Magnetism, Dynamo Action and the Solar-Stellar Connection
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Characterizing Two Solar-Type Kepler Subgiants with Asteroseismology: Kic 10920273 and Kic 11395018
The Astrophysical Journal, 763:49 (10pp), 2013 January 20 doi:10.1088/0004-637X/763/1/49 C 2013. The American Astronomical Society. All rights reserved. Printed in the U.S.A. CHARACTERIZING TWO SOLAR-TYPE KEPLER SUBGIANTS WITH ASTEROSEISMOLOGY: KIC 10920273 AND KIC 11395018 G. Doganˇ 1,2,3, T. S. Metcalfe1,3,4, S. Deheuvels3,5,M.P.DiMauro6, P. Eggenberger7, O. L. Creevey8,9,10, M. J. P. F. G. Monteiro11, M. Pinsonneault3,12, A. Frasca13, C. Karoff2, S. Mathur1,S.G.Sousa11,I.M.Brandao˜ 11, T. L. Campante11,14, R. Handberg2, A. O. Thygesen2,15, K. Biazzo16,H.Bruntt2, E. Niemczura17, T. R. Bedding18, W. J. Chaplin3,14, J. Christensen-Dalsgaard2,3,R.A.Garc´ıa3,19, J. Molenda-Zakowicz˙ 17, D. Stello18, J. L. Van Saders3,12, H. Kjeldsen2, M. Still20, S. E. Thompson21, and J. Van Cleve21 1 High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307, USA; [email protected] 2 Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark 3 Kavli Institute for Theoretical Physics, Kohn Hall, University of California, Santa Barbara, CA 93106, USA 4 Space Science Institute, Boulder, CO 80301, USA 5 Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101, USA 6 INAF-IAPS, Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy 7 Geneva Observatory, University of Geneva, Maillettes 51, 1290 Sauverny, Switzerland 8 Universite´ de Nice, Laboratoire Cassiopee,´ CNRS UMR 6202, Observatoire de la Coteˆ d’Azur, BP 4229, F-06304 Nice Cedex 4, France 9 IAC Instituto de Astrof´ısica de Canarias, C/V´ıa Lactea´ s/n, E-38200 Tenerife, Spain 10 Universidad de La Laguna, Avda. -
Arxiv:0906.0144V1 [Physics.Hist-Ph] 31 May 2009 Event
Solar physics at the Kodaikanal Observatory: A Historical Perspective S. S. Hasan, D.C.V. Mallik, S. P. Bagare & S. P. Rajaguru Indian Institute of Astrophysics, Bangalore, India 1 Background The Kodaikanal Observatory traces its origins to the East India Company which started an observatory in Madras \for promoting the knowledge of as- tronomy, geography and navigation in India". Observations began in 1787 at the initiative of William Petrie, an officer of the Company, with the use of two 3-in achromatic telescopes, two astronomical clocks with compound penduumns and a transit instrument. By the early 19th century the Madras Observatory had already established a reputation as a leading astronomical centre devoted to work on the fundamental positions of stars, and a principal source of stellar positions for most of the southern hemisphere stars. John Goldingham (1796 - 1805, 1812 - 1830), T. G. Taylor (1830 - 1848), W. S. Jacob (1849 - 1858) and Norman R. Pogson (1861 - 1891) were successive Government Astronomers who led the activities in Madras. Scientific high- lights of the work included a catalogue of 11,000 southern stars produced by the Madras Observatory in 1844 under Taylor's direction using the new 5-ft transit instrument. The observatory had recently acquired a transit circle by Troughton and Simms which was mounted and ready for use in 1862. Norman Pogson, a well known astronomer whose name is associated with the modern definition of the magnitude scale and who had considerable experience with transit instruments in England, put this instrument to good use. With the help of his Indian assistants, Pogson measured accurate positions of about 50,000 stars from 1861 until his death in 1891. -
The Ubvri and Infrared Colour Indices of the Sun and Sun-Like Stars
The 19th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun Edited by G. A. Feiden THE UBVRI AND INFRARED COLOUR INDICES OF THE SUN AND SUN-LIKE STARS Mehmet TANRIVER1, Ferhat Fikri ÖZEREN1 1 Erciyes University, Astronomy and Space Sciences Department, 38039, Kayseri, Turkey Abstract The Sun is not a point source, the photometric observational techniques that are utilised for observing other stars cannot be utilised for the Sun, meaning that it is dicult to derive its colours accurately for astronomical work from direct measurements in dierent passbands. The solar twins are the best choices because they are the stars that are ideally the same as the Sun in all parameters, and also, their colours are highly similar to those of the Sun. From the 60 articles on the Sun and Sun-like stars in the literature from 1964 until today, the solar colour indices in the optic and infrared regions have been estimated. 1 INTRODUCTION Table 1: The obtained average colour indices values of the The Sun is an average-low-mass star in the main sequence Sun with standart deviation (±σ)( Tanrıver (2012), Tanrıver of the Hertzsprung-Russell diagram. Moreover, the Sun is (2014a), Tanrıver (2014b) ). not a point source, the photometric observational techniques that are utilised for observing other stars cannot be utilised B-V 0.6457 ± 0.0421 V-J 1.1413 ± 0.1063 for the Sun. Therefore, the colours and colour indices of the H-K 0.0572 ± 0.0351 U-B 0.1463 ± 0.0596 sun-like stars are used in order to determine the sun’s colour V-H 1.4613 ± 0.1183 J-K 0.3777 ± 0.0494 indices. -
