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Sky April 2011
EDITORIAL ................. 2 ONE TO ONE WITH TONY MARSH 3 watcher CAPTION COMPETITION 7 April 2011 Sky OUTREACH EVENT AT CHANDLER SCHOOL .... 8 MOON AND SATURN WATCH 9 MY TELESCOPE BUILDING PROJECT 10 CONSTELLATION OF THE MONTH - VIRGO 15 OUTREACH AT BENTLEY COPSE 21 THE NIGHT SKY IN APRIL 22 Open-Air Planisphere taken by Adrian Lilly Page 1 © copyright 2011 guildford astronomical society www.guildfordas.org From the Editor Welcome to this, the April issue of Skywatcher. With the clocks going forward a hour the night sky has undergone a radical shift, the winter constellations are rapidly disappearing into the evening twilight, and the galaxy-filled reaches of Virgo are high up in the south and well-placed for observation. But I digress, whatever telescope you own or have stashed away at the back of the garage, the thought of making your own has probably crossed your mind at some point. I‟m delighted to have an article from Jonathan Shinn describing how he built a 6-inch Dobsonian – including grinding the mirror! Our lead-off article this issue is the interview from Brian Gordon-States with Tony Marsh. Tony has been a Committee member for many years, and much like previous interviews the story behind how he became fascinated with Astronomy is a compelling one. If there is a theme to this issue it‟s probably one of Outreach as I have two reports to share with you all. These events give youngsters the chance to look through a telescope at the wonders of the universe, and our closer celestial neighbours with someone on-hand to explain what they are looking at. -
1. Introduction
THE ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 122:109È150, 1999 May ( 1999. The American Astronomical Society. All rights reserved. Printed in U.S.A. GALAXY STRUCTURAL PARAMETERS: STAR FORMATION RATE AND EVOLUTION WITH REDSHIFT M. TAKAMIYA1,2 Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637; and Gemini 8 m Telescopes Project, 670 North Aohoku Place, Hilo, HI 96720 Received 1998 August 4; accepted 1998 December 21 ABSTRACT The evolution of the structure of galaxies as a function of redshift is investigated using two param- eters: the metric radius of the galaxy(Rg) and the power at high spatial frequencies in the disk of the galaxy (s). A direct comparison is made between nearby (z D 0) and distant(0.2 [ z [ 1) galaxies by following a Ðxed range in rest frame wavelengths. The data of the nearby galaxies comprise 136 broad- band images at D4500A observed with the 0.9 m telescope at Kitt Peak National Observatory (23 galaxies) and selected from the catalog of digital images of Frei et al. (113 galaxies). The high-redshift sample comprises 94 galaxies selected from the Hubble Deep Field (HDF) observations with the Hubble Space Telescope using the Wide Field Planetary Camera 2 in four broad bands that range between D3000 and D9000A (Williams et al.). The radius is measured from the intensity proÐle of the galaxy using the formulation of Petrosian, and it is argued to be a metric radius that should not depend very strongly on the angular resolution and limiting surface brightness level of the imaging data. It is found that the metric radii of nearby and distant galaxies are comparable to each other. -
![Arxiv:0709.0302V1 [Astro-Ph] 3 Sep 2007 N Ro,M,414 USA 48104, MI, Arbor, Ann USA As(..Mcayne L 01.Sc Aeilcudslow Could Material Such Some 2001)](https://docslib.b-cdn.net/cover/0661/arxiv-0709-0302v1-astro-ph-3-sep-2007-n-ro-m-414-usa-48104-mi-arbor-ann-usa-as-mcayne-l-01-sc-aeilcudslow-could-material-such-some-2001-380661.webp)
Arxiv:0709.0302V1 [Astro-Ph] 3 Sep 2007 N Ro,M,414 USA 48104, MI, Arbor, Ann USA As(..Mcayne L 01.Sc Aeilcudslow Could Material Such Some 2001)
DRAFT VERSION NOVEMBER 4, 2018 Preprint typeset using LATEX style emulateapj v. 03/07/07 SN 2005AP: A MOST BRILLIANT EXPLOSION ROBERT M. QUIMBY1,GREG ALDERING2,J.CRAIG WHEELER1,PETER HÖFLICH3,CARL W. AKERLOF4,ELI S. RYKOFF4 Draft version November 4, 2018 ABSTRACT We present unfiltered photometric observations with ROTSE-III and optical spectroscopic follow-up with the HET and Keck of the most luminous supernova yet identified, SN 2005ap. The spectra taken about 3 days before and 6 days after maximum light show narrow emission lines (likely originating in the dwarf host) and absorption lines at a redshift of z =0.2832, which puts the peak unfiltered magnitude at −22.7 ± 0.1 absolute. Broad P-Cygni features corresponding to Hα, C III,N III, and O III, are further detected with a photospheric velocity of ∼ 20,000kms−1. Unlike other highly luminous supernovae such as 2006gy and 2006tf that show slow photometric evolution, the light curve of SN 2005ap indicates a 1-3 week rise to peak followed by a relatively rapid decay. The spectra also lack the distinct emission peaks from moderately broadened (FWHM ∼ 2,000kms−1) Balmer lines seen in SN 2006gyand SN 2006tf. We briefly discuss the origin of the extraordinary luminosity from a strong interaction as may be expected from a pair instability eruption or a GRB-like engine encased in a H/He envelope. Subject headings: Supernovae, SN 2005ap 1. INTRODUCTION the ultra-relativistic flow and thus mask the gamma-ray bea- Luminous supernovae (SNe) are most commonly associ- con announcing their creation, unlike their stripped progeni- ated with the Type Ia class, which are thought to involve tor cousins. -
