Optical Monitoring of the BL Lac Object on 231 in 1972–1990 M
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Lurking in the Shadows: Wide-Separation Gas Giants As Tracers of Planet Formation
Lurking in the Shadows: Wide-Separation Gas Giants as Tracers of Planet Formation Thesis by Marta Levesque Bryan In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2018 Defended May 1, 2018 ii © 2018 Marta Levesque Bryan ORCID: [0000-0002-6076-5967] All rights reserved iii ACKNOWLEDGEMENTS First and foremost I would like to thank Heather Knutson, who I had the great privilege of working with as my thesis advisor. Her encouragement, guidance, and perspective helped me navigate many a challenging problem, and my conversations with her were a consistent source of positivity and learning throughout my time at Caltech. I leave graduate school a better scientist and person for having her as a role model. Heather fostered a wonderfully positive and supportive environment for her students, giving us the space to explore and grow - I could not have asked for a better advisor or research experience. I would also like to thank Konstantin Batygin for enthusiastic and illuminating discussions that always left me more excited to explore the result at hand. Thank you as well to Dimitri Mawet for providing both expertise and contagious optimism for some of my latest direct imaging endeavors. Thank you to the rest of my thesis committee, namely Geoff Blake, Evan Kirby, and Chuck Steidel for their support, helpful conversations, and insightful questions. I am grateful to have had the opportunity to collaborate with Brendan Bowler. His talk at Caltech my second year of graduate school introduced me to an unexpected population of massive wide-separation planetary-mass companions, and lead to a long-running collaboration from which several of my thesis projects were born. -
Herschel Observations of Debris Discs Orbiting Planet-Hosting Subgiants
Mon. Not. R. Astron. Soc. 000, 000–000 (0000) Printed 14 November 2013 (MN LATEX style file v2.2) Herschel Observations of Debris Discs Orbiting Planet-hosting Subgiants Amy Bonsor1,2⋆, Grant M. Kennedy3, Mark C. Wyatt3, John A. Johnson4 and Bruce Sibthorpe5 1UJF-Grenoble 1 / CNRS-INSU, Institut de Plantologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041, France 2School of Physics, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK 3Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA, UK 4Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 5SRON Netherlands Institute for Space Research, Zernike Building, P.O. Box 800, 9700 AV Groningen, The Netherlands 14 November 2013 ABSTRACT Debris discs are commonly detected orbiting main-sequence stars, yet little is known regarding their fate as the star evolves to become a giant. Recent observations of radial velocity detected planets orbiting giant stars highlight this population and its im- portance for probing, for example, the population of planetary systems orbiting intermediate mass stars. Our Herschel ∗ survey observed a subset of the Johnson et al program subgiants, find- ing that 4/36 exhibit excess emission thought to indicate debris, of which 3/19 are planet-hosting stars and 1/17 are stars with no current planet detections. Given the small numbers involved, there is no evidence that the disc detection rate around stars with plan- ets is different to that around stars without planets. Our detections provide a clear indication that large quantities of dusty material can survive the stars’ main-sequence lifetime and be detected on the subgiant branch, with important implications for the evolution of planetary systems and observations of polluted or dusty white dwarfs. -
Module 09 Colour Index TABLE of CONTENTS 1. Learning Outcomes
