DOCSLIB.ORG

Magnetic Fields at the Surfaces of Stars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Magnetic Fields at the Surfaces of Stars THE The Astron AstrophysRev (1992) 4:35-77 ASTRONOMY AND ASTROPHYSICS REVIEW Springer-Verlag 1992 Magnetic fields at the surfaces of stars J.D. Landstreet Department of Astronomy, University of Western Ontario, London, Ontario, Canada N6A 3K7 Observatoire Midi-Pyr6n6es, 14, ave. Edouard-Belin, F-31400 Toulouse, France Summary. Magnetic fields have now been detected in stars in several parts of the Hertzsprung-Russell diagram. Roughly dipolar fields ranging in strength between 3 • 102 and 3 x 104 G are found in many chemically peculiar A and B main sequence stars. Dipolar fields are also found in some 2-3% of white dwarfs, but with strengths between 1 • 106 and 5 • 108 G. In both these types of stars, the observed fields vary as the underlying star turns, but do not change in a secular manner. In solar- type stars, structurally complex fields of a few kG are found with filling factors of the order of 0.1 to 0.8. Further indirect evidence of fields in cool main sequence stars is provided by detection of visible and ultraviolet line emission (chromospheric activity), x radiation (coronal matter), and giant starspots. In this review, we survey the observations of stellar magnetism in all these types of stars, as well as efforts to model the observed magnetic fields and associated photospheric peculiarities and activity. Key words: Magnetic field - Stars: activity of- Stars: magnetic field - Stars: peculiar A - Stars: white dwarf 1. Introduction Magnetic fields are now known to occur in a wide variety of types of stars. The first detection of a stellar field occurred nearly a century ago, when Hale (1908) observed the magnetic splitting of spectral lines in sunspots. The first evidence for a field in a star other than our sun was reported more than forty years ago, when Babcock (1947) discovered a large and variable magnetic field in the star 78 Vir. In 1967, pulsars (and thus neutron stars) were detected for the first time by virtue of radio emission produced in magnetic fields of the order of 1012 G (Pacini 1967; Hewish et al 1967; Gold 1968). Shortly afterwards, Kemp et al (1970) reported evidence for a large magnetic field (since estimated to have a strength of the order of 250 MG) in the white dwarf Grw +70 ~ 8247. A decade later, the circle was closed with the discovery by Robinson et al (1980) of magnetic fields in the cool main sequence stars Boo A and 70 Oph A, stars very much like the sun. Each of these discoveries has opened up a new area of research. The magnetic field of the sun has been studied extensively (see for example Stenflo's 1989 article inaugurating this journal). It is clear that the solar magnetic field is very complex. It seems to be concentrated into small flux tubes which emerge from the solar pho- 36 J.D. Landstreet tosphere in sunspots and in boundary regions between several granules. Regions of opposite polarity occur in close proximity to one another. The structure of the surface field changes on a timescale of days and perhaps even more quickly. The magnetic field is involved in almost all aspects of solar activity. It maintains the low tempera- ture and structure of sunspots, may provide the energy source for flares, defines the structure of filaments and prominences, probably contributes to heating the chromo- sphere and corona, and controls the outflow of the solar wind. Our knowledge of the magnetic fields of other cool stars similar to the sun is still rather fragmentary, but it appears that all of these aspects of the solar magnetic field have analogues on other stars. We find direct evidence of kilogauss fields on a number of cool main sequence stars stars, differing from that of the sun primarily in having far greater filling factors. These magnetic stars (and others in which fields have not been detected directly) typ- ically have active chromospheres and coronae. They sometimes exhibit giant spots, and the coolest main sequence stars (M dwarfs) frequently show flares. The magnetic fields of upper main sequence stars appear to be much simpler in structure than those of the lower main sequence. These fields, typically also of kilogauss strength, are roughly dipolar in global structure. The field distribution on a given star does not appear to change on an observable time-scale, although the measured field strength usually varies due to rotation of the underlying star. The fields are invariably found in stars whose photospheres display highly anomalous chemical abundances compared to the sun. In addition, it appears that in many of these stars the abundances of some elements are very non-uniform over the surface. As such a star rotates, we see (in some cases quite