar PDS 456. The findings are presented in a paper published March 25 on arXiv.org, in which the authors investigate the properties of this outflow. […]