DOCSLIB.ORG

April 2020 Journal

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

The Journal of The Royal Astronomical Society of Canada PROMOTING ASTRONOMY IN CANADA April/avril 2020 Volume/volume 114 Le Journal de la Société royale d’astronomie du Canada Number/numéro 2 [801] Inside this issue: Cepheid Variables in Andromeda Supernova Redshifts 2019 Awards Corona Australis The Best of Monochrome. Drawings, images in black and white, or narrow-band photography. The magnificent California Nebula was imaged by Ron Brecher’s home observatory in Guelph, Ontario. It is a 16-hour exposure through a 106mm ƒ/3.6 refractor, combining 12hr20m collected with a one-shot colour camera and 4hr30m collected with a monochrome camera. April / avril 2020 | Vol. 114, No. 2 | Whole Number 801 contents / table des matières Research Articles / Articles de recherche 92 Dish on the Cosmos: King of The Radio Sky by Erik Rosolowsky 56 Cepheid Variables in the Andromeda Galaxy from Simon Fraser University’s Trottier 94 Celestial Review: Algol at Minimum Observatory by Dave Garner by Howard Trottier et al. 96 Imager’s Corner: CGX-L Review 67 Matching Supernova Redshifts with Special by Blair MacDonald Relativity and no Dark Energy by Simon Brissenden 100 Observing: Springtime Observing with Coma Berenices by Chris Beckett Feature Articles / Articles de fond 80 Pen and Pixel: Orion / Comet PANSTARRS Departments / Départements C/2017 T2 / Dumbbell Nebula / Cone Nebula. 50 President’s Corner Blake Nancarrow / Klaus Brasch / Tom Owen / Gary Palmer by Dr. Chris Gainor Columns / Rubriques 51 News Notes / En manchettes Compiled by Jay Anderson 71 Skyward: First Light and Something Old, Something New 101 Awards for 2019 by David Levy Compiled by James Edgar 73 CFHT Chronicles: Behind the Data at CFHT 112 Astrocryptic and February Answers by Mary Beth Laychak by Curt Nason 77 Binary Universe: Take Control of Your Mount iii Great Images by Blake Nancarrow by Luca Vanzella 89 John Percy’s Universe: Assassin: The Survey by John R. Percy “Space is a pretty dynamic place, and there is a lot going on in this area called Corona Australis Complex,” said Debra Ceravolo. Peter Ceravolo acquired the data from San Pedro de Atacama in Chile, using the Ceravolo 300 Astrograph at ƒ/4.9 on a Paramount ME. Debra processed the image using MaximDL and PixInsight. Total exposure was 7.2 hours: LRGB: 285, 50, 30 and 35 minutes. “Some dust (blue refl ection nebula) is getting lit up by nearby bright stars and the dark dust cloud is not. It is all about 500 light-years away except the globular cluster (NGC 6723) is 30,000 light-years away. Put that in perspective!” she says. April / avril 2020 JRASC | Promoting Astronomy in Canada 49 The Journal is a bi-monthly publication of The Royal President’s Corner Astronomical Society of Canada and is devoted to the advancement of astronomy and allied by Christopher Gainor, Ph.D., Victoria Centre sciences. It contains articles on Canadian astronomers and current activities of the RASC and its Centres, research and review papers by professional and amateur astronomers, ([email protected]) and articles of a historical, biographical, or educational nature of general interest to the astronomical community. All contributions are welcome, but the editors reserve the right to edit material prior to publication. Research papers are reviewed prior to publication, For most RASC members, getting together usually means and professional astronomers with institutional affi liations are asked to pay publication some activity within a Centre, such as a monthly meeting, charges of $100 per page. Such charges are waived for RASC members who do not have access to professional funds as well as for solicited articles. Manuscripts and other observing night, annual banquet, or even an informal activity submitted material may be in English or French, and should be sent to the Editor-in-Chief. like the weekly Astro Café that has become a popular event in my home Centre in Victoria. Editor-in-Chief Contributing Editors Nicole Mortillaro Jay Anderson (News Notes) Email: [email protected] Chris Beckett (Observing Tips) Getting the Society together at the National level is more Web site: www.rasc.ca Mary Beth Laychak (CFHT Chronicles) di cult because, as our former Prime Minister, William Lyon David Levy (Skyward) Telephone: 416-924-7973 Mackenzie King, once observed, in Canada we have too much Fax: 416-924-2911 Blair MacDonald (Imager’s Corner) Blake Nancarrow (Binary Universe) geography. Associate Editor, Research Curt Nason (Astrocryptic) Douglas Hube John R. Percy (John Percy’s Universe) Email: [email protected] Randall Rosenfeld (Art & Artifact) For much of its existence, the RASC’s only National event was Associate Editor, General Eric Rosolowsky (Dish on the Cosmos) its Annual General Meeting, which, until 1960, always took Leslie J. Sage (Second Light) Michael Attas place in Toronto. at event traditionally involved only dealing David Turner (Reviews) Email: [email protected] Proofreaders with Society business, but in 1959 the meeting was expanded