dramatic) line profile and line strength variations, and usually also small variations in brightness and colour. The observed rotation periods are generally longer than those of normal A and B stars, ranging from half a day up to many years. The magnetic white dwarfs have fields of between 1 and 500 MG. In structure, the white dwarf fields are similar to those of the upper main sequence magnetic fields, with roughly dipolar distributions. About a quarter of the known magnetic white dwarfs rotate, with periods of hours or days. A number of magnetic white dwarfs have also been found in close binary systems in which magnetically channelled mass transfer is taking place. This review presents a summary of our current observational knowledge of the fields of single (or if double, non-interacting) magnetic stars, and of efforts to under- stand and model the available data. It thus focusses on the directly observable surface magnetic fields detected either through the Zeeman effect or through some kind of magnetically generated activity. It does not attempt to describe in any serious way the theoretical studies of the internal structure of magnetic stars or of the generation and evolution of their magnetic fields. All the classes of stars in which magnetic fields are directly detected are discussed, with the exception of magnetic neutron stars (pulsars). The recent review of Srinivasan (1989) makes it unnecessary to include a discussion of pulsars here; in any case, the methods of observation and physical problems con- nected with these stars do not have a lot in common with studies of other magnetic stars. The magnetic field of the sun is recalled only rather briefly, as the excellent recent review of Stenflo (1989) makes a lengthly review here unnecessary, but the sun will of course receive a certain attention as a more-or-less typical solar-type star. The review is not intended mainly to explain to the small group of specialists in stellar magnetic fields, who know many parts of the subject better than the author, the latest developments in their own fields. Instead, it is intended to review for such Magnetic fields at the surfaces of stars 37 specialists related areas of research with which they may not be so familiar, with some emphasis on the similarities of tactics and methods in different specialities. The review is equally intended to introduce the topic in an intelligible and comprehensive way to astrophysicists whose research areas overlap this field to some extent, and to others who may be simply curious. As a result, many simple but fundamental points are discussed in detail, while other interesting but more advanced or speculative ideas are mentioned more briefly. Although many references will be included, no effort has been made to cite all the significant work in this rather large field. Instead, the intent is to provide enough references to help the interested reader to explore more deeply any topics of special interest. The paper will summarize briefly in Section 2 the methods by which magnetic fields in stars are detected and measured. In Section 3, the observations of magnetic fields and their interpretation in upper main sequence stars will be discussed; magnetic white dwarfs will be surveyed in Section 4; and finally in Section 5 we will review the fields of solar-type and other cool stars. 2. The Zeeman effect and the measurement of magnetic fields 2.1 Physics of the Zeeman effect We start with a discussion of the effects by which the presence of a magnetic field is detected and measured, as an understanding of the underlying physics is very useful in appreciating the significance and limitations of the observations. A readable (though not modem) discussion of the interaction of an atom with a not-to-large magnetic field is found in Condon and Shortley (1951), especially in chapter XVI. An excellent recent review of both the Zeeman effect in atoms and of measurements of magnetic fields in main sequence stars has been prepared by Mathys (1989). For information on the physics of atoms in megagauss fields, the reader may consult the reviews of Garstang (1977, 1982). Consider a many-electron atom placed in a magnetic field of strength B which is small enough to alter the energy E~ of some level by considerably less than the spacing between that level and its nearest neighbors. The energy level, of total angular momentum quantum number J, splits in general into 2J 4- 1 states (sometimes called magnetic substates) of energy E = Ei + 9MheB/47vmc, (1) where M is the magnetic quantum number of one of the magnetic substates, (-J < M < J), h is Planck's constant, e is the charge of the electron and m is its mass, c is the speed of light, and 9, the Land6 factor, is a number of order 1 which depends on the quantum numbers of the level.
