v1 - ESO
... evolution of the galaxy distribution. The directly observable components of any galaxy are gas, dust and stars, and there is an intimate link between them. Stars form from gas, and synthesise elements in their interiors and the stars that explode at death disperse these elements into the gas from wh ...
... evolution of the galaxy distribution. The directly observable components of any galaxy are gas, dust and stars, and there is an intimate link between them. Stars form from gas, and synthesise elements in their interiors and the stars that explode at death disperse these elements into the gas from wh ...
- newmanlib.ibri.org
... 1. The universe is big. The distances to stars are measured in light years (6 trillion miles each) or parsecs (3.26 ly). The distances to globular clusters in thousands of light years (or kiloparsecs), to galaxies in millions of light years (or megaparsecs), the distances to the most distant observa ...
... 1. The universe is big. The distances to stars are measured in light years (6 trillion miles each) or parsecs (3.26 ly). The distances to globular clusters in thousands of light years (or kiloparsecs), to galaxies in millions of light years (or megaparsecs), the distances to the most distant observa ...
2P10.pdf
... The scientific goals of the Gaia mission require complementary astrometry, photometry and radial velocity data. After five years scanning the entire sky, Gaia will have performed measurements with broad (BBP), and medium (MBP) bands, and white light (G magnitude). The main goal of the photometry is ...
... The scientific goals of the Gaia mission require complementary astrometry, photometry and radial velocity data. After five years scanning the entire sky, Gaia will have performed measurements with broad (BBP), and medium (MBP) bands, and white light (G magnitude). The main goal of the photometry is ...
Dark Matter Spiral Structure Basic Galaxy Morphology Disk Galaxy Rotation Curves:
... • Self-gravity of the compressed clump will tend to compress it further. • Extra pressure will resist compression. If the disk is massive (strong self-gravity) and cold (less pressure support) first effect wins and develop spiral wave pattern. ...
... • Self-gravity of the compressed clump will tend to compress it further. • Extra pressure will resist compression. If the disk is massive (strong self-gravity) and cold (less pressure support) first effect wins and develop spiral wave pattern. ...
Astro-MilkyWay
... 2. What did the Herschels find when they counted stars in 683 regions around the Milky Way? a. The Doppler shifts in stellar spectra are about half red shifted and half blue shifted. b. Many more stars are in the direction of the constellation Sagittarius than in any other direction in the Milky Way ...
... 2. What did the Herschels find when they counted stars in 683 regions around the Milky Way? a. The Doppler shifts in stellar spectra are about half red shifted and half blue shifted. b. Many more stars are in the direction of the constellation Sagittarius than in any other direction in the Milky Way ...
Chapter 15
... 2. What did the Herschels find when they counted stars in 683 regions around the Milky Way? a. The Doppler shifts in stellar spectra are about half red shifted and half blue shifted. b. Many more stars are in the direction of the constellation Sagittarius than in any other direction in the Milky Way ...
... 2. What did the Herschels find when they counted stars in 683 regions around the Milky Way? a. The Doppler shifts in stellar spectra are about half red shifted and half blue shifted. b. Many more stars are in the direction of the constellation Sagittarius than in any other direction in the Milky Way ...
Chemical Signatures in Dwarf Galaxies
... How these different types of galaxies are related to one another raises an interesting series of questions. Are dwarf gal axies related to protogalactic fragments, the low mass systems that formed in a L Cold Dark Matter (LCDM) Universe that later merged to build up the large spirals that we see to ...
... How these different types of galaxies are related to one another raises an interesting series of questions. Are dwarf gal axies related to protogalactic fragments, the low mass systems that formed in a L Cold Dark Matter (LCDM) Universe that later merged to build up the large spirals that we see to ...
Cataclysmic Cosmic Events and How to Observe Them www.springer.com/series/5338
... their violence and energy output. Active galaxies, containing supermassive black holes at their centers, can swallow a solar mass every month, releasing huge amounts of energy that amateur astronomers can observe as a fluctuation in light output. The luminosity of some of these objects is truly mind ...