Machine Learning for Star Cluster Identification∗ Submitted to Apj
Draft version December 1, 2020 Typeset using LATEX default style in AASTeX63 StarcNet: Machine Learning for Star Cluster Identification∗ Gustavo Perez´ ,1 Matteo Messa ,2 Daniela Calzetti ,2 Subhransu Maji ,1 Dooseok E. Jung ,2 Angela Adamo ,3 and Mattia Siressi3 1Department of Computer Science University of Massachusetts Amherst 40 Governors Drive Amherst, MA 01003, USA 2Department of Astronomy University of Massachusetts Amherst 710 North Pleasant Street Amherst, MA 01003, USA 3Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm, Sweden (Received July 1, 2020; Revised; Accepted) Submitted to ApJ ABSTRACT We present a machine learning (ML) pipeline to identify star clusters in the multi{color images of nearby galaxies, from observations obtained with the Hubble Space Telescope as part of the Treasury Project LEGUS (Legacy ExtraGalactic Ultraviolet Survey). StarcNet (STAR Cluster classification NETwork) is a multi{scale convolutional neural network (CNN) which achieves an accuracy of 68.6% (4 classes)/86.0% (2 classes: cluster/non{cluster) for star cluster classification in the images of the LEGUS galaxies, nearly matching human expert performance. We test the performance of StarcNet by applying pre{trained CNN model to galaxies not included in the training set, finding accuracies similar to the reference one. We test the effect of StarcNet predictions on the inferred cluster properties by comparing multi{color luminosity functions and mass{age plots from catalogs produced by StarcNet and by human{labeling; distributions in luminosity, color, and physical characteristics of star clusters are similar for the human and ML classified samples. There are two advantages to the ML approach: (1) reproducibility of the classifications: the ML algorithm's biases are fixed and can be measured for subsequent analysis; and (2) speed of classification: the algorithm requires minutes for tasks that humans require weeks to months to perform. -
A Search For" Dwarf" Seyfert Nuclei. VII. a Catalog of Central Stellar
TO APPEAR IN The Astrophysical Journal Supplement Series. Preprint typeset using LATEX style emulateapj v. 26/01/00 A SEARCH FOR “DWARF” SEYFERT NUCLEI. VII. A CATALOG OF CENTRAL STELLAR VELOCITY DISPERSIONS OF NEARBY GALAXIES LUIS C. HO The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA 91101 JENNY E. GREENE1 Department of Astrophysical Sciences, Princeton University, Princeton, NJ ALEXEI V. FILIPPENKO Department of Astronomy, University of California, Berkeley, CA 94720-3411 AND WALLACE L. W. SARGENT Palomar Observatory, California Institute of Technology, MS 105-24, Pasadena, CA 91125 To appear in The Astrophysical Journal Supplement Series. ABSTRACT We present new central stellar velocity dispersion measurements for 428 galaxies in the Palomar spectroscopic survey of bright, northern galaxies. Of these, 142 have no previously published measurements, most being rela- −1 tively late-type systems with low velocity dispersions (∼<100kms ). We provide updates to a number of literature dispersions with large uncertainties. Our measurements are based on a direct pixel-fitting technique that can ac- commodate composite stellar populations by calculating an optimal linear combination of input stellar templates. The original Palomar survey data were taken under conditions that are not ideally suited for deriving stellar veloc- ity dispersions for galaxies with a wide range of Hubble types. We describe an effective strategy to circumvent this complication and demonstrate that we can still obtain reliable velocity dispersions for this sample of well-studied nearby galaxies. Subject headings: galaxies: active — galaxies: kinematics and dynamics — galaxies: nuclei — galaxies: Seyfert — galaxies: starburst — surveys 1. INTRODUCTION tors, apertures, observing strategies, and analysis techniques. -
Synapses of Active Galactic Nuclei: Comparing X-Ray and Optical Classifications Using Artificial Neural Networks?