Load more

Recommended publications
  • Does GD356 Have a Terrestrial Planetary Companion
    Mon. Not. R. Astron. Soc. 404, 1984–1991 (2010) doi:10.1111/j.1365-2966.2010.16417.x Does GD 356 have a terrestrial planetary companion? Dayal T. Wickramasinghe,1 Jay Farihi,2 Christopher A. Tout,1,3,4 Lilia Ferrario1 and Richard J. Stancliffe4 1Mathematical Sciences Institute, The Australian National University, ACT 0200, Australia 2Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH 3Institute of Astronomy, The Observatories, Madingley Road, Cambridge CB3 0HA 4Centre for Stellar and Planetary Astrophysics, Monash University, PO Box 28M, VIC 3800, Australia Accepted 2010 January 25. Received 2010 January 20; in original form 2009 November 2 Downloaded from ABSTRACT GD 356 is unique among magnetic white dwarfs because it shows Zeeman-split Balmer lines in pure emission. The lines originate from a region of nearly uniform field strength (δB/B ≈ 0.1) that covers 10 per cent of the stellar surface in which there is a temperature inversion. The energy source that heats the photosphere remains a mystery but it is likely to be associated with http://mnras.oxfordjournals.org/ the presence of a companion. Based on current models, we use archival Spitzer Infrared Array Camera (IRAC) observations to place a new and stringent upper limit of 12 MJ for the mass of such a companion. In the light of this result and the recent discovery of a 115-min photometric period for GD 356, we exclude previous models that invoke accretion and revisit the unipolar inductor model that has been proposed for this system. In this model, a highly conducting planet with a metallic core orbits the magnetic white dwarf and, as it cuts through field lines, a current is set flowing between the two bodies.
    [Show full text]
  • Galactic Parameters Derived from Open-Cluster Data T
    Astronomy Reports, Vol. 48, No. 2, 2004, pp. 103–107. Translated from Astronomicheski˘ı Zhurnal, Vol. 81, No. 2, 2004, pp. 124–128. Original Russian Text Copyright c 2004 by Gerasimenko. Galactic Parameters Derived from Open-Cluster Data T. P. Gerasimenko Astronomical Observatory, Ural State University, Yekaterinburg, Russia Received September 20, 2001; in final form, July 26, 2003 Abstract—The components U0 and V0 of the solar motion and the Oort constant A0 are determined using the data of a homogeneous open-cluster catalog with corrected distance moduli. The results are based on a sample of 146 open clusters with known radial velocities located in the Galactic plane (b<7◦)within 4 kpc of the Sun. The solar Galactocentric distance R0 is determined usingtwo kinematic methods. The followingresults are obtained: A0 =17.0 ± 0.9 km/s kpc, U0 =10.5 ± 1.0 km/s, V0 =11.5 ± 1.1 km/s, R0 =8.3 ± 0.3 pc. c 2004 MAIK “Nauka/Interperiodica”. 1. INTRODUCTION distance-modulus estimates from the Uniform Cata- logand those determined usingHipparcos trigono- One of the traditional areas of kinematic studies metric parallaxes [12]; the distance scale changed is the determination of the main Galactic parameters by −0.153m, independent of the cluster age. The required to construct theoretical equilibrium models: clusters span a fairly wide age interval. Clusters the gradient of the angular velocity (the Oort constant in different age groups are known to have different AO), the Oort constant B0, and the principal scale motions. Analysis of the rotation of the open-cluster parameter—the distance of the Sun from the Galactic subsystem revealed a small group among the young center, RO.
    [Show full text]
  • Arxiv:2001.10147V1
    Magnetic fields in isolated and interacting white dwarfs Lilia Ferrario1 and Dayal Wickramasinghe2 Mathematical Sciences Institute, The Australian National University, Canberra, ACT 2601, Australia Adela Kawka3 International Centre for Radio Astronomy Research, Curtin University, Perth, WA 6102, Australia Abstract The magnetic white dwarfs (MWDs) are found either isolated or in inter- acting binaries. The isolated MWDs divide into two groups: a high field group (105 − 109 G) comprising some 13 ± 4% of all white dwarfs (WDs), and a low field group (B < 105 G) whose incidence is currently under investigation. The situation may be similar in magnetic binaries because the bright accretion discs in low field systems hide the photosphere of their WDs thus preventing the study of their magnetic fields’ strength and structure. Considerable research has been devoted to the vexed question on the origin of magnetic fields. One hypothesis is that WD magnetic fields are of fossil origin, that is, their progenitors are the magnetic main-sequence Ap/Bp stars and magnetic flux is conserved during their evolution. The other hypothesis is that magnetic fields arise from binary interaction, through differential rotation, during common envelope evolution. If the two stars merge the end product is a single high-field MWD. If close binaries survive and the primary develops a strong field, they may later evolve into the arXiv:2001.10147v1 [astro-ph.SR] 28 Jan 2020 magnetic cataclysmic variables (MCVs). The recently discovered population of hot, carbon-rich WDs exhibiting an incidence of magnetism of up to about 70% and a variability from a few minutes to a couple of days may support the [email protected] [email protected] [email protected] Preprint submitted to Journal of LATEX Templates January 29, 2020 merging binary hypothesis.
