Stellar Structure and Evolution: Syllabus 3.3 the Virial Theorem and Its Implications (ZG: P5-2; CO: 2.4) Ph
Total Page:16
File Type:pdf, Size:1020Kb

Load more
Recommended publications
-
Radio and IR Interferometry of Sio Maser Stars
Cosmic Masers - from OH to H0 Proceedings IAU Symposium No. 287, 2012 c International Astronomical Union 2012 R.S. Booth, E.M.L. Humphreys & W.H.T. Vlemmings, eds. doi:10.1017/S1743921312006989 Radio and IR interferometry of SiO maser stars Markus Wittkowski1, David A. Boboltz2,MalcolmD.Gray3, Elizabeth M. L. Humphreys1 Iva Karovicova4, and Michael Scholz5,6 1 ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei M¨unchen, Germany 2 US Naval Observatory, 3450 Massachusetts Avenue, NW, Washington, DC 20392-5420, USA 3 Jodrell Bank Centre for Astrophysics, Alan Turing Building, University of Manchester, Manchester M13 9PL, UK 4 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, 69117 Heidelberg, Germany 5 Zentrum f¨ur Astronomie der Universit¨at Heidelberg (ZAH), Institut f¨ur Theoretische Astrophysik, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany 6 Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney NSW 2006, Australia Abstract. Radio and infrared interferometry of SiO maser stars provide complementary infor- mation on the atmosphere and circumstellar environment at comparable spatial resolution. Here, we present the latest results on the atmospheric structure and the dust condensation region of AGB stars based on our recent infrared spectro-interferometric observations, which represent the environment of SiO masers. We discuss, as an example, new results from simultaneous VLTI and VLBA observations of the Mira variable AGB star R Cnc, including VLTI near- and mid- infrared interferometry, as well as VLBA observations of the SiO maser emission toward this source. We present preliminary results from a monitoring campaign of high-frequency SiO maser emission toward evolved stars obtained with the APEX telescope, which also serves as a pre- cursor of ALMA images of the SiO emitting region. -
Lurking in the Shadows: Wide-Separation Gas Giants As Tracers of Planet Formation
Lurking in the Shadows: Wide-Separation Gas Giants as Tracers of Planet Formation Thesis by Marta Levesque Bryan In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2018 Defended May 1, 2018 ii © 2018 Marta Levesque Bryan ORCID: [0000-0002-6076-5967] All rights reserved iii ACKNOWLEDGEMENTS First and foremost I would like to thank Heather Knutson, who I had the great privilege of working with as my thesis advisor. Her encouragement, guidance, and perspective helped me navigate many a challenging problem, and my conversations with her were a consistent source of positivity and learning throughout my time at Caltech. I leave graduate school a better scientist and person for having her as a role model. Heather fostered a wonderfully positive and supportive environment for her students, giving us the space to explore and grow - I could not have asked for a better advisor or research experience. I would also like to thank Konstantin Batygin for enthusiastic and illuminating discussions that always left me more excited to explore the result at hand. Thank you as well to Dimitri Mawet for providing both expertise and contagious optimism for some of my latest direct imaging endeavors. Thank you to the rest of my thesis committee, namely Geoff Blake, Evan Kirby, and Chuck Steidel for their support, helpful conversations, and insightful questions. I am grateful to have had the opportunity to collaborate with Brendan Bowler. His talk at Caltech my second year of graduate school introduced me to an unexpected population of massive wide-separation planetary-mass companions, and lead to a long-running collaboration from which several of my thesis projects were born. -
Evidence for Very Extended Gaseous Layers Around O-Rich Mira Variables and M Giants B