Module 09 Colour Index TABLE OF CONTENTS 1. Learning Outcomes 2. Introduction 3. Dependence of magnitudes on wavelength 3.1. UBV System of Johnson and Morgan 3.2. Colour Index 3.3. Colour-Colour Diagrams 3.4. Colour Excess 3.5. Reddening and Redshift 4. Summary 1. Learning Outcomes After studying this module, you should be able to Appreciate that the magnitude depends on the wavelength at which it is measured Understand the need of UBV photometric system Realize that the UBV system at present measures magnitudes at various wavelength bands other than the visual region Understand why magnitudes of stars at various wavelength bands of their spectra are not equal Grasp the concept of colour index Understand that the colour index follows the surface temperature of the star Realize the importance of colour-colour diagrams in describing stars 2. Introduction In the last module we introduced the concept of magnitudes. Apparent magnitude is a number assigned to a star (or any other celestial object) to indicate its brightness. Brighter stars are assigned lower magnitudes and fainter stars are characterized by higher magnitudes. Only stars brighter than 6th magnitude are visible to the unaided eye. Since brightness is a function of distance and the intrinsic brightness of a star, apparent magnitude does not allow us to compare stars with respect to their intrinsic brightness. Therefore, to compare brightness all stars are thought to be at a standard distance of 10 pc. The apparent magnitude at this distance is called the absolute magnitude of the star. It turns out that the difference between the absolute magnitudes of two stars is proportional to the ratio of their luminosities. -
Information Bulletin on Variable Stars
COMMISSIONS AND OF THE I A U INFORMATION BULLETIN ON VARIABLE STARS Nos November July EDITORS L SZABADOS K OLAH TECHNICAL EDITOR A HOLL TYPESETTING K ORI ADMINISTRATION Zs KOVARI EDITORIAL BOARD L A BALONA M BREGER E BUDDING M deGROOT E GUINAN D S HALL P HARMANEC M JERZYKIEWICZ K C LEUNG M RODONO N N SAMUS J SMAK C STERKEN Chair H BUDAPEST XI I Box HUNGARY URL httpwwwkonkolyhuIBVSIBVShtml HU ISSN COPYRIGHT NOTICE IBVS is published on b ehalf of the th and nd Commissions of the IAU by the Konkoly Observatory Budap est Hungary Individual issues could b e downloaded for scientic and educational purp oses free of charge Bibliographic information of the recent issues could b e entered to indexing sys tems No IBVS issues may b e stored in a public retrieval system in any form or by any means electronic or otherwise without the prior written p ermission of the publishers Prior written p ermission of the publishers is required for entering IBVS issues to an electronic indexing or bibliographic system to o CONTENTS C STERKEN A JONES B VOS I ZEGELAAR AM van GENDEREN M de GROOT On the Cyclicity of the S Dor Phases in AG Carinae ::::::::::::::::::::::::::::::::::::::::::::::::::: : J BOROVICKA L SAROUNOVA The Period and Lightcurve of NSV ::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::: W LILLER AF JONES A New Very Long Period Variable Star in Norma ::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::::: EA KARITSKAYA VP GORANSKIJ Unusual Fading of V Cygni Cyg X in Early November ::::::::::::::::::::::::::::::::::::::: -
A Study of Two Open Clusters Containing Wolf-Rayet Stars
A STUDY OF TWO OPEN CLUSTERS CONTAINING WOLF-RAYET STARS by Stephen L. Shorlin A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF ASTRONOlMY AND PHYSICS SAINT MARY'S UMNERSITY MAY 1998 HALIFAX, NOVA SCOTIA Ostephen L. Shorlin, 1998 National Library Bibliothèque nationale I*m of Canada du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. nie Wellington Ottawa ON K1A ON4 Ottawa ON KIA ON4 Canada Canada The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loau, distribute or seU reproduire, prêter, distribuer ou copies of this thesis in microfoq vendre des copies de cette thèse sous paper or electronic formats. la fome de microfiche/nIm, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fiom it Ni la thèse ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent être imprimes reproduced *out the author's ou autrement reproduits sans son permission. autorisation- Abstract The results of UBV CCD photornetry are presented for a newly discovered open cluster, as well as new photornetry for thirty-seven members of the open cluster HM 1. The new open cluster, to be designated OCL 1104610, has a distance modulus of Vo - l'LIV = 15.5 & 0.2: corresponding to a distance of 12.61::: kpc, and is several Myr old. -
2016 Publication Year 2021-04-23T14:32:39Z Acceptance in OA@INAF Age Consistency Between Exoplanet Hosts and Field Stars Title B
