Discrete Scale Relativity and Sx Phoenicis Variable Stars
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Arxiv:1710.00185V1
Accepted for publication in the Publications of the Astronomical Society of the Pacific, 21 July 2017 Preprint typeset using LATEX style emulateapj v. 05/12/14 PROJECT SOLARIS – A GLOBAL NETWORK OF AUTONOMOUS OBSERVATORIES – DESIGN, COMMISSIONING AND FIRST SCIENCE RESULTS S.K. Koz lowski1,2, P.W. Sybilski1,3, M. Konacki1,2,3, R.K. Paw laszek1,3, M. Ratajczak 4, K.G. He lminiak1 and M. Litwicki1,2 Accepted for publication in the Publications of the Astronomical Society of the Pacific, 21 July 2017 ABSTRACT We present the design and commissioning of Project Solaris, a global network of autonomous observatories. Solaris is a Polish scientific undertaking aimed at the detection and characterization of circumbinary exoplanets and eclipsing binary stars. To accomplish this task, a network of four fully autonomous observatories has beed deployed in the Southern Hemisphere: Solaris-1 and Solaris-2 in the South African Astronomical Observatory in South Africa, Solaris-3 in Siding Spring Observatory in Australia and Solaris-4 in Complejo Astronomico El Leoncito in Argentina. The four stations are nearly identical and are equipped with 0.5-m Ritchey-Cr´etien (f/15) or Cassegrain (f/9, Solaris-3) optics and high-grade 2K x 2K CCD cameras with Johnson and Sloan filter sets. We present the design and implementation of low-level security, data logging and notification systems, weather monitoring components, all-sky vision system, surveillance system and distributed temperature and humidity sensors. We describe dedicated grounding and lighting protection system design and robust fiber data transfer interfaces in electrically demanding conditions. We discuss the outcomes of our design as well as the resulting software engineering requirements. -
Highlights of Discoveries for $\Delta $ Scuti Variable Stars from the Kepler
Highlights of Discoveries for δ Scuti Variable Stars from the Kepler Era Joyce Ann Guzik1,∗ 1Los Alamos National Laboratory, Los Alamos, NM 87545 USA Correspondence*: Joyce Ann Guzik [email protected] ABSTRACT The NASA Kepler and follow-on K2 mission (2009-2018) left a legacy of data and discoveries, finding thousands of exoplanets, and also obtaining high-precision long time-series data for hundreds of thousands of stars, including many types of pulsating variables. Here we highlight a few of the ongoing discoveries from Kepler data on δ Scuti pulsating variables, which are core hydrogen-burning stars of about twice the mass of the Sun. We discuss many unsolved problems surrounding the properties of the variability in these stars, and the progress enabled by Kepler data in using pulsations to infer their interior structure, a field of research known as asteroseismology. Keywords: Stars: δ Scuti, Stars: γ Doradus, NASA Kepler Mission, asteroseismology, stellar pulsation 1 INTRODUCTION The long time-series, high-cadence, high-precision photometric observations of the NASA Kepler (2009- 2013) [Borucki et al., 2010; Gilliland et al., 2010; Koch et al., 2010] and follow-on K2 (2014-2018) [Howell et al., 2014] missions have revolutionized the study of stellar variability. The amount and quality of data provided by Kepler is nearly overwhelming, and will motivate follow-on observations and generate new discoveries for decades to come. Here we review some highlights of discoveries for δ Scuti (abbreviated as δ Sct) variable stars from the Kepler mission. The δ Sct variables are pre-main-sequence, main-sequence (core hydrogen-burning), or post-main-sequence (undergoing core contraction after core hydrogen burning, and beginning shell hydrogen burning) stars with spectral types A through mid-F, and masses around 2 solar masses. -
Estimating the Parameters of Globular Cluster M 30 (NGC 7099) from Time-Series Photometry
