Variable Stars Observer Bulletin
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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. -
Astronomy and Astrophysics Report for 2016
Astronomy and Astrophysics Report for 2016 Submitted to the Governing Board at its meeting on 1st March 2017 1.Research output and activities The primary research output of the section consists of peer-reviewed publications in the leading astronomical and astrophysical journals. The section has a green open-access publishing policy whereby all publications are placed as preprints on the freely accessible arXiv server. To this end DIAS supports arXiv with a modest financial contribution. During the calendar year seventy three papers were published, or posted as preprints on arXiv, and with at least one co-author from the section as well as six non-refereed papers. Full details can be found in the detailed bibliography at the end of this report (which replaces the former summary text). In some ways what is more interesting than the raw number of papers is the trend over time which shows considerable year on year fluctuations, but no major change over the last decade. Refereed Preprints Non-refereed 160 120 80 40 0 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Note that pre 2010 preprints were classified as non-refereed and not treated as a separate category. In addition to research papers, talks and conference presentations are an important means of communicating our research to our peers and a useful measure of the esteem in which we are held. During the year the following were delivered. Felix Aharonian: 1. Rome, Italy, workshop “Towards a large field-of-view TeV experiment” (14.01-15.01.2016) Evidence for a PeVatron in the Galactic Center: is it Sgr A*? 2. -
Variable Stars Observer Bulletin 15.000 – 30.000
the appropriate amount of shots with the same comparison stars and their brightness in the range exposures. Making the Flat files is a little more the data frames are. Amateurs' Guide to Variable Stars September-October 2013 | Issue #2 complicated. Ideally, they are easy to get on evening or predawn twilight sky. You need to With a series of photometric observations, we can choose the exposure to get a ¼ - ½ of the value of build a light curve, find the period of a variable complete saturation of the pixel. For example, full star, other parameters, depending on the saturation for 16 bit camera is 65535. The value of variability type. a pixel in the Flat file should be in the range of Variable Stars Observer Bulletin 15.000 – 30.000. I use 20.000. There are lots of software to make the analysis of the photometric data. A good example is a ISSN 2309-5539 Another way of obtaining the Flat files is to use the software package created by Andrey Prokopovich so-called flat-box. I use a white screen which is and Ivan Adamin (the VS-COMPAS project core attached to the dome. Am bringing him a team). There are desktop and web versions Twenty new W Ursae Majoris-type eclipsing telescope and the illuminating light bulb. For more available. It is a powerful software that allows you binaries from the Catalina Sky Survey scattered light, the telescope tube can be covered to build the light curves, search for possible with a white cloth. Flat files must be taken periods, combine data from a number of separately for each filter. -
Interstellarum 25 Schließen Wir Den Ersten Jahrgang Der Neuen Interstellarum-Hefte Ab
Liebe Leserinnen, liebe Leser, Meade gegen Celestron, das ist das große Duell der beiden Teleskopgiganten aus Amerika. Wir sind stolz darauf, als erste deutschsprachige Zeitschrift einen fairen Zweikampf der weltgröß- ten Fernrohrhersteller anbieten zu können; un- getrübt von wirtschaftlichen oder redaktionellen Vorbehalten. Dazu haben wir die neuen aufre- genden GPS-Teleskope von Meade und Celes- tron in einem Produktvergleich gegenüberge- stellt. Im ersten Teil in diesem Heft erfahren Sie mehr über Mechanik und Elektronik der beiden Computerteleskope (Seite 60); die Ergebnisse der Praxis unter den Sternen lesen Sie dann in einem kommenden Heft. Mit interstellarum 25 schließen wir den ersten Jahrgang der neuen interstellarum-Hefte ab. Ein Plus von 30% bei den Abonnentenzahlen spricht für unseren Weg, den wir konsequent fortsetzen Polarlichter in Deutschland (Foto: Thomas Jäger) werden. Dabei möchten wir verstärkt das Augen- merk auf hochqualitative Beiträge für praktisch tätige Amateurastronomen lenken. werden wir uns zusätzlich der Jupiterbeobach- tung und dem Merkurdurchgang vom 7.5.2003 2003 wird bei interstellarum zum Jahr der widmen. Schließlich stehen 2003 mit zwei Planetenbeobachtung