The Astrophysical Journal, 579:446–454, 2002 November 1 # 2002. The American Astronomical Society. All rights reserved. Printed in U.S.A. EVIDENCE FOR VERY EXTENDED GASEOUS LAYERS AROUND O-RICH MIRA VARIABLES AND M GIANTS B. Mennesson,1 G. Perrin,2 G. Chagnon,2 V. Coude du Foresto,2 S. Ridgway,3 A. Merand,2 P. Salome,2 P. Borde,2 W. Cotton,4 S. Morel,5 P. Kervella,5 W. Traub,6 and M. Lacasse6 Received 2002 March 15; accepted 2002 July 3 ABSTRACT Nine bright O-rich Mira stars and five semiregular variable cool M giants have been observed with the Infrared and Optical Telescope Array (IOTA) interferometer in both K0 (2.15 lm) and L0 (3.8 lm) broad- band filters, in most cases at very close variability phases. All of the sample Mira stars and four of the semire- gular M giants show strong increases, from ’20% to ’100%, in measured uniform-disk (UD) diameters between the K0 and L0 bands. (A selection of hotter M stars does not show such a large increase.) There is no evidence that K0 and L0 broadband visibility measurements should be dominated by strong molecular bands, and cool expanding dust shells already detected around some of these objects are also found to be poor candi- dates for producing these large apparent diameter increases. Therefore, we propose that this must be a con- tinuum or pseudocontinuum opacity effect. Such an apparent enlargement can be reproduced using a simple two-component model consisting of a warm (1500–2000 K), extended (up to ’3 stellar radii), optically thin ( ’ 0:5) layer located above the classical photosphere. -
This Work Is Protected by Copyright and Other Intellectual Property Rights
This work is protected by copyright and other intellectual property rights and duplication or sale of all or part is not permitted, except that material may be duplicated by you for research, private study, criticism/review or educational purposes. Electronic or print copies are for your own personal, non- commercial use and shall not be passed to any other individual. No quotation may be published without proper acknowledgement. For any other use, or to quote extensively from the work, permission must be obtained from the copyright holder/s. Fundamental properties of M-dwarfs in eclipsing binary star systems Samuel Gill Doctor of Philosophy Department of Physics, Keele University March 2019 i Abstract The absolute parameters of M-dwarfs in eclipsing binary systems provide important tests for evolutionary models. Those that have been measured reveal significant discrepancies with evolutionary models. There are two problems with M-dwarfs: 1. M-dwarfs generally appear bigger and cooler than models predict (such that their luminosity agrees with models) and 2. some M-dwarfs in eclipsing binaries are measured to be hotter than expected for their mass. The exact cause of this is unclear and a variety of conjectures have been put forward including enhanced magnetic activity and spotted surfaces. There is a lack of M-dwarfs with absolute parameters and so the exact causes of these disparities are unclear. As the interest in low-mass stars rises from the ever increasing number of exoplanets found around them, it is important that a considerable effort is made to understand why this is so. A solution to the problem lies with low-mass eclipsing binary systems discovered by the WASP (Wide Angle Search for Planets) project. -
SHELL BURNING STARS: Red Giants and Red Supergiants
SHELL BURNING STARS: Red Giants and Red Supergiants There is a large variety of stellar models which have a distinct core – envelope structure. While any main sequence star, or any white dwarf, may be well approximated with a single polytropic model, the stars with the core – envelope structure may be approximated with a composite polytrope: one for the core, another for the envelope, with a very large difference in the “K” constants between the two. This is a consequence of a very large difference in the specific entropies between the core and the envelope. The original reason for the difference is due to a jump in chemical composition. For example, the core may have no hydrogen, and mostly helium, while the envelope may be hydrogen rich. As a result, there