A&A 567, A92 (2014) Astronomy DOI: 10.1051/0004-6361/201322592 & c ESO 2014 Astrophysics Synapses of active galactic nuclei: Comparing X-ray and optical classifications using artificial neural networks? O. González-Martín1;2;??, D. Díaz-González3, J. A. Acosta-Pulido1;2, J. Masegosa4, I. E. Papadakis5;6, J. M. Rodríguez-Espinosa1;2, I. Márquez4, and L. Hernández-García4 1 Instituto de Astrofísica de Canarias (IAC), C/Vía Láctea s/n, 38205 La Laguna, Spain e-mail: [email protected] 2 Departamento de Astrofísica, Universidad de La Laguna (ULL), 38205 La Laguna, Spain 3 Shidix Technologies, 38320, La Laguna, Spain 4 Instituto de Astrofísica de Andalucía, CSIC, C/ Glorieta de la Astronomía s/n, 18005 Granada, Spain 5 Physics Department, University of Crete, PO Box 2208, 710 03 Heraklion, Crete, Greece 6 IESL, Foundation for Research and Technology, 711 10 Heraklion, Crete, Greece Received 2 September 2013 / Accepted 3 April 2014 ABSTRACT Context. Many classes of active galactic nuclei (AGN) have been defined entirely through optical wavelengths, while the X-ray spectra have been very useful to investigate their inner regions. However, optical and X-ray results show many discrepancies that have not been fully understood yet. Aims. The main purpose of the present paper is to study the synapses (i.e., connections) between X-ray and optical AGN classifications. Methods. For the first time, the newly implemented efluxer task allowed us to analyse broad band X-ray spectra of a sample of emission-line nuclei without any prior spectral fitting. Our sample comprises 162 spectra observed with XMM-Newton/pn of 90 lo- cal emission line nuclei in the Palomar sample. -
Astrophysics in 2006 3
ASTROPHYSICS IN 2006 Virginia Trimble1, Markus J. Aschwanden2, and Carl J. Hansen3 1 Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575, Las Cumbres Observatory, Santa Barbara, CA: ([email protected]) 2 Lockheed Martin Advanced Technology Center, Solar and Astrophysics Laboratory, Organization ADBS, Building 252, 3251 Hanover Street, Palo Alto, CA 94304: ([email protected]) 3 JILA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder CO 80309: ([email protected]) Received ... : accepted ... Abstract. The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the universe) and others of which there are always many, like meteors and molecules, black holes and binaries. Keywords: cosmology: general, galaxies: general, ISM: general, stars: general, Sun: gen- eral, planets and satellites: general, astrobiology CONTENTS 1. Introduction 6 1.1 Up 6 1.2 Down 9 1.3 Around 10 2. Solar Physics 12 2.1 The solar interior 12 2.1.1 From neutrinos to neutralinos 12 2.1.2 Global helioseismology 12 2.1.3 Local helioseismology 12 2.1.4 Tachocline structure 13 arXiv:0705.1730v1 [astro-ph] 11 May 2007 2.1.5 Dynamo models 14 2.2 Photosphere 15 2.2.1 Solar radius and rotation 15 2.2.2 Distribution of magnetic fields 15 2.2.3 Magnetic flux emergence rate 15 2.2.4 Photospheric motion of magnetic fields 16 2.2.5 Faculae production 16 2.2.6 The photospheric boundary of magnetic fields 17 2.2.7 Flare prediction from photospheric fields 17 c 2008 Springer Science + Business Media. -
SAC's 110 Best of the NGC
SAC's 110 Best of the NGC by Paul Dickson Version: 1.4 | March 26, 1997 Copyright °c 1996, by Paul Dickson. All rights reserved If you purchased this book from Paul Dickson directly, please ignore this form. I already have most of this information. Why Should You Register This Book? Please register your copy of this book. I have done two book, SAC's 110 Best of the NGC and the Messier Logbook. In the works for late 1997 is a four volume set for the Herschel 400. q I am a beginner and I bought this book to get start with deep-sky observing. q I am an intermediate observer. I bought this book to observe these objects again. q I am an advance observer. I bought this book to add to my collect and/or re-observe these objects again. The book I'm registering is: q SAC's 110 Best of the NGC q Messier Logbook q I would like to purchase a