Part 1. Frequency Upshifting of Light Rays/Electromagnetic Radiation Near Stars in Dynamic Universe Model
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Luminosity - Wikipedia
12/2/2018 Luminosity - Wikipedia Luminosity In astronomy, luminosity is the total amount of energy emitted by a star, galaxy, or other astronomical object per unit time.[1] It is related to the brightness, which is the luminosity of an object in a given spectral region.[1] In SI units luminosity is measured in joules per second or watts. Values for luminosity are often given in the terms of the luminosity of the Sun, L⊙. Luminosity can also be given in terms of magnitude: the absolute bolometric magnitude (Mbol) of an object is a logarithmic measure of its total energy emission rate. Contents Measuring luminosity Stellar luminosity Image of galaxy NGC 4945 showing Radio luminosity the huge luminosity of the central few star clusters, suggesting there is an Magnitude AGN located in the center of the Luminosity formulae galaxy. Magnitude formulae See also References Further reading External links Measuring luminosity In astronomy, luminosity is the amount of electromagnetic energy a body radiates per unit of time.[2] When not qualified, the term "luminosity" means bolometric luminosity, which is measured either in the SI units, watts, or in terms of solar luminosities (L☉). A bolometer is the instrument used to measure radiant energy over a wide band by absorption and measurement of heating. A star also radiates neutrinos, which carry off some energy (about 2% in the case of our Sun), contributing to the star's total luminosity.[3] The IAU has defined a nominal solar luminosity of 3.828 × 102 6 W to promote publication of consistent and comparable values in units of https://en.wikipedia.org/wiki/Luminosity 1/9 12/2/2018 Luminosity - Wikipedia the solar luminosity.[4] While bolometers do exist, they cannot be used to measure even the apparent brightness of a star because they are insufficiently sensitive across the electromagnetic spectrum and because most wavelengths do not reach the surface of the Earth. -
Ground-Based High Sensitivity Radio Astronomy at Decameter Wavelengths
"Planetary Radio Emissions IV" (Graz, 9/1996), H.O. Rucker et al. Eds., Austrian Acad. Sci. press, Vienna, p. 101-127, 1997 GROUND-BASED HIGH SENSITIVITY RADIO ASTRONOMY AT DECAMETER WAVELENGTHS Philippe Zarka1, Julien Queinnec1, Boris P. Ryabov2, Vladimir B. Ryabov2, Vyacheslav A. Shevchenko2, Alexei V. Arkhipov2, Helmut O. Rucker3 Laurent Denis4, Alain Gerbault4, Patrick Dierich5 and Carlo Rosolen5 1DESPA, CNRS/Observatoire de Paris, F-92195 Meudon, France 2Institute of RadioAstronomy, Krasnoznamennaya 4, Kharkov 310002, Ukraine 3Space Research Institute, Halbaerthgasse 1, Graz A-8010, Austria 4Station de RadioAstronomie de Nancay, USR B704, Observatoire de Paris, 18 Nançay, France 5ARPEGES, CNRS/Observatoire de Paris, F-92195 Meudon, France Abstract The decameter wave radio spectrum (~10-50 MHz) suffers a very high pollution by man- made interference. However, it is a range well-suited to the search for exoplanets and the study of planetary (especially Saturnian) lightning, provided that very high sensitivity (~1 Jansky) is available at high time resolution (0.1-1 second). Such conditions require a very large decameter radiotelescope and a broad, clean frequency band of observation. The latter can be achieved only through the use of a broadband multichannel-type receiving system, efficient data processing techniques for eliminating interference, and selection and integration of non-polluted frequency channels. This processing is then followed by an algorithm performing bursts detection and measuring their significance. These requirements have been met with the installation of an Acousto-Optical Spectrograph at the giant Ukrainian radiotelescope UTR-2, and four observations campaigns of Jupiter, Saturn, and the environment of nearby stars (including 51 Peg and 47 UMa) have been performed in 1995-96. -
Infrared Flux Excesses from Hot Subdwarfs