is a nuclear burning shell at the bottom of the envelope; hydrogen burning shell in our example. The heat generated in the shell is diffusing out with radiation, and keeps the entropy very high throughout the envelope. The core – envelope structure is most pronounced when the core is degenerate, and its specific entropy near zero. It is supported against its own gravity with the non-thermal pressure of degenerate electron gas, while all stellar luminosity, and all entropy for the envelope, are provided by the shell source. A common property of stars with well developed core – envelope structure is not only a very large jump in specific entropy but also a very large difference in pressure between the center, Pc, the shell, Psh, and the photosphere, Pph. Of course, the two characteristics are closely related to each other. -
April 2008 SKYSCRAPERS, INC · Amateur Astronomical Society of Rhode Island · 47 Peeptoad Road North Scituate, RI 02857 · April Meeting with Dr
The SkyscraperVol. 35 No. 4 April 2008 SKYSCRAPERS, INC · Amateur Astronomical Society Of Rhode Island · 47 Peeptoad Road North Scituate, RI 02857 · www.theSkyscrapers.org April Meeting with Dr. Alan Guth Friday, April 4 at Seagrave Memorial Observatory Dr. Alan Guth, Professor of Origins, Alan Guth, A Golden Age of Physics at the Massachusetts Insti- Cosmology and other publications. tute of Technology, is best known He will be presenting a talk entitled The Orion Nebula: SBIG 1001E on Meade 16” for the “inflationary” theory of “Inflationary Cosmology.” SCT at Barus and Holley Observatory; L = 12 ex- cosmology in which many features For the April meeting we will be posures x 5 seconds each, binned 1x1; R,G,B = of our universe, including how it returning to Seagrave Observatory. 3 exposures each x 5 seconds each, binned 2x2; came to be so uniform and why it Elections will be held at the April 27 exposures total, total exposure time = 2.25 began so close to the critical density meeting and membership renewals minutes. Images combined and processed using can be explained by. Dr. Guth is the are due. An elections ballot and Maxim DL. Photo by Bob Horton. author of The Inflationary Universe, renewal form are included in the the Quest for a New Theory of Cosmic back of this issue. In This Issue April Meeting with 1 Dr. Alan Guth April 2008 President’s Message 2 Glenn Jackson 4 7:30 pm Annual Meeting with Dr. Alan Guth April Lyrids Meteor 3 Friday Seagrave Memorial Observatory Shower Dave Huestis 5 8:00 pm Public Observing Night Tracking Wildlife -
Astro 404 Lecture 30 Nov. 6, 2019 Announcements
Astro 404 Lecture 30 Nov. 6, 2019 Announcements: • Problem Set 9 due Fri Nov 8 2 3/2 typo corrected in L24 notes: nQ = (2πmkT/h ) • Office Hours: Instructor – after class or by appointment • TA: Thursday noon-1pm or by appointment • Exam: grading elves hard at work Last time: low-mass stars after main sequence Q: burning phases? 1 Q: shell burning “mirror” principle? Low-Mass Stars After Main Sequence unburnt H ⋆ helium core contracts H He H burning in shell around core He outer layers expand → red giant “mirror” effect of shell burning: • core contraction, envelope expansion • total gravitational potential energy Ω roughly conserved core becomes more tightly bound, envelope less bound ⋆ helium ignition degenerate core unburnt H H He runaway burning: helium flash inert He → 12 He C+O 2 then core helium burning 3α C and shell H burning “horizontal branch” star unburnt H H He ⋆ for solar mass stars: after CO core forms inert He He C • helium shell burning begins inert C • hydrogen shell burning continues Q: star path on HR diagram during these phases? 3 Low-Mass Post-Main-Sequence: HR Diagram ⋆ H shell burning ↔ red giant ⋆ He flash marks “tip of the red giant branch” ⋆ core He fusion ↔ horizontal branch ⋆ He + H shell burning ↔ asymptotic giant branch asymptotic giant branch H+He shell burn He flash core He burn L main sequence horizontal branch red giant branch H shell burning Sun Luminosity 4 Temperature T iClicker Poll: AGB Star Intershell Region in AGB phase: burning in two shells, no core fusion unburnt H H He inert He He C Vote your conscience–all -