Astronomy & Astrophysics manuscript no. ngc7099 c ESO 2018 September 23, 2018 Estimating the parameters of globular cluster M 30 (NGC 7099) from time-series photometry⋆,⋆⋆ N. Kains1, D. M. Bramich1, A. Arellano Ferro2, R. Figuera Jaimes1,3, U. G. Jørgensen4,5, S. Giridhar6 and K.A. Alsubai7, J. M. Andersen8,5, V. Bozza9,10, P. Browne3, M. Burgdorf11, S. Calchi Novati9,12, Y. Damerdji13, C. Diehl14,15, P. Dodds3, M. Dominik3,⋆⋆⋆, A. Elyiv13,16, X.-S. Fang17,18, E. Giannini14, S.-H. Gu17,18, S. Hardis4, K. Harpsøe4,5, T.C. Hinse19,4, A. Hornstrup20, M. Hundertmark3, J. Jessen-Hansen21, D. Juncher4,5, E. Kerins22, H. Kjeldsen21, H. Korhonen4,5, C. Liebig3, M. N. Lund21, M. Lundkvist21, L. Mancini23, R. Martin24, M. Mathiasen4, M.T. Penny25, M. Rabus26, S. Rahvar27,28, D. Ricci29,13, K. Sahu30, G. Scarpetta9,31, J. Skottfelt4,5, C. Snodgrass32, J. Southworth33, J. Surdej13, J. Tregloan-Reed33, C. Vilela33, O. Wertz13, and A. Williams24 (The MiNDSTEp consortium) (Affiliations can be found after the references) Received ... ; accepted ... Abstract Aims. We present the analysis of 26 nights of V and I time-series observations from 2011 and 2012 of the globular cluster M 30 (NGC 7099). We used our data to search for variable stars in this cluster and refine the periods of known variables; we then used our variable star light curves to derive values for the cluster’s parameters. Methods. We used difference image analysis to reduce our data to obtain high-precision light curves of variable stars. We then estimated the cluster parameters by performing a Fourier decomposition of the light curves of RR Lyrae stars for which a good period estimate was possible. -
Meeting Program
A A S MEETING PROGRAM 211TH MEETING OF THE AMERICAN ASTRONOMICAL SOCIETY WITH THE HIGH ENERGY ASTROPHYSICS DIVISION (HEAD) AND THE HISTORICAL ASTRONOMY DIVISION (HAD) 7-11 JANUARY 2008 AUSTIN, TX All scientific session will be held at the: Austin Convention Center COUNCIL .......................... 2 500 East Cesar Chavez St. Austin, TX 78701 EXHIBITS ........................... 4 FURTHER IN GRATITUDE INFORMATION ............... 6 AAS Paper Sorters SCHEDULE ....................... 7 Rachel Akeson, David Bartlett, Elizabeth Barton, SUNDAY ........................17 Joan Centrella, Jun Cui, Susana Deustua, Tapasi Ghosh, Jennifer Grier, Joe Hahn, Hugh Harris, MONDAY .......................21 Chryssa Kouveliotou, John Martin, Kevin Marvel, Kristen Menou, Brian Patten, Robert Quimby, Chris Springob, Joe Tenn, Dirk Terrell, Dave TUESDAY .......................25 Thompson, Liese van Zee, and Amy Winebarger WEDNESDAY ................77 We would like to thank the THURSDAY ................. 143 following sponsors: FRIDAY ......................... 203 Elsevier Northrop Grumman SATURDAY .................. 241 Lockheed Martin The TABASGO Foundation AUTHOR INDEX ........ 242 AAS COUNCIL J. Craig Wheeler Univ. of Texas President (6/2006-6/2008) John P. Huchra Harvard-Smithsonian, President-Elect CfA (6/2007-6/2008) Paul Vanden Bout NRAO Vice-President (6/2005-6/2008) Robert W. O’Connell Univ. of Virginia Vice-President (6/2006-6/2009) Lee W. Hartman Univ. of Michigan Vice-President (6/2007-6/2010) John Graham CIW Secretary (6/2004-6/2010) OFFICERS Hervey (Peter) STScI Treasurer Stockman (6/2005-6/2008) Timothy F. Slater Univ. of Arizona Education Officer (6/2006-6/2009) Mike A’Hearn Univ. of Maryland Pub. Board Chair (6/2005-6/2008) Kevin Marvel AAS Executive Officer (6/2006-Present) Gary J. Ferland Univ. of Kentucky (6/2007-6/2008) Suzanne Hawley Univ. -
Variable Star
Variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) fluctuates. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either: Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks. Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes Trifid Nebula contains Cepheid variable stars eclipses it. Many, possibly most, stars have at least some variation in luminosity: the energy output of our Sun, for example, varies by about 0.1% over an 11-year solar cycle.[1] Contents Discovery Detecting variability Variable star observations Interpretation of observations Nomenclature Classification Intrinsic variable stars Pulsating variable stars Eruptive variable stars Cataclysmic or explosive variable stars Extrinsic variable stars Rotating variable stars Eclipsing binaries Planetary transits See also References External links Discovery An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star, the eclipsing binary Algol.[2][3][4] Of the modern astronomers, the first variable star was identified in 1638 when Johannes Holwarda noticed that Omicron Ceti (later named Mira) pulsated in a cycle taking 11 months; the star had previously been described as a nova by David Fabricius in 1596. This discovery, combined with supernovae observed in 1572 and 1604, proved that the starry sky was not eternally invariable as Aristotle and other ancient philosophers had taught. -
