DOCSLIB.ORG

AD Leonis: Radial Velocity Signal of Stellar Rotation Or Spin-Orbit

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
AD Leonis: Radial Velocity Signal of Stellar Rotation Or Spin-Orbit Draft version June 28, 2021 A Preprint typeset using LTEX style emulateapj v. 12/16/11 AD LEONIS: RADIAL VELOCITY SIGNAL OF STELLAR ROTATION OR SPIN-ORBIT RESONANCE? Mikko Tuomi1, Hugh R. A. Jones1, John R. Barnes2, Guillem Anglada-Escude´3, R. Paul Butler4, Marcin Kiraga5, Steven S. Vogt6 Draft version June 28, 2021 ABSTRACT AD Leonis is a nearby magnetically active M dwarf. We find Doppler variability with a period of 2.23 days as well as photometric signals: (1) a short period signal which is similar to the radial velocity signal albeit with considerable variability; and (2) a long term activity cycle of 4070±120 days. We examine the short-term photometric signal in the available ASAS and MOST photometry and find that the signal is not consistently present and varies considerably as a function of time. This signal undergoes a phase change of roughly 0.8 rad when considering the first and second halves of the MOST data set which are separated in median time by 3.38 days. In contrast, the Doppler signal is stable in the combined HARPS and HIRES radial velocities for over 4700 days and does not appear to vary in time in amplitude, phase, period or as a function of extracted wavelength. We consider a variety of star-spot scenarios and find it challenging to simultaneously explain the rapidly varying photometric signal and the stable radial velocity signal as being caused by starspots co-rotating on the stellar surface. This suggests that the origin of the Doppler periodicity might be the gravitational tug of a planet orbiting the star in spin-orbit resonance. For such a scenario and no spin-orbit misalignment, the measured v sin i indicates an inclination angle of 15.5±2.5 deg and a planetary companion mass of 0.237±0.047 MJup. Subject headings: methods: statistical, numerical – techniques: radial velocities – planets and satellites: detection – stars: individual: GJ 388 1. INTRODUCTION signals differently or even disagreed in how many signals The Doppler spectroscopy technique has been a suc- could be detected. However, the controversial signals cessful method for the detection of planets orbiting in the radial velocities of these targets have very low nearby stars by enabling observers to measure the amplitudes, which necessarily makes their detection and changes in stellar radial velocities caused by planets interpretation difficult. This is not the case for AD orbiting them on Keplerian orbits. For such detec- Leonis (AD Leo, GJ 388, BD +20 2465) that has been tion of planets, M dwarfs are especially fruitful tar- reported to experience radial velocity variations with a gets by being hosts to at least 2.5 planets per star period of 2.23 days (Bonfils et al. 2013; Reiners et al. (Dressing & Charbonneau 2015; Tuomi et al. 2017); be- 2013). Both Bonfils et al. (2013) and Reiners et al. cause their star-planet mass-ratios are lower than for F, (2013) interpreted the 2.23-day periodicity as a signal G, and K dwarfs and therefore better enable detections originating from the co-rotation of starspots on the of planetary signals; and because they are the most fre- stellar surface because the spectra showed line asymme- quent stars in the galaxy and in the Solar neighbourhood tries that were correlated with the velocity variations. (Chabrier & Baraffe 2000; Winters et al. 2015). This means that the radial velocities of AD Leo might Some nearby M dwarfs, such as GJ 581 provide a benchmark case for examining the differences (Vogt et al. 2010, 2012; Tuomi 2011; Baluev 2013; between Doppler signals caused by stellar rotation and Robertson et al. 2014), GJ 667C (Anglada-Escud´eet al. planets on Keplerian orbits. 