    [Show full text]
  • An Upper Limit to Coronal X-Rays from Single, Magnetic White Dwarfs
    J. Astrophys. Astr. (1993) 14, 141–143 An Upper Limit to Coronal X-rays from Single, Magnetic White Dwarfs 1 1 2 Rob Cavallo , Keith A. Arnaud & Virginia Trimble Astronomy Department, University of Maryland, College Park MD 20742 USA 1 Also Code 666, Goddard Space Flight Center, Greenbelt MD 20771 USA 2 Also Physics Department, University of California, Irvine CA 92717 Received 1993 August 19; accepted 1993 September 28 Abstract. Pointed ROSAT PSPC exposures of 9277 and 6992 sec, directed toward the nearby, single, cool, magnetic white dwarfs GR 290 and EG 250 yielded no counts significantly above the expected background rate. The corresponding flux limits (for an assumed source temperature of l keV) are 1.0 and 1.7 × 10 –14erg cm–2 s–1, within the 0.1–2.5 keV bandpass of the instrument (99% confidence limits). This is more than an order of magnitude below the tentative detection level (for GR 290) and limits (for four other similar stars) obtained from archival Einstein data in 1991. The corresponding limits on coronal electron density are comparable with those implied if cyclotron emission is not responsible for any of the features observed in the optical spectra of magnetic white dwarfs. X-ray data currently provide no evidence for the existence of coronae around these stars. A final long observation (25,000 sec of GD 356) is scheduled for later this year on ROSAT, along with coordinated EUVE observations. Key words: White dwarfs—stellar coronae—X-ray emission 1. Introduction Motivated by theoretical considerations (Zheleznyakov & Litvinchuk 1985; Serber 1990) and by the preponderance of magnetic systems among known cataclysmic variable X-ray sources, Arnaud et al.
    [Show full text]
  • Post-Main-Sequence Planetary System Evolution Rsos.Royalsocietypublishing.Org Dimitri Veras
    Post-main-sequence planetary system evolution rsos.royalsocietypublishing.org Dimitri Veras Department of Physics, University of Warwick, Coventry CV4 7AL, UK Review The fates of planetary systems provide unassailable insights Cite this article: Veras D. 2016 into their formation and represent rich cross-disciplinary Post-main-sequence planetary system dynamical laboratories. Mounting observations of post-main- evolution. R. Soc. open sci. 3: 150571. sequence planetary systems necessitate a complementary level http://dx.doi.org/10.1098/rsos.150571 of theoretical scrutiny. Here, I review the diverse dynamical processes which affect planets, asteroids, comets and pebbles as their parent stars evolve into giant branch, white dwarf and neutron stars. This reference provides a foundation for the Received: 23 October 2015 interpretation and modelling of currently known systems and Accepted: 20 January 2016 upcoming discoveries. 1. Introduction Subject Category: Decades of unsuccessful attempts to find planets around other Astronomy Sun-like stars preceded the unexpected 1992 discovery of planetary bodies orbiting a pulsar [1,2]. The three planets around Subject Areas: the millisecond pulsar PSR B1257+12 were the first confidently extrasolar planets/astrophysics/solar system reported extrasolar planets to withstand enduring scrutiny due to their well-constrained masses and orbits. However, a retrospective Keywords: historical analysis reveals even more surprises. We now know that dynamics, white dwarfs, giant branch stars, the eponymous celestial body that Adriaan van Maanen observed pulsars, asteroids, formation in the late 1910s [3,4]isanisolatedwhitedwarf(WD)witha metal-enriched atmosphere: direct evidence for the accretion of planetary remnants. These pioneering discoveries of planetary material around Author for correspondence: or in post-main-sequence (post-MS) stars, although exciting, Dimitri Veras represented a poor harbinger for how the field of exoplanetary e-mail: [email protected] science has since matured.
