THE COMET’S TALE Newsletter of the Comet Section of the British Astronomical Association Volume 4, No 1 (Issue 7), 1997 May COMET OF THE CENTURY ? From a colour print by Mike Cook, Romford. 1997 March 29. 50-mm lens, 10 mins, Kodak Panther 1600 BAA COMET SECTION NEWSLETTER ii THE COMET’S TALE Comet Section contacts Director: Jonathan Shanklin, 11 City Road, CAMBRIDGE. CB1 1DP, England. Phone: (+44) (0)1223 571250 (H) or (+44) (0)1223 251400 (W) Fax: (+44) (0)1223 362616 (W) E-Mail: JDS @ AST.CAM.AC.UK or J.SHANKLIN @ BAS.AC.UK WWW page : http://www.ast.cam.ac.uk/~jds/ Assistant Director (Observations): Guy Hurst, 16 Westminster Close, Kempshott Rise, BASINGSTOKE, Hampshire. (and also Editor of RG22 4PP, England. The Astronomer magazine) Phone & Fax: (+44) (0)1256 471074 E-Mail: GUY @ TAHQ.DEMON.CO.UK or GMH @ AST.STAR.RL.AC.UK Assistant Director: James Lancashire