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Hertzsprung-Russell Diagram Outline
Hertzsprung-Russell Diagram Outline

... From a star’s spectrum, we can determine its spectral and luminosity class. Given the star’s apparent brightness (observed flux), we can then estimate its distance. This distance determination technique is called spectroscopic parallax Example: Observe a G2 Ia star (supergiant) with ...
Open access - ORBi
Open access - ORBi

Chapter 12: The Life Cycle of Stars
Chapter 12: The Life Cycle of Stars

... Gravity causes dense cores in molecular clouds to collapse. ...
Pop Quiz Question
Pop Quiz Question

Giant Stars
Giant Stars

... •At 100 million K, three Heliums can join to make carbon plus a little energy 3He  C + Energy •With a little higher temperature, they can add one more to make oxygen C + He  O + Energy •These processes produce far less energy than hydrogen burning ...
Variable Stars – II. Pulsating stars
Variable Stars – II. Pulsating stars

mufon ufo symposium -1974
mufon ufo symposium -1974

... C. The distance of Gliese 95 was thought of as 37.5 light years (pi.087 ±11) or 35.8 light years (pi..091) before the 1969 catalog. This would move it above rather than below the line of Gliese 111. ...
Chapter 12: The Life Cycle of Stars (contʼd)
Chapter 12: The Life Cycle of Stars (contʼd)

Early stages of clustered star formation -massive dark clouds
Early stages of clustered star formation -massive dark clouds

... prominently visible throughout the Galaxy. In contrast to the previous phases, HII regions are not in equilibrium but continuously fed by stellar activity. The final phase comprises the cold molecular gas (n ≥ 200 cm−3 , T ∼ 10 K) that is confined to giant molecular clouds. The clouds are held toget ...
doc
doc

... certain point, the newly forming object becomes visible. At this stage the large luminous body is called a protostar. The other half of its gravitational energy remains within the protostar as heat. As contraction continues, the internal temperature of the protostar keeps rising, and when it reaches ...
Stellar Properties
Stellar Properties

... “but they are not the same things for different people. For some, who are travelers, the stars are guides. For others they are no more than little lights in the sky. For others, who are scholars, they are problems. For my businessman they were wealth. But all these stars are silent. You – you alone ...
Project 8 : Stellar Spectra: Classification
Project 8 : Stellar Spectra: Classification

... The  spectra  shown  at  Fig.  6  come  from  stars  with  the  same  temperature  T  but  pressure  P  increasing downwards in the plot. Because the collision rate between atoms is higher for denser  gas. When an atom collides with another particle, its energy levels are temporarily shifted making  ...
10 Astrophysics (Option E)
10 Astrophysics (Option E)

16_Testbank
16_Testbank

... (redder) wavelengths by the dust grains. Thus starlight passing through a cloud appears redder than in the absence of a cloud. The amount of reddening can be measured by comparing a star's observed color to that expected for its spectral type. By looking at many stars and measuring the reddening tow ...
A prevalence of dynamo-generated magnetic fields in the
A prevalence of dynamo-generated magnetic fields in the

Evidence for a signature of the galactic bar in the solar neighbourhood
Evidence for a signature of the galactic bar in the solar neighbourhood

The Sculptor dwarf irregular galaxy SDIG: present and past
The Sculptor dwarf irregular galaxy SDIG: present and past

H-Band spectroscopic classification of OB stars
H-Band spectroscopic classification of OB stars

Letter to the Editor The formation of bipolar planetary nebulae
Letter to the Editor The formation of bipolar planetary nebulae

Spectral Classification of Stars
Spectral Classification of Stars

Observing Stellar Evolution
Observing Stellar Evolution

... Many stars have multiple names and appear in multiple catalogs. It is confusing. Software that maps the sky can use one or more of the designations to identify a star, but not all. Astronomy is an old science and over time many names and catalogs have been developed. Those of us who are amateur astr ...
File - Adriana Romo
File - Adriana Romo

... Interviewer: Describe the physical properties of white dwarf stars- what would one look like up close? Scientist: White dwarfs are about the size of earth or 10,000 km. In diameter, very hot and very dim. Interviewer: What is the surface temperature of a white dwarf? Scientist: Its about 20,000 deg ...
Family of stars - Inside Mines
Family of stars - Inside Mines

Satellities - stoweschools.com
Satellities - stoweschools.com

Stars
Stars

... • While stars are in the main sequence, they are fusing hydrogen in their cores. As stars evolve off the main sequence, they begin to fuse helium in their cores and burn hydrogen around the core edges. ...
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Star



A star is a luminous sphere of plasma held together by its own gravity. The nearest star to Earth is the Sun. Other stars are visible 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, and the brightest stars gained proper names. Extensive catalogues of stars have been assembled by astronomers, which provide standardized star designations.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. Once the hydrogen in the core of a star is nearly exhausted, 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, luminosity, and spectrum respectively. The total mass of a star is the principal determinant of 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, known as a Hertzsprung–Russell diagram (H–R diagram), allows the age and evolutionary state of a 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. Once 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 processes. The star's internal pressure prevents it from collapsing further under its own gravity. Once the hydrogen fuel at the core is exhausted, a star with at least 0.4 times the mass of the Sun expands to become a red giant, in some cases fusing heavier elements at the core or in shells around the core. The star then evolves into a degenerate form, recycling a portion of its matter into the interstellar environment, where it will contribute to the formation of a new generation of stars with a higher proportion of heavy elements. 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.
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