Assistant Editors Michael Attas to include papers on astronomy. e following year the Michael Allen Margaret Brons Martin Beech enlarged event took place in Montréal, marking the beginning Angelika Hackett Dave Chapman Michelle Johns of our annual General Assemblies. Ralph Chou Barry Jowett Ralph Croning Kim Leitch e GAs that followed over the past six decades have usually Dave Garner Alida MacLeod Patrick Kelly taken place on university campuses in various parts of the Design/Production Production Manager Michael Gatto, Grant Tomchuk country, usually on either the Victoria Day or, more recently, James Edgar Email: [email protected], the Canada Day long weekends. National Council meetings, Email: [email protected] [email protected] Society banquets, the Annual General Meeting and paper Advertising Printing Adela Zyfi Cansel presentations have been staples of every GA. Email: [email protected] www.cansel.ca For many years Centres competed to host the GA, but in Her Excellency the Right Honourable Julie Payette, C.C., C.M.M., C.O.M., C.Q., C.D., recent years interest in hosting these meetings has declined Governor General of Canada, is the Viceregal Patron of the RASC. to the point where the 2019 GA was largely organized out of The Journal of The Royal Astronomical Society of Canada is published at an annual the National O ce. ere are several reasons for this change, subscription rate of $93.45 (including tax) by The Royal Astronomical Society of Canada. Membership, which includes the publications (for personal use), is open to anyone but a major one is that General Assemblies based at univer- interested in astronomy. Applications for subscriptions to the Journal or membership in the sities have become more complicated to organize and less RASC and information on how to acquire back issues of the Journal can be obtained from: convenient for many people to attend. The Royal Astronomical Society of Canada 203 – 4920 Dundas St W A few years ago I asked for input from interested members Toronto ON M9A 1B7, Canada and then wrote a report suggesting that we make some Email: nationaloffi [email protected] changes to the format of GAs. In 2019, we held the GA in Web site: www.rasc.ca Telephone: 416-924-7973 the middle of June instead of on a long weekend, a change Fax: 416-924-2911 that was seen as successful. Canadian Publications Mail Registration No. 09818 Canada Post: Send address changes to 203 – 4920 Dundas St W, Toronto ON M9A 1B7 Another idea was to move the GA away from universities. e 2020 General Assembly is taking place the weekend of Canada Post Publication Agreement No. 40069313 June 5 to 7 at the Executive Plaza and Conference Centre in We acknowledge the fi nancial support of the Government of Canada through the Coquitlam, B.C., which is conveniently located near a stop on Canada Periodical Fund (CPF) for our publishing activities. Greater Vancouver’s SkyTrain system. In a nod to our history, © 2020 The Royal Astronomical Society of Canada. one evening’s activities will take place at Simon Fraser Univer- All rights reserved. ISSN 0035-872X sity in Burnaby and include a visit to the Trottier observatory on campus. Cert no. SW-COC-005174 While hotel accommodations are more expensive than university residences, meetings in hotels are generally easier 50 JRASC | Promoting Astronomy in Canada April / avril 2020 to organize since that is their business and not a sideline. We such as Bob McDonald, host of CBC’s Quirks and Quarks, and also believe that GA organizers should focus more on activities top- ight astrophysicists including Michael Landry, Aaron that will draw local audiences and help build their Centres. We Boley, Jess McIver, and Jaymie Mathews. More speakers and hope that these changes encourage more Centres to consider many exciting activities can be found on the 2020 GA website hosting GAs and rebuild interest in this vital national activity. ga2020.rasc-vancouver.com. e Vancouver organizing committee for the 2020 GA is I look forward to seeing many friends from Greater Vancouver ✶ doing a great job putting the weekend together with speakers and around Canada at the 2020 General Assembly! News Notes / En manchette with northern lights enthusiasts and the answers she provided to questions about the physics of the phenomenon in the (Compiled by Jay Anderson) hobbyists’ Facebook group. Green dunes: A new form of aurora ousands of magni cent photographs of the northern lights taken by hobbyists were surveyed and categorized for the book. Working together with space researchers, Finnish amateur Each auroral form is like a ngerprint, typical only of a certain photographers have discovered a new auroral form. Named phenomenon in the auroral zone. During the classi cation, “dunes” by the hobbyists, the origins of the feature were hobbyists pointed out that a certain auroral form did not t tracked to a wave guide formed within the mesosphere and its into any of the pre-existing categories.
Recommended publications
  • Timing Studies of X Persei and the Discovery of Its Transient Quasi-Periodic Oscillation Feature

