Lokal fulltext - Chalmers Publication Library
... fairly easily excited and emit radiation at radio frequencies, which can penetrate the atmosphere, and are hence observable from the Earth (see § 1.2.5 and Figure 1.5). Radio frequencies also allow for good velocity resolution, through the use of heterodyne spectrometers with resolving power, R =ν/∆ ...
... fairly easily excited and emit radiation at radio frequencies, which can penetrate the atmosphere, and are hence observable from the Earth (see § 1.2.5 and Figure 1.5). Radio frequencies also allow for good velocity resolution, through the use of heterodyne spectrometers with resolving power, R =ν/∆ ...
September 2013 - astronomy for beginners
... application and shows graphically the availability of the planets during September. Along the top of the chart is the key to the colour of each planet on the chart. The vertical bars above a planet line indicate the planet will be visible from the time inferred by that line until dawn. Bars below th ...
... application and shows graphically the availability of the planets during September. Along the top of the chart is the key to the colour of each planet on the chart. The vertical bars above a planet line indicate the planet will be visible from the time inferred by that line until dawn. Bars below th ...
2017 MIT Invitational
... observe a similar population in the field surrounding NGC lows one to clearly identify the primary cluster sequences. ...
... observe a similar population in the field surrounding NGC lows one to clearly identify the primary cluster sequences. ...
Chapter 30 Review
... 1. recording radio waves 2. observing RR Lyrae variables 3. measuring infrared radiation 4. observing hydrogen emission spectra ...
... 1. recording radio waves 2. observing RR Lyrae variables 3. measuring infrared radiation 4. observing hydrogen emission spectra ...
Quasars: Back to the Infant Universe
... Quasars appear extremely bright. Is this because they’re close to us or because they’re intrinsically luminous? What observations of quasars tell us they are small? What are Seyferts and Radio Galaxies? What is at the center of a galaxy that powers a quasar? Why are there few quasars close to us? Co ...
... Quasars appear extremely bright. Is this because they’re close to us or because they’re intrinsically luminous? What observations of quasars tell us they are small? What are Seyferts and Radio Galaxies? What is at the center of a galaxy that powers a quasar? Why are there few quasars close to us? Co ...
Hubble`s Expansion of the Universe
... Leavitt learnt that there was a relationship between their variation period and their luminosity. This is now known as the period-luminosity (P-L) relationship where the longer the period, the more luminous the star. A few years later, astronomer Harlow Shapley successfully calibrated Leavitt’s rela ...
... Leavitt learnt that there was a relationship between their variation period and their luminosity. This is now known as the period-luminosity (P-L) relationship where the longer the period, the more luminous the star. A few years later, astronomer Harlow Shapley successfully calibrated Leavitt’s rela ...
h-r_diagram_online_lab
... Step 4: Now add a series. Name it “Nearby Stars” and again make sure the cells within the “Type” column for “Table 2: Nearby Stars” are set as your X values, and cells within the “log (L/Lsun)” column for “Table 2: Nearby Stars” are set as your Y values. (Define the x values by clicking on the litt ...
... Step 4: Now add a series. Name it “Nearby Stars” and again make sure the cells within the “Type” column for “Table 2: Nearby Stars” are set as your X values, and cells within the “log (L/Lsun)” column for “Table 2: Nearby Stars” are set as your Y values. (Define the x values by clicking on the litt ...
Making Heavier Metals
... The production of elements heavier than Iron takes place by adding neutrons to the atomic nuclei. These neutral particles do not feel any electrical repulsion from the charged nuclei. They can therefore easily approach them and thereby create heavier nuclei. This is indeed the way the heaviest chemi ...
... The production of elements heavier than Iron takes place by adding neutrons to the atomic nuclei. These neutral particles do not feel any electrical repulsion from the charged nuclei. They can therefore easily approach them and thereby create heavier nuclei. This is indeed the way the heaviest chemi ...
PHYSICS – Astrophysics Section I
... Stars produce absorption spectra. The light actually produced by nuclear fusion is continuous, but the atmosphere of the star selectively absorbs wavelengths, forming an absorption spectrum. This is used to identify elements on the surface of the star. Emission nebulae produce emission spectra. The ...
... Stars produce absorption spectra. The light actually produced by nuclear fusion is continuous, but the atmosphere of the star selectively absorbs wavelengths, forming an absorption spectrum. This is used to identify elements on the surface of the star. Emission nebulae produce emission spectra. The ...