ernannt. Auftakt ist der Mondfinsternissen und einer partiellen Sonnen- Beitrag zur Beobachtung der Saturnringe in die- finsternis drei weitere Großereignisse auf dem ser Ausgabe (Seite 34). Mit dem nächsten Heft Programm. beginnen wir zusätzlich eine intensive Vorberei- tung auf die große Mars-Opposition in diesem Was wir noch 2003 geplant haben, ist auf Sommer mit Beiträgen zu verschiedenen prakti- www.interstellarum.de nachzulesen. Ihren eige- schen Themenkreisen in jedem Heft. Verstärkt nen Bericht nehmen wir gerne entgegen. Mit interstellarum 25 endet die Comic-Serie Astromax (Seite 80), die Schöpfer Rainer Töpler aus Zeitgründen aufgeben muss – vielen Dank für die sechs kurzweiligen Geschichtchen. -
1. Introduction
1. Introduction Three variable stars with short periods and high-amplitude, CY Aqr, BP Peg, and GP And, are selected for the study, and the characteristic of each variable star is analyzed from their light curves. These three variable stars are difference a little, CY Aqr is probability a binary system, BP Peg is a type of delta Scuti star with two stable periods (Rodriguez et al., 1992), and GP And is a simple delta Scuti star. 1.1 Delta Scuti stars Delta Scuti, the fourth bright star in Scutum at V magnitude, 4.71, stand out as the prototype of one of these. On the HR diagram or temperature-luminosity diagram, the kind of variable stars were located in intersects of main sequence with instability strip shown in Figure 1. Figure 1. Delta Scuti stars were in intersects of main sequence with instability strip. Delta Scuti stars is the group of the second most numerous of pulsators in the Galaxy, after the pulsating white dwarfs, and their spectrum belong to type A to early F. Most delta Scuti stars belong to Population I (Antonello, Broglia & Mantegazza, 1986), but a few variables show low metals and 6 high space velocities typical of Population II (Rodriguez E., Rolland A. & Lopez de coca P., 1990). The delta Scuti stars is divided into two types, variable stars with high-amplitude delta Scuti (HADS) and high-amplitude SX Phe (HASXP) (Breger, 1983;Andreasen, 1983;Frolov and Irkaev, 1984). Both of them have asymmetrical light curve in V with amplitudes > 0.25 magnitude and probably hydrogen-burning stars in the main sequence or post main sequence stage. -
A Long-Term Photometric Study of the FU Orionis Star V 733 Cephei
A&A 515, A24 (2010) Astronomy DOI: 10.1051/0004-6361/201014092 & c ESO 2010 Astrophysics A long-term photometric study of the FU Orionis star V 733 Cephei S. P. Peneva1,E.H.Semkov1, U. Munari2, and K. Birkle3 1 Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose Blvd., 1784 Sofia, Bulgaria e-mail: [speneva;esemkov]@astro.bas.bg 2 INAF Osservatorio Astronomico di Padova, Sede di Asiago, 36032 Asiago (VI), Italy 3 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany Received 18 January 2010 / Accepted 17 February 2010 ABSTRACT Context. The FU Orionis candidate V733 Cep was discovered by Roger Persson in 2004. The star is located in the dark cloud L1216 close to the Cepheus OB3 association. Because only a small number of FU Orionis stars have been detected to date, photometric and spectral studies of V733 Cep are of great interest. Aims. The studies of the photometrical variability of PMS stars are very important to the understanding of stellar evolution. The main purpose of our study is to construct a long-time light curve of V733 Cep. On the basis of BVRI monitoring we also study the photometric behavior of the star. Methods. We gather data from CCD photometry and archival photographic plates. The photometric BVRI data (Johnson-Cousins system) that we present were collected from June 2008 to October 2009. To facilitate transformation from instrumental measurements to the standard system, fifteen comparison stars in the field of V733 Cep were calibrated in BVRI bands. To construct a historical light curve of V733 Cep, a search for archival photographic observations in the Wide-Field Plate Database was performed. -
00E the Construction of the Universe Symphony