2012a, 2013; Feroz& Hobson 2014) and GJ 191 Newton et al. (2016) has articulated the detectability arXiv:1802.06064v2 [astro-ph.EP] 21 Feb 2018 (Anglada-Escud´eet al. 2014, 2016; Robertson et al. challenge that is faced for older M dwarfs. Their range 2015) have been sources of controversies in the sense of stellar rotation periods coincides with both the pe- that different authors have interpreted the observed riods where many of their planets lie as well as with their habitable zones. Therefore, a rotational signal 1 Centre for Astrophysics Research, School of Physics, As- might impersonate a radial velocity signal that would tronomy and Mathematics, University of Hertfordshire, College be assigned to a candidate planet. A further consider- Lane, AL10 9AB, Hatfield, UK ation is that the rotation period of star might become 2 Department of Physical Sciences, The Open University, Wal- locked to the orbital period of the planet and that even- ton Hall, Milton Keynes, MK7 6AA, UK tually spiral in will occur (e.g. Hut 1980; Adams & Bloch 3 School of Physics and Astronomy, Queen Mary University of 2015). For Kepler stars there does appear to be a dearth London, 327 Mile End Road, E1 4NS, London, United Kingdom 4 Department of Terrestrial Magnetism, Carnegie Institution of planets at short orbital periods around fast rotat- of Washington, 5241 Broad Branch Road NW, Washington D.C. ing stars (McQuillan et al. 2013; Teitler & K¨onigl 2014). USA Only slow stellar rotators, with rotation periods longer 20015-1305 than 5-10 days, have planets with periods shorter than 5 Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478 Warszawa, Poland 2 or 3 days (see e.g. Fig. 2 of McQuillan et al. 2013). 6 UCO/Lick Observatory, University of California, Santa Teitler & K¨onigl (2014) ran numerical simulations to in- Cruz, CA 95064, USA vestigate “why there is a dearth of close-orbiting planets 2 Tuomi et al. around fast-orbiting stars” and find that this can be at- by “spots distributed at different longitudes or, possi- tributed to tidal ingestion of close-in planets by their host bly, that the modulation is caused by varying surface stars. Finding examples of such stars in the Solar neigh- coverage of a large polar spot or a spot that is viewed bourhood would then enable studying this mechanism in nearly pole-on.” This suggests a young age and indeed detail. Shkolnik et al. (2009) have estimated an age of 25-300 In the current work, we analyse the available HARPS Myr. Since the results of Hunt-Walker et al. (2012) were and HIRES data in order to test the validity of the inter- based on a MOST photometric time-series with a base- pretation that the 2.23-day signal in the radial velocities line of only eight days, and there was evidence for vari- of AD Leo is indeed caused by stellar rotation rather ation of the parameters of the periodic signal caused than tidal locking. In particular, we study the proper- by stellar rotation, their results suggest the presence of ties of the signal given different models accounting for changing spot patterns that would be unlikely to produce activity-induced radial velocity variations or not, and by stable signals in photometric or spectroscopic data over examining the dependence of the signal on the spectral longer time-scales. wavelength range used to derive the differential radial ve- AD Leo has been observed to be variable on longer locities. We also analyse the All-Sky Automated Survey time-scales as well. Buccino et al. (2014) reported (ASAS; Pojma´nski 1997, 2002) V-band photometry data an approximately seven-year activity cycle based on and Microvariability and Oscillations of STars (MOST) ASAS photometry and CASLEO spectroscopy. Al- photometry (Hunt-Walker et al. 2012) of