Exercises - Leiden Observatory
... i-iii. Answer question (a) iii, iv and v for the dynamical timescale. iv. In stellar evolution models one often assumes that stars evolve quasi-statically, i.e. that the star remains in hydrostatic equilibrium throughout. Why can we make this assumption? v. Rapid changes that are sometimes observed ...
... i-iii. Answer question (a) iii, iv and v for the dynamical timescale. iv. In stellar evolution models one often assumes that stars evolve quasi-statically, i.e. that the star remains in hydrostatic equilibrium throughout. Why can we make this assumption? v. Rapid changes that are sometimes observed ...
Society News - Bristol Astronomical Society
... One of the other highlights in Leo is the lovely double star gamma (γ) Leonis (Algieba), this is a great double for small telescopes. The primary is a magnitude +2.2 K-class yellow-orange giant, it’s companion is a magnitude +2.5 yellow Gclass star. The pair are separated by 4.4 arcseconds. Just to ...
... One of the other highlights in Leo is the lovely double star gamma (γ) Leonis (Algieba), this is a great double for small telescopes. The primary is a magnitude +2.2 K-class yellow-orange giant, it’s companion is a magnitude +2.5 yellow Gclass star. The pair are separated by 4.4 arcseconds. Just to ...
Section 15
... [Jeans himself derived this limiting mass by supposing that a cloud collapses if the sound-crossing time is greater than the free-fall time. Jeans’ original argument was actually flawed, but his general results still provides a useful rule of thumb indicating whether or not a given system is liable ...
... [Jeans himself derived this limiting mass by supposing that a cloud collapses if the sound-crossing time is greater than the free-fall time. Jeans’ original argument was actually flawed, but his general results still provides a useful rule of thumb indicating whether or not a given system is liable ...
Document
... forms (enriched by previous stellar generations) • Z gives a 1st approximation to the chemical composition ...
... forms (enriched by previous stellar generations) • Z gives a 1st approximation to the chemical composition ...
The HR Diagram - Faculty Web Pages
... squeeze the gas all down to a single point, and radiation pressure, which wants to blast all the gas out to infinity. These two opposite forces balance out in a process called Hydrostatic Equilibrium, and keep the gas in a stable, fairly constant-sized sphere. The radiation itself is due to the fusi ...
... squeeze the gas all down to a single point, and radiation pressure, which wants to blast all the gas out to infinity. These two opposite forces balance out in a process called Hydrostatic Equilibrium, and keep the gas in a stable, fairly constant-sized sphere. The radiation itself is due to the fusi ...
Lecture 15
... We see young star clusters with gas and dust around them. Infrared and microwave telescopes let us see inside dust clouds and see protostars. Computer models predict that if a cloud has enough mass it will contract from the pull of gravity, heat up, and form a star. The Hubble Telescope lets us watc ...
... We see young star clusters with gas and dust around them. Infrared and microwave telescopes let us see inside dust clouds and see protostars. Computer models predict that if a cloud has enough mass it will contract from the pull of gravity, heat up, and form a star. The Hubble Telescope lets us watc ...
What is a star?
... • Two or more stars may be bound together by gravity, which causes them to orbit each other. • Three or more stars that are bound by gravity are called multiple stars or multiple star systems. ...
... • Two or more stars may be bound together by gravity, which causes them to orbit each other. • Three or more stars that are bound by gravity are called multiple stars or multiple star systems. ...
THE HR DIAGRAM
... This is a plot of 22,000 stars from the Hipparcos Catalogue together with 1,000 low‐luminosity stars (red and white dwarfs) from the Gliese Catalogue of Nearby Stars. The ordinary hydrogen‐ burning dwarf stars like the Sun are found in a band running from top‐left to bottom‐right called the Main ...
... This is a plot of 22,000 stars from the Hipparcos Catalogue together with 1,000 low‐luminosity stars (red and white dwarfs) from the Gliese Catalogue of Nearby Stars. The ordinary hydrogen‐ burning dwarf stars like the Sun are found in a band running from top‐left to bottom‐right called the Main ...
sachkov_2013 - Putting A Stars into Context
... spectra and strong globally organized magnetic fields. They often show remarkable variations of line strengths, light and magnetic field with periods ranging from a few days to many years. It is believed that this abnormal chemical composition is limited only to the outer stellar envelopes. Chemical ...