    [Show full text]
  • A Chandra Search for Coronal X Rays from the Cool White Dwarf GD
    DRAFT 2006.09.19: ApJ to be submitted A Chandra Search for Coronal X Rays from the Cool White Dwarf GD 356 Martin C. Weisskopf1, Kinwah Wu2, Virginia Trimble3,4, Stephen L. O’Dell5, Ronald F. Elsner5, Vyacheslav E. Zavlin5,6, and Chryssa Kouveliotou5 ABSTRACT We report observations with the Chandra X-ray Observatory of the single, cool, magnetic white dwarf GD 356. For consistent comparison with other X-ray observations of single white dwarfs, we also re-analyzed archival ROSAT data for GD 356 (GJ 1205), G 99-47 (GR 290 = V1201 Ori), GD 90, G 195-19 (EG250 = GJ 339.1), and WD 2316+123 and archival Chandra data for LHS 1038 (GJ 1004) and GD 358 (V777 Her). Our Chandra observation detected no X rays from GD 356, setting the most restrictive upper limit to the X-ray luminosity from 25 −1 any cool white dwarf — LX < 6.0×10 erg s , at 99.7% confidence, for a 1- keV thermal-bremsstrahlung spectrum. The corresponding limit to the electron 11 −3 density is n0 < 4.4×10 cm . Our re-analysis of the archival data confirmed the non-detections reported by the original investigators. We discuss the implications of our and prior observations on models for coronal emission from white dwarfs. For magnetic white dwarfs, we emphasize the more stringent constraints imposed by cyclotron radiation. In addition, we describe (in an appendix) a statistical methodology for detecting a source and for constraining the strength of a source, which applies even when the number of source or background events is small.
    [Show full text]
  • Biennial Report 2004 2005 Published in Spain by the ISAAC NEWTON GROUP of TELESCOPES (ING) ISSN 1575–8966 Legal License: TF–1142 /99
    I SAAC N EWTON G ROUP OF T ELESCOPES Biennial Report 2004 2005 Published in Spain by the ISAAC NEWTON GROUP OF TELESCOPES (ING) ISSN 1575–8966 Legal license: TF–1142 /99 Apartado de correos, 321 E-38700 Santa Cruz de La Palma; Canary Islands; Spain Tel: +34 922 425 400 Fax: +34 922 425 401 URL: http://www.ing.iac.es/; http://www.ast.cam.ac.uk/ING/ (UK mirror) Editor and designer: Javier Méndez ([email protected]) Preprinting: Gráficas El Time. Tel: +34 922 416 651 Printing: Gráficas Sabater. Tel: +34 922 623 555 Front cover: IC1396 or the Elephant Trunk Nebula. Image obtained as part of the Isaac Newton Telescope Photometric Hα Survey of the Northen Galactic Plane, and it was prepared by Nick Wright, University College London. Inset: Photograph of laser test on the William Herschel Telescope as part of GLAS preparatory study. Credit: Javier Méndez. Other picture credits: Nik Szymanek (WHT, p. 4); Nik Szymanek (INT, p. 4); Nik Szymanek (JKT, p. 4); Nik Szymanek (ING, p. 5); Jens Moser (WHT, back); Jens Moser (INT, back); Nik Szymanek (JKT, back). The ING Biennial Report is available online at http://www.ing.iac.es/PR/AR/ or at http://www.ast.cam.ac.uk/ING/PR/AR/. ISAAC NEWTON GROUP OF TELESCOPES Biennial Report of the PPARC-NWO-IAC ING Board 2004 – 2005 ISAAC NEWTON GROUP William Herschel Telescope Isaac Newton Telescope Jacobus Kapteyn Telescope 4 • ING BIENNIAL R EPORT 2004–2005 OF TELESCOPES The Isaac Newton Group of Telescopes (ING) consists of the 4.2- metre William Herschel Telescope (WHT), the 2.5-metre Isaac Newton Telescope (INT) and the 1.0-metre Jacobus Kapteyn Telescope (JKT).