    Timing Studies of X Persei and the Discovery of Its Transient Quasi-Periodic Oscillation Feature

    MNRAS 444, 457–465 (2014) doi:10.1093/mnras/stu1351 Timing studies of X Persei and the discovery of its transient quasi-periodic oscillation feature Downloaded from https://academic.oup.com/mnras/article-abstract/444/1/457/1009862 by Baskent University Library (BASK) user on 17 December 2019 Z. Acuner,1‹ S. C¸.Inam,˙ 2 S¸. S¸ahiner,1 M. M. Serim,1 A. Baykal1 and J. Swank3 1Physics Department, Middle East Technical University, 06531 Ankara, Turkey 2Department of Electrical and Electronics Engineering, Bas¸kent University, 06810 Ankara, Turkey 3Astrophysics Science Division, Goddard Space Flight Center, NASA, Greenbelt, MD 20771, USA Accepted 2014 July 3. Received 2014 July 2; in original form 2014 May 15 ABSTRACT We present a timing analysis of X Persei (X Per) using observations made between 1998 and 2010 with the Proportional Counter Array (PCA) onboard the Rossi X-ray Timing Explorer (RXTE) and with the INTEGRAL Soft Gamma-Ray Imager (ISGRI). All pulse arrival times obtained from the RXTE-PCA observations are phase-connected and a timing solution is obtained using these arrival times. We update the long-term pulse frequency history of the source by measuring its pulse frequencies using RXTE-PCA and ISGRI data. From the RXTE- PCA data, the relation between the frequency derivative and X-ray flux suggests accretion via the companion’s stellar wind. However, the detection of a transient quasi-periodic oscillation feature, peaking at ∼0.2 Hz, suggests the existence of an accretion disc. We find that double- break models fit the average power spectra well, which suggests that the source has at least two different accretion flow components dominating the overall flow.
  • An Eccentric Wave in the Circumstellar Disc of the Be/X-Ray Binary X Persei

    An Eccentric Wave in the Circumstellar Disc of the Be/X-Ray Binary X Persei

    MNRAS 000, 1–7 (2020?) Preprint 6 October 2020 Compiled using MNRAS LATEX style file v3.0 An eccentric wave in the circumstellar disc of the Be/X-ray binary X Persei R. K. Zamanov,1⋆ K. A. Stoyanov1, U. Wolter2, D. Marchev3, N. A. Tomov1, M. F. Bode4,5, Y. M. Nikolov1, V. Marchev1, L. Iliev1, I. K. Stateva1 1 Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, 1784 Sofia, Bulgaria 2 Hamburger Sternwarte, Universit¨at Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany 3 Department of Physics and Astronomy, Shumen University, 115 Universitetska Str., 9700 Shumen, Bulgaria 4 Astrophysics Research Institute, Liverpool John Moores University, IC2, 149 Brownlow Hill, Liverpool, L3 5RF, UK 5 Office of the Vice Chancellor, Botswana International University of Science and Technology, Private Bag 16, Palapye, Botswana Accepted 2020 September 30. Received 2020 September 18; in original form 2020 March 16 ABSTRACT We present spectroscopic observations of the Be/X-ray binary X Per obtained during the period December 2017 - January 2020 (MJD 58095 - MJD 58865). In December 2017 the Hα, Hβ, and HeI 6678 emission lines were symmetric with violet-to-red peak ratio V/R ≈ 1. During the first part of the period (December 2017 - August 2018) the V/R- ratio decreased to 0.5 and the asymmetry developed simultaneously in all three lines. In September 2018, a third component with velocity ≈ 250 km s−1 appeared on the red side of the HeI line profile. Later this component emerged in Hβ, accompanied by the appearance of a red shoulder in Hα.
  • Variable Star Section Circular