the target in though ASAS could not cover a whole period of this cy- order to study the signatures of stellar rotation. More- cle, and CASLEO detected it only weakly significantly over, we attempt to explain the photometric and spec- (with a false alarm probability of 8%), together they in- troscopic variability by simulating simple starspot sce- dicate the presence of such a cycle rather convincingly. narios. Finally, we compare the results to other known It is worth noting that Engle et al. (2009) mentioned a rapidly rotating nearby M dwarfs in order to see what, if photometric periodicity of 2.23 days (with an amplitude any, connections there are between photometric rotation of ≈ 17 mmag, judging by their phase-folded plot) but periods and radial velocity variations. the significance and uniqueness of their solution was not discussed. 2. AD LEO The estimated v sin i of AD Leo is 2.63 kms−1 AD Leo (GJ 388) is a frequently flaring (Houdebine et al. 2016). Together with a radius estimate (Hunt-Walker et al. 2012; Buccino et al. 2014) M4.5V of 0.436±0.049, Houdebine et al. (2016) then calculated +1.2 dwarf with a parallax of 213±4 mas implying a distance a projected rotation period of 8.38−1.1 days. Thus, be- of only 4.9 pc. Based on Delfosse et al. (2000) and cause the rotation period of the star is 2.23 days, this im- ◦ +2.5 the V and J-band magnitudes, Bonfils et al. (2013) plies inclination of the rotation axis of 15.5 −2.0, which estimate a mass of 0.42 M⊙ and a luminosity of 0.023 means that the star is oriented nearly pole-on. L⊙ as the star was included in their HARPS Search for Southern Extra-Solar Planets programme. Given V 3. SPECTROSCOPIC AND PHOTOMETRIC DATA and J magnitudes of 9.52 (Zacharias et al. 2013) and 3.1. HARPS radial velocities 5.449±0.027 (Cutri et al. 2003) we obtain a mass of 0.36 Spectroscopic data of AD Leo were obtained from two by also applying the relation of Delfosse et al.
Load more

Recommended publications
  • The Transfiguration in the Theology of Gregory Palamas And
    Duquesne University Duquesne Scholarship Collection Electronic Theses and Dissertations Spring 2015 Deus in se et Deus pro nobis: The rT ansfiguration in the Theology of Gregory Palamas and Its Importance for Catholic Theology Cory Hayes Follow this and additional works at: https://dsc.duq.edu/etd Recommended Citation Hayes, C. (2015). Deus in se et Deus pro nobis: The rT ansfiguration in the Theology of Gregory Palamas and Its Importance for Catholic Theology (Doctoral dissertation, Duquesne University). Retrieved from https://dsc.duq.edu/etd/640 This Immediate Access is brought to you for free and open access by Duquesne Scholarship Collection. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of Duquesne Scholarship Collection. For more information, please contact [email protected]. DEUS IN SE ET DEUS PRO NOBIS: THE TRANSFIGURATION IN THE THEOLOGY OF GREGORY PALAMAS AND ITS IMPORTANCE FOR CATHOLIC THEOLOGY A Dissertation Submitted to the McAnulty Graduate School of Liberal Arts Duquesne University In partial fulfillment of the requirements for the degree of Doctor of Philosophy By Cory J. Hayes May 2015 Copyright by Cory J. Hayes 2015 DEUS IN SE ET DEUS PRO NOBIS: THE TRANSFIGURATION IN THE THEOLOGY OF GREGORY PALAMAS AND ITS IMPORTANCE FOR CATHOLIC THEOLOGY By Cory J. Hayes Approved March 31, 2015 _______________________________ ______________________________ Dr. Bogdan Bucur Dr. Radu Bordeianu Associate Professor of Theology Associate Professor of Theology (Committee Chair) (Committee Member) _______________________________ Dr. Christiaan Kappes Professor of Liturgy and Patristics Saints Cyril and Methodius Byzantine Catholic Seminary (Committee Member) ________________________________ ______________________________ Dr. James Swindal Dr.