Publication Year 2016 Acceptance in OA@INAF 2021-04-23T14:32:39Z Title Age consistency between exoplanet hosts and field stars Authors Bonfanti, A.; Ortolani, S.; NASCIMBENI, VALERIO DOI 10.1051/0004-6361/201527297 Handle http://hdl.handle.net/20.500.12386/30887 Journal ASTRONOMY & ASTROPHYSICS Number 585 A&A 585, A5 (2016) Astronomy DOI: 10.1051/0004-6361/201527297 & c ESO 2015 Astrophysics Age consistency between exoplanet hosts and field stars A. Bonfanti1;2, S. Ortolani1;2, and V. Nascimbeni2 1 Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy e-mail: [email protected] 2 Osservatorio Astronomico di Padova, INAF, Vicolo dell’Osservatorio 5, 35122 Padova, Italy Received 2 September 2015 / Accepted 3 November 2015 ABSTRACT Context. Transiting planets around stars are discovered mostly through photometric surveys. Unlike radial velocity surveys, photo- metric surveys do not tend to target slow rotators, inactive or metal-rich stars. Nevertheless, we suspect that observational biases could also impact transiting-planet hosts. Aims. This paper aims to evaluate how selection effects reflect on the evolutionary stage of both a limited sample of transiting-planet host stars (TPH) and a wider sample of planet-hosting stars detected through radial velocity analysis. Then, thanks to uniform deriva- tion of stellar ages, a homogeneous comparison between exoplanet hosts and field star age distributions is developed. Methods. Stellar parameters have been computed through our custom-developed isochrone placement algorithm, according to Padova evolutionary models. The notable aspects of our algorithm include the treatment of element diffusion, activity checks in terms of 0 log RHK and v sin i, and the evaluation of the stellar evolutionary speed in the Hertzsprung-Russel diagram in order to better constrain age. -
Publications of the Astronomical Society of the Pacific 107: 945-958, 1995 October
Publications of the Astronomical Society of the Pacific 107: 945-958, 1995 October Galaxy Colors in Various Photometric Band Systems M. Fukugita1 Institute for Advanced Study, Princeton, New Jersey 08540 Electronic mail: [email protected] K. Shimasaku2 Princeton University Observatory, Princeton, New Jersey 08544 Electronic mail: [email protected] T. ICHIKAWA Kiso Observatory, University of Tokyo, Kiso-gun, Nagano 397-01, Japan Electronic mail: [email protected] Received 1995 March 10; accepted 1995 June 14 ABSTRACT. A study is made of stellar and galaxy colors using a spectrophotometric synthesis technique. We show that use of good color response functions and a modem determination of the spectroscopic energy distribution for a Lyr gives synthetic stellar colors in a good agreement with photometric observations to about 0.05 mag. The synthetic method then is applied to study galaxy colors using the spectrophotometric atlas of Kennicutt (1992, ApJS, 79, 255), and a comparison is made with observed galaxy colors. The Κ correction is calculated and compared with that of Coleman, Wu, and Weedman (1980, ApJS, 43, 393). We then study colors of galaxies in various photometric band systems and obtain color transformation laws, which enable us to find offsets among different systems. We include 48 photometric bands in our study. 1. INTRODUCTION in addition to a good sample of galaxy SED over a wide range of wavelength. Continual efforts to obtain the SED of Colors of galaxies provide us with valuable information Vega (Oke and Schild 1970; Hayes and Latham 1975; Oke concerning their present-day composition of stars, and ac- and Gunn 1983; Kurucz 1979; Hayes 1985, hereafter re- cordingly it gives us hints about the formation and evolution ferred to as H85; Castelli and Kurucz 1994, hereafter re- of galaxies. -
The ∆A Photometric System
Ernst Paunzen (Autor) The _a photometric system https://cuvillier.de/de/shop/publications/8305 Copyright: Cuvillier Verlag, Inhaberin Annette Jentzsch-Cuvillier, Nonnenstieg 8, 37075 Göttingen, Germany Telefon: +49 (0)551 54724-0, E-Mail: [email protected], Website: https://cuvillier.de 1 Summary This book describes the history, characteristics, observations, results and future prospects of the Δa photometric system. Up to now, it success- fully produced countless scientific output since its development and first appearance on the astronomical scene initiated by Hans-Michael Maitzen in 1976. It was intended to study the typical and unique flux depression at 5200 A˚ found in mainly