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1. What is parallax? What unit is it measured in? 1a. Parallax is the
1. What is parallax? What unit is it measured in? 1a. Parallax is the

1 The Milky Way
1 The Milky Way

... objects. The dust clouds can be clearly seen in Fig. 1. The dust clouds make it hard to see through the disc, so that we can’t see the centre of the Galaxy, but we can see easily see out of the disc vertically up and down, as illustrated in Fig. 3. This is a good thing, otherwise we would never have ...
BML_V
BML_V

... magnetic fields, quite apart from the injection of energy from supernova outbursts, bursts of star formation, as well as from sundry other denizens of the Galactic zoo (O-B stars, µquasars, the central black hole, Galactic γ & X-ray sources, etc). Our Galaxy is much the best laboratory for these exp ...
Document
Document

... them → know their distance (with ~6% uncertainty) • Bright (V ~ 21 at 110 kpc) • Variable stars (P ~ 0.6 day) with distinct light curves ( ~1 mag amplitude) → easily identifiable ...
PowerPoint
PowerPoint

... • In-Class Q and A: On Wed., Nov. 5th, some time will be allotted in class to ask questions about material on the exam. For example, if there are homework answers you do not understand, this would be an excellent time to ask. To get the most out of this time, you are strongly encouraged to begin stu ...
The Hα Balmer line as an effective temperature criterion
The Hα Balmer line as an effective temperature criterion

Spica The Star - Emmi
Spica The Star - Emmi

... the mass of the Earth or 1,048 times the mass of Juipiter  Spicas temperature is about 457. 490541 degrees fahrenhieght and the sun is 5778 kelvin red giant.  Spicas distance from the sun is 260 light years away  Spica is a blue giant the sun is yellow ...
Chapter 18 - Astro1010
Chapter 18 - Astro1010

... The pressure within the helium core is almost totally due to “electron degeneracy” – two electrons cannot be in the same quantum state, so the core cannot contract beyond a certain point. This pressure is almost independent of temperature so when the helium starts fusing, the pressure cannot adjust ...
Stellar Properties
Stellar Properties

... magnitudes are plotted against surface temperatures).  The H-R diagram reveals the existence of four major groupings of stars: main-sequence stars, giants, supergiants, and white dwarfs.  The mass-luminosity relation expresses a direct correlation between a main-sequence star’s mass and the total ...
2.3 Peculiar galaxies
2.3 Peculiar galaxies

Condensates in Neutron Star Interiors
Condensates in Neutron Star Interiors

... The basic concern for calculating the limiting mass of a neutron star is same as that for any astrophysical system: hydrostatic equilibrium, which in this case means balance of gravitational pressure (trying to collapse the system) and the neutron degeneracy pressure (trying to keep it from collapsi ...
PSU/TCfA search for planets around evolved stars
PSU/TCfA search for planets around evolved stars

Stellar Winds and Hydrodynamic Atmospheres of Stars
Stellar Winds and Hydrodynamic Atmospheres of Stars

Abundances of RGB stars in NGC 6752 Grundahl
Abundances of RGB stars in NGC 6752 Grundahl

7 Structure of Distorted Stars
7 Structure of Distorted Stars

... quantity, the radiative flux, and an additional term that anticipates some results from later in the chapter. The quantity S is the entropy of the gas, and in Chapter 4 [see equation (4.6.9)] we saw that this term had to be included when the models were changing rapidly in time. In this case, the te ...
Ivelina Sotirova Major: Biochemistry Senior at CUNY Hunter College
Ivelina Sotirova Major: Biochemistry Senior at CUNY Hunter College

... A supernova is the violent death of a star thousands of times the size of our Sun. As its fuel gets depleted, the star swells up and grows fainter until it becomes a slow-burning red giant. When all the hydrogen and helium are used up, gravity disintegrates the star’s outer layers, leaving behind on ...
The Sun and Energy
The Sun and Energy

pierrehumbert_lecture_1
pierrehumbert_lecture_1

... the atmosphere, and heat it to the point where the atmosphere can escape to space. • i.e. it’s the rocket fuel that brings molecules up to escape velocity and can launch atmosphere out of the gravity well. • Shorter wave ultraviolet drives photochemistry, and can break up heavy molecules into lighte ...
Living with a Red Dwarf - Center for Space and Habitability (CSH)
Living with a Red Dwarf - Center for Space and Habitability (CSH)

Labeling the HR Diagram - Mastering Physics Answers
Labeling the HR Diagram - Mastering Physics Answers

... Hint 2. Is the inverse square law for the apparent brightness of light always valid? Consider two stars that are identical to the Sun, but one is 10 times as far away as the other. According to the inverse square law for light, the more distant star should appear dimmer by a factor of 10 2 = 100. Bu ...
Formation of a Black Hole in the Dark - CEA-Irfu
Formation of a Black Hole in the Dark - CEA-Irfu

Density, Mass and Surface Area
Density, Mass and Surface Area

... Density, Mass and Surface Area The relationship between diameter and mass yields a third important parameter: density. The old ‘trick question” goes: which weighs more, a pound of feathers or a pound of bricks? The clever student will respond: neither, they both weigh a pound, that is, they have th ...
A search for a new class of pulsating DA white dwarf stars in the DB
A search for a new class of pulsating DA white dwarf stars in the DB

Constellations and Light Pollution
Constellations and Light Pollution

The Milky Way
The Milky Way

... that has been ionized by young, massive, hot stars. Their light is highly red-shifted because especially the star-forming regions are moving away from us at high speed. This is the red color of interstellar dust that is present in the molecular clouds out of which stars are formed. Star forming regi ...
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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.
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