Variable Stars Across the Observational HR Diagram
Variable stars across the observational HR diagram Laurent Eyer1, Nami Mowlavi1;2 1 Observatoire de Gen`eve, Universit´ede Gen`eve, 1290 Sauverny, Switzerland 2 ISDC, Universit´ede Gen`eve, 1290 Versoix, Switzerland E-mail: [email protected] Abstract. An overview of pulsating variable stars across the observational Hertzprung-Russel (HR) diagram is presented, together with a summary of their global properties. The HR diagram is presented with a third colour-coded dimension, visualizing the fraction of variable, the amplitude of variability or the period of variability. The distribution of variable stars in the other observational diagrams, such as the Period-Amplitude diagram, is also presented. Some of the progresses performed in the field of variable stars during the last decade are briefly summarized, and future projects that will improve our knowledge of variable stars are mentioned. 1. Introduction There are in the literature several global descriptions of variable stars. We can mention four books, one by Richter, Wenzel and Hoffmeister (1985, out of print), one by Sterken and Jaschek [1], one by Percy ([2]) and one, soon to come, by Aerts et al. [3]. There have also been two excellent and detailed reviews by Gautschy and Saio ([4], [5]) about a decade ago. With the advent of Charge-Coupled Devices (CCDs) and large scale surveys like the Optical Gravitational Lensing Experiment (OGLE), the Massive Compact Halo Object project (MACHO) or the "Exp´eriencepour la Recherche d'Objets Sombres" (EROS), the subject of variable star studies is now under a remarkable expansion. As we will see the expansion will continue in the coming decade because there are many future projects which will sample frequently large regions of the sky. -
A Deeper Look at Leo Iv: Star Formation History and Extended Structure
A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Sand, David J., Anil Seth, Edward W. Olszewski, Beth Willman, Dennis Zaritsky, and Nitya Kallivayalil. “A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE.” The Astrophysical Journal 718, no. 1 (July 1, 2010): 530–542. © 2010 The American Astronomical Society As Published http://dx.doi.org/10.1088/0004-637x/718/1/530 Publisher IOP Publishing Version Final published version Citable link http://hdl.handle.net/1721.1/95689 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The Astrophysical Journal, 718:530–542, 2010 July 20 doi:10.1088/0004-637X/718/1/530 C 2010. The American Astronomical Society. All rights reserved. Printed in the U.S.A. A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE∗ David J. Sand1,5, Anil Seth1, Edward W. Olszewski2, Beth Willman3, Dennis Zaritsky2, and Nitya Kallivayalil4,6 1 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA; [email protected] 2 Steward Observatory, University of Arizona, Tucson, AZ 85721, USA 3 Haverford College, Department of Astronomy, 370 Lancaster Avenue, Haverford PA 19041, USA 4 MIT Kavli Institute for Astrophysics & Space Research, 70 Vassar Street, Cambridge, MA 02139, USA Received 2009 November 26; accepted 2010 May 24; published 2010 July 1 ABSTRACT We present MMT/Megacam imaging of the Leo IV dwarf galaxy in order to investigate its structure and star formation history, and to search for signs of association with the recently discovered Leo V satellite. -
Variable Stars in the Globular Cluster M 13 Ability of V7 Was Confirmed by Shapley (1915B)