Naming the Extrasolar Planets
Naming the extrasolar planets W. Lyra Max Planck Institute for Astronomy, K¨onigstuhl 17, 69177, Heidelberg, Germany [email protected] Abstract and OGLE-TR-182 b, which does not help educators convey the message that these planets are quite similar to Jupiter. Extrasolar planets are not named and are referred to only In stark contrast, the sentence“planet Apollo is a gas giant by their assigned scientific designation. The reason given like Jupiter” is heavily - yet invisibly - coated with Coper- by the IAU to not name the planets is that it is consid- nicanism. ered impractical as planets are expected to be common. I One reason given by the IAU for not considering naming advance some reasons as to why this logic is flawed, and sug- the extrasolar planets is that it is a task deemed impractical. gest names for the 403 extrasolar planet candidates known One source is quoted as having said “if planets are found to as of Oct 2009. The names follow a scheme of association occur very frequently in the Universe, a system of individual with the constellation that the host star pertains to, and names for planets might well rapidly be found equally im- therefore are mostly drawn from Roman-Greek mythology. practicable as it is for stars, as planet discoveries progress.” Other mythologies may also be used given that a suitable 1. This leads to a second argument. It is indeed impractical association is established. to name all stars. But some stars are named nonetheless. In fact, all other classes of astronomical bodies are named. -
Habitability on Local, Galactic and Cosmological Scales
Habitability on local, Galactic and cosmological scales Luigi Secco1 • Marco Fecchio1 • Francesco Marzari1 Abstract The aim of this paper is to underline con- detectable studying our site. The Climatic Astronom- ditions necessary for the emergence and development ical Theory is introduced in sect.5 in order to define of life. They are placed at local planetary scale, at the circumsolar habitable zone (HZ) (sect.6) while the Galactic scale and within the cosmological evolution, translation from Solar to extra-Solar systems leads to a as pointed out by the Anthropic Cosmological Princi- generalized circumstellar habitable zone (CHZ) defined ple. We will consider the circumstellar habitable zone in sect.7 with some exemplifications to the Gliese-667C (CHZ) for planetary systems and a Galactic Habitable and the TRAPPIST-1 systems; some general remarks Zone (GHZ) including also a set of strong cosmologi- follow (sect.8). A first conclusion related to CHZ is cal constraints to allow life (cosmological habitability done moving toward GHZ and COSH (sect.9). The (COSH)). Some requirements are specific of a single conditions for the development of life are indeed only scale and its related physical phenomena, while others partially connected to the local scale in which a planet are due to the conspired effects occurring at more than is located. A strong interplay between different scales one scale. The scenario emerging from this analysis is exists and each single contribution to life from individ- that all the habitability conditions here detailed must ual scales is difficult to be isolated. However we will at least be met. -
UC Irvine UC Irvine Previously Published Works
UC Irvine UC Irvine Previously Published Works Title Astrophysics in 2006 Permalink https://escholarship.org/uc/item/5760h9v8 Journal Space Science Reviews, 132(1) ISSN 0038-6308 Authors Trimble, V Aschwanden, MJ Hansen, CJ Publication Date 2007-09-01 DOI 10.1007/s11214-007-9224-0 License https://creativecommons.org/licenses/by/4.0/ 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Space Sci Rev (2007) 132: 1–182 DOI 10.1007/s11214-007-9224-0 Astrophysics in 2006 Virginia Trimble · Markus J. Aschwanden · Carl J. Hansen Received: 11 May 2007 / Accepted: 24 May 2007 / Published online: 23 October 2007 © Springer Science+Business Media B.V. 2007 Abstract The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the Universe) and others of which there are always many, like meteors and molecules, black holes and binaries. Keywords Cosmology: general · Galaxies: general · ISM: general · Stars: general · Sun: general · Planets and satellites: general · Astrobiology · Star clusters · Binary stars · Clusters of galaxies · Gamma-ray bursts · Milky Way · Earth · Active galaxies · Supernovae 1 Introduction Astrophysics in 2006 modifies a long tradition by moving to a new journal, which you hold in your (real or virtual) hands. The fifteen previous articles in the series are referenced oc- casionally as Ap91 to Ap05 below and appeared in volumes 104–118 of Publications of V. -