... their violence and energy output. Active galaxies, containing supermassive black holes at their centers, can swallow a solar mass every month, releasing huge amounts of energy that amateur astronomers can observe as a fluctuation in light output. The luminosity of some of these objects is truly mind ...
CHAPTER 1 The Formation and Structure of Stars
... • Nuclear fusion at the centers of stars heats their interiors, creates high gas pressures, and thus balances the inward forces of gravity. – If an increase or decrease in temperature produces a corresponding change in pressure, then the thermostat is functioning correctly— and the star is stable. ...
... • Nuclear fusion at the centers of stars heats their interiors, creates high gas pressures, and thus balances the inward forces of gravity. – If an increase or decrease in temperature produces a corresponding change in pressure, then the thermostat is functioning correctly— and the star is stable. ...
Astronomy Astrophysics
... 2003), which confirmed that the amplitudes indeed are as low as predicted. Even if the broadening were caused by rotation it would be difficult to understand how white dwarfs could spinup when entering the instability strip during their evolution – and spin-down again after leaving it. ...
... 2003), which confirmed that the amplitudes indeed are as low as predicted. Even if the broadening were caused by rotation it would be difficult to understand how white dwarfs could spinup when entering the instability strip during their evolution – and spin-down again after leaving it. ...
Fossil Galaxies
... and stars. In ultra-faint dwarf galaxies, dark matter outweighs ordinary matter by at least a factor of 100. Because their gas was expelled and their star formation quenched, the small galaxies in Brown’s study are made up of mostly dark matter. Thus, these dark-matter islands where dwarf galaxies f ...
... and stars. In ultra-faint dwarf galaxies, dark matter outweighs ordinary matter by at least a factor of 100. Because their gas was expelled and their star formation quenched, the small galaxies in Brown’s study are made up of mostly dark matter. Thus, these dark-matter islands where dwarf galaxies f ...
PPT - Chandra X-Ray Observatory
... white dwarfs • Hydrogen in hot DAs almost completely ionized, EUV/soft X-ray opacity strongly reduced → DAs with Teff >30,000 K can emit thermal soft X-rays from deep hot layers • However, ROSAT All-Sky Survey revealed that X-ray emission is the exception rather than the rule → additional absorbers ...
... white dwarfs • Hydrogen in hot DAs almost completely ionized, EUV/soft X-ray opacity strongly reduced → DAs with Teff >30,000 K can emit thermal soft X-rays from deep hot layers • However, ROSAT All-Sky Survey revealed that X-ray emission is the exception rather than the rule → additional absorbers ...
A rocky planet transiting a nearby low-mass star
... stable against thermal escape. This is not the case for the other rocky exoplanets for which precise densities are known, all of which are considerably hotter. The rocky planet Kepler-78b (refs 8, 9), which is comparable in size and density to GJ 1132b, receives 200 times more irradiation than GJ 11 ...
... stable against thermal escape. This is not the case for the other rocky exoplanets for which precise densities are known, all of which are considerably hotter. The rocky planet Kepler-78b (refs 8, 9), which is comparable in size and density to GJ 1132b, receives 200 times more irradiation than GJ 11 ...
55 Ignacio Negueruela and Amparo Marco
... The number of stars that we could detect in all filters is limited by the long exposure time in the U filter. We identify all stars with good photometry in all three filters on the image in Figures 1 and 2. In Table 2, we list their X and Y positions as seen in Figure 1, and their identification wit ...
... The number of stars that we could detect in all filters is limited by the long exposure time in the U filter. We identify all stars with good photometry in all three filters on the image in Figures 1 and 2. In Table 2, we list their X and Y positions as seen in Figure 1, and their identification wit ...
ph507lecnote06
... incident flux per unit area, from all directions. Of course a star is a point light source, and the incident light is only from one direction. Apparent magnitude per square degree is a radiance, luminance, intensity, or "specific intensity". This is sometimes also called "surface brightness". Still ...
... incident flux per unit area, from all directions. Of course a star is a point light source, and the incident light is only from one direction. Apparent magnitude per square degree is a radiance, luminance, intensity, or "specific intensity". This is sometimes also called "surface brightness". Still ...
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.