Fundamental Problems in the Evaluation of Electron Micrographs
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Arxiv:1809.07342V1 [Astro-Ph.SR] 19 Sep 2018
Draft version September 21, 2018 Preprint typeset using LATEX style emulateapj v. 11/10/09 FAR-ULTRAVIOLET ACTIVITY LEVELS OF F, G, K, AND M DWARF EXOPLANET HOST STARS* Kevin France1, Nicole Arulanantham1, Luca Fossati2, Antonino F. Lanza3, R. O. Parke Loyd4, Seth Redfield5, P. Christian Schneider6 Draft version September 21, 2018 ABSTRACT We present a survey of far-ultraviolet (FUV; 1150 { 1450 A)˚ emission line spectra from 71 planet- hosting and 33 non-planet-hosting F, G, K, and M dwarfs with the goals of characterizing their range of FUV activity levels, calibrating the FUV activity level to the 90 { 360 A˚ extreme-ultraviolet (EUV) stellar flux, and investigating the potential for FUV emission lines to probe star-planet interactions (SPIs). We build this emission line sample from a combination of new and archival observations with the Hubble Space Telescope-COS and -STIS instruments, targeting the chromospheric and transition region emission lines of Si III,N V,C II, and Si IV. We find that the exoplanet host stars, on average, display factors of 5 { 10 lower UV activity levels compared with the non-planet hosting sample; this is explained by a combination of observational and astrophysical biases in the selection of stars for radial-velocity planet searches. We demonstrate that UV activity-rotation relation in the full F { M star sample is characterized by a power-law decline (with index α ≈ −1.1), starting at rotation periods & 3.5 days. Using N V or Si IV spectra and a knowledge of the star's bolometric flux, we present a new analytic relationship to estimate the intrinsic stellar EUV irradiance in the 90 { 360 A˚ band with an accuracy of roughly a factor of ≈ 2. -
Arxiv:2107.05688V1 [Astro-Ph.GA] 12 Jul 2021
FERMILAB-PUB-21-274-AE-LDRD Draft version September 6, 2021 Typeset using LATEX twocolumn style in AASTeX63 RR Lyrae stars in the newly discovered ultra-faint dwarf galaxy Centaurus I∗ C. E. Mart´ınez-Vazquez´ ,1 W. Cerny ,2, 3 A. K. Vivas ,1 A. Drlica-Wagner ,4, 2, 3 A. B. Pace ,5 J. D. Simon,6 R. R. Munoz,7 A. R. Walker ,1 S. Allam,4 D. L. Tucker,4 M. Adamow´ ,8 J. L. Carlin ,9 Y. Choi,10 P. S. Ferguson ,11, 12 A. P. Ji,6 N. Kuropatkin,4 T. S. Li ,6, 13, 14 D. Mart´ınez-Delgado,15 S. Mau ,16, 17 B. Mutlu-Pakdil ,2, 3 D. L. Nidever,18 A. H. Riley,11, 12 J. D. Sakowska ,19 D. J. Sand ,20 G. S. Stringfellow ,21 (DELVE Collaboration) 1Cerro Tololo Inter-American Observatory, NSF's NOIRLab, Casilla 603, La Serena, Chile 2Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA 3Department of Astronomy and Astrophysics, University of Chicago, Chicago IL 60637, USA 4Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510, USA 5McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA 6Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101, USA 7Departamento de Astronom´ıa,Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile 8Center for Astrophysical Surveys, National Center for Supercomputing Applications, 1205 West Clark St., Urbana, IL 61801, USA 9Rubin Observatory/AURA, 950 North Cherry Avenue, Tucson, AZ, 85719, USA 10Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 11George P. -
Appendix A: Scientific Notation
Appendix A: Scientific Notation Since in astronomy we often have to deal with large numbers, writing a lot of zeros is not only cumbersome, but also inefficient and difficult to count. Scientists use the system of scientific notation, where the number of zeros is short handed to a superscript. For example, 10 has one zero and is written as 101 in scientific notation. Similarly, 100 is 102, 100 is 103. So we have: 103 equals a thousand, 106 equals a million, 109 is called a billion (U.S. usage), and 1012 a trillion. Now the U.S. federal government budget is in the trillions of dollars, ordinary people really cannot grasp the magnitude of the number. In the metric system, the prefix kilo- stands for 1,000, e.g., a kilogram. For a million, the prefix mega- is used, e.g. megaton (1,000,000 or 106 ton). A billion hertz (a unit of frequency) is gigahertz, although I have not heard of the use of a giga-meter. More rarely still is the use of tera (1012). For small numbers, the practice is similar. 