Rotational Cherecteristics of Solar Radio Emissions
Rotational charecteristics of solar radio emissions and IMF: A comparative study Mehul Mehta1, and Hari Om Vats2 1 VP & RPTP Science college, Vallabh Vidyanagar, 388 120, INDIA. meghdhanusha@yahoo,co.in 2 Physical Research Laboratory, Navrangpura, Ahmedabad, 380 009, INDIA. [email protected] Abstract In present work we have performed autocorrelation analysis of time series of disc integrated solar flux at 2800 MHz and daily observations of Interplanetary magnetic field (IMF) for the period of 1987 to 2010 to infer rotation period. The analysis presents a comparison between rotation periods obtained from radio emissions, a coronal feature and interplanetary magnetic field. The results show a correlation between two which indicates that IMF seems to emanate from regions of low latitudes while it is expected to originate from polar regions. 1.Introduction: The problem of solar rotation is being studied systematically since mid of 19th century. It was made clear that the Sun does not rotate like a solid body. Solar rotation is measured, mainly by two methods. One is observation of tracers like sunspots, faculae, filaments etc. and other is spectroscopic observations of Doppler shift of selected spectral lines. Each of these methods has its own limitations as pointed by Howard [1], in the review of observation and interpretation of solar rotation. In last two decades it has been shown by several groups that solar radio emissions can be used to estimate solar rotation [2,3 & 4] In this paper, we have used yet another method of inferring solar rotation using daily observations of solar radio emissions at 2800 MHz and interplanetary magnetic field (IMF). -
Asteroseismology Notes
2 observed pulsations • operate on the dynamical time scale Asteroseismology • accessible on convenient time scale • probe global and local structure Steve Kawaler • periods change on ‘evolutionary’ time scale Iowa State University (thermal or nuclear) - depend on global properties • amplitudes change on ~ ‘local’ thermal time scale 3 4 dynamical stability a more complex example: a star • “stable” configuration represents a stable mean configuration • multiple oscillation modes • on short time scale, oscillations occur, but the • radial modes - enumerated by number of mean value is fixed on longer time scales nodes between center and surface • simple example: a pendulum (single mode) • most likely position - extrema • non-radial modes - nodes also across • mean position is at zero displacement surface of constant radius with no damping would oscillate forever • • modes frequencies determined by solution of • more complex example: a vibrating string the appropriate wave equation • multiple modes with different frequencies • enumerated by number of nodes 5 6 stability, damping, and driving Okay, start your engines... • PG 1159: light curve • zero energy change: what kind of star might this be? constant amplitude oscillation • • what kind of star can this not possibly be? • energy loss via pulsation: • what about the amplitude over the run? oscillation amplitude drops with time • PG 1336 light curve • if net energy input: • huh? what time scale(s) are involved amplitude increases with time • what kind of star (or stars)? (if properly phased) -
Exoplanet Community Report
JPL Publication 09‐3 Exoplanet Community Report Edited by: P. R. Lawson, W. A. Traub and S. C. Unwin National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California March 2009 The work described in this publication was performed at a number of organizations, including the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). Publication was provided by the Jet Propulsion Laboratory. Compiling and publication support was provided by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement by the United States Government, or the Jet Propulsion Laboratory, California Institute of Technology. © 2009. All rights reserved. The exoplanet community’s top priority is that a line of probeclass missions for exoplanets be established, leading to a flagship mission at the earliest opportunity. iii Contents 1 EXECUTIVE SUMMARY.................................................................................................................. 1 1.1 INTRODUCTION...............................................................................................................................................1 1.2 EXOPLANET FORUM 2008: THE PROCESS OF CONSENSUS BEGINS.....................................................2 -
Solar Dynamo Wu Xuanyi Adviser: Prof
