• Study Resource
  • Explore Categories
    • Arts & Humanities
    • Business
    • Engineering & Technology
    • Foreign Language
    • History
    • Math
    • Science
    • Social Science

    Top subcategories

    • Advanced Math
    • Algebra
    • Basic Math
    • Calculus
    • Geometry
    • Linear Algebra
    • Pre-Algebra
    • Pre-Calculus
    • Statistics And Probability
    • Trigonometry
    • other →

    Top subcategories

    • Astronomy
    • Astrophysics
    • Biology
    • Chemistry
    • Earth Science
    • Environmental Science
    • Health Science
    • Physics
    • other →

    Top subcategories

    • Anthropology
    • Law
    • Political Science
    • Psychology
    • Sociology
    • other →

    Top subcategories

    • Accounting
    • Economics
    • Finance
    • Management
    • other →

    Top subcategories

    • Aerospace Engineering
    • Bioengineering
    • Chemical Engineering
    • Civil Engineering
    • Computer Science
    • Electrical Engineering
    • Industrial Engineering
    • Mechanical Engineering
    • Web Design
    • other →

    Top subcategories

    • Architecture
    • Communications
    • English
    • Gender Studies
    • Music
    • Performing Arts
    • Philosophy
    • Religious Studies
    • Writing
    • other →

    Top subcategories

    • Ancient History
    • European History
    • US History
    • World History
    • other →

    Top subcategories

    • Croatian
    • Czech
    • Finnish
    • Greek
    • Hindi
    • Japanese
    • Korean
    • Persian
    • Swedish
    • Turkish
    • other →
 
Profile Documents Logout
Upload
An automated 2 epoch Proper Motion search of UKIDSS and VISTA
An automated 2 epoch Proper Motion search of UKIDSS and VISTA

From studying our solar system to searching for worlds beyond and
From studying our solar system to searching for worlds beyond and

... and how quickly they move.” This European Space Agency spacecraft is scheduled to launch later this year, and Belokurov has big plans for its data: “As I look at the stars torn off other celestial bodies as they now travel around the Milky Way, I plan to study the shape and lumpiness of the gravitat ...
Neutron Stars and Pulsars
Neutron Stars and Pulsars

... • Radius ~ 10 km (about 600 times smaller than Earth). • Mass ~1.4 to 3 times the mass of the Sun. • Density ~ 1017 kg per cubic meter. A ½ inch cube of this material with would weigh more than 100 million tons. • Neutron degeneracy prevents it from collapsing further ...
STA Binary star model
STA Binary star model

... Two stars orbiting each other so that the stars pass in front of each other when viewed from the earth are called eclipsing binary stars. You are going to use the model of an eclipsing binary star to see how to calculate the mass of a star in an eclipsing binary system. Apparatus: Binary star model ...
GenGeoAstroII_Stars
GenGeoAstroII_Stars

... • Dense clusters of 50,000 – a million stars • Old (11 billion years), lower-main-sequence stars • Approx. 200 globular clusters in our Milky Way ...
The Components and Origin of the Universe
The Components and Origin of the Universe

... energy expanded from a hot dense mass with an incredibly small volume 2. at first, the universe was hot (10 32 C) and energy went rushing out in all directions energy became cooled enough to become matter 3. matter then cooled enough to form protons, electrons and neutrons (subatomic particles) 4. ...
ISM&Galaxy
ISM&Galaxy

... Emission and Absorption Spectra More accurately, a gas cloud is only opaque within spectral lines, while a star is opaque at all wavelengths. The brightness of each depends on the usual T4 relation. If, as is usually the case, the cloud is colder than the star (or the star’s atmosphere is colder th ...
Here
Here

... protons) combine to form 1 helium nucleus (which has two protons and two neutrons). • The details are a bit complex:  In the Sun, 6 hydrogen nuclei are involved in a sequence that produces two hydrogen nuclei and one helium nucleus. This is the proton-proton chain.  In more massive stars, a carbon ...
Superhero science 2
Superhero science 2