The basic construction of the Universe Symphony. There are 30 asterisms (Suites) in the Universe Symphony. I divided the asterisms into 15 groups. The asterisms in the same group, lay close to each other. Asterisms!! in Constellation!Stars!Objects nearby 01 The W!!!Cassiopeia!!Segin !!!!!!!Ruchbah !!!!!!!Marj !!!!!!!Schedar !!!!!!!Caph !!!!!!!!!Sailboat Cluster !!!!!!!!!Gamma Cassiopeia Nebula !!!!!!!!!NGC 129 !!!!!!!!!M 103 !!!!!!!!!NGC 637 !!!!!!!!!NGC 654 !!!!!!!!!NGC 659 !!!!!!!!!PacMan Nebula !!!!!!!!!Owl Cluster !!!!!!!!!NGC 663 Asterisms!! in Constellation!Stars!!Objects nearby 02 Northern Fly!!Aries!!!41 Arietis !!!!!!!39 Arietis!!! !!!!!!!35 Arietis !!!!!!!!!!NGC 1056 02 Whale’s Head!!Cetus!! ! Menkar !!!!!!!Lambda Ceti! !!!!!!!Mu Ceti !!!!!!!Xi2 Ceti !!!!!!!Kaffalijidhma !!!!!!!!!!IC 302 !!!!!!!!!!NGC 990 !!!!!!!!!!NGC 1024 !!!!!!!!!!NGC 1026 !!!!!!!!!!NGC 1070 !!!!!!!!!!NGC 1085 !!!!!!!!!!NGC 1107 !!!!!!!!!!NGC 1137 !!!!!!!!!!NGC 1143 !!!!!!!!!!NGC 1144 !!!!!!!!!!NGC 1153 Asterisms!! in Constellation Stars!!Objects nearby 03 Hyades!!!Taurus! Aldebaran !!!!!! Theta 2 Tauri !!!!!! Gamma Tauri !!!!!! Delta 1 Tauri !!!!!! Epsilon Tauri !!!!!!!!!Struve’s Lost Nebula !!!!!!!!!Hind’s Variable Nebula !!!!!!!!!IC 374 03 Kids!!!Auriga! Almaaz !!!!!! Hoedus II !!!!!! Hoedus I !!!!!!!!!The Kite Cluster !!!!!!!!!IC 397 03 Pleiades!! ! Taurus! Pleione (Seven Sisters)!! ! ! Atlas !!!!!! Alcyone !!!!!! Merope !!!!!! Electra !!!!!! Celaeno !!!!!! Taygeta !!!!!! Asterope !!!!!! Maia !!!!!!!!!Maia Nebula !!!!!!!!!Merope Nebula !!!!!!!!!Merope -
The Fifth Level of Learning: the Vedic Gods
The Wes Penre Papers || The Fifth Level of Learning The Vedic Texts The Wes Penre Papers: The Vedic Texts The Fifth Level of Learning Part 2 by Wes Penre The Wes Penre Papers || The Fifth Level of Learning The Vedic Texts Copyright © 2014-2015 Wes Penre All rights reserved. This is an electronic paper free of charge, which can be downloaded, quoted from, and copied to be shared with other people, as long as nothing in this paper is altered or quoted out of context. Not for commercial use. Editing provided by Bob Stannard: www.twilocity.com 1st Edition, February 27, 2015 Wes Penre Productions Oregon, USA The Wes Penre Papers || The Fifth Level of Learning The Vedic Texts Table of Contents PAPER 10: THE NAKSHATRAS—THE GOD AND THEIR STAR SYSTEMS ...... 6 I. The Nakshatras or Lunar Mansions ...................................................................... 6 II. Star Systems and Constellations in Domain of the Orion Empire ...................... 9 ii.i. The Orion Empire in the Vedas ....................................................................... 17 III. Domains Conquered by the AIF with Marduk in Charge ................................ 20 IV. Star Systems and Constellations under En.ki’s Control .................................. 40 V. Asterism Ruled by Queen Ereškigal ................................................................. 61 PAPER 11: DISCUSSING STAR SYSTEMS NOT MENTIONED IN THE NAKSHATRAS ........................................................................................................... 65 I. Introduction -
GEORGE HERBIG and Early Stellar Evolution
GEORGE HERBIG and Early Stellar Evolution Bo Reipurth Institute for Astronomy Special Publications No. 1 George Herbig in 1960 —————————————————————– GEORGE HERBIG and Early Stellar Evolution —————————————————————– Bo Reipurth Institute for Astronomy University of Hawaii at Manoa 640 North Aohoku Place Hilo, HI 96720 USA . Dedicated to Hannelore Herbig c 2016 by Bo Reipurth Version 1.0 – April 19, 2016 Cover Image: The HH 24 complex in the Lynds 1630 cloud in Orion was discov- ered by Herbig and Kuhi in 1963. This near-infrared HST image shows several collimated Herbig-Haro jets emanating from an embedded multiple system of T Tauri stars. Courtesy Space Telescope Science Institute. This book can be referenced as follows: Reipurth, B. 2016, http://ifa.hawaii.edu/SP1 i FOREWORD I first learned about George Herbig’s work when I was a teenager. I grew up in Denmark in the 1950s, a time when Europe was healing the wounds after the ravages of the Second World War. Already at the age of 7 I had fallen in love with astronomy, but information was very hard to come by in those days, so I scraped together what I could, mainly relying on the local library. At some point I was introduced to the magazine Sky and Telescope, and soon invested my pocket money in a subscription. Every month I would sit at our dining room table with a dictionary and work my way through the latest issue. In one issue I read about Herbig-Haro objects, and I was completely mesmerized that these objects could be signposts of the formation of stars, and I dreamt about some day being able to contribute to this field of study. -
A Long-Term Photometric Study of the FU Orionis Star V 733 Cep Tronomer Roger Persson in 2004 (Persson 2004)