copy of Herschel 400 book when it becomes available. Club Name: __________________________________________ Your Name: __________________________________________ Address: ____________________________________________ City: __________________ State: ____ Zip Code: _________ Mail this to: or E-mail it to: Paul Dickson 7714 N 36th Ave [email protected] Phoenix, AZ 85051-6401 After Observing the Messier Catalog, Try this Observing List: SAC's 110 Best of the NGC [email protected] http://www.seds.org/pub/info/newsletters/sacnews/html/sac.110.best.ngc.html SAC's 110 Best of the NGC is an observing list of some of the best objects after those in the Messier Catalog. -
Strongly Decelerated Expansion of SN 1979C
A&A 384, 408–413 (2002) Astronomy DOI: 10.1051/0004-6361:20011794 & c ESO 2002 Astrophysics Strongly decelerated expansion of SN 1979C J. M. Marcaide1,M.A.P´erez-Torres1,2,E.Ros3, A. Alberdi4,P.J.Diamond5, J. C. Guirado1,L.Lara4, S. D. Van Dyk6, and K. W. Weiler7 1 Departamento de Astronom´ıa, Universitat de Val`encia, 46100 Burjassot, Spain 2 Istituto di Radioastronomia/CNR, via P. Gobetti 101, 40129 Bologna, Italy 3 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, 53121 Bonn, Germany 4 Instituto de Astrof´ısica de Andaluc´ıa, CSIC, Apdo. Correos 3004, 18080 Granada, Spain 5 MERLIN/VLBI National Facility, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL, UK 6 Infrared Processing and Analysis Center, California Institute of Technology, Mail Code 100-22, Pasadena, CA 91125, USA 7 Remote Sensing Division, Naval Research Laboratory, Code 7213, Washington, DC 20375-5320, USA Received 20 July 2001 / Accepted 11 December 2001 Abstract. We observed SN 1979C in M100 on 4 June 1999, about twenty years after explosion, with a very sensitive four-antenna VLBI array at the wavelength of λ18 cm. The distance to M100 and the expansion velocities are such that the supernova cannot be fully resolved by our Earth-wide array. Model-dependent sizes for the source have been determined and compared with previous results. We conclude that the supernova shock was initially in free expansion for 6 2 yrs and then experienced a very strong deceleration. The onset of deceleration took place a few years before the abrupt trend change in the integrated radio flux density curves. -
Gas Accretion from Minor Mergers in Local Spiral Galaxies⋆
A&A 567, A68 (2014) Astronomy DOI: 10.1051/0004-6361/201423596 & c ESO 2014 Astrophysics Gas accretion from minor mergers in local spiral galaxies? E. M. Di Teodoro1 and F. Fraternali1;2 1 Department of Physics and Astronomy, University of Bologna, 6/2, Viale Berti Pichat, 40127 Bologna, Italy e-mail: [email protected] 2 Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, The Netherlands Received 7 February 2014 / Accepted 28 May 2014 ABSTRACT We quantify the gas accretion rate from minor mergers onto star-forming galaxies in the local Universe using Hi observations of 148 nearby spiral galaxies (WHISP sample). We developed a dedicated code that iteratively analyses Hi data-cubes, finds dwarf gas-rich satellites around larger galaxies, and estimates an upper limit to the gas accretion rate. We found that 22% of the galaxies have at least one detected dwarf companion. We made the very stringent assumption that all satellites are going to merge in the shortest possible time, transferring all their gas to the main galaxies. This leads to an estimate of the maximum gas accretion rate of −1 0.28 M yr , about five times lower than the average star formation rate of the sample. Given the assumptions, our accretion rate is clearly an overestimate. Our result strongly suggests that minor mergers do not play a significant role in the total gas accretion budget in local galaxies. Key words. galaxies: interactions – galaxies: evolution – galaxies: kinematics and dynamics – galaxies: star formation – galaxies: dwarf 1. Introduction structures in the Universe grow by several inflowing events and have increased their mass content through a small number of The evolution of galaxies is strongly affected by their capabil- major mergers, more common at high redshifts, and through an ity of retaining their gas and accreting fresh material from the almost continuous infall of dwarf galaxies (Bond et al. -