    [Show full text]
  • AD Leonis: Flares Observed by XMM-Newton and Chandra
    A&A 411, 587–593 (2003) Astronomy DOI: 10.1051/0004-6361:20031398 & c ESO 2003 Astrophysics AD Leonis: Flares observed by XMM-Newton and Chandra E. J. M. van den Besselaar1;2, A. J. J. Raassen1;3,R.Mewe1,R.L.J.vanderMeer1,M.G¨udel4, and M. Audard5 1 SRON National Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands e-mail: [email protected];[email protected];[email protected] 2 Department of Astrophysics, University of Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands 3 Astronomical Institute “Anton Pannekoek”, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands 4 Paul Scherrer Institut, W¨urenlingen & Villigen, 5232 Villigen PSI, Switzerland e-mail: [email protected] 5 Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027, USA e-mail: [email protected] Received 3 February 2003 / Accepted 2 September 2003 Abstract. The M-dwarf AD Leonis has been observed with the Reflection Grating Spectrometers and the European Photon Imaging Camera aboard XMM-Newton and also with the Low Energy Transmission Grating Spectrometer aboard the Chandra X-ray Observatory. In the observation taken with XMM-Newton five large flares produced by AD Leo were identified and only one in the observation taken with Chandra. A quiescent level to the lightcurves is difficult to define, since several smaller flares mutually overlap each other. However, we defined a quasi-steady state outside of obvious flares or flare decays. The spectra from the flare state and the quasi-steady state are analysed separately.
    [Show full text]
  • Microwave Kinetic Inductance Detectors for High Contrast Imaging with DARKNESS and MEC
    Mazin Lab at UCSB http://mazinlab.org Microwave Kinetic Inductance Detectors for High Contrast Imaging with DARKNESS and MEC Ben Mazin, June 2017 The UVOIR MKID Team: UCSB: Ben Mazin, Seth Meeker, Paul Szypryt, Gerhard Ulbricht, Alex Walter, Clint Bocksteigel, Giulia Collura, Neelay Fruitwala, Isabel Liparito, Nicholas Zobrist, Gregoire Coiffard, Miguel Daal, James Massie JPL/IPAC: Bruce Bumble, Julian van Eyken Oxford: Kieran O’Brien, Rupert Dodkins Fermilab: Juan Estrada, Gustavo Cancelo, Chris Stoughton Mazin Lab at UCSB http://mazinlab.org Superconductors A superconductor is a material where all DC resistance disappears at a “critical temperature”. 9 K for Nb, 1.2 K for Al, 0.9 for PtSi This is caused by electrons pairing up to form “Cooper Pairs” Nobel Prize to BCS in 1972 Like a semiconductor, there is a “gap” in a superconductor, but it is 1000-10000x lower than the gap in Si Instead of one electron per photon in a semiconductor, we get ~5000 electrons per photon in a superconductor – much easier to measure (no noise and energy determination)! We call these excitations quasiparticles. However, superconductors don’t support electric fields (perfect conductors!) so CCD methods of shuffling charge around don’t work Excitations are short lived, lifetimes of ~50 microseconds Mazin Lab at UCSB http://mazinlab.org MKIDs MKID Equivalent Circuit Typical Single Photon Event Inductor is a Superconductor! Energy Gap Silicon – 1.10000 eV PtSi or TiN – 0.00013 eV Cooper Energy resolution: Pair Mazin Lab at UCSB http://mazinlab.org What
    [Show full text]
  • 1 the Effect of a Strong Stellar Flare on the Atmospheric Chemistry of An
    The Effect of a Strong Stellar Flare on the Atmospheric Chemistry of an Earth-like Planet Orbiting an M dwarf (Astrobiology, accepted) Antígona Segura 1,* , Lucianne Walkowicz 2,* , Victoria Meadows 3,* , James Kasting 4,* , Suzanne Hawley 5 1Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, 2University of California at Berkeley, 3University of Washington, 4Pennsylvania State University, 5University of Washington *Members of the Virtual Planet Laboratory Lead Team of the NASA Astrobiology Institute. To whom correspondence should be directed: Antígona Segura Universidad Nacional Autónoma de México Instituto de Ciencias Nucleares Circuito Exterior C.U. A.Postal 70-543 04510 México D.F. Phone: 52 (55) 5622 4739 ext. 269 Fax 52 (55) 56 22 46 82 E-mail: [email protected] Running title: Flare effect on an Earth-like planet Abstract Main sequence M stars pose an interesting problem for astrobiology: their abundance in our galaxy makes them likely targets in the hunt for habitable planets, but their strong chromospheric activity produces high energy radiation and charged particles that may be detrimental to life. We studied the impact of the 1985 April 12 flare from the M dwarf, AD Leonis (AD Leo), simulating the effects from both UV radiation and protons on the atmospheric chemistry of a hypothetical, Earth-like planet located within its habitable zone. Based on observations of solar proton events and the Neupert effect we estimated a proton flux associated with the flare of 5.9×10 8 protons cm -2 sr -1 s -1 for particles with energies >10MeV. Then we calculated the abundance of nitrogen oxides produced by the flare by scaling the production of these compounds during a large solar proton event called the “Carrington event”.