    Variable Star Section Circular

    British Astronomical Association Variable Star Section Circular No 82, December 1994 CONTENTS A New Director 1 Credit for Observations 1 Submission of 1994 Observations 1 Chart Problems 1 Recent Novae Named 1 Z Ursae Minoris - A New R CrB Star? 2 The February 1995 Eclipse of 0¼ Geminorum 2 Computerisation News - Dave McAdam 3 'Stella Haitland, or Love and the Stars' - Philip Hurst 4 The 1994 Outburst of UZ Bootis - Gary Poyner 5 Observations of Betelgeuse by the SPA-VSS - Tony Markham 6 The AAVSO and the Contribution of Amateurs to VS Research Suspected Variables - Colin Henshaw 8 From the Literature 9 Eclipsing Binary Predictions 11 Summaries of IBVS's Nos 4040 to 4092 14 The BAA Instruments and Imaging Section Newsletter 16 Light-curves (TZ Per, R CrB, SV Sge, SU Tau, AC Her) - Dave McAdam 17 ISSN 0267-9272 Office: Burlington House, Piccadilly, London, W1V 9AG Section Officers Director Tristram Brelstaff, 3 Malvern Court, Addington Road, READING, Berks, RG1 5PL Tel: 0734-268981 Section Melvyn D Taylor, 17 Cross Lane, WAKEFIELD, Secretary West Yorks, WF2 8DA Tel: 0924-374651 Chart John Toone, Hillside View, 17 Ashdale Road, Cressage, Secretary SHREWSBURY, SY5 6DT Tel: 0952-510794 Computer Dave McAdam, 33 Wrekin View, Madeley, TELFORD, Secretary Shropshire, TF7 5HZ Tel: 0952-432048 E-mail: COMPUSERV 73671,3205 Nova/Supernova Guy M Hurst, 16 Westminster Close, Kempshott Rise, Secretary BASINGSTOKE, Hants, RG22 4PP Tel & Fax: 0256-471074 E-mail: [email protected] [email protected] Pro-Am Liaison Roger D Pickard, 28 Appletons, HADLOW, Kent TN11 0DT Committee Tel: 0732-850663 Secretary E-mail: [email protected] KENVAD::RDP Eclipsing Binary See Director Secretary Circulars Editor See Director Telephone Alert Numbers Nova and First phone Nova/Supernova Secretary.
  • A Basic Requirement for Studying the Heavens Is Determining Where In

    A Basic Requirement for Studying the Heavens Is Determining Where In

    Abasic requirement for studying the heavens is determining where in the sky things are. To specify sky positions, astronomers have developed several coordinate systems. Each uses a coordinate grid projected on to the celestial sphere, in analogy to the geographic coordinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth's equator) . Each coordinate system is named for its choice of fundamental plane. The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the one most closely related to the geographic coordinate system, because they use the same fun­ damental plane and the same poles. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles on to the celest ial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate systems: the geographic system is fixed to the Earth; it rotates as the Earth does . The equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but of course it's really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec for short) . It measures the angle of an object above or below the celestial equator. The longitud inal angle is called the right ascension (RA for short).
  • FIXED STARS a SOLAR WRITER REPORT for Churchill Winston WRITTEN by DIANA K ROSENBERG Page 2

    FIXED STARS a SOLAR WRITER REPORT for Churchill Winston WRITTEN by DIANA K ROSENBERG Page 2