ASTRONOMY & ASTROPHYSICS OCTOBER I 1998,PAGE1 SUPPLEMENT SERIES Astron. Astrophys. Suppl. Ser. 132, 1–12 (1998) Infrared flux excesses from hot subdwarfs? II. 72 more objects?? A. Ulla1,2 and P. Thejll3 1 Universidade de Vigo, Departamento de F´ısica Aplicada, Area de F´ısica da Terra, Astronom´ıa e Astrof´ısica, Facultade de Ciencias, Campus Marcosende-Lagoas, Apartado Postal 874, E-36200 Vigo, Spain 2 Instituto de Astrof´ısica de Canarias, E-38200 La Laguna, Spain 3 Danish Meteorological Institute, Lyngbyvej 100, DK-2100 Copenhagen, Denmark Received December 19, 1996; accepted March 20, 1998 Abstract. In our search, started in February, 1994, for 1. Introduction JHK excess fluxes among the hot subdwarf population as an indicator for the presence of binary companions, Thejll et al. (1995; hereafter Paper I) discussed the pos- results for 72 more hot objects (=63 hot subdwarfs + sible origin for excess infrared fluxes detected from the 1 Horizontal Branch B star + 7 white dwarfs + 1 non- direction of a hot subdwarf star (sd). They presented a subdwarf object) observed with the Carlos S´anchez CVF set of JHK measurements for 27 hot objects: 23 hot sds, IR photometer (in June and October, 1994), are presented. GD274 –which the authors reclassify as sd+K3-K8, and 3 The exact number of binary hot subdwarfs has gained re- white dwarfs (WDs). An analysis was also presented for newed importance after the recent discovery of pulsators the, then 24, hot subdwarfs. After considering a wind ex- with G-F companions. The total number of candidates we pelled from the hot atmosphere as the source of the excess propose may help to set some constraints; for example, IR radiation, the authors concluded that the most likely out of 41 objects with excesses, 13 may have G-type bi- explanation is the presence of a cool stellar companion nary companions. -
Discovery of a Close Substellar Companion to the Hot Subdwarf Star Hd 149382—The Decisive Influence of Substellar Objects on Late Stellar Evolution
The Astrophysical Journal, 702:L96–L99, 2009 September 1 doi:10.1088/0004-637X/702/1/L96 C 2009. The American Astronomical Society. All rights reserved. Printed in the U.S.A. DISCOVERY OF A CLOSE SUBSTELLAR COMPANION TO THE HOT SUBDWARF STAR HD 149382—THE DECISIVE INFLUENCE OF SUBSTELLAR OBJECTS ON LATE STELLAR EVOLUTION S. Geier1, H. Edelmann1,3, U. Heber1, and L. Morales-Rueda2 1 Dr. Remeis-Sternwarte, Institute for Astronomy, University Erlangen-Nurnberg,¨ Sternwartstr. 7, 96049 Bamberg, Germany; [email protected] 2 Department of Astrophysics, Faculty of Science, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands 3 McDonald Observatory, University of Texas at Austin, 1 University Station, C1402, Austin, TX 78712-0259, USA Received 2009 April 29; accepted 2009 August 5; published 2009 August 17 ABSTRACT Substellar objects, like planets and brown dwarfs orbiting stars, are by-products of the star formation process. The evolution of their host stars may have an enormous impact on these small companions. Vice versa a planet might also influence stellar evolution as has recently been argued. Here, we report the discovery of an 8−23 Jupiter-mass substellar object orbiting the hot subdwarf HD 149382 in 2.391 d at a distance of only about five solar radii. Obviously, the companion must have survived engulfment in the red giant envelope. Moreover, the substellar companion has triggered envelope ejection and enabled the sdB star to form. Hot subdwarf stars have been identified as the sources of the unexpected ultraviolet (UV) emission in elliptical galaxies, but the formation of these stars is not fully understood. -
Constellation Is the Corona Australis