    [Show full text]
  • The Bright Sharc Survey: the Cluster Catalog1 Ak Romer2 and Rc Nichol3,4
    THE ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 126:209È269, 2000 February ( 2000. The American Astronomical Society. All rights reserved. Printed in U.S.A. THE BRIGHT SHARC SURVEY: THE CLUSTER CATALOG1 A. K. ROMER2 AND R. C. NICHOL3,4 Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213; romer=cmu.edu, nichol=cmu.edu B. P. HOLDEN2,3 Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637; holden=oddjob.uchicago.edu M. P. ULMER AND R. A. PILDIS Department of Physics and Astronomy, Northwestern University, 2131 North Sheridan Road, Evanston, IL 60207; ulmer=ossenu.astro.nwu.edu A. J. MERRELLI2 Department of Physics, Carnegie Mellon University, 5000. Forbes Avenue, Pittsburgh, PA 15213; merrelli=andrew.cmu.edu C. ADAMI4 Department of Physics and Astronomy, Northwestern University, 2131 North Sheridan Road, Evanston, IL 60207;adami=lilith.astro.nwu.edu; and Laboratoire d Astronomie Spatiale, Traverse du Siphon, 13012 Marseille, France D. J. BURKE3 AND C. A. COLLINS3 Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead, L41 1LD, UK; djb=astro.livjm.ac.uk, cac=astro.livjm.ac.uk A. J. METEVIER UCO/Lick Observatory, University of California, Santa Cruz, CA 95064; anne=ucolick.org R. G. KRON Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637; rich=oddjob.uchicago.edu AND K. COMMONS2 Department of Physics and Astronomy, Northwestern University, 2131 North Sheridan Road, Evanston, IL 60207; commons=lilith.astro.nwu.edu Received 1999 April 12; accepted 1999 August 23 ABSTRACT We present the Bright SHARC (Serendipitous High-Redshift Archival ROSAT Cluster) Survey, which is an objective search for serendipitously detected extended X-ray sources in 460 deep ROSAT PSPC pointings.
    [Show full text]
  • First Kepler Results on Compact Pulsators - VI
    BearWorks College of Natural and Applied Sciences 2011 First Kepler results on compact pulsators - VI. Targets in the final half of the survey phase R. H. Østensen Rl Silvotti S. Charpinet R. Oreiro S. Bloemen See next page for additional authors Follow this and additional works at: https://bearworks.missouristate.edu/articles-cnas Recommended Citation Østensen, Roy H., Roberto Silvotti, S. Charpinet, R. Oreiro, Steven Bloemen, A. S. Baran, M. D. Reed et al. "First Kepler results on compact pulsators–VI. Targets in the final half of the survey phase." Monthly Notices of the Royal Astronomical Society 414, no. 4 (2011): 2860-2870. This article or document was made available through BearWorks, the institutional repository of Missouri State University. The work contained in it may be protected by copyright and require permission of the copyright holder for reuse or redistribution. For more information, please contact [email protected]. Authors R. H. Østensen; Rl Silvotti; S. Charpinet; R. Oreiro; S. Bloemen; A. S. Baran; Michael D. Reed; S. D. Kawaler; J. H. Telting; and For complete list of authors, see publisher's website. This article is available at BearWorks: https://bearworks.missouristate.edu/articles-cnas/983 Mon. Not. R. Astron. Soc. 414, 2860–2870 (2011) doi:10.1111/j.1365-2966.2011.18405.x First Kepler results on compact pulsators – VI. Targets in the final half of the survey phase , , R. H. Østensen,1 R. Silvotti,2 S. Charpinet,3 R. Oreiro,1 4 S. Bloemen,1 A. S. Baran,5 6 M. D. Reed,7 S. D. Kawaler,6 J.