Solar dynamo Wu Xuanyi Adviser: Prof. Yuqing Lou, Prof. Xuening Bai 2019/05/24 OUTLINE • Introduction: sunspots and solar cycle • Solar dynamo model • α Ω dynamo • Interface dynamo (Babcock-Leighton mechanism) • Flux transport dynamo • Summary −4 Observation: sunspots 1G = 10 T earliest extant record of sunspots: Book of Changes dark spots on sun (Galileo) have lower temperature with respect to surrounding life time: days to weeks Regions of intense magnetic fields : 0.1~0.3T ( the normal magnetic field of sun is ~10G; for earth, 0.5G) Often in pairs: leading and trailing sunspots Hale’s polarity law: opposite polarity from north to south hemisphere;the polarity changes each solar cycle Observation: solar cycle • Sunspot activity changes spatially and periodically • Sunspot activity has a period of ~11 years with magnetic field reversed • Solar cycle ~ 22 years Sunspot activity caused by advection/diffusion? Induction equation: Advection Diffusion B ηB Reynolds number: diffusion time scale : = 2 τd L τd Lu Rm = = B uB τa η advection time scale : = τa L • Rm of sun>>1 => advection dominated; field line frozen in the plasma flow • But, the diffusion time scale of sun ~ 10 10 years ≫ solar cycle period • Need other mechanism to explain solar activities Solar dynamo theory A solar dynamo model should… • Sustain the magnetic field • Cyclic polarity of 11year period • Equator-ward migration of sunspots and pole-ward migration of diffuse surface field • Polar field strength • Observed antisymmetric parity • … Solar dynamo model • αΩ dynamo • Interface dynamo -
Planet Hunters1 (Fischer Et Al
draft version May 31, 2012 Planet Hunters: Assessing the Kepler Inventory of Short Period Planets Megan E. Schwamb1,2,3,Chris J. Lintott4,5, Debra A. Fischer6, Matthew J. Giguere6, Stuart Lynn5,4, Arfon M. Smith5,4, John M. Brewer6, Michael Parrish5, Kevin Schawinski2,3,7, and Robert J. Simpson4 [email protected] ABSTRACT We present the results from a search of data from the first 33.5 days of the Kepler science mission (Quarter 1) for exoplanet transits by the Planet Hunters citizen science project. Planet Hunters enlists members of the general public to visually identify tran- sits in the publicly released Kepler light curves via the World Wide Web. Over 24,000 volunteers reviewed the Kepler Quarter 1 data set. We examine the abundance of ≥ 2 R⊕ planets on short period (< 15 days) orbits based on Planet Hunters detections. We present these results along with an analysis of the detection efficiency of human classifiers to identify planetary transits including a comparison to the Kepler inventory of planet candidates. Although performance drops rapidly for smaller radii, ≥ 4 R⊕ Planet Hunters ≥ 85% efficient at identifying transit signals for planets with periods less than 15 days for the Kepler sample of target stars. Our high efficiency rate for simulated transits along with recovery of the majority of Kepler ≥4R⊕ planets suggest suggests the Kepler inventory of ≥4 R⊕ short period planets is nearly complete. Subject headings: Planets and satellites: detection-Planets and satellites: general 1. Introduction In the past nearly two decades, there has been an explosion in the number of known planets arXiv:1205.6769v1 [astro-ph.EP] 30 May 2012 orbiting stars beyond our own solar system, with over 700 extrasolar planets (exoplanets) known 1Yale Center for Astronomy and Astrophysics, Yale University,P.O. -
Solar and Heliospheric Magnetism in 5D
Heliophysics 2050 White Papers (2021) 4034.pdf Solar and Heliospheric Magnetism in 5D A. Pevtsov (NSO), T. Woods (CU/LASP), V. Martinez Pillet (NSO), D. Hassler (SwRI), T. Berger (CU/SWx TREC), S. Gosain (NSO), T. Hoeksema (Stanford U), A. Jones (CU/LASP), R. Kohnert (CU/LASP) Magnetic field in the solar atmosphere and heliosphere is a global, ever-changing, multi-scale system. Active regions that emerge, evolve, and decay in one “place” on the solar surface may cause small or big changes in other remote areas and in the extreme cases, over the whole solar corona. Small-scale instabilities could cause localized eruptions, or they may cascade to much larger scales, both across the “surface” and with height. Once the magnetized structures start erupting from the solar atmosphere, their magnetic systems may go through a complex reconnection process with overlaying large-scale fields including those rooted in solar polar areas. After it erupts, the magnetic system continues evolving as it travels towards Earth, Mars and beyond. In addition to spatial scales, magnetic fields may evolve on different time scales from rapid eruption processes to relatively slow evolutionary changes. To properly capture and study these changes in different spatial and temporal scales requires taking observations from multiple vantage points at sufficiently high time cadence, which we refer to as 5D concept (3D for three spatial directions, 1D time, and 1D magnetic field). The following six key inter-related science objectives are important to address before 2050 to advance the understanding of solar and heliospheric magnetism in 5D. 1. Understand the global interconnected magnetic system in the solar corona Active region emergence may cause magnetic field restructuring in remote locations (Zhang & Low 2001, 2002; Longcope et al.