0.1 is 10À1, 0.01 is 10À2, and 0.001 is 10À3. The prefix of milli- refers to 10À3, e.g. as in millimeter, whereas a micro- second is 10À6 ¼ 0.000001 s. It is now trendy to talk about nano-technology, which refers to solid-state device with sizes on the scale of 10À9 m, or about 10 times the size of an atom. With this kind of shorthand convenience, one can really go overboard. -
A New Form of Estimating Stellar Parameters Using an Optimization Approach
A&A 532, A20 (2011) Astronomy DOI: 10.1051/0004-6361/200811182 & c ESO 2011 Astrophysics Modeling nearby FGK Population I stars: A new form of estimating stellar parameters using an optimization approach J. M. Fernandes1,A.I.F.Vaz2, and L. N. Vicente3 1 CFC, Department of Mathematics and Astronomical Observatory, University of Coimbra, Portugal e-mail: [email protected] 2 Department of Production and Systems, University of Minho, Portugal e-mail: [email protected] 3 CMUC, Department of Mathematics, University of Coimbra, Portugal e-mail: [email protected] Received 17 October 2008 / Accepted 27 May 2011 ABSTRACT Context. Modeling a single star with theoretical stellar evolutionary tracks is a nontrivial problem because of a large number of unknowns compared to the number of observations. A current way of estimating stellar age and mass consists of using interpolations in grids of stellar models and/or isochrones, assuming ad hoc values for the mixing length parameter and the metal-to-helium enrichment, which is normally scaled to the solar values. Aims. We present a new method to model the FGK main-sequence of Population I stars. This method is capable of simultaneously estimating a set of stellar parameters, namely the mass, the age, the helium and metal abundances, the mixing length parameter, and the overshooting. Methods. The proposed method is based on the application of a global optimization algorithm (PSwarm) to solve an optimization problem that in turn consists of finding the values of the stellar parameters that lead to the best possible fit of the given observations. -
Variable Star Section Circular
British Astronomical Association Variable Star Section Circular No 77, August 1993 ISSN 0267-9272 Office: Burlington House, Piccadilly, London, W1V 9AG Section Officers Director Tristram Brelstaff, 3 Malvern Court, Addington Road, Reading, Berks, RG1 5PL Tel: 0734-268981 Assistant Director Storm R Dunlop 140 Stocks Lane, East Wittering, Chichester, West Sussex, P020 8NT Tel: 0243-670354 Telex: 9312134138 (SD G) Email: CompuServe:100015,1610 JANET:SDUNLOP@UK. AC. SUSSEX.STARLINK Secretary Melvyn D Taylor, 17 Cross Lane, Wakefield, West Yorks, WF2 8DA Tel: 0924-374651 Chart John Toone, Hillside View, 17 Ashdale Road, Secretary Cressage, Shrewsbury, SY5 6DT Tel: 0952-510794 Nova/Supernova Guy M Hurst, 16 Westminster Close, Kempshott Rise, Secretary Basingstoke, Hants, RG22 4PP Tel & Fax: 0256-471074 Telex: 9312111261 (TA G) Email: Telecom Gold:10074:MIK2885 STARLINK:RLSAC::GMH JANET:GMH0UK. AC. RUTHERFORD.STARLINK. ASTROPHYSICS Pro-Am Liaison Roger D Pickard, 28 Appletons, Hadlow, Kent, TN11 0DT Committee Tel: 0732-850663 Secretary Email: JANET:RDP0UK.AC.UKC.STAR STARLINK:KENVAD: :RDP Computer Dave McAdam, 33 Wrekin View, Madeley, Telford, Secretary Shropshire, TF7 5HZ Tel: 0952-432048 Email: Telecom Gold 10087:YQQ587 Eclipsing Binary Director Secretary Circulars Editor Director Circulars Assistant Director Subscriptions Telephone Alert Numbers Nova and Supernova First phone Nova/Supernova Secretary. If only Discoveries answering machine response then try the following: Denis Buczynski 0524-68530 Glyn Marsh 0772-690502 Martin Mobberley 0245-475297 (weekdays) 0284-828431 (weekends) Variable Star Gary Poyner 021-3504312 Alerts Email: JANET:[email protected] STARLINK:BHVAD::GP For subscription rates and charges for charts and other publications see inside back cover Forthcoming Variable Star Meeting in Cambridge Jonathan Shanklin says that the Cambridge University Astronomical Society is planning a one-day meeting on the subject of variable stars to be held in Cambridge on Saturday, 19th February 1994. -