    [Show full text]
  • II Cluster Catalog Donald J
    Dartmouth College Dartmouth Digital Commons Open Dartmouth: Faculty Open Access Articles 2008 The ARPSW Survey. VII. The ARPSW ‐II Cluster Catalog Donald J. Horner NASA Goddard Space Flight Center Eric S. Perlman University of Maryland-Baltimore County Harald Ebeling Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI Laurence Jones University of Birmingham Caleb A. Scharf Columbia University See next page for additional authors Follow this and additional works at: https://digitalcommons.dartmouth.edu/facoa Part of the Astrophysics and Astronomy Commons Recommended Citation Horner, Donald J.; Perlman, Eric S.; Ebeling, Harald; Jones, Laurence; Scharf, Caleb A.; Wegner, Gary; Malkan, Matthew; and Maughan, Ben, "The AW RPS Survey. VII. The AW RPS‐II Cluster Catalog" (2008). Open Dartmouth: Faculty Open Access Articles. 3497. https://digitalcommons.dartmouth.edu/facoa/3497 This Article is brought to you for free and open access by Dartmouth Digital Commons. It has been accepted for inclusion in Open Dartmouth: Faculty Open Access Articles by an authorized administrator of Dartmouth Digital Commons. For more information, please contact [email protected]. Authors Donald J. Horner, Eric S. Perlman, Harald Ebeling, Laurence Jones, Caleb A. Scharf, Gary Wegner, Matthew Malkan, and Ben Maughan This article is available at Dartmouth Digital Commons: https://digitalcommons.dartmouth.edu/facoa/3497 The Astrophysical Journal Supplement Series, 176:374Y413, 2008 June # 2008. The American Astronomical Society. All rights reserved. Printed in U.S.A. THE WARPS SURVEY. VII. THE WARPS-II CLUSTER CATALOG Donald J. Horner,1 Eric S. Perlman,2,3 Harald Ebeling,4 Laurence R. Jones,5 Caleb A. Scharf,6 Gary Wegner,7 Matthew Malkan,8 and Ben Maughan9 Received 2007 November 19; accepted 2007 December 26 ABSTRACT We present the galaxy cluster catalog from the second, larger phase of the Wide Angle ROSAT Pointed Survey (WARPS), an X-ray selected survey for high-redshift galaxy clusters.
    [Show full text]
  • Download Full-Text
    International Journal of Astronomy 2020, 9(1): 3-11 DOI: 10.5923/j.astronomy.20200901.02 The Processes that Determine the Formation and Chemical Composition of the Atmosphere of the Body in Orbit Weitter Duckss Independent Researcher, Zadar, Croatia Abstract The goal of this article is to analyze the formation of an atmosphere on the orbiting planets and to determine the processes that participate in the formation of an atmospheric chemical composition, as well as in determining it. The research primarily analyzes the formation of atmospheres on the objects of different sizes (masses) and at the same or different orbital distances. This paper analyzes the influence of a star's temperature, the space and the orbit's distance to an object's temperature level, as well as the influence of the operating temperature of atoms and chemical compounds to chemical composition and the representation of elements and compounds in an atmosphere. The objects, which possess different masses and temperatures, are able to create and do create different compositions and sizes of atmospheres in the same or different distances from their main objects (Saturn/Titan or Pluto). The processes that are included in the formation of an atmosphere are the following: operating temperatures of compounds and atoms, migrations of hydrogen, helium and the other elements and compounds towards a superior mass. The lack of oxygen and hydrogen is additionally related to the level of temperature of space, which can be classified into internal (characterized by the lack of hydrogen) and the others (characterized by the lack of oxygen). Keywords Atmosphere, Chemical composition of the atmosphere, Migration of the atmosphere the atmosphere even though they are not in a gaseous state at 1.
    [Show full text]
  • A Magnetic White Dwarf in a Detached Eclipsing Binary
    This is a repository copy of A magnetic white dwarf in a detached eclipsing binary. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/108497/ Version: Accepted Version Article: Parsons, S. G., Marsh, T. R., Gaensicke, B. T. et al. (4 more authors) (2013) A magnetic white dwarf in a detached eclipsing binary. Monthly Notices of the Royal Astronomical Society, 436 (1). pp. 241-252. ISSN 0035-8711 https://doi.org/10.1093/mnras/stt1588 Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version - refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher’s website. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ Mon. Not. R. Astron. Soc. 000, 1–13 (2013) Printed 22 August 2013 (MN LATEX style file v2.2) A magnetic white dwarf in a detached eclipsing binary S. G. Parsons1⋆, T.
    [Show full text]