    FIXED STARS A SOLAR WRITER REPORT for Churchill Winston WRITTEN BY DIANA K ROSENBERG Page 2 Prepared by Cafe Astrology cafeastrology.com Page 23 Churchill Winston Natal Chart Nov 30 1874 1:30 am GMT +0:00 Blenhein Castle 51°N48' 001°W22' 29°‚ 53' Tropical ƒ Placidus 02' 23° „ Ý 06° 46' Á ¿ 21° 15° Ý 06' „ 25' 23° 13' Œ À ¶29° Œ 28° … „ Ü É Ü 06° 36' 26' 25° 43' Œ 51'Ü áá Œ 29° ’ 29° “ àà … ‘ à ‹ – 55' á á 55' á †32' 16° 34' ¼ † 23° 51'Œ 23° ½ † 06' 25° “ ’ † Ê ’ ‹ 43' 35' 35' 06° ‡ Š 17° 43' Œ 09° º ˆ 01' 01' 07° ˆ ‰ ¾ 23° 22° 08° 02' ‡ ¸ Š 46' » Ï 06° 29°ˆ 53' ‰ Page 234 Astrological Summary Chart Point Positions: Churchill Winston Planet Sign Position House Comment The Moon Leo 29°Le36' 11th The Sun Sagittarius 7°Sg43' 3rd Mercury Scorpio 17°Sc35' 2nd Venus Sagittarius 22°Sg01' 3rd Mars Libra 16°Li32' 1st Jupiter Libra 23°Li34' 1st Saturn Aquarius 9°Aq35' 5th Uranus Leo 15°Le13' 11th Neptune Aries 28°Ar26' 8th Pluto Taurus 21°Ta25' 8th The North Node Aries 25°Ar51' 8th The South Node Libra 25°Li51' 2nd The Ascendant Virgo 29°Vi55' 1st The Midheaven Gemini 29°Ge53' 10th The Part of Fortune Capricorn 8°Cp01' 4th Chart Point Aspects Planet Aspect Planet Orb App/Sep The Moon Semisquare Mars 1°56' Applying The Moon Trine Neptune 1°10' Separating The Moon Trine The North Node 3°45' Separating The Moon Sextile The Midheaven 0°17' Applying The Sun Semisquare Jupiter 0°50' Applying The Sun Sextile Saturn 1°52' Applying The Sun Trine Uranus 7°30' Applying Mercury Square Uranus 2°21' Separating Mercury Opposition Pluto 3°49' Applying Venus Sextile
  • Stars and Their Spectra: an Introduction to the Spectral Sequence Second Edition James B

    Stars and Their Spectra: an Introduction to the Spectral Sequence Second Edition James B

    Cambridge University Press 978-0-521-89954-3 - Stars and Their Spectra: An Introduction to the Spectral Sequence Second Edition James B. Kaler Index More information Star index Stars are arranged by the Latin genitive of their constellation of residence, with other star names interspersed alphabetically. Within a constellation, Bayer Greek letters are given first, followed by Roman letters, Flamsteed numbers, variable stars arranged in traditional order (see Section 1.11), and then other names that take on genitive form. Stellar spectra are indicated by an asterisk. The best-known proper names have priority over their Greek-letter names. Spectra of the Sun and of nebulae are included as well. Abell 21 nucleus, see a Aurigae, see Capella Abell 78 nucleus, 327* ε Aurigae, 178, 186 Achernar, 9, 243, 264, 274 z Aurigae, 177, 186 Acrux, see Alpha Crucis Z Aurigae, 186, 269* Adhara, see Epsilon Canis Majoris AB Aurigae, 255 Albireo, 26 Alcor, 26, 177, 241, 243, 272* Barnard’s Star, 129–130, 131 Aldebaran, 9, 27, 80*, 163, 165 Betelgeuse, 2, 9, 16, 18, 20, 73, 74*, 79, Algol, 20, 26, 176–177, 271*, 333, 366 80*, 88, 104–105, 106*, 110*, 113, Altair, 9, 236, 241, 250 115, 118, 122, 187, 216, 264 a Andromedae, 273, 273* image of, 114 b Andromedae, 164 BDþ284211, 285* g Andromedae, 26 Bl 253* u Andromedae A, 218* a Boo¨tis, see Arcturus u Andromedae B, 109* g Boo¨tis, 243 Z Andromedae, 337 Z Boo¨tis, 185 Antares, 10, 73, 104–105, 113, 115, 118, l Boo¨tis, 254, 280, 314 122, 174* s Boo¨tis, 218* 53 Aquarii A, 195 53 Aquarii B, 195 T Camelopardalis,
  • 19 67 Ap J. . .149. .107F the Astrophysical Journal, Vol. 149