magnetic chemically peculiar stars of the upper main sequence. Therefore the most important measurement is through the g2 filter centred at this wavelength region. In addition, one needs the information about the continuum flux of the same object. Originally, the g1 (centred at 5000A)˚ and Str¨omgren y (5500A)˚ was used to get the continuum flux. In principle, any other filters such as Johnson BV RI can be used. However, the closer it is measured to the 5200A˚ region and the narrower the used filters are, the results become more accurate. The a index is then defined as the flux in g2 compared to the continuum one. Because there is a general increase of opacity around 5200A˚ with decreasing temperature, one has to normalize a with the index a0 of a non-peculiar star of the same temperature, to compare different peculiar (or deviating) stars with each other (Δa index). With this photometric system it is possible to measure any peculiarities, such as abnormal absorption and emission lines, in the region of 5200A.˚ Soon, it was used to investigate metal-weak, Be/shell and supergiants in the Galactic field and open clusters. -
Fundamental Stellar Photometry for Standards of Spectral Type on the Revised System of the Yerkes Spectral Atlas “
COMMENTS ON THE PAPER “FUNDAMENTAL STELLAR PHOTOMETRY FOR STANDARDS OF SPECTRAL TYPE ON THE REVISED SYSTEM OF THE YERKES SPECTRAL ATLAS “ BY H.L. JOHNSON AND W.W. MORGAN (1953) SIDNEY VAN DEN BERGH Dominion Astrophysical Observatory Herzberg Institute of Astrophysics National Research Council of Canada 5071 West Saanich Road Victoria, British Columbia, V8X 4M6 Canada Received 1998, December 3 Photometry and spectroscopy are among the most important and fundamental types of astronomical observations. By the middle of the twentieth century most spectral classification was defined in terms of MKK type standards (Morgan, Keenan & Kellerman 1943). However, for a variety of reasons (Weaver 1947), the establishment of photometric standards remained problematic. Commission 25 (Photometry) of the International Astronomical Union devoted seemingly endless years to discussions on the establishment of an international photometric standard system. Weaver (1952) advocated that a new sub- commission should be created which would have as its task “The establishment of an ‘ideal’ photo-electric color and magnitude system.” A subsequent IAU resolution (Oosterhoff 1954) suggested that “La Commission recommende que soit constituJe une nouvelle sous-commission des Jtalons de magnitudes - 2 - stellaire....”. Additional problems were: (1) The Commission could not decide between monochromatic magnitudes and broad-band magnitudes, and (2) some advocated a two-color system (Hertzsprung 1950), whereas others (Becker 1946) favored a three-color (photographic, photovisual, red) photometric system. In his characteristically energetic fashion Johnson (Johnson & Morgan 1951) then took the bull by the horns and started to observe so many stars and clusters on his UBV system that it soon became the de facto international photometric system1. -
Visualizing Large-Scale Uncertainty in Astrophysical Data
Visualizing Large-Scale Uncertainty in Astrophysical Data Hongwei Li, Student Member, IEEE, Chi-Wing Fu, Member, IEEE, Yinggang Li, Member, IEEE, and Andrew J. Hanson, Member, IEEE Abstract— Visualization of uncertainty or error in astrophysical data is seldom available in simulations of astronomical phenomena, and yet almost all rendered attributes possess some degree of uncertainty due to observational error. Uncertainties associated with spatial location typically vary significantly with scale and thus introduce further complexity in the interpretation of a given visualization. This paper introduces effective techniques for visualizing uncertainty in large-scale virtual astrophysical environments. Building upon our previous transparently scalable visualization architecture, we develop tools that enhance the perception and comprehension of uncertainty across wide scale ranges. Our methods include a unified color-coding scheme for representing log-scale distances and percentage errors, an ellipsoid model to represent positional uncertainty, an ellipsoid envelope model to expose trajectory uncertainty, and a magic-glass design supporting the selection