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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)
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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.
- Supernova's 'fizzled' gamma-ray burston July 26, 2021 at 6:48 pm
On Aug. 26, 2020, NASA's Fermi Gamma-ray Space Telescope detected a pulse of high-energy radiation that had been racing toward Earth for nearly half the present age of the universe. Lasting only about a second, it turned out to be one for the record books -- the shortest gamma-ray burst (GRB) caused by the death of a massive star ever seen.
- Planetary shields will buckle under stellar winds...on July 22, 2021 at 4:12 pm
Any life identified on planets orbiting white dwarf stars almost certainly evolved after the star's death, says a new study that reveals the consequences of the intense and furious stellar winds that will batter a planet as its star is dying.
- New study reveals previously unseen star...on July 22, 2021 at 3:28 pm
A new survey of our home galaxy, the Milky Way, combines the capabilities of the Very Large Array and the Effelsberg telescope in Germany to provide astronomers with valuable new insights into how stars much more massive than the Sun are formed.
- Supermassive black holes put a brake on stellar...on July 19, 2021 at 11:16 pm
Black holes with masses equivalent to millions of suns do put a brake on the birth of new stars, say astronomers. Using machine learning and three state of the art simulations to back up results from a large sky survey, the researchers resolve a 20-year long debate on the formation of stars.
- Millimeter-tall 'mountains' on neutron starson July 18, 2021 at 11:14 pm
New models of neutron stars show that their tallest mountains may be only fractions of millimeters high, due to the huge gravity on the ultra-dense objects.
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.
- GLOSTAR: Tracing atomic and molecular gas in the...on July 22, 2021 at 1:39 pm
By combining two of the most powerful radio telescopes on Earth, an international team of researchers led by the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, created the most sensitive maps of the radio emission of large parts of the Northern Galactic plane so far. The data were taken with the Karl G. Jansky Very Large Array (VLA) in New Mexico in two different configurations and the 100-m Effelsberg telescope near Bonn. This provides for the first time a radio survey covering all […]
- Italian astronomers inspect galaxy Markarian 509...on July 22, 2021 at 12:50 pm
Using the Atacama Large Millimeter/submillimeter Array (ALMA), Italian astronomers have investigated an active galaxy known as Markarian 509. Results of the study, presented in a paper published July 14 on arXiv.org, deliver important insights into the distribution and kinematics of the galaxy's cold molecular gas.
- Astronomers make first clear detection of a...on July 22, 2021 at 12:00 pm
Using the Atacama Large Millimetre/submillimeter Array (ALMA), in which the European Southern Observatory (ESO) is a partner, astronomers have unambiguously detected the presence of a disk around a planet outside our Solar System for the first time. The observations will shed new light on how moons and planets form in young stellar systems.
- A large tidal stream observed in the Sombrero...on July 21, 2021 at 3:35 pm
According to the latest cosmological models, large spiral galaxies such as the Milky Way grew by absorbing smaller galaxies, by a sort of galactic cannibalism. Evidence for this is given by very large structures, the tidal stellar streams, which are observed around them, which are the remains of these satellite galaxies. But the full histories of the majority of these cases are hard to study, because these flows of stars are very faint, and only the remains of the most recent mergers have been […]
- Supermassive black holes put a brake on stellar...on July 20, 2021 at 7:23 am
Black holes with masses equivalent to millions of suns do put a brake on the birth of new stars, say astronomers. Using machine learning and three state of the art simulations to back up results from a large sky survey, the researchers resolve a 20-year long debate on the formation of stars. Joanna Piotrowska, a Ph.D. student at the University of Cambridge, will present the new work today at the virtual National Astronomy Meeting (NAM 2021).