The Pulsation Properties of Procyon A
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2. Astrophysical Constants and Parameters
2. Astrophysical constants 1 2. ASTROPHYSICAL CONSTANTS AND PARAMETERS Table 2.1. Revised May 2010 by E. Bergren and D.E. Groom (LBNL). The figures in parentheses after some values give the one standard deviation uncertainties in the last digit(s). Physical constants are from Ref. 1. While every effort has been made to obtain the most accurate current values of the listed quantities, the table does not represent a critical review or adjustment of the constants, and is not intended as a primary reference. The values and uncertainties for the cosmological parameters depend on the exact data sets, priors, and basis parameters used in the fit. Many of the parameters reported in this table are derived parameters or have non-Gaussian likelihoods. The quoted errors may be highly correlated with those of other parameters, so care must be taken in propagating them. Unless otherwise specified, cosmological parameters are best fits of a spatially-flat ΛCDM cosmology with a power-law initial spectrum to 5-year WMAP data alone [2]. For more information see Ref. 3 and the original papers. Quantity Symbol, equation Value Reference, footnote speed of light c 299 792 458 m s−1 exact[4] −11 3 −1 −2 Newtonian gravitational constant GN 6.674 3(7) × 10 m kg s [1] 19 2 Planck mass c/GN 1.220 89(6) × 10 GeV/c [1] −8 =2.176 44(11) × 10 kg 3 −35 Planck length GN /c 1.616 25(8) × 10 m[1] −2 2 standard gravitational acceleration gN 9.806 65 m s ≈ π exact[1] jansky (flux density) Jy 10−26 Wm−2 Hz−1 definition tropical year (equinox to equinox) (2011) yr 31 556 925.2s≈ π × 107 s[5] sidereal year (fixed star to fixed star) (2011) 31 558 149.8s≈ π × 107 s[5] mean sidereal day (2011) (time between vernal equinox transits) 23h 56m 04.s090 53 [5] astronomical unit au, A 149 597 870 700(3) m [6] parsec (1 au/1 arc sec) pc 3.085 677 6 × 1016 m = 3.262 ...ly [7] light year (deprecated unit) ly 0.306 6 .. -
Lecture 3 - Minimum Mass Model of Solar Nebula
Lecture 3 - Minimum mass model of solar nebula o Topics to be covered: o Composition and condensation o Surface density profile o Minimum mass of solar nebula PY4A01 Solar System Science Minimum Mass Solar Nebula (MMSN) o MMSN is not a nebula, but a protoplanetary disc. Protoplanetary disk Nebula o Gives minimum mass of solid material to build the 8 planets. PY4A01 Solar System Science Minimum mass of the solar nebula o Can make approximation of minimum amount of solar nebula material that must have been present to form planets. Know: 1. Current masses, composition, location and radii of the planets. 2. Cosmic elemental abundances. 3. Condensation temperatures of material. o Given % of material that condenses, can calculate minimum mass of original nebula from which the planets formed. • Figure from Page 115 of “Physics & Chemistry of the Solar System” by Lewis o Steps 1-8: metals & rock, steps 9-13: ices PY4A01 Solar System Science Nebula composition o Assume solar/cosmic abundances: Representative Main nebular Fraction of elements Low-T material nebular mass H, He Gas 98.4 % H2, He C, N, O Volatiles (ices) 1.2 % H2O, CH4, NH3 Si, Mg, Fe Refractories 0.3 % (metals, silicates) PY4A01 Solar System Science Minimum mass for terrestrial planets o Mercury:~5.43 g cm-3 => complete condensation of Fe (~0.285% Mnebula). 0.285% Mnebula = 100 % Mmercury => Mnebula = (100/ 0.285) Mmercury = 350 Mmercury o Venus: ~5.24 g cm-3 => condensation from Fe and silicates (~0.37% Mnebula). =>(100% / 0.37% ) Mvenus = 270 Mvenus o Earth/Mars: 0.43% of material condensed at cooler temperatures. -
Hertzsprung-Russell Diagram
Hertzsprung-Russell Diagram Astronomers have made surveys of the temperatures and luminosities of stars and plot the result on H-R (or Temperature-Luminosity) diagrams. Many stars fall on a diagonal line running from the upper left (hot and luminous) to the lower right (cool and faint). The Sun is one of these stars. But some fall in the upper right (cool and luminous) and some fall toward the bottom of the diagram (faint). What can we say about the stars in the upper right? What can we say about the stars toward the bottom? If all stars had the same size, what pattern would they make on the diagram? Masses of Stars The gravitational force of the Sun keeps the planets in orbit around it. The force of the Sun’s gravity is proportional to the mass of the Sun, and so the speeds of the planets as they orbit the Sun depend on the mass of the Sun. Newton’s generalization of Kepler’s 3rd law says: P2 = a3 / M where P is the time to orbit, measured in years, a is the size of the orbit, measured in AU, and M is the sum of the two masses, measured in solar masses. Masses of stars It is difficult to see planets orbiting other stars, but we can see stars orbiting other stars. By measuring the periods and sizes of the orbits we can calculate the masses of the stars. If P2 = a3 / M, M = a3 / P2 This mass in the formula is actually the sum of the masses of the two stars. -