of ranges of log-scale distance and uncertainty parameters, as well as an overview mode and a scalable WIM tool for exposing the magnitudes of spatial context and uncertainty. Index Terms—Uncertainty visualization, large spatial scale, interstellar data, astronomy. F 1 INTRODUCTION Uncertainty and error are common and crucial entities in scientific representations is lacking in a large fraction of 3D astronomical visu- studies. As pointed out by Johnson [23, 24], if we look at leading alization products. In visually spectacular animations depicting nebula peer-reviewed science and engineering journals, we can see that the flythroughs or travel from the Earth through the Milky Way Galaxy majority of 2D graphs represent error or uncertainty in the experimen- produced for planetariums and television programs, rarely does the tal or simulated data. -
Evaluating Stars Temperature Through the B-V Index Using a Virtual Real Experiment…
Paper—Evaluating Stars Temperature Through the B-V Index Using a Virtual Real Experiment… Evaluating Stars Temperature Through the B-V Index Using a Virtual Real Experiment from Distance: A Case Scenario for Secondary Education. https://doi.org/10.3991/ijoe.v14i01.7842 Nikolaos Dintsios ! , Stamatia Artemi, Hariton Polatoglou Aristotle University! " of Thessaloniki, Thessaloniki, Greece [email protected] Abstract—In this paper we propose a scenario for secondary education at which students could estimate the temperature, the radius and the age of stars. To achieve this, we built a virtual real experiment which can be performed from distance on any portable device. Students can connect to a webpage and choose a star from a list. After applying B and V filters they obtain the B and V magni- tude. Consequently, they calculate the B-V index of a star and using a simple formula they estimate the star’s surface temperature. Furthermore, guided through a worksheet and with the use of Hertzsprung–Russell diagram they can estimate the radius and the age of the star. Keywords—remote virtual experiments, astronomy, remote experiments, star surface temperature 1 Introduction 1.1 Astronomy in Education Astronomy is a very interesting scientific subject and many students are highly mo- tivated to study it. Studying the literature on astronomy education we found that most studies have been focused on Earth, day/night cycle, Earth-Sun-Moon system, seasons and Moon phases [1], [2] while fewer studies were referring to stars. More specifical- ly, the great majority of studies which are focused on stars deal with the motion, the position and the origin of stars’ light [3]-[6]. -
Serpens – the Serpent
A JPL Image of surface of Mars, and JPL Ingenuity Helicioptor illustration, in flight Monthly Meeting May 10th at 7:00 PM at HRPO, and via Jitsi (Monthly meetings are on 2nd Mondays at Highland Road Park Observatory, will also broadcast via. (meet.jit.si/BRASMeet). PRESENTATION: Dr. Alan Hale, professional astronomer and co-discoverer of Comet Hale-Bopp, among other endeavors. What's In This Issue? President’s Message Member Meeting Minutes Business Meeting Minutes Outreach Report Light Pollution Committee Report Globe at Night SubReddit and Discord Messages from the HRPO REMOTE DISCUSSION Solar Viewing International Astronomy Day American Radio Relay League Field Day Observing Notes: Serpens - The Serpent & Mythology Like this newsletter? See PAST ISSUES online back to 2009 Visit us on Facebook – Baton Rouge Astronomical Society BRAS YouTube Channel Baton Rouge Astronomical Society Newsletter, Night Visions Page 2 of 20 May 2021 President’s Message Ahhh, welcome to May, the last pleasant month in Louisiana before the start of the hurricane season and the brutal summer months that follow. April flew by pretty quickly, and with the world slowly thawing from the long winter, why shouldn’t it? To celebrate, we decided we’re going to try to start holding our monthly meetings at Highland Road Park Observatory again, only with the added twist of incorporating an on-line component for those who for whatever reason don’t feel like making it out. To that end, we’ll have both our usual live broadcast on the BRAS YouTube channel and the Brasmeet page on Jitsi—which is where our out of town guests and, at least this month, our guest speaker can join us.