Astronomy & Astrophysics manuscript no. h3895 October 23, 2018 (DOI: will be inserted by hand later) Variable stars in the globular cluster M 13 G. Kopacki, Z. Kołaczkowski, and A. Pigulski Wrocław University Observatory, Kopernika 11, 51-622 Wrocław, Poland Received .....; accepted ..... Abstract. Results of a search for variable stars in the central region of the globular cluster M 13 are presented. Prior to this study, 36 variable and suspected variable stars were known in this cluster (Osborn 2000; Clement et al. 2001). Of these stars, five were not observed by us. We find v3, v4, v10, v12, and v13 to be constant in light. Surprisingly, only two out of the ten variable star candidates of Kadla et al. (1980) appear to be variable. Both are RRc variables. Additionally, three RR Lyrae stars and one SX Phoenicis variable are discovered. Three close frequencies are detected for an RRc star v36. It appears that this variable is another multi-periodic RR Lyrae star pulsating in non-radial modes. Light curves of the three known BL Herculis stars and all known RR Lyrae stars are presented. The total number of known RR Lyrae stars in M 13 is now nine. Only one is an RRab star. The mean period of RRc variables amounts to 0.36 ± 0.05 d, suggesting that M 13 should be included in the group of Oosterhoff type II globular clusters. Mean V magnitudes and ranges of variation are derived for seven RR Lyrae and three BL Herculis variables. Almost all observed bright giants show some degree of variability. -
Blications of the Astronomical Society of the Pacific, 115:755–760, 2003 June ᭧ 2003
Publications of the Astronomical Society of the Pacific, 115:755–760, 2003 June ᭧ 2003. The Astronomical Society of the Pacific. All rights reserved. Printed in U.S.A. Differential Time-Series CCD Photometry of BL Camelopardalis Revisited Chulhee Kim Department of Earth Science Education, Chonbuk National University, Korea; [email protected] and Y.-B. Jeon and S.-L. Kim Department of Earth Science Education, Chonbuk National University, Korea; and Korea Astronomy Observatory, Yeoungcheon 770-880, Korea Received 2003 January 11; accepted 2003 February 28 ABSTRACT. New differential time-series observations of BL Camelopardalis were secured using B and V filters. It was confirmed that BL Cam is an optical double star. Differential magnitudes were obtained through a photometric profile reduction procedure to eliminate the influence of a faint adjacent star. Variations inO Ϫ C values for light maxima were investigated. We found that the parabolic period variation was recently reversed. The periods of BL Cam were investigated, and five frequencies were determined using Fourier analysis. We also investigated the relationship between metallicities and period ratios, and we compared the theoretical and observational relationships. It was found that the theoretical relationship is better than the observational one for BL Cam. 1. INTRODUCTION been discovered. Interestingly, three of the 12 are double-mode pulsators (McNamara 1997; Martin & Rodrı´guez 1995). BL Camelopardalis ( p 03h47m19s, p ϩ63Њ22 7 a d BL Cam was first discovered by Giclas, Burnham, & Thomas [J2000.0],V p 13.10 ,V p 0.33 mag) was classified as an D (1970) as a possible white dwarf candidate. -
NEW SX PHOENICIS VARIABLES in the GLOBULAR CLUSTER NGC 48331 Andrew N
Journal of the Southeastern Association for Research in Astronomy, 6, 00-00, November 8, 2018 c 2010. Southeastern Association for Research in Astronomy. All rights reserved. NEW SX PHOENICIS VARIABLES IN THE GLOBULAR CLUSTER NGC 48331 Andrew N. Darragh and Brian W. Murphy Department of Physics and Astronomy, Butler University, Indianapolis, IN, 46208 & SARA ABSTRACT We report the discovery of 6 SX Phoenicis stars in the southern globular cluster NGC 4833. Images were obtained from January through June 2011 with the Southeastern Association for Research in Astronomy 0.6 meter telescope located at Cerro Tololo Interamerican Observatory. The image sub- traction method of Alard & Lupton (1998) was used to search for variable stars in the cluster. We confirmed 17 previously cataloged variables by Demers & Wehlau(1977). In addition to the previously known variables we have identified 10 new variables. Of the total number of confirmed variables in our 10×10 arcmin2 field, we classified 10 RRab variables, with a mean period of 0.69591 days, 7 RRc, with a mean period of 0.39555 days, 2 possible RRe variables with a mean period of 0.30950 days, a W Ursae Majoris contact binary, an Algol-type binary, and the 6 SX Phoenicis stars with a mean period of 0.05847 days. The periods, relative numbers of RRab and RRc variables, and Bailey diagram are indicative of the cluster being of the Oosterhoff type II. We present the phased-light curves, periods of previously known variables and the periods and classifications of the newly discovered variables, and their location on the color-magnitude diagram. -