    [Show full text]
  • Planet Searching from Ground and Space
    Planet Searching from Ground and Space Olivier Guyon Japanese Astrobiology Center, National Institutes for Natural Sciences (NINS) Subaru Telescope, National Astronomical Observatory of Japan (NINS) University of Arizona Breakthrough Watch committee chair June 8, 2017 Perspectives on O/IR Astronomy in the Mid-2020s Outline 1. Current status of exoplanet research 2. Finding the nearest habitable planets 3. Characterizing exoplanets 4. Breakthrough Watch and Starshot initiatives 5. Subaru Telescope instrumentation, Japan/US collaboration toward TMT 6. Recommendations 1. Current Status of Exoplanet Research 1. Current Status of Exoplanet Research 3,500 confirmed planets (as of June 2017) Most identified by Jupiter two techniques: Radial Velocity with Earth ground-based telescopes Transit (most with NASA Kepler mission) Strong observational bias towards short period and high mass (lower right corner) 1. Current Status of Exoplanet Research Key statistical findings Hot Jupiters, P < 10 day, M > 0.1 Jupiter Planetary systems are common occurrence rate ~1% 23 systems with > 5 planets Most frequent around F, G stars (no analog in our solar system) credits: NASA/CXC/M. Weiss 7-planet Trappist-1 system, credit: NASA-JPL Earth-size rocky planets are ~10% of Sun-like stars and ~50% abundant of M-type stars have potentially habitable planets credits: NASA Ames/SETI Institute/JPL-Caltech Dressing & Charbonneau 2013 1. Current Status of Exoplanet Research Spectacular discoveries around M stars Trappist-1 system 7 planets ~3 in hab zone likely rocky 40 ly away Proxima Cen b planet Possibly habitable Closest star to our solar system Faint red M-type star 1. Current Status of Exoplanet Research Spectroscopic characterization limited to Giant young planets or close-in planets For most planets, only Mass, radius and orbit are constrained HR 8799 d planet (direct imaging) Currie, Burrows et al.
    [Show full text]
  • April 2016 BRAS Newsletter
    April 2016 Issue th Next Meeting: Monday, April 11 at 7PM at HRPO (2nd Mondays, Highland Road Park Observatory) April 6th through April 10th is our annual Hodges Gardens Star Party. You can pre-register using the form on the BRAS website. If you have never attended this star party, make plans to attend this one. What's In This Issue? President’s Message Photos: BRAS Telescope donated to EBRP Library Secretary's Summary of March Meeting Recent BRAS Forum Entries 20/20 Vision Campaign Message from the HRPO Astro Short: Stellar Dinosaurs? International Astronomy Day Observing Notes: Leo The Lion, by John Nagle Newsletter of the Baton Rouge Astronomical Society April 2016 Page 2 President’s Message There were 478 people who stopped by the BRAS display at the March 19th ―Rockin at the Swamp‖ event at the Bluebonnet Swamp and Nature Center. I give thanks to all our volunteers for our success in this outreach event. April 6th through April 10th is our annual Hodges Gardens Star Party. You can pre-register on the BRAS website, or register when you arrive (directions are on the BRAS website). If you have never attended a star party, of if you are an old veteran star partier; make plans to attend this one. Our Guest Speaker for the BRAS meeting on April 11th will be Dr. Joseph Giaime, Observatory Head, LIGO Livingston (Caltech), Professor of Physics and Astronomy (LSU). Yes, he will be talking about gravity waves and the extraordinary discovery LIGO has made. We need volunteers to help at our display on Earth Day on Sunday, April 17th.