CORONA AUSTRALIS, THE SOUTHERN CROWN Corona Australis is a constellation in the southern celestial hemisphere. Its Latin name means "southern crown", and it is the southern counterpart of Corona Borealis, the northern crown. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations. The Ancient Greeks saw Corona Australis as a wreath rather than a crown and associated it with Sagittarius or Centaurus. Other cultures have likened the pattern to a turtle, ostrich nest, a tent, or even a hut belonging to a rock hyrax (a shrewmouse; a small, well-furred, rotund animals with short tails). Although fainter than its northern namesake, the oval - or horseshoe-shaped pattern of its brighter stars renders it distinctive. Alpha and Beta Coronae Australis are its two brightest stars with an apparent magnitude of around 4.1. Epsilon Coronae Australis is the brightest example of a W Ursae Majoris variable in the southern sky (an eclipsing contact binary). Lying alongside the Milky Way, Corona Australis contains one of the closest star-forming regions to our Solar System —a dusty dark nebula known as the Corona Australis Molecular Cloud, lying about 430 light years away. Within it are stars at the earliest stages of their lifespan. The variable stars R and TY Coronae Australis light up parts of the nebula, which varies in brightness accordingly. Corona Australis is bordered by Sagittarius to the north, Scorpius to the west, Telescopium to the south, and Ara to the southwest. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is 'CrA'. -
The HR Diagram
Name_______________________ Class_______________________ Date_______________________ Assignment #10 – The H-R Diagram A star is a delicately balanced ball of gas, fighting between two impulses: gravity, which wants to 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 protons in the star's core – a process that produces huge amounts of energy. In class we've examined the most important properties of stars: their temperatures, colors and brightnesses. Now let's see if we can find some relationships between these stellar properties. We know that hotter stars are brighter, as described by the Stefan-Boltzmann Law, and we know that the hotter stars are also bluer, as described by Wien's Law. The H-R diagram is a way of displaying an important relationship between a star's Absolute Magnitude (or Luminosity), and its Spectral Type (or temperature). Remember, Absolute Magnitude is how bright a star would appear to be, if it were 10 parsecs away. Luminosity is how much total energy a star gives off per second. As we studied in a previous exercise, Spectral Type is a system of classifying stars by temperature, from hottest (type O) to coldest (type M). Each letter in the Spectral Type list (O, B, A, F, G, K, and M) is further subdivided into 10 steps, numbered 0 through 9, to make finer distinctions between stars. -
Mètodes De Detecció I Anàlisi D'exoplanetes
MÈTODES DE DETECCIÓ I ANÀLISI D’EXOPLANETES Rubén Soussé Villa 2n de Batxillerat Tutora: Dolors Romero IES XXV Olimpíada 13/1/2011 Mètodes de detecció i anàlisi d’exoplanetes . Índex - Introducció ............................................................................................. 5 [ Marc Teòric ] 1. L’Univers ............................................................................................... 6 1.1 Les estrelles .................................................................................. 6 1.1.1 Vida de les estrelles .............................................................. 7 1.1.2 Classes espectrals .................................................................9 1.1.3 Magnitud ........................................................................... 9 1.2 Sistemes planetaris: El Sistema Solar .............................................. 10 1.2.1 Formació ......................................................................... 11 1.2.2 Planetes .......................................................................... 13 2. Planetes extrasolars ............................................................................ 19 2.1 Denominació .............................................................................. 19 2.2 Història dels exoplanetes .............................................................. 20 2.3 Mètodes per detectar-los i saber-ne les característiques ..................... 26 2.3.1 Oscil·lació Doppler ........................................................... 27 2.3.2 Trànsits -