The Chemical Composition of Solar-Type Stars and Its Impact on the Presence of Planets
The chemical composition of solar-type stars and its impact on the presence of planets Patrick Baumann Munchen¨ 2013 The chemical composition of solar-type stars and its impact on the presence of planets Patrick Baumann Dissertation der Fakultat¨ fur¨ Physik der Ludwig-Maximilians-Universitat¨ Munchen¨ durchgefuhrt¨ am Max-Planck-Institut fur¨ Astrophysik vorgelegt von Patrick Baumann aus Munchen¨ Munchen,¨ den 31. Januar 2013 Erstgutacher: Prof. Dr. Achim Weiss Zweitgutachter: Prof. Dr. Joachim Puls Tag der mündlichen Prüfung: 8. April 2013 Zusammenfassung Wir untersuchen eine mogliche¨ Verbindung zwischen den relativen Elementhaufig-¨ keiten in Sternatmospharen¨ und der Anwesenheit von Planeten um den jeweili- gen Stern. Um zuverlassige¨ Ergebnisse zu erhalten, untersuchen wir ausschließlich sonnenahnliche¨ Sterne und fuhren¨ unsere spektroskopischen Analysen zur Bestim- mung der grundlegenden Parameter und der chemischen Zusammensetzung streng differenziell und relativ zu den solaren Werten durch. Insgesamt untersuchen wir 200 Sterne unter Zuhilfenahme von Spektren mit herausragender Qualitat,¨ die an den modernsten Teleskopen gewonnen wurden, die uns zur Verfugung¨ stehen. Mithilfe der Daten fur¨ 117 sonnenahnliche¨ Sterne untersuchen wir eine mogliche¨ Verbindung zwischen der Oberflachenh¨ aufigkeit¨ von Lithium in einem Stern, seinem Alter und der Wahrscheinlichkeit, dass sich ein oder mehrere Sterne in einer Um- laufbahn um das Objekt befinden. Fur¨ jeden Stern erhalten wir sehr exakte grundle- gende Parameter unter Benutzung einer sorgfaltig¨ zusammengestellten Liste von Fe i- und Fe ii-absorptionslinien, modernen Modellatmospharen¨ und Routinen zum Erstellen von Modellspektren. Die Massen und das Alter der Objekte werden mithilfe von Isochronen bestimmt, was zu sehr soliden relativen Werten fuhrt.¨ Bei jungen Sternen, fur¨ die die Isochronenmethode recht unzuverlssig¨ ist, vergleichen wir verschiedene alternative Methoden. -
A Terrestrial Planet Candidate in a Temperate Orbit Around Proxima Centauri
A terrestrial planet candidate in a temperate orbit around Proxima Centauri Guillem Anglada-Escude´1∗, Pedro J. Amado2, John Barnes3, Zaira M. Berdinas˜ 2, R. Paul Butler4, Gavin A. L. Coleman1, Ignacio de la Cueva5, Stefan Dreizler6, Michael Endl7, Benjamin Giesers6, Sandra V. Jeffers6, James S. Jenkins8, Hugh R. A. Jones9, Marcin Kiraga10, Martin Kurster¨ 11, Mar´ıa J. Lopez-Gonz´ alez´ 2, Christopher J. Marvin6, Nicolas´ Morales2, Julien Morin12, Richard P. Nelson1, Jose´ L. Ortiz2, Aviv Ofir13, Sijme-Jan Paardekooper1, Ansgar Reiners6, Eloy Rodr´ıguez2, Cristina Rodr´ıguez-Lopez´ 2, Luis F. Sarmiento6, John P. Strachan1, Yiannis Tsapras14, Mikko Tuomi9, Mathias Zechmeister6. July 13, 2016 1School of Physics and Astronomy, Queen Mary University of London, 327 Mile End Road, London E1 4NS, UK 2Instituto de Astrofsica de Andaluca - CSIC, Glorieta de la Astronoma S/N, E-18008 Granada, Spain 3Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, UK 4Carnegie Institution of Washington, Department of Terrestrial Magnetism 5241 Broad Branch Rd. NW, Washington, DC 20015, USA 5Astroimagen, Ibiza, Spain 6Institut fur¨ Astrophysik, Georg-August-Universitat¨ Gottingen¨ Friedrich-Hund-Platz 1, 37077 Gottingen,¨ Germany 7The University of Texas at Austin and Department of Astronomy and McDonald Observatory 2515 Speedway, C1400, Austin, TX 78712, USA 8Departamento de Astronoma, Universidad de Chile Camino El Observatorio 1515, Las Condes, Santiago, Chile 9Centre for Astrophysics Research, Science & Technology Research Institute, University of Hert- fordshire, Hatfield AL10 9AB, UK 10Warsaw University Observatory, Aleje Ujazdowskie 4, Warszawa, Poland 11Max-Planck-Institut fur¨ Astronomie Konigstuhl¨ 17, 69117 Heidelberg, Germany 12Laboratoire Univers et Particules de Montpellier, Universit de Montpellier, Pl. -