Astronomy & Astrophysics manuscript no. 14092 c ESO 2018 October 10, 2018 A long-term photometric study of the FU Orionis star V 733 Cep S. P. Peneva1, E. H. Semkov1, U. Munari2, and K. Birkle3 1 Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose blvd., BG-1784 Sofia, Bulgaria e-mail: [email protected] 2 INAF Osservatorio Astronomico di Padova, Sede di Asiago, I-36032 Asiago (VI), Italy 3 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, D-69117 Heidelberg, Germany Received ; accepted ABSTRACT Context. The FU Orionis candidate V733 Cep was discovered by Roger Persson in 2004. The star is located in the dark cloud L1216 close to the Cepheus OB3 association. Because only a small number of FU Orionis stars have been detected to date, photometric and spectral studies of V733 Cep are of great interest. Aims. The studies of the photometrical variability of PMS stars are very important to the understanding of stellar evolution. The main purpose of our study is to construct a long-time light curve of V733 Cep. On the basis of BVRI monitoring we also study the photometric behavior of the star. Methods. We gather data from CCD photometry and archival photographic plates. The photometric BVRI data (Johnson-Cousins system) that we present were collected from June 2008 to October 2009. To facilitate transformation from instrumental measurements to the standard system, fifteen comparison stars in the field of V733 Cep were calibrated in BVRI bands. To construct a historical light curve of V733 Cep, a search for archival photographic observations in the Wide-Field Plate Database was performed. -
The FU Orionis Phenomenon
FU Orionis stars are pre-main-sequence eruptive variables which make up a small class of young low- mass stars appear to be a stage in the development of T Tauri stars. They gradually brighten by up to six magnitudes over several months, during which time matter is ejected, then remain almost steady or slowly decline by a magnitude or two over years. All known FU Ori stars (commonly known as fuors) are associated with reflection nebulae. The article gives a brief description of this kind of objects. FU Orionis is somewhat 1600 light-years away and associated with a reflection nebulae in the Orion constellation. It is located about three degrees NW of Betelgeuse, and less than a degree east of the small planetary nebula NGC2022. FU Orionis is the prototype of a class of young stellar objects (YSOs), which have undergone photometric outbursts on the order of 4-6 mag in less than one year (Herbig 1966). These stars are still in the process of forming, accreting gas from the clouds they formed from. The first outburst of FU Ori was observed in 1936-37, when an ordinary undiscovered 16th magnitude star began to brighten steadily. Unlike novae bursts, which forth suddenly and then begin to fade within weeks , the FU Ori kept getting brighter and brighter for almost a year being around 10 th magnitude ever since. Typically, FU Orionis star's luminosity peaks at approximately 500 luminosities of the Sun and then appears to decay for decades. FU Orionis stars exhibit large infrared excesses, double-peaked line profiles, apparent spectral types that vary with wavelength, broad, blueshifted Balmer line absorption, and are often associated with strong mass outflows. -
THE STAR FORMATION NEWSLETTER an Electronic Publication Dedicated to Early Stellar Evolution and Molecular Clouds
THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar evolution and molecular clouds No. 194 — 23 Feb 2009 Editor: Bo Reipurth ([email protected]) Abstracts of recently accepted papers V1647 Orionis: Reinvigorated Accretion and the Re-Appearance of McNeil’s Nebula Colin Aspin1, Bo Reipurth1, Tracy L. Beck2, Greg Aldering3, Ryan L. Doering4, Heidi B. Hammel5, David K. Lynch6, Margaret Meixner2, Emmanuel Pecontal7, Ray W. Russell6, Michael L. Sitko8, Rollin C. Thomas3 and Vivian U1 1 Institute for Astronomy, University of Hawaii, 640 North A’ohoku Place, Hilo, HI 96720, USA 2 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 3 Lawrence Berkeley Lab, Physics Division, MS-50/232, One Cyclotron Road, Berkeley, CA 94720, USA 4 Department of Physics and Astronomy, Valparaiso University, Valparaiso, IN 46383, USA 5 Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USA 6 The Aerospace Corporation, Los Angeles, CA 90009, USA 7 Observatoire de Lyon, 9 Avenue Charles-Andr´e, 69561 Saint-Genis-Laval Cedex, France 8 Department of Physics, University of Cincinnati, Cincinnati, OH 45221, USA E-mail contact: caa at ifa.hawaii.edu In late 2003, the young eruptive variable star V1647 Orionis optically brightened by over 5 mag, stayed bright for around 26 months, and then declined to its pre-outburst level. In 2008 August, the star was reported to have unexpectedly brightened yet again and we herein present the first detailed observations of this new outburst. Photometrically, the star is now as bright as it ever was following the 2003 eruption.