... spectra and strong globally organized magnetic fields. They often show remarkable variations of line strengths, light and magnetic field with periods ranging from a few days to many years. It is believed that this abnormal chemical composition is limited only to the outer stellar envelopes. Chemical ...
The HR Diagram - Faculty Web Pages
... squeeze the gas all down to a single point, and radiation pressure, which wants to blast all the gas out to infinity. These two opposite forces balance out in a process called Hydrostatic Equilibrium, and keep the gas at a stable, fairly constant size. The radiation itself is due to the fusion of pr ...
... squeeze the gas all down to a single point, and radiation pressure, which wants to blast all the gas out to infinity. These two opposite forces balance out in a process called Hydrostatic Equilibrium, and keep the gas at a stable, fairly constant size. The radiation itself is due to the fusion of pr ...
Lect16-3-28-and-30-1..
... That is, the concentrations of C, N, and O are left unchanged by the fusion reactions, but they permit hydrogen to fuse into helium through a chain of reactions, called the CNO cycle, that makes the helium production rate far higher than would be possible through the proton-proton chain alone. p of ...
... That is, the concentrations of C, N, and O are left unchanged by the fusion reactions, but they permit hydrogen to fuse into helium through a chain of reactions, called the CNO cycle, that makes the helium production rate far higher than would be possible through the proton-proton chain alone. p of ...
Constellations, Looking Far Away, and Stars/Stellar Evolution
... Read aloud. The graph of how the temperatures and luminosities of stars are related is known as the Hertzsprung-Russell or H-R diagram. From this graph, we can also get an estimate of the size of a star, its radius. Astronomers worked with this graph long before they knew why stars varied in this wa ...
... Read aloud. The graph of how the temperatures and luminosities of stars are related is known as the Hertzsprung-Russell or H-R diagram. From this graph, we can also get an estimate of the size of a star, its radius. Astronomers worked with this graph long before they knew why stars varied in this wa ...
What is a Hertzsprung
... • Cepheid variable’s magnitude will vary between 0.5-2 magnitudes over a period from days to months. • They have been show to have a period of variability that depends on luminosity. • This allows Cepheid variables to be used as a standard candle to measure distance. ...
... • Cepheid variable’s magnitude will vary between 0.5-2 magnitudes over a period from days to months. • They have been show to have a period of variability that depends on luminosity. • This allows Cepheid variables to be used as a standard candle to measure distance. ...
proper motion
... will last only 30 million years. A star with 0.25 solar masses can last 320 billion years. ...
... will last only 30 million years. A star with 0.25 solar masses can last 320 billion years. ...
H II region
An H II region is a large, low-density cloud of partially ionized gas in which star formation has recently taken place. The short-lived blue stars forged in these regions emit copious amounts of ultraviolet light that ionize the surrounding gas. H II regions—sometimes several hundred light-years across—are often associated with giant molecular clouds. The first known H II region was the Orion Nebula, which was discovered in 1610 by Nicolas-Claude Fabri de Peiresc.H II regions are named for the large amount of ionised atomic hydrogen they contain, referred to as H II, pronounced H-two by astronomers (an H I region being neutral atomic hydrogen, and H2 being molecular hydrogen). Such regions have extremely diverse shapes, because the distribution of the stars and gas inside them is irregular. They often appear clumpy and filamentary, sometimes showing bizarre shapes such as the Horsehead Nebula. H II regions may give birth to thousands of stars over a period of several million years. In the end, supernova explosions and strong stellar winds from the most massive stars in the resulting star cluster will disperse the gases of the H II region, leaving behind a cluster of birthed stars such as the Pleiades.H II regions can be seen to considerable distances in the universe, and the study of extragalactic H II regions is important in determining the distance and chemical composition of other galaxies. Spiral and irregular galaxies contain many H II regions, while elliptical galaxies are almost devoid of them. In the spiral galaxies, including the Milky Way, H II regions are concentrated in the spiral arms, while in the irregular galaxies they are distributed chaotically. Some galaxies contain huge H II regions, which may contain tens of thousands of stars. Examples include the 30 Doradus region in the Large Magellanic Cloud and NGC 604 in the Triangulum Galaxy.