    [Show full text]
  • Download This Issue (Pdf)
    Volume 43 Number 1 JAAVSO 2015 The Journal of the American Association of Variable Star Observers The Curious Case of ASAS J174600-2321.3: an Eclipsing Symbiotic Nova in Outburst? Light curve of ASAS J174600-2321.3, based on EROS-2, ASAS-3, and APASS data. Also in this issue... • The Early-Spectral Type W UMa Contact Binary V444 And • The δ Scuti Pulsation Periods in KIC 5197256 • UXOR Hunting among Algol Variables • Early-Time Flux Measurements of SN 2014J Obtained with Small Robotic Telescopes: Extending the AAVSO Light Curve Complete table of contents inside... The American Association of Variable Star Observers 49 Bay State Road, Cambridge, MA 02138, USA The Journal of the American Association of Variable Star Observers Editor John R. Percy Edward F. Guinan Paula Szkody University of Toronto Villanova University University of Washington Toronto, Ontario, Canada Villanova, Pennsylvania Seattle, Washington Associate Editor John B. Hearnshaw Matthew R. Templeton Elizabeth O. Waagen University of Canterbury AAVSO Christchurch, New Zealand Production Editor Nikolaus Vogt Michael Saladyga Laszlo L. Kiss Universidad de Valparaiso Konkoly Observatory Valparaiso, Chile Budapest, Hungary Editorial Board Douglas L. Welch Geoffrey C. Clayton Katrien Kolenberg McMaster University Louisiana State University Universities of Antwerp Hamilton, Ontario, Canada Baton Rouge, Louisiana and of Leuven, Belgium and Harvard-Smithsonian Center David B. Williams Zhibin Dai for Astrophysics Whitestown, Indiana Yunnan Observatories Cambridge, Massachusetts Kunming City, Yunnan, China Thomas R. Williams Ulisse Munari Houston, Texas Kosmas Gazeas INAF/Astronomical Observatory University of Athens of Padua Lee Anne M. Willson Athens, Greece Asiago, Italy Iowa State University Ames, Iowa The Council of the American Association of Variable Star Observers 2014–2015 Director Arne A.
    [Show full text]
  • The Astrology of Space
    The Astrology of Space 1 The Astrology of Space The Astrology Of Space By Michael Erlewine 2 The Astrology of Space An ebook from Startypes.com 315 Marion Avenue Big Rapids, Michigan 49307 Fist published 2006 © 2006 Michael Erlewine/StarTypes.com ISBN 978-0-9794970-8-7 All rights reserved. No part of the publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the publisher. Graphics designed by Michael Erlewine Some graphic elements © 2007JupiterImages Corp. Some Photos Courtesy of NASA/JPL-Caltech 3 The Astrology of Space This book is dedicated to Charles A. Jayne And also to: Dr. Theodor Landscheidt John D. Kraus 4 The Astrology of Space Table of Contents Table of Contents ..................................................... 5 Chapter 1: Introduction .......................................... 15 Astrophysics for Astrologers .................................. 17 Astrophysics for Astrologers .................................. 22 Interpreting Deep Space Points ............................. 25 Part II: The Radio Sky ............................................ 34 The Earth's Aura .................................................... 38 The Kinds of Celestial Light ................................... 39 The Types of Light ................................................. 41 Radio Frequencies ................................................. 43 Higher Frequencies ...............................................