    19 67 Ap J. . .149. .107F the Astrophysical Journal, Vol. 149

    .107F The Astrophysical Journal, Vol. 149, July 1967 .149. J. Ap 67 19 COLLINDER 121: A YOUNG SOUTHERN OPEN CLUSTER SIMILAR TO h AND x PERSEI* Alejandro FEiNSTEmf Observatorio Astronómico, Universidad Nacional de La Plata, Argentina Received September 6, 1966; revised February 1, 1967 ABSTRACT Three-color photoelectric photometry has been carried out for stars in the open cluster Cr 121. The data state that the cluster is nearly identical to h and x Persei but has fewer members It was found that some bright and high-luminosity stars in Canis Major (7,6,77,6, are members of this cluster A Wolf-Rayet star (HD 50896) may also be a member according to the observed colors Its position in the color-magnitude diagram is close to the turnoff point of the main sequence. Cr 121 is situated at a dis- tance of 630 pc, and is as young as the double cluster in Perseus. The reddening is very small. I. INTRODUCTION The open cluster Collinder 121, which lies around the red supergiant o1 CMa, was measured in connection with a program of photoelectric observations of some bright southern clusters. This cluster, located in Canis Major (/n = 235°4, b11 — —10°4), became of considerable interest after Roberts (1958) pointed out that a Wolf-Rayet star lies within one cluster radius. Schmidt-Kaler (1961) called attention to Cr 121 because around the K supergiant, which is inside the cluster boundaries, there are some B stars of apparent visual magnitude between mv — 1 and mv — S which have similar values of the radial velocities and proper motions.
  • December 2019 BRAS Newsletter

    December 2019 BRAS Newsletter

    A Monthly Meeting December 11th at 7PM at HRPO (Monthly meetings are on 2nd Mondays, Highland Road Park Observatory). Annual Christmas Potluck, and election of officers. What's In This Issue? President’s Message Secretary's Summary Outreach Report Asteroid and Comet News Light Pollution Committee Report Globe at Night Member’s Corner – The Green Odyssey Messages from the HRPO Friday Night Lecture Series Science Academy Solar Viewing Stem Expansion Transit of Murcury Edge of Night Natural Sky Conference Observing Notes: Perseus – Rescuer Of Andromeda, or the Hero & Mythology Like this newsletter? See PAST ISSUES online back to 2009 Visit us on Facebook – Baton Rouge Astronomical Society Baton Rouge Astronomical Society Newsletter, Night Visions Page 2 of 25 December 2019 President’s Message I would like to thank everyone for having me as your president for the last two years . I hope you have enjoyed the past two year as much as I did. We had our first Members Only Observing Night (MOON) at HRPO on Sunday, 29 November,. New officers nominated for next year: Scott Cadwallader for President, Coy Wagoner for Vice- President, Thomas Halligan for Secretary, and Trey Anding for Treasurer. Of course, the nominations are still open. If you wish to be an officer or know of a fellow member who would make a good officer contact John Nagle, Merrill Hess, or Craig Brenden. We will hold our annual Baton Rouge “Gastronomical” Society Christmas holiday feast potluck and officer elections on Monday, December 9th at 7PM at HRPO. I look forward to seeing you all there. ALCon 2022 Bid Preparation and Planning Committee: We’ll meet again on December 14 at 3:00.pm at Coffee Call, 3132 College Dr F, Baton Rouge, LA 70808, UPCOMING BRAS MEETINGS: Light Pollution Committee - HRPO, Wednesday December 4th, 6:15 P.M.
  • The British Astronomical Association

    The British Astronomical Association

    ` ISSN 2631-4843 The British Astronomical Association Variable Star Section Circular No. 184 June 2020 Office: Burlington House, Piccadilly, London W1J 0DU Contents From the Director ....................................................................................................... 3 Summer Miras............................................................................................................ 3 Missing data from 1980-1995 – John Toone .............................................................. 6 Pulsating Star Programme – Shaun Albrighton .......................................................... 7 Report on the Long Period Variable Z Ursae Majoris using BAAVSS Archival Data – John Greaves .................................................................................... 9 Betelgeuse: the expected recovery happens – Mark Kidger ....................................... 14 Betelgeuse – A Century and more of Variation – Christopher Lloyd ........................... 22 CV & E News – Gary Poyner ..................................................................................... 28 Supernova 2020ue in NGC 4636 – Guy Hurst............................................................ 31 Spectrum of SN 2020hvf – David Boyd ...................................................................... 32 Eclipsing Binary News – Des Loughney ..................................................................... 33 Algol type eclipsing binary TX UMa. Can all sources have the correct period? – James Screech ..............................................................................
  • Photoelectric Observations of X Persei