Double and Multiple Star Measurements in the Northern Sky with a 10” Newtonian and a Fast CCD Camera in 2006 Through 2009
Vol. 6 No. 3 July 1, 2010 Journal of Double Star Observations Page 180 Double and Multiple Star Measurements in the Northern Sky with a 10” Newtonian and a Fast CCD Camera in 2006 through 2009 Rainer Anton Altenholz/Kiel, Germany e-mail: rainer.anton”at”ki.comcity.de Abstract: Using a 10” Newtonian and a fast CCD camera, recordings of double and multiple stars were made at high frame rates with a notebook computer. From superpositions of “lucky images”, measurements of 139 systems were obtained and compared with literature data. B/w and color images of some noteworthy systems are also presented. mented double stars, as will be described in the next Introduction section. Generally, I used a red filter to cope with By using the technique of “lucky imaging”, seeing chromatic aberration of the Barlow lens, as well as to effects can strongly be reduced, and not only the reso- reduce the atmospheric spectrum. For systems with lution of a given telescope can be pushed to its limits, pronounced color contrast, I also made recordings but also the accuracy of position measurements can be with near-IR, green and blue filters in order to pro- better than this by about one order of magnitude. This duce composite images. This setup was the same as I has already been demonstrated in earlier papers in used with telescopes under the southern sky, and as I this journal [1-3]. Standard deviations of separation have described previously [1-3]. Exposure times varied measurements of less than +/- 0.05 msec were rou- between 0.5 msec and 100 msec, depending on the tinely obtained with telescopes of 40 or 50 cm aper- star brightness, and on the seeing. -
Hongkong Double Star Observations
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The Habitability of Proxima Centauri B: II: Environmental States and Observational Discriminants
The Habitability of Proxima Centauri b: II: Environmental States and Observational Discriminants Victoria S. Meadows1,2,3, Giada N. Arney1,2, Edward W. Schwieterman1,2, Jacob Lustig-Yaeger1,2, Andrew P. Lincowski1,2, Tyler Robinson4,2, Shawn D. Domagal-Goldman5,2, Rory K. Barnes1,2, David P. Fleming1,2, Russell Deitrick1,2, Rodrigo Luger1,2, Peter E. Driscoll6,2, Thomas R. Quinn1,2, David Crisp7,2 1Astronomy Department, University of Washington, Box 951580, Seattle, WA 98195 2NASA Astrobiology Institute – Virtual Planetary Laboratory Lead Team, USA 3E-mail: [email protected] 4Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, 5Planetary Environments Laboratory, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 6Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC 7Jet Propulsion Laboratory, California Institute of Technology, M/S 183-501, 4800 Oak Grove Drive, Pasadena, CA 91109 Abstract Proxima Centauri b provides an unprecedented opportunity to understand the evolution and nature of terrestrial planets orbiting M dwarfs. Although Proxima Cen b orbits within its star’s habitable zone, multiple plausible evolutionary paths could have generated different environments that may or may not be habitable. Here we use 1D coupled climate-photochemical models to generate self- consistent atmospheres for several of the evolutionary scenarios predicted in our companion paper (Barnes et al., 2016). These include high-O2, high-CO2, and more Earth-like atmospheres, with either oxidizing or reducing compositions. We show that these modeled environments can be habitable or uninhabitable at Proxima Cen b’s position in the habitable zone. We use radiative transfer models to generate synthetic spectra and thermal phase curves for these simulated environments, and use instrument models to explore our ability to discriminate between possible planetary states. -