    [Show full text]
  • A Green Line Around the Box Means a Habitable Planet Exists in the Starsystem
    Hussey 575 BD+30 2494 BD+24 2733 1.5 BD+14 2774 2.5 1.5 1.5 Ross 512 1.5 WO 9502 1.5 BD+17 2785 2 BD+15 3108 G136-101 Sigma Bootis BD+30 2512 1 Struve 1785 1.5 1 2.5 via LP441.33 1.5 BD+24 2786 1.5 1.5 1.5 1.5 1.5 45 Bootis L1344-37 GJ 3966 Ross 863 1.5 Lambda Serpentis Wolf 497 BD+25 2874 1.5 3 via V645 Herc Gliese 625 1 1.5 3.5 via GJ 3910 3 via V645 Herc 1.5 BD-9 3413 GJ-1179 Zeta Herculis 1.5 Eta Bootes 1 Rho Coronae Borealis 1.5 1.5 2.5 via Giclas 258.33 Luyten 758-105 BD+54 1716 1 BD+25 3173 Giclas 179-43 1.5 1.5 1.5 1 3 via Ross 948 3 via WO 9564 3 via GJ 3796 3 via Ross 948 Eta Coronae Borealis Chi Draconis 3 via HYG86887 1 3.5 via V645 Herc 1 Gamma Serpentis 2 BD+17 2611 (VESTA) Arcturus 3 via V645 Herc 3 via BD+21 2763 3.5 via BD+0 2989, DT Virginis 4 via HYG86887&8 Struve 2135 BD+33 2777 14 Herculis Porimma (Gamma Virginis) 3.5 via BD+45 2247 3 via BD+41 2695 1.5 3.5 BD+60 1623 BD+53 1719 THETIS 1.5 Chi Hercules 2 3.5 1.5 1.5 BD+38 3095 3.5 via BD+46 1189 Mu Herculis 4 via WO 9564 CR Draconis BD+52 2045 3 via BD+43 2796 1.5 3 via Giclas 179-43 BD+36 2393 Queen Isabel Star Sigma Draconis 3.5 via BD+43 2796 CE Bootes 1.5 BD+19 2881 1 1.5 1.5 1.5 2.5 I Bootis via BD+45 2247 BD+47 2112 1 4 via EGWD 329, CR Draconis 3 via LP 272-25 4.5 via Ross 948, L 910-10 44 Bootis Aitkens Double Star 1 ADS 10288 3 via BD+61 2068 1.5 Gilese 625 1.5 Vega 3 via Kuiper 79 3 via Giclas 179-43 4 via BD+46 1189, BD+50 2030 Ross 52 Theta Draconis 2 EV Lacertae Gliese 892 BD+39 2947 3 via BD+18 3421 1.5 0.5 Theta Bootis 1.5 3 via EV Lacertae 2.5 via
    [Show full text]
  • Scientific American
    Medicine Climate Science Electronics How to Find the The Last Great Hacking the Best Treatments Global Warming Power Grid Winner of the 2011 National Magazine Award for General Excellence July 2011 ScientificAmerican.com PhysicsTHE IntellıgenceOF Evolution has packed 100 billion neurons into our three-pound brain. CAN WE GET ANY SMARTER? www.diako.ir© 2011 Scientific American www.diako.ir SCIENTIFIC AMERICAN_FP_ Hashim_23april11.indd 1 4/19/11 4:18 PM ON THE COVER Various lines of research suggest that most conceivable ways of improving brainpower would face fundamental limits similar to those that affect computer chips. Has evolution made us nearly as smart as the laws of physics will allow? Brain photographed by Adam Voorhes at the Department of Psychology, Institute for Neuroscience, University of Texas at Austin. Graphic element by 2FAKE. July 2011 Volume 305, Number 1 46 FEATURES ENGINEERING NEUROSCIENCE 46 Underground Railroad 20 The Limits of Intelligence A peek inside New York City’s subway line of the future. The laws of physics may prevent the human brain from By Anna Kuchment evolving into an ever more powerful thinking machine. BIOLOGY By Douglas Fox 48 Evolution of the Eye ASTROPHYSICS Scientists now have a clear view of how our notoriously complex eye came to be. By Trevor D. Lamb 28 The Periodic Table of the Cosmos CYBERSECURITY A simple diagram, which celebrates its centennial this 54 Hacking the Lights Out year, continues to serve as the most essential conceptual A powerful computer virus has taken out well-guarded tool in stellar astrophysics. By Ken Croswell industrial control systems.