Optically Identified Supernova Remnants in the Nearby Spiral Galaxies NGC 5204, NGC 5585, NGC 6946, M81, and M101
Dartmouth College Dartmouth Digital Commons Open Dartmouth: Peer-reviewed articles by Dartmouth faculty Faculty Work 9-1997 Optically Identified Supernova Remnants in the Nearby Spiral Galaxies NGC 5204, NGC 5585, NGC 6946, M81, and M101 David M. Matonick Dartmouth College Robert A. Fesen Dartmouth College Follow this and additional works at: https://digitalcommons.dartmouth.edu/facoa Part of the Stars, Interstellar Medium and the Galaxy Commons Dartmouth Digital Commons Citation Matonick, David M. and Fesen, Robert A., "Optically Identified Supernova Remnants in the Nearby Spiral Galaxies NGC 5204, NGC 5585, NGC 6946, M81, and M101" (1997). Open Dartmouth: Peer-reviewed articles by Dartmouth faculty. 2307. https://digitalcommons.dartmouth.edu/facoa/2307 This Article is brought to you for free and open access by the Faculty Work at Dartmouth Digital Commons. It has been accepted for inclusion in Open Dartmouth: Peer-reviewed articles by Dartmouth faculty by an authorized administrator of Dartmouth Digital Commons. For more information, please contact [email protected]. THE ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 112:49È107, 1997 September ( 1997. The American Astronomical Society. All rights reserved. Printed in U.S.A. OPTICALLY IDENTIFIED SUPERNOVA REMNANTS IN THE NEARBY SPIRAL GALAXIES NGC 5204, NGC 5585, NGC 6946, M81, AND M101 DAVID M. MATONICK AND ROBERT A. FESEN Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755 Received 1997 January 24; accepted 1997 April 11 ABSTRACT We present the results of an optical search for supernova remnants (SNRs) in the spiral galaxies NGC 5204, NGC 5585, NGC 6946, M81, and M101. Using the criterion that emission nebulae with [S II]/ Ha º 0.45 are identiÐed as SNRs, we found three SNRs in NGC 5204, Ðve in NGC 5585, 27 in NGC 6946, 41 in M81, and 93 in M101. -
042021-Aktuelles Am Sternenhimmel
A N T A R E S NÖ AMATEURASTRONOMEN NOE VOLKSSTERNWARTE Michelbach Dorf 62 3074 MICHELBACH NOE VOLKSSTERNWARTE 3074 MICHELBACH Die VOLKSSTERNWARTE im Zentralraum Niederösterreich 02.04.1966 Luna 10 schwenkt als 1. Sonde in einen Mondorbit ein (UdSSR) 03.04.1959 Die ersten sieben Astronauten der USA werden bekanntgegeben 10.04.1970 Start Apollo 13; Nach einer Explosion kehren Jim Lovell, Jack Swigert und Fred Haise mit der Mondlandefähre als Rettungsboot zur Erde zurück 12.04.1960 Start von Transit 1B: Erster Navigationssatellit im All 12.04.1961 Vostok 1 (UdSSR) bringt den 1. Menschen ins All (Juri Gagarin!) 13.04.1862 Christian Huygens, Saturnforscher, wird geboren 18.04.1971 Start der 1. Weltraumstation Saljut 1 (UdSSR) 21.04.1971 Die erste Besatzung dockt an der ersten Raumstation Saljut 1 an (UdSSR) 22.04.1967 Wladimir Komarov stirbt als erster Kosmonaut im Weltraum (Sojus 1) 23.04.1990 Weltraumteleskop Hubble wird mit dem Shuttle Flug 31 gestartet 24.04.1962 Ariel 1, der erste internationale Satellit, wird gestartet (USA, England) AKTUELLES AM STERNENHIMMEL APRIL 2021 Die Wintersternbilder sind Objekte der westlichen Himmelshälfte; der Große Bär steht hoch im Zenit, die Frühlingssternbilder Löwe, Bärenhüter und Jungfrau mit den Galaxienhaufen können in der östlichen Himmelshälfte beobachtet werden; südlich der Jungfrau stehen Becher und Rabe, über dem Südhorizont schlänget sich die unscheinbare Wasserschlange. Mars ist am Abendhimmel in den Zwillingen auffindbar, Jupiter und Saturn werden die Planeten der zweiten Nachthälfte. INHALT Auf- und Untergangszeiten Sonne und Mond Fixsternhimmel Monatsthema – Juri Gagarin, 1. Mensch im Weltraum – 12.04.1961 Planetenlauf Sternschnuppenschwärme Vereinsabend – 09.04.2021 – ONLINE-Veranstaltung Führungstermin 16.04.2021 - ABSAGE VEREINSABEND 09.04.2021 REFERENT Doz.