Variabelbulletinen Nr. 1
Variabelbulletinen Nr 1 Augusti 2012 54600 54800 55000 55200 55400 55600 55800 56000 56200 3 4 5 6 7 8 9 10 11 12 13 14 Ljuskurva för miran Chi Cygni 2 Variabelbulletinen Nr 1. Augusti 2012. ISSN 2001-3930 En publikation från Svensk AmatörAstronomisk Förening Variabelsektionen (SAAF/V) Sektionsledare Chris Allen Ansvariga för databasen SVO Thomas Karlsson och Robert Wahlström Redaktör Hans Bengtsson Icke signerat material har författats av redaktören. Innehållsförteckning Introduktion. …………………...…………………………………………………………………….……………………….…… 4 Hans Bengtsson: Klassiska miror och legendariska variabilister. ………………...…….…..... 4 Thomas Karlsson: Epsilon Aurigae. ….……………………...……………………………...………………..…. 16 Hans Bengtsson: Våra variabler. Första delen. ………………………………………..…….....….……. 16 Thomas Karlsson: Ljusstark supernova i M101. ………………………………………………..…….… 26 Gustav Holmberg: Några RCB-stjärnor säsongen 2011-2012. …....…………...……….……. 28 Thomas Karlsson: Bestämning av period för 58 variabler. …………..……………...……….…... 31 Thomas Karlsson: Maxima för miror. ………………………………………………………………...……….… 33 Thomas Karlsson: Fotometri i Sagitta och Vulpecula. …………………………………………….… 34 Statistisk från SVO. ……………..…………………………………………...………………………………………...…… 38 Hans Bengtsson: Variabelmöten – en ny tradition. …………...……………………………………….. 39 Hans Bengtsson: Flera flugor i samma smäll. …………………………...............................…………... 40 Förstasidan Ljuskurva för miran Chi Cygni. Följande observatörer har bidragit till diagrammet: Chris Allen (45), Hans Bengtsson (102), Göran Fredriksson (9), -
RR Lyrae Stars As Seen by the Kepler Space Telescope
RR Lyrae stars as seen by the Kepler space telescope Emese Plachy 1;2;3,Robert´ Szabo,´ 1;2;3∗ 1Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Konkoly Thege Miklos´ ut´ 15-17, H-1121 Budapest, Hungary 2MTA CSFK Lendulet¨ Near-Field Cosmology Research Group 3ELTE Eotv¨ os¨ Lorand´ University, Institute of Physics, Budapest, Hungary Correspondence*: Robert´ Szabo´ [email protected] ABSTRACT The unprecedented photometric precision along with the quasi-continuous sampling provided by the Kepler space telescope revealed new and unpredicted phenomena that reformed and invigorated RR Lyrae star research. The discovery of period doubling and the wealth of low- amplitude modes enlightened the complexity of the pulsation behavior and guided us towards nonlinear and nonradial studies. Searching and providing theoretical explanation for these newly found phenomena became a central question, as well as understanding their connection to the oldest enigma of RR Lyrae stars, the Blazhko effect. We attempt to summarize the highest impact RR Lyrae results based on or inspired by the data of the Kepler space telescope both from the nominal and the K2 missions. Besides the three most intriguing topics, the period doubling, the low-amplitude modes, and the Blazhko effect, we also discuss the challenges of Kepler photometry that played a crucial role in the results. The secrets of these amazing variables, uncovered by Kepler, keep the theoretical, ground-based and space-based research inspired in the post-Kepler era, since light variation of RR Lyrae stars is still not completely understood. Keywords: RR Lyrae stars, Kepler spacecraft, Blazkho effect, pulsating variable stars, horizontal-branch stars, pulsation, asteroseismology, nonradial oscillations 1 INTRODUCTION RR Lyrae stars are large-amplitude, horizontal-branch pulsating stars which serve as tracers and distance indicators of old stellar populations in the Milky Way and neighboring galaxies.