Stellar Metamorphosis: an Alternative for the Star Sciences
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Astronomie in Theorie Und Praxis 8. Auflage in Zwei Bänden Erik Wischnewski
Astronomie in Theorie und Praxis 8. Auflage in zwei Bänden Erik Wischnewski Inhaltsverzeichnis 1 Beobachtungen mit bloßem Auge 37 Motivation 37 Hilfsmittel 38 Drehbare Sternkarte Bücher und Atlanten Kataloge Planetariumssoftware Elektronischer Almanach Sternkarten 39 2 Atmosphäre der Erde 49 Aufbau 49 Atmosphärische Fenster 51 Warum der Himmel blau ist? 52 Extinktion 52 Extinktionsgleichung Photometrie Refraktion 55 Szintillationsrauschen 56 Angaben zur Beobachtung 57 Durchsicht Himmelshelligkeit Luftunruhe Beispiel einer Notiz Taupunkt 59 Solar-terrestrische Beziehungen 60 Klassifizierung der Flares Korrelation zur Fleckenrelativzahl Luftleuchten 62 Polarlichter 63 Nachtleuchtende Wolken 64 Haloerscheinungen 67 Formen Häufigkeit Beobachtung Photographie Grüner Strahl 69 Zodiakallicht 71 Dämmerung 72 Definition Purpurlicht Gegendämmerung Venusgürtel Erdschattenbogen 3 Optische Teleskope 75 Fernrohrtypen 76 Refraktoren Reflektoren Fokus Optische Fehler 82 Farbfehler Kugelgestaltsfehler Bildfeldwölbung Koma Astigmatismus Verzeichnung Bildverzerrungen Helligkeitsinhomogenität Objektive 86 Linsenobjektive Spiegelobjektive Vergütung Optische Qualitätsprüfung RC-Wert RGB-Chromasietest Okulare 97 Zusatzoptiken 100 Barlow-Linse Shapley-Linse Flattener Spezialokulare Spektroskopie Herschel-Prisma Fabry-Pérot-Interferometer Vergrößerung 103 Welche Vergrößerung ist die Beste? Blickfeld 105 Lichtstärke 106 Kontrast Dämmerungszahl Auflösungsvermögen 108 Strehl-Zahl Luftunruhe (Seeing) 112 Tubusseeing Kuppelseeing Gebäudeseeing Montierungen 113 Nachführfehler -
February 2020 Page 1 of 11
Newsletter Pretoria Centre ASSA February 2020 Page 1 of 11 NEWSLETTER FEBRUARY 2020 NEXT MEETING Venue: The auditorium behind the main building at Christian Brothers College (CBC), Mount Edmund, Pretoria Road, Silverton, Pretoria. Date and time: Wednesday 26 February at 19h15. Programme: ➢ Beginner’s Corner: “Discoveries by amateurs” by Michelle Ferreira. ➢ What’s Up: by Michael Poll. ----------------------------------- 10-minute break. Library will be open. -------------------------------- ➢ Main talk: TBA by e-mail to members. ➢ Socializing over tea/coffee and biscuits. The chairperson at the meeting will be Pierre Lourens. NEXT OBSERVING EVENING Friday 21 February from sunset onwards at the Pretoria Centre Observatory, which is also situated at CBC. Turn left immediately after entering the main gate and follow the road. TABLE OF CONTENTS Astronomy-related articles on the Internet 2 Report of observing evening on January 17th 2020 3 Astronomy basics: How Earth moves 3 Feature of the month: Does extraterrestrial life exist? 3 Observing: The Elephant’s Trunk 4 Chairperson’s report for the meeting on 22 January 2020 5 Summary of coming presentation on 26 February under “What's Up?” 6 NOTICE BOARD 7 Pretoria Centre committee 7 Astronomy-related images and video clips on the Internet 7 Determination of the Earth-Sun distance using the transit of Mercury on 11 8 November 2019 Newsletter Pretoria Centre ASSA February 2020 Page 2 of 11 Astronomy-related articles on the Internet These 2 outbound comets are likely from another solar system. https://earthsky.org/space/outbound-comets-are-likely-of-interstellar-origin? utm_source=EarthSky+News&utm_campaign=5b6df3e574- EMAIL_CAMPAIGN_2018_02_02_COPY_01&utm_medium=email&utm_term=0_c64394 5d79-5b6df3e574-394671529 Rigel in Orion is blue-white. -
Luminous Blue Variables
Review Luminous Blue Variables Kerstin Weis 1* and Dominik J. Bomans 1,2,3 1 Astronomical Institute, Faculty for Physics and Astronomy, Ruhr University Bochum, 44801 Bochum, Germany 2 Department Plasmas with Complex Interactions, Ruhr University Bochum, 44801 Bochum, Germany 3 Ruhr Astroparticle and Plasma Physics (RAPP) Center, 44801 Bochum, Germany Received: 29 October 2019; Accepted: 18 February 2020; Published: 29 February 2020 Abstract: Luminous Blue Variables are massive evolved stars, here we introduce this outstanding class of objects. Described are the specific characteristics, the evolutionary state and what they are connected to other phases and types of massive stars. Our current knowledge of LBVs is limited by the fact that in comparison to other stellar classes and phases only a few “true” LBVs are known. This results from the lack of a unique, fast and always reliable identification scheme for LBVs. It literally takes time to get a true classification of a LBV. In addition the short duration of the LBV phase makes it even harder to catch and identify a star as LBV. We summarize here what is known so far, give an overview of the LBV population and the list of LBV host galaxies. LBV are clearly an important and still not fully understood phase in the live of (very) massive stars, especially due to the large and time variable mass loss during the LBV phase. We like to emphasize again the problem how to clearly identify LBV and that there are more than just one type of LBVs: The giant eruption LBVs or h Car analogs and the S Dor cycle LBVs. -