Times of Maximum of KZ Hya from OACS -UNAH
REF-UNAH v8i2, 90-93 (2020) • DOI: Pendiente Times of maximum of KZ Hya from OACS -UNAH M. MEZA1,†, A. PINEDA2,†, C. ARGUETA1,†, Y. MENDOZA2,†, M.C. PEREIRA1,†, W. FUENTES3,†, M. INTERIANO2,† Recibido: 15 de octubre de 2020 / Aceptado: 5 de enero de 2021 A pulsating variable star is one whose brightness changes periodically 1 due to the expansion and contraction of the surface layers of the star. Facultad de Ciencias Espaciales, Universidad Several times of maximum light can be obtained in brief observations Nacional Autónoma de Honduras. of SX Phoenicis variable stars due to their short periods of pulsation (P ∼ 1:0 − 1:75 h). We report three new times of maximum light of SX 2Escuela de Física, Facultad de Ciencias, Phoenicis star KZ Hya obtained from photometric observations made on the night of April 5-6, 2019 from the Observatorio Astronómico Cen- Universidad Nacional Autónoma de Honduras. troaméricano de Suyapa (OACS) of the Universidad Nacional Autónoma de Honduras. 3Departamento de Física, Universidad Nacional Autónoma de Honduras en el Valle de Sula. Una estrella variable pulsante es una cuyo brillo cambia periódicamente debido a la expansión y contracción de las capas superficiales de la es- †Grupo de Investigación en Estrellas Pulsantes - trella. Las estrellas variables SX Phoenicis tienen periodos de pulsación UNAH. [email protected] cortos (P ∼ 1:0 − 1:75 h) por lo que se pueden obtener varios tiempos de máximo en observaciones cortas. Se reportan tres tiempos de máximo para la estrella SX Phoenicis KZ Hya, obtenidos a partir de observa- ciones fotométricas hechas en la noche del 5-6 de abril de 2019 desde Special Thanks el Observatorio Astronómico Centroaméricano de Suyapa (OACS) de la UNAH. -
Report on the Photometric Observations of the Variable Stars DH Pegasi, DY Pegasi, and RZ Cephei
Abu-Sharkh et al., JAAVSO Volume 42, 2014 1 Report on the Photometric Observations of the Variable Stars DH Pegasi, DY Pegasi, and RZ Cephei Ibrahim Abu-Sharkh Shuxing Fang Sahil Mehta Dang Pham Harvard Summer School, Harvard University, Cambridge, MA; address correspondence to Dang Pham ([email protected]) Received September 4, 2014; revised September 16, 2014; accepted September 16, 2014 Abstract We report 872 observations on two RR Lyrae variable stars, DH Pegasi and RZ Cephei, and on one SX Phoenicis variable, DY Pegasi. This paper discusses the methodology of our measurements, the light curves, magnitudes, epochs, and epoch prediction of the above stars. We also derived the period of DY Pegasi. All measurements and analyses are compared with prior publications and known values from multiple databases. 1. Introduction The Harvard Summer School is a program of Harvard University for secondary and college students to experience a Harvard education through two undergraduate courses at Harvard. The authors were enrolled in “Fundamentals of Contemporary Astronomy” taught by Prof. Rosanne Di Stefano. Part of this paper was meant to be a class project, but we found this topic interesting and decided to do more—thus, we observed the stars instead of just researching facts about them. Throughout this study, we have focused on pulsating variable stars with exceptionally short periods. We have inspected the length of their periods, their change in apparent magnitude, time of epoch, and general shape of their light curves. Measurements of the following stars are presented, DH Pegasi, DY Pegasi, and RZ Cephei, all taken at the Clay Telescope (Harvard University, 0.4 m) with the Apogee Alta U47 Imaging CCD coupled with the Johnson V filter.