1. Attach Your Completed H-R Diagram…Along with Procedure Steps 2 & 3
Lab: Classifying Stars Name: ________________________ Earth Science Date: ________________ Hr: ____ Introduction: Astronomers use two basic properties of stars to classify them. These two properties are luminosity, or brightness, and surface temperature. Astronomers will often use a star’s color to measure it’s temperature. Stars with low temperature produce a reddish light, while stars with high temperature shine with a brilliant blue white light. Surface temperatures of stars range from 2,000 Kelvin to 50,000 Kelvin. When these surface temperatures are plotted on a graph against luminosity, the stars fall into 3 groups: Main Sequence, Giants, and White Dwarfs. Question: When plotting stars using brightness and temperature, what group do most stars belong to? Hypothesis: Procedure: 1. Plot the stars listed below on the graph provided. 2. Circle around/label each group of stars (Main Sequence, Giants/Supergiants, White Dwarfs). 3. Find the Sun and make its DOT darker. OBSERVATIONS: Table #1: Star Brightness and Surface Temperature Star Brightness (x Sun) Surface Temperature ( x 1000 K) Rigel 10,000 11 Polaris 2,500 6 Antares 65,000 3 Van Maanen 2 0.001 6.2 Spica 12,000 22 Vega 40 10 Procyon A 7 6.5 Regulus 150 10.3 Lacaille 0.02 3.6 Sirius B 0.01 10 Betelgeuse 100,000 3 Achernar 3,100 15 Aldebaran 500 4 Tau Ceti 0.5 5.3 Sirius A 25 10 Sun 1 5.7 Procyon B 0.004 8 Altair 10.8 8 Alpha Centauri A 1.6 5.7 Eridani B 0.08 16 ------------------EVERYTHING MUST BE HAND-WRITTEN FROM THIS POINT ON----------------------- Analysis: 1. -
GEORGE HERBIG and Early Stellar Evolution
GEORGE HERBIG and Early Stellar Evolution Bo Reipurth Institute for Astronomy Special Publications No. 1 George Herbig in 1960 —————————————————————– GEORGE HERBIG and Early Stellar Evolution —————————————————————– Bo Reipurth Institute for Astronomy University of Hawaii at Manoa 640 North Aohoku Place Hilo, HI 96720 USA . Dedicated to Hannelore Herbig c 2016 by Bo Reipurth Version 1.0 – April 19, 2016 Cover Image: The HH 24 complex in the Lynds 1630 cloud in Orion was discov- ered by Herbig and Kuhi in 1963. This near-infrared HST image shows several collimated Herbig-Haro jets emanating from an embedded multiple system of T Tauri stars. Courtesy Space Telescope Science Institute. This book can be referenced as follows: Reipurth, B. 2016, http://ifa.hawaii.edu/SP1 i FOREWORD I first learned about George Herbig’s work when I was a teenager. I grew up in Denmark in the 1950s, a time when Europe was healing the wounds after the ravages of the Second World War. Already at the age of 7 I had fallen in love with astronomy, but information was very hard to come by in those days, so I scraped together what I could, mainly relying on the local library. At some point I was introduced to the magazine Sky and Telescope, and soon invested my pocket money in a subscription. Every month I would sit at our dining room table with a dictionary and work my way through the latest issue. In one issue I read about Herbig-Haro objects, and I was completely mesmerized that these objects could be signposts of the formation of stars, and I dreamt about some day being able to contribute to this field of study. -
The 10 Parsec Sample in the Gaia Era?,?? C
A&A 650, A201 (2021) Astronomy https://doi.org/10.1051/0004-6361/202140985 & c C. Reylé et al. 2021 Astrophysics The 10 parsec sample in the Gaia era?,?? C. Reylé1 , K. Jardine2 , P. Fouqué3 , J. A. Caballero4 , R. L. Smart5 , and A. Sozzetti5 1 Institut UTINAM, CNRS UMR6213, Univ. Bourgogne Franche-Comté, OSU THETA Franche-Comté-Bourgogne, Observatoire de Besançon, BP 1615, 25010 Besançon Cedex, France e-mail: [email protected] 2 Radagast Solutions, Simon Vestdijkpad 24, 2321 WD Leiden, The Netherlands 3 IRAP, Université de Toulouse, CNRS, 14 av. E. Belin, 31400 Toulouse, France 4 Centro de Astrobiología (CSIC-INTA), ESAC, Camino bajo del castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain 5 INAF – Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese (TO), Italy Received 