    [Show full text]
  • Open Mroute-Dissertation.Pdf
    The Pennsylvania State University The Graduate School Department of Astronomy and Astrophysics RADIO OBSERVATIONS OF THE BROWN DWARF- EXOPLANET BOUNDARY A Dissertation in Astronomy and Astrophysics by Matthew Philip Route 2013 Matthew Philip Route Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August 2013 The dissertation of Matthew Philip Route was reviewed and approved* by the following: Alexander Wolszczan Evan Pugh Professor of Astronomy and Astrophysics Dissertation Advisor Chair of Committee Lyle Long Distinguished Professor of Aerospace Engineering, and Mathematics Director of the Computational Science Graduate Minor Program Kevin Luhman Associate Professor of Astronomy and Astrophysics John Mathews Professor of Electrical Engineering Steinn Sigurdsson Professor of Astronomy and Astrophysics Chair of the Graduate Program for the Department of Astronomy and Astrophysics Special Signatory Richard Wade Associate Professor of Astronomy and Astrophysics Donald Schneider Distinguished Professor of Astronomy and Astrophysics Head of the Department of Astronomy and Astrophysics *Signatures are on file in the Graduate School iii ABSTRACT Although exoplanets and brown dwarfs have been hypothesized to exist for many years, it was only in the last two decades that their existence has been directly verified. Since then, a large number of both types of substellar objects have been discovered; they have been studied, characterized, and classified. Yet knowledge of their magnetic properties remains difficult to obtain. Only radio emission provides a plausible means to study the magnetism of these cool objects. At the initiation of this research project, not a single exoplanet had been detected in the radio, and only a handful of radio emitting brown dwarfs were known.
    [Show full text]
  • Atmospheric Activity in Red Dwarf Stars
    CONTENTS SUMMARY AND CONCLUSIONS PAPERS ON CHROMOSPHERIC LINES IN RED DWARF FLARE STARS I. AD LEONIS AND GX ANDROMEDAE B. R. Pettersen and L. A. Coleman, 1981, Ap.J. 251, 571. II. EV LACERTAE, EQ PEGASI A, AND V1054 OPHIUCHI B. R. Pettersen, D. S. Evans, and L. A. Coleman, 1984, Ap.J. 282, 214. III. AU MICROSCOPII AND YY GEMINORUM B. R. Pettersen, 1986, Astr. Ap., in press. IV. V1005 ORIONIS AND DK LEONIS B. R. Pettersen, 1986, Astr. Ap., submitted. V. EQ VIRGINIS AND BY DRACONIS B. R. Pettersen, 1986, Astr. Ap., submitted. PAPERS ON FLARE ACTIVITY VI. THE FLARE ACTIVITY OF AD LEONIS B. R. Pettersen, L. A. Coleman, and D. S. Evans, 1984, Ap.J.suppl. 5£, 275. VII. DISCOVERY OF FLARE ACTIVITY ON THE VERY LOW LUMINOSITY RED DWARF G 51-15 B. R. Pettersen, 1981, Astr. Ap. 95, 135. VIII. THE FLARE ACTIVITY OF V780 TAU B. R. Pettersen, 1983, Astr. Ap. 120, 192. IX. DISCOVERY OF FLARE ACTIVITY ON THE LOW LUMINOSITY RED DWARF SYSTEM G 9-38 AB B. R. Pettersen, 1985, Astr. Ap. 148, 151. Den som påstår seg ferdig utlært, - han er ikke utlært, men ferdig. 1 ATMOSPHERIC ACTIVITY IN RED DWARF STARS SUMMARY AND CONCLUSIONS Active and inactive stars of similar mass and luminosity have similar physical conditions in their photospheres/ outside of magnetically disturbed regions. Such field structures give rise to stellar activity, which manifests itself at all heights of the atmosphere. Observations of uneven distributions of flux across the stellar disk have led to the discovery of photospheric starspots, chromospheric plage areas, and coronal holes.
    [Show full text]