... In a Tokomak a magnetic field is used to hold an extremely hot plasma of isotopes of hydrogen (deuterium and tritium). The isotopes collide and undergo fusion to create a helium atom and a neutron. This process releases vast amounts of energy and once we have a continuous process will change the way ...
STELLAR ATMOSPHERES
STELLAR ATMOSPHERES

... • Understand stars from spectra formed in outer 1000 km of radius • Use laws of physics to develop a layer by layer description of T temperature P pressure and n density that leads to spectra consistent with observations ...
Supernova
Supernova

... Could there be neutron stars that appear as pulsars to other civilizations but not to us? A. Yes B. No ...
Introduction to the Big Bang Theory
Introduction to the Big Bang Theory

... provided clues for how our universe began: ...
Published by the Association Pro ISSI No. 37, May 2016
Published by the Association Pro ISSI No. 37, May 2016

... protostar. The cloud as a whole does not collapse into just one single protostar, but each different knot produces an individual protostar. This is why these nebulae are often referred to as stellar nurseries, the places where myriads of stars are born. ...
Abstract
Abstract

... An ultra-high-resolution (1,0243 grids) hydrodynamic simulation pursues the early evolution of a proto-galaxy as an assemblage of sub-galactic condensations with a mass of 109 M (where M is the solar mass) building up a total mass of 1011 M. The overdensity region of this mass-scale decouples fro ...
Sama (Sky) | Questions on Islam
Sama (Sky) | Questions on Islam

... of hydrogen and that a great deal of helium is present in the sun. The most common element in the universe is hydrogen. Other elements are derivatives of hydrogen. In order to convert hydrogen to helium, the needed heat of millions of degrees is present in the sun (cold fusion is not possible). The ...
Lesson 4. Wiens and Stefans Laws
Lesson 4. Wiens and Stefans Laws

User`s Guide to the Sky Notes
User`s Guide to the Sky Notes

SPACE QUIZ
SPACE QUIZ

... boy band. ...
Classnotes 9_159 - University of Texas Astronomy
Classnotes 9_159 - University of Texas Astronomy

The Sun – Our closest star - E
The Sun – Our closest star - E

... The Sun rises in the East and sets in the West The Sun is large enough that approximately 1.3 million Earths could fit inside it. The mass of the Sun is approximately 330,000 times greater than that of Earth. It is almost three quarters Hydrogen, whilst most of the remaining mass is Helium. The Sun ...
Astronomy C - Scioly.org
Astronomy C - Scioly.org

PDF version (two pages, including the full text)
PDF version (two pages, including the full text)

... At about 40 times the diameter of the sun and 400 times as bright, Alphard is one of the ‘bright giants’ in our neighborhood. But our ‘neighborhood’ is rather large. Alphard is 11 million times as far away from us as our own sun – so it looks a lot dimmer to us! To the south of Sirius, and nearly ov ...
document
document

... “Astronomy is more than the study of stars and planets. It is the study of the universe in which we humans exist. You and I live on a small planet circling a small sun drifting through the universe, but astronomy can take us beyond these boundaries and help us not only see where we are in the univer ...
lecture
lecture

... • Because the gas hits the star before it reaches a stable orbital speed, there is no way to tell where the gas is in the system. • Therefore the only way to map it is with the velocities from the Doppler Shift and phases from the timing of the observations. • Make a contour map using velocity and p ...
Big Bang and Beyond
Big Bang and Beyond

... – Nuclear reactions will be very efficient (fast) – Most or all hydrogen will be converted to Helium and then on into Iron – No hydrogen, no water, and thus, no life possible… ...
< 1 ... 229 230 231 232 233 234 235 236 237 ... 410 >

Stellar evolution



Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.
  • studyres.com © 2025
  • DMCA
  • Privacy
  • Terms
  • Report