The W-Type W Uma Contact Binary MU Cancri
226 Odell and Eaton, JAAVSO Volume 48, 2020 The W-type W UMa Contact Binary MU Cancri Andrew P. Odell (deceased May 2019) Emeritus Associate Professor of Physics and Astronomy, Northern Arizona University, Flagstaff, AZ 86011 Joel A. Eaton 7050 Bakerville Road, Waverly, TN 37185; [email protected] Received August 11, 2020; revised October 15, 2020; accepted October 20, 2020 Abstract We use three complete light curves for MU Cancri, a faint W-type W UMa contact binary, to investigate possible mechanisms for changes in such binaries’ light curves. The standard Roche model, as implemented by the Wilson-Devinney code, does not fit the observations at their level of precision. Most of this discrepancy can be explained by placing one or two moderate starspots (rspot ~ 10–12°) on the more massive component. However, this does not resolve the discrepancy, since the solutions for the three epochs have different mass ratios, implying unmodelled changes in eclipse depths. This, in turn, implies that more spots are changing the depths in unpredictable ways. Thus we are confronted with limits on just how precisely light curve solutions can define the physical properties of a contact binary. We use spectra to classify the star (G3–G7) and to measure a spectroscopic mass ratio (q = 2.63), significantly closer to 1.0 than the photometric mass ratios (3.0–3.3), but this difference is unlikely to be caused by third light. And we also extend the period study of Alton and Stępień. 1. Introduction MUCnc-JAAVSO-482.txt at ftp://ftp.aavso.org/public/datasets/. -
METEOR CSILLAGÁSZATI ÉVKÖNYV 2019 Meteor Csillagászati Évkönyv 2019
METEOR CSILLAGÁSZATI ÉVKÖNYV 2019 meteor csillagászati évkönyv 2019 Szerkesztette: Benkő József Mizser Attila Magyar Csillagászati Egyesület www.mcse.hu Budapest, 2018 Az évkönyv kalendárium részének összeállításában közreműködött: Tartalom Bagó Balázs Görgei Zoltán Kaposvári Zoltán Kiss Áron Keve Kovács József Bevezető ....................................................................................................... 7 Molnár Péter Sánta Gábor Kalendárium .............................................................................................. 13 Sárneczky Krisztián Szabadi Péter Cikkek Szabó Sándor Szőllősi Attila Zsoldos Endre: 100 éves a Nemzetközi Csillagászati Unió ........................191 Zsoldos Endre Maria Lugaro – Kereszturi Ákos: Elemkeletkezés a csillagokban.............. 203 Szabó Róbert: Az OGLE égboltfelmérés 25 éve ........................................218 A kalendárium csillagtérképei az Ursa Minor szoftverrel készültek. www.ursaminor.hu Beszámolók Mizser Attila: A Magyar Csillagászati Egyesület Szakmailag ellenőrizte: 2017. évi tevékenysége .........................................................................242 Szabados László Kiss László – Szabó Róbert: Az MTA CSFK Csillagászati Intézetének 2017. évi tevékenysége .........................................................................248 Petrovay Kristóf: Az ELTE Csillagászati Tanszékének működése 2017-ben ............................................................................ 262 Szabó M. Gyula: Az ELTE Gothard Asztrofi zikai Obszervatórium -
10. Scientific Programme 10.1
10. SCIENTIFIC PROGRAMME 10.1. OVERVIEW (a) Invited Discourses Plenary Hall B 18:00-19:30 ID1 “The Zoo of Galaxies” Karen Masters, University of Portsmouth, UK Monday, 20 August ID2 “Supernovae, the Accelerating Cosmos, and Dark Energy” Brian Schmidt, ANU, Australia Wednesday, 22 August ID3 “The Herschel View of Star Formation” Philippe André, CEA Saclay, France Wednesday, 29 August ID4 “Past, Present and Future of Chinese Astronomy” Cheng Fang, Nanjing University, China Nanjing Thursday, 30 August (b) Plenary Symposium Review Talks Plenary Hall B (B) 8:30-10:00 Or Rooms 309A+B (3) IAUS 288 Astrophysics from Antarctica John Storey (3) Mon. 20 IAUS 289 The Cosmic Distance Scale: Past, Present and Future Wendy Freedman (3) Mon. 27 IAUS 290 Probing General Relativity using Accreting Black Holes Andy Fabian (B) Wed. 22 IAUS 291 Pulsars are Cool – seriously Scott Ransom (3) Thu. 23 Magnetars: neutron stars with magnetic storms Nanda Rea (3) Thu. 23 Probing Gravitation with Pulsars Michael Kremer (3) Thu. 23 IAUS 292 From Gas to Stars over Cosmic Time Mordacai-Mark Mac Low (B) Tue. 21 IAUS 293 The Kepler Mission: NASA’s ExoEarth Census Natalie Batalha (3) Tue. 28 IAUS 294 The Origin and Evolution of Cosmic Magnetism Bryan Gaensler (B) Wed. 29 IAUS 295 Black Holes in Galaxies John Kormendy (B) Thu. 30 (c) Symposia - Week 1 IAUS 288 Astrophysics from Antartica IAUS 290 Accretion on all scales IAUS 291 Neutron Stars and Pulsars IAUS 292 Molecular gas, Dust, and Star Formation in Galaxies (d) Symposia –Week 2 IAUS 289 Advancing the Physics of Cosmic -
Hertzsprung-Russell Diagram and Mass Distribution of Barium Stars ? A
Astronomy & Astrophysics manuscript no. HRD_Ba c ESO 2019 May 14, 2019 Hertzsprung-Russell diagram and mass distribution of barium stars ? A. Escorza1; 2, H.M.J. Boffin3, A.Jorissen2, S. Van Eck2, L. Siess2, H. Van Winckel1, D. Karinkuzhi2, S. Shetye2; 1, and D. Pourbaix2 1 Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium 2 Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles, ULB, Campus Plaine C.P. 226, Boulevard du Triomphe, B-1050 Bruxelles, Belgium 3 ESO, Karl Schwarzschild Straße 2, D-85748 Garching bei München, Germany Received; Accepted ABSTRACT With the availability of parallaxes provided by the Tycho-Gaia Astrometric Solution, it is possible to construct the Hertzsprung-Russell diagram (HRD) of barium and related stars with unprecedented accuracy. A direct result from the derived HRD is that subgiant CH stars occupy the same region as barium dwarfs, contrary to what their designations imply. By comparing the position of barium stars in the HRD with STAREVOL evolutionary tracks, it is possible to evaluate their masses, provided the metallicity is known. We used an average metallicity [Fe/H] = −0.25 and derived the mass distribution of barium giants. The distribution peaks around 2.5 M with a tail at higher masses up to 4.5 M . This peak is also seen in the mass distribution of a sample of normal K and M giants used for comparison and is associated with stars located in the red clump. When we compare these mass distributions, we see a deficit of low-mass (1 – 2 M ) barium giants. -
GTO Keypad Manual, V5.001
ASTRO-PHYSICS GTO KEYPAD Version v5.xxx Please read the manual even if you are familiar with previous keypad versions Flash RAM Updates Keypad Java updates can be accomplished through the Internet. Check our web site www.astro-physics.com/software-updates/ November 11, 2020 ASTRO-PHYSICS KEYPAD MANUAL FOR MACH2GTO Version 5.xxx November 11, 2020 ABOUT THIS MANUAL 4 REQUIREMENTS 5 What Mount Control Box Do I Need? 5 Can I Upgrade My Present Keypad? 5 GTO KEYPAD 6 Layout and Buttons of the Keypad 6 Vacuum Fluorescent Display 6 N-S-E-W Directional Buttons 6 STOP Button 6 <PREV and NEXT> Buttons 7 Number Buttons 7 GOTO Button 7 ± Button 7 MENU / ESC Button 7 RECAL and NEXT> Buttons Pressed Simultaneously 7 ENT Button 7 Retractable Hanger 7 Keypad Protector 8 Keypad Care and Warranty 8 Warranty 8 Keypad Battery for 512K Memory Boards 8 Cleaning Red Keypad Display 8 Temperature Ratings 8 Environmental Recommendation 8 GETTING STARTED – DO THIS AT HOME, IF POSSIBLE 9 Set Up your Mount and Cable Connections 9 Gather Basic Information 9 Enter Your Location, Time and Date 9 Set Up Your Mount in the Field 10 Polar Alignment 10 Mach2GTO Daytime Alignment Routine 10 KEYPAD START UP SEQUENCE FOR NEW SETUPS OR SETUP IN NEW LOCATION 11 Assemble Your Mount 11 Startup Sequence 11 Location 11 Select Existing Location 11 Set Up New Location 11 Date and Time 12 Additional Information 12 KEYPAD START UP SEQUENCE FOR MOUNTS USED AT THE SAME LOCATION WITHOUT A COMPUTER 13 KEYPAD START UP SEQUENCE FOR COMPUTER CONTROLLED MOUNTS 14 1 OBJECTS MENU – HAVE SOME FUN!