    Photoelectric Observations of X Persei

    COMMISSIONS 27 AND 42 OF THE IAU INFORMATION BULLETIN ON VARIABLE STARS b er 4454 Num Konkoly Observatory Budap est 6 March 1997 HU ISSN 0374 { 0676 PHOTOELECTRIC OBSERVATIONS OF X PERSEI X Persei (HD 24534) is the optical counterpart of X-ray transient source 4U 0352+30. The system consists of a neutron star secondary accreting from an O9.5I I Ie primary via stellar wind pro cesses. To investigate whether the last fading phase of X Persei b eginning in 1990 is going on, we observed the system. The present observations were made in John- son's UBV bands with the 30-cm Maksutov telescop e of Ankara University Observatory. In the observations, BD+31 0655 was used as comparison star while BD+29 0632 and were chosen as the check stars. The magnitude di erences b etween check BD+30 0582 0:026 in V band. The stars and comparison star were constant within probable errors of individual di erential observations were corrected for atmospheric extinction and light motion, and the V band di erential magnitude determinations were time e ect of Earth's transformed to the standard system. Since the end of 19th century X Persei has b een known to b e a variable on a long che et al. (1993) presented the most comprehensive optical light curve over time-scale. Ro the p erio d 1964-1992. During this p erio d the Be star has undergone two extended faint, non-variable phases, seen in 1974-1977 and 1990-1992 . After this study, Zamanov and Zamanova (1995) have observed X Persei in the p erio d 1992-1994 .
  • Arxiv:1807.06252V2

    Arxiv:1807.06252V2

    Publ. Astron. Soc. Japan (2014) 00(0), 1–11 1 doi: 10.1093/pasj/xxx000 An application of the Ghosh & Lamb model to the accretion powered X-ray pulsar X Persei Fumiaki YATABE1,2 , Kazuo MAKISHIMA1 , Tatehiro MIHARA1, Motoki NAKAJIMA3 , Mutsumi SUGIZAKI4 , Shunji KITAMOTO2 , Yuki YOSHIDA2 and Toshihiro TAKAGI1 1High Energy Astrophysics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan 2Department of Physics, College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan 3School of Dentistry at Matsudo, Nihon University, 2-870-1 Sakaecho-nishi, Matsudo, Chiba 101-8308, Japan 4Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan ∗E-mail: [email protected] Received ; Accepted Abstract The accretion-induced pulse-period changes of the Be/X-ray binary pulsar X Persei were inves- tigated over a period of 1996 January to 2017 September. This study utilized the monitoring data acquired with the RXTE/ASM in 1.5–12 keV and MAXI/GSC in 2–20 keV. The source intensity changed by a factor of 5–6 over this period. The pulsar was spinning down for 1996- 2003, and has been spinning up since 2003, as already reported. The spin up/down rate and the 3–12 keV flux, determined every 250 d, showed a clear negative correlation, which can be successfully explained by the accretion torque model proposed by Ghosh & Lamb (1979). When the mass, radius and distance of the neutron star are allowed to vary over a range of 1.0–2.4 solar masses, 9.5–15 km, and 0.77–0.85 kpc, respectively, the magnetic field strength of B = (4 − 25) × 1013 G gave the best fits to the observation.
  • The Electric Sun Hypothesis

    The Electric Sun Hypothesis

    Basics of astrophysics revisited. II. Mass- luminosity- rotation relation for F, A, B, O and WR class stars Edgars Alksnis [email protected] Small volume statistics show, that luminosity of bright stars is proportional to their angular momentums of rotation when certain relation between stellar mass and stellar rotation speed is reached. Cause should be outside of standard stellar model. Concept allows strengthen hypotheses of 1) fast rotation of Wolf-Rayet stars and 2) low mass central black hole of the Milky Way. Keywords: mass-luminosity relation, stellar rotation, Wolf-Rayet stars, stellar angular momentum, Sagittarius A* mass, Sagittarius A* luminosity. In previous work (Alksnis, 2017) we have shown, that in slow rotating stars stellar luminosity is proportional to spin angular momentum of the star. This allows us to see, that there in fact are no stars outside of “main sequence” within stellar classes G, K and M. METHOD We have analyzed possible connection between stellar luminosity and stellar angular momentum in samples of most known F, A, B, O and WR class stars (tables 1-5). Stellar equatorial rotation speed (vsini) was used as main parameter of stellar rotation when possible. Several diverse data for one star were averaged. Zero stellar rotation speed was considered as an error and corresponding star has been not included in sample. RESULTS 2 F class star Relative Relative Luminosity, Relative M*R *eq mass, M radius, L rotation, L R eq HATP-6 1.29 1.46 3.55 2.950 2.28 α UMi B 1.39 1.38 3.90 38.573 26.18 Alpha Fornacis 1.33