Educator's Guide: Orion
Legends of the Night Sky Orion Educator’s Guide Grades K - 8 Written By: Dr. Phil Wymer, Ph.D. & Art Klinger Legends of the Night Sky: Orion Educator’s Guide Table of Contents Introduction………………………………………………………………....3 Constellations; General Overview……………………………………..4 Orion…………………………………………………………………………..22 Scorpius……………………………………………………………………….36 Canis Major…………………………………………………………………..45 Canis Minor…………………………………………………………………..52 Lesson Plans………………………………………………………………….56 Coloring Book…………………………………………………………………….….57 Hand Angles……………………………………………………………………….…64 Constellation Research..…………………………………………………….……71 When and Where to View Orion…………………………………….……..…77 Angles For Locating Orion..…………………………………………...……….78 Overhead Projector Punch Out of Orion……………………………………82 Where on Earth is: Thrace, Lemnos, and Crete?.............................83 Appendix………………………………………………………………………86 Copyright©2003, Audio Visual Imagineering, Inc. 2 Legends of the Night Sky: Orion Educator’s Guide Introduction It is our belief that “Legends of the Night sky: Orion” is the best multi-grade (K – 8), multi-disciplinary education package on the market today. It consists of a humorous 24-minute show and educator’s package. The Orion Educator’s Guide is designed for Planetarians, Teachers, and parents. The information is researched, organized, and laid out so that the educator need not spend hours coming up with lesson plans or labs. This has already been accomplished by certified educators. The guide is written to alleviate the fear of space and the night sky (that many elementary and middle school teachers have) when it comes to that section of the science lesson plan. It is an excellent tool that allows the parents to be a part of the learning experience. The guide is devised in such a way that there are plenty of visuals to assist the educator and student in finding the Winter constellations. -
1. (A) Give the Equation Which Represents Stefan's Law for a Black
PhysicsAndMathsTutor.com 1 1. (a) Give the equation which represents Stefan’s law for a black body source of radiation, defining the symbols used. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (3) (b) (i) The space probe Voyager I is travelling out of the solar system and is, at present, approximately 8000 × 106 km from the Sun. The power source on board is a nuclear generator providing 400 W. If this power had to be obtained from solar panels, calculate the area of the solar panels which would be necessary. power received on Earth from the Sun = 1400 Wm–2 distance of the Earth from the Sun = 150 × 106 km ........................................................................................................................... ........................................................................................................................... .......................................................................................................................... -
February 2018 BRAS Newsletter
Novemb Monthly Meeting Monday, February 12th at 7PM at HRPO er 2017 Issue nd (Monthly meetings are on 2 Mondays, Highland Road Park Observatory) . Program: Star Clusters, a presentation by Rory Bentley. What's In This Issue? President’s Message Secretary's Summary Outreach Report Light Pollution Committee Report Recent Forum Entries 20/20 Vision Campaign Messages from the HRPO Friday Night Lecture Series Globe at Night Adult Astronomy Courses International Astronomy Day Observing Notes – Canis Minor, The Little Dog & Mythology Like this newsletter? See past issues back to 2009 at http://brastro.org/newsletters.html Newsletter of the Baton Rouge Astronomical Society February 2018 © 2018 President’s Message We are now entering the month of February 2018. This month will be unusual for the fact there will be no full moon. This lack of a full moon can happen because the Moon's synodic orbit around Earth takes longer than the 28 days in February. I would remind you that our monthly meeting is on 12th of February at 7 pm. There will be a talk on star clusters given by Rory Bentley. I would also like to remind you of our Business Meeting which will be 7 pm on 7th of February at HRPO. We are investigating ideas which include: an asteroid observing group 2018 Officers: an astrophotography study group President: Steven M. Tilley a BRAS Youtube channel Vice-President: Scott Louque adding additional stargazes for BRAS members Secretary: Krista Reed ways to better utilize BRAS equipment Treasurer: Trey Anding adding another dark sky site BRAS Liaison for BREC: We may not do everything listed if there is not sufficient interest Chris Kersey from members, so if you are willing to help let us know. -
Three Editions of the Star Catalogue of Tycho Brahe*
