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Posts
- Touch the Sun (12/6/2019) - Remember how Icarus wanted to touch the Sun, but met his demise instead? Well, scientists at NASA wanted to touch the Sun too, but unlike Icarus, they succeeded! Better yet, they are beginning to share what they learned by doing it! Before we get into all of that, let’s go back and start at the … Continue reading Touch the Sun
- Halloween@NASA (10/31/2019) - The folks at NASA love Halloween, and they do something to celebrate every year. For example, the engineers at NASA Jet Propulsion Lab have been holding a pumpkin carving contest for almost a decade, and stories about their ingenuity invariably make it into the news. Here’s a video from Wired about their 2016 competition. Here’s … Continue reading Halloween@NASA
- 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
- 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)
Dictionary
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)
Search
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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Gigantic, red and full of spots
on July 13, 2020 at 4:55 pm
Starspots are more common among red giant stars than previously thought. Astronomers report that approximately eight percent of red giants exhibit such spots. Although red giants are generally regarded as slowly rotating stars, those with starspots are apparently an exception. The new publication offers a comprehensive analysis of the reasons for their short rotation periods.
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How colliding neutron stars could shed light on...
on July 8, 2020 at 4:14 pm
Researchers have discovered an unusual pulsar - one of deep space's magnetized spinning neutron-star 'lighthouses' that emits highly focused radio waves from its magnetic poles. It is unusual because the masses of its two neutron stars are quite different -- with one far larger than the other. The breakthrough provides clues about unsolved mysteries in astrophysics -- including the expansion rate of the Universe (the Hubble constant).
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The cosmic commute towards star and planet...
on July 7, 2020 at 3:32 pm
Interconnected gas flows reveal how star-forming gas is assembled in galaxies.
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New collection of stars, not born in our galaxy,...
on July 7, 2020 at 3:32 pm
Astrophysicists announced the discovery of Nyx, a new collection of 250 stars that they believe are the remnant of a dwarf galaxy that merged with the Milky Way eons ago. The research combined massive cosmological simulations and observational data from the Gaia space observatory. It required large scale supercomputers and deep learning algorithms. The team plans to explore Nyx further using ground-based telescopes.
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White dwarfs reveal new insights into the origin...
on July 6, 2020 at 6:08 pm
A new analysis of white dwarf stars supports their role as a key source of carbon in galaxies. Every carbon atom in the universe was created by stars, but astrophysicists still debate which types of stars are the primary source of the carbon in our galaxy. Some studies favor low-mass stars that blew off their envelopes in stellar winds and became white dwarfs, while others favor massive stars that eventually exploded as supernovae.
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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About eight percent of red giants are covered by...
on July 13, 2020 at 4:23 pm
Starspots are more common among red giant stars than previously thought. In the journal Astronomy & Astrophysics, researchers led by the Max Planck Institute for Solar System Research (MPS) in Germany report that approximately eight percent of red giants exhibit such spots. They are the expression of strong magnetic fields at the stellar surface. These magnetic fields are created deep inside the star in a process that requires, among other things, convection and a fast rotation of the star. […]
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Structure of the molecular cloud Orion A...
on July 13, 2020 at 12:18 pm
Using a 3-D mapping technique, astronomers from Sweden and Germany have explored a nearby molecular cloud known as Orion A. The new study unveils more details about the structure and nature of this cloud. The research was presented in a paper published July 6 on the arXiv pre-print repository.
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Study determines fundamental parameters of the...
on July 8, 2020 at 1:00 pm
Astronomers have carried out a spectroscopic analysis of the atmosphere of a magnetic chemically peculiar star designated HD 108662. The study, described in a paper published June 29 on the arXiv preprint server, resulted in determining fundamental parameters of this star.
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New collection of stars, not born in our galaxy,...
on July 7, 2020 at 4:10 pm
Astronomers can go their whole career without finding a new object in the sky. But for Lina Necib, a postdoctoral scholar in theoretical physics at Caltech, the discovery of a cluster of stars in the Milky Way, but not born of the Milky Way, came early—with a little help from supercomputers, the Gaia space observatory, and new deep learning methods.
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Dying stars breathe life into Earth: study
on July 6, 2020 at 5:21 pm
As dying stars take their final few breaths of life, they gently sprinkle their ashes into the cosmos through the magnificent planetary nebulae. These ashes, spread via stellar winds, are enriched with many different chemical elements, including carbon.