2 April 2021 / Accepted 23 April 2021 ABSTRACT Context. The nearest stars provide a fundamental constraint for our understanding of stellar physics and the Galaxy. The nearby sample serves as an anchor where all objects can be seen and understood with precise data. This work is triggered by the most recent data release of the astrometric space mission Gaia and uses its unprecedented high precision parallax measurements to review the census of objects within 10 pc. Aims. The first aim of this work was to compile all stars and brown dwarfs within 10 pc observable by Gaia and compare it with the Gaia Catalogue of Nearby Stars as a quality assurance test. We complement the list to get a full 10 pc census, including bright stars, brown dwarfs, and exoplanets. -
Desert Skies
Desert Skies Tucson Amateur Astronomy Association Volume LII, Number 8 August, 2006 Jupiter Dominates the August Night Sky ♦ Learn the latest about comets at ♦ Constellation of the month the monthly meeting ♦ Grand Canyon Star Party Report ♦ Star party for U of A students ♦ Object of the Month Desert Skies: August, 2006 2 Volume LII, Number 8 Cover Photo: Imaged by Rik Hill using a C14 and a ToUCam. It's a stack of about 3600 images taken in 3 minutes time. The stacking was done with Registax 3 and the final processing with GIMP. TAAA Web Page: http://www.tucsonastronomy.org TAAA Phone Number: (520) 792-6414 Office/Position Name Phone E-mail Address President Bill Lofquist 297-6653 [email protected] Vice President Ken Shaver 762-5094 [email protected] Secretary Steve Marten 307-5237 [email protected] Treasurer Terri Lappin 977-1290 [email protected] Member-at-Large George Barber 822-2392 [email protected] Member-at-Large JD Metzger 760-8248 [email protected] Member-at-Large Teresa Plymate 883-9113 [email protected] Chief Observer Wayne Johnson 586-2244 [email protected] AL Correspondent (ALCor) Nick de Mesa 797-6614 [email protected] Astro-Imaging SIG Steve Peterson 762-8211 [email protected] Computers in Astronomy SIG Roger Tanner 574-3876 [email protected] Beginners SIG Bill Lofquist 297-6653 [email protected] Newsletter Editor George Barber 822-2392 [email protected] School Star Party -
Comparative Planetology and the Search for Life Beyond the Solar System
Beichman et al.: The Search for Life Beyond the Solar System 915 Comparative Planetology and the Search for Life Beyond the Solar System Charles A. Beichman California Institute of Technology Malcolm Fridlund European Space Agency Wesley A. Traub and Karl R. Stapelfeldt Jet Propulsion Laboratory Andreas Quirrenbach University of Leiden Sara Seager Carnegie Institute of Washington The study of planets beyond the solar system and the search for other habitable planets and life is just beginning. Groundbased (radial velocity and transits) and spacebased surveys (tran- sits and astrometry) will identify planets spanning a wide range of size and orbital location, from Earth-sized objects within 1 AU to giant planets beyond 5 AU, orbiting stars as near as a few parsec and as far as a kiloparsec. After this initial reconnaissance, the next generation of space observatories will directly detect photons from planets in the habitable zones of nearby stars. The synergistic combination of measurements of mass from astrometry and radial velocity, of radius and composition from transits, and the wealth of information from the direct detection of visible and mid-IR photons will create a rich field of comparative planetology. Information on protoplanetary and debris disks will complete our understanding of the evolution of habitable environments from the earliest stages of planet formation to the transport into the inner solar system of the volatiles necessary for life. The suite of missions necessary to carry out the search for nearby, habitable planets and life requires a “Great Observatories” program for planet finding (SIM PlanetQuest, Terrestrial Planet Finder-Coronagraph, and Terrestrial Planet Finder-Interfer- ometer/Darwin), analogous to the highly successful “Great Observatories Program” for astro- physics.