A&A 516, A28 (2010) Astronomy DOI: 10.1051/0004-6361/201014002 & c ESO 2010 Astrophysics Three editions of the star catalogue of Tycho Brahe Machine-readable versions and comparison with the modern Hipparcos Catalogue F. Verbunt1 andR.H.vanGent2,3 1 Astronomical Institute, Utrecht University, PO Box 80 000, 3508 TA Utrecht, The Netherlands e-mail: [email protected] 2 URU-Explokart, Faculty of Geosciences, Utrecht University, PO Box 80 115, 3508 TC Utrecht, The Netherlands 3 Institute for the History and Foundations of Science, PO Box 80 000, 3508 TA Utrecht, The Netherlands Received 6 January 2010 / Accepted 3 February 2010 ABSTRACT Tycho Brahe completed his catalogue with the positions and magnitudes of 1004 fixed stars in 1598. This catalogue circulated in manuscript form. Brahe edited a shorter version with 777 stars, printed in 1602, and Kepler edited the full catalogue of 1004 stars, printed in 1627. We provide machine-readable versions of the three versions of the catalogue, describe the differences between them and briefly discuss their accuracy on the basis of comparison with modern data from the Hipparcos Catalogue. We also compare our results with earlier analyses by Dreyer (1916, Tychonis Brahe Dani Scripta Astronomica, Vol. II) and Rawlins (1993, DIO, 3, 1), finding good overall agreement. The magnitudes given by Brahe correlate well with modern values, his longitudes and latitudes have error distributions with widths of 2, with excess numbers of stars with larger errors (as compared to Gaussian distributions), in particular for the faintest stars. Errors in positions larger than 10, which comprise about 15% of the entries, are likely due to computing or copying errors. -
ASTRONOMY 220C ADVANCED STAGES of STELLAR EVOLUTION and NUCLEOSYNTHESIS Spring, 2015
ASTRONOMY 220C ADVANCED STAGES OF STELLAR EVOLUTION AND NUCLEOSYNTHESIS Spring, 2015 http://www.ucolick.org/~woosley This is a one quarter course dealing chiefly with: a) Nuclear astrophysics and the relevant nuclear physics b) The evolution of massive stars - especially their advanced stages c) Nucleosynthesis – the origin of each isotope in nature d) Supernovae of all types e) First stars, ultraluminous supernovae, subluminous supernovae f) Stellar mass high energy transients - gamma-ray bursts, novae, and x-ray bursts. Our study of supernovae will be extensive and will cover not only the mechanisms currently thought responsible for their explosion, but also their nucleosynthesis, mixing, spectra, compact remnants and light curves, the latter having implications for cosmology. The student is expected to be familiar with the material presented in Ay 220A, a required course in the UCSC graduate program, and thus to already know the essentials of stellar evolution, as well as basic quantum mechanics and statistical mechanics. The course material is extracted from a variety of sources, much of it the results of local research. It is not contained, in total, in any one or several books. The powerpoint slides are on the web, but you will need to come to class. A useful textbook, especially for material early in the course, is Clayton’s, Principles of Stellar Evolution and Nucleosynthesis. Also of some use are Arnett’s Supernovae and Nucleosynthesis (Princeton) and Kippenhahn and Weigert’s Stellar Evolution and Nucleosynthesis (Springer Verlag). Course performance will be based upon four graded homework sets and an in-class final examination. The anticipated class material is given, in outline form, in the following few slides, but you can expect some alterations as we go along. -
How Stars Work: • Basic Principles of Stellar Structure • Energy Production • the H-R Diagram
Ay 122 - Fall 2004 - Lecture 7 How Stars Work: • Basic Principles of Stellar Structure • Energy Production • The H-R Diagram (Many slides today c/o P. Armitage) The Basic Principles: • Hydrostatic equilibrium: thermal pressure vs. gravity – Basics of stellar structure • Energy conservation: dEprod / dt = L – Possible energy sources and characteristic timescales – Thermonuclear reactions • Energy transfer: from core to surface – Radiative or convective – The role of opacity The H-R Diagram: a basic framework for stellar physics and evolution – The Main Sequence and other branches – Scaling laws for stars Hydrostatic Equilibrium: Stars as Self-Regulating Systems • Energy is generated in the star's hot core, then carried outward to the cooler surface. • Inside a star, the inward force of gravity is balanced by the outward force of pressure. • The star is stabilized (i.e., nuclear reactions are kept under control) by a pressure-temperature thermostat. Self-Regulation in Stars Suppose the fusion rate increases slightly. Then, • Temperature increases. (2) Pressure increases. (3) Core expands. (4) Density and temperature decrease. (5) Fusion rate decreases. So there's a feedback mechanism which prevents the fusion rate from skyrocketing upward. We can reverse this argument as well … Now suppose that there was no source of energy in stars (e.g., no nuclear reactions) Core Collapse in a Self-Gravitating System • Suppose that there was no energy generation in the core. The pressure would still be high, so the core would be hotter than the envelope. • Energy would escape (via radiation, convection…) and so the core would shrink a bit under the gravity • That would make it even hotter, and then even more energy would escape; and so on, in a feedback loop Ë Core collapse! Unless an energy source is present to compensate for the escaping energy. -
Neutron Star
Phys 321: Lecture 8 Stellar Remnants Prof. Bin Chen, Tiernan Hall 101, [email protected] Evolution of a low-mass star Planetary Nebula Main SequenceEvolution and Post-Main-Sequence track of an 1 Stellar solar Evolution-mass star Post-AGB PN formation Superwind First He shell flash White dwarf TP-AGB Second dredge-up He core flash ) Pre-white dwarf L / L E-AGB ( 10 He core exhausted Log RGB Ring Nebula (M57) He core burning First Red: Nitrogen, Green: Oxygen, Blue: Helium dredge-up H shell burning SGB Core contraction H core exhausted ZAMS To white dwarf phase 1 M Log (T ) 10 e Sirius B FIGURE 4 A schematic diagram of the evolution of a low-mass star of 1 M from the zero-age main sequence to the formation of a white dwarf star. The dotted ph⊙ase of evolution represents rapid evolution following the helium core flash. The various phases of evolution are labeled as follows: Zero-Age-Main-Sequence (ZAMS), Sub-Giant Branch (SGB), Red Giant Branch (RGB), Early Asymptotic Giant Branch (E-AGB), Thermal Pulse Asymptotic Giant Branch (TP-AGB), Post- Asymptotic Giant Branch (Post-AGB), Planetary Nebula formation (PN formation), and Pre-white dwarf phase leading to white dwarf phase. and becomes nearly isothermal. At points 4 in Fig. 1, the Schönberg–Chandrasekhar limit is reached and the core begins to contract rapidly, causing the evolution to proceed on the much faster Kelvin–Helmholtz timescale. The gravitational energy released by the rapidly contracting core again causes the envelope of the star to expand and the effec- tive temperature cools, resulting in redward evolution on the H–R diagram. -
GLAST Science Glossary (PDF)
GLAST SCIENCE GLOSSARY Source: http://glast.sonoma.edu/science/gru/glossary.html Accretion — The process whereby a compact object such as a black hole or neutron star captures matter from a normal star or diffuse cloud. Active galactic nuclei (AGN) — The central region of some galaxies that appears as an extremely luminous point-like source of radiation. They are powered by supermassive black holes accreting nearby matter. Annihilation — The process whereby a particle and its antimatter counterpart interact, converting their mass into energy according to Einstein’s famous formula E = mc2. For example, the annihilation of an electron and positron results in the emission of two gamma-ray photons, each with an energy of 511 keV. Anticoincidence Detector — A system on a gamma-ray observatory that triggers when it detects an incoming charged particle (cosmic ray) so that the telescope will not mistake it for a gamma ray. Antimatter — A form of matter identical to atomic matter, but with the opposite electric charge. Arcminute — One-sixtieth of a degree on the sky. Like latitude and longitude on Earth's surface, we measure positions on the sky in angles. A semicircle that extends up across the sky from the eastern horizon to the western horizon is 180 degrees. One degree, therefore, is not a very big angle. An arcminute is an even smaller angle, 1/60 as large as a degree. The Moon and Sun are each about half a degree across, or about 30 arcminutes. If you take a sharp pencil and hold it at arm's length, then the point of that pencil as seen from your eye is about 3 arcminutes across. -
Stars: Interdisciplinary Exploration Unit 3
ANCHORAGE MUSEUM STARS: INTERDISCIPLINARY EXPLORATION UNIT 3. STARS BACKGROUND INFORMATION KEY TERMS The sun is arguably the most important ingredient for life on Earth. Our sun Star: a hot, dense ball of gaseous material that emits light created by nuclear is one of billions upon billions of stars in the universe. Studying these objects fusion reactions can reveal how our universe, stars, and even planets and life on Earth, have evolved over billions of years. In this unit, you will learn about what stars are Nuclear fusion: the process by which multiple nuclei join together to form a made out of and how they are important factories for seeding the universe with heavier nucleus; this process takes place at the center of all stars and releases most elements found on the periodic table. energy in the form of heat and light STUDENTS WILL: Nebula: a giant cloud of gas and dust out in space; often, nebula are both the birthplaces for stars and the remains left after a star dies • Investigate the composition and anatomy of stars • Learn about the life cycle of stars and stellar evolution Protostar: a dense, hot core of gas and dust, not yet hot enough to start • Explore the night sky and discover examples of different types of stars nuclear fusion; this object is almost a star but has not started nuclear fusion MATERIALS ACTIVITIES • Computer or tablet with internet connection This lesson provides four activity sets and explains each of them in detail • Stars Challenge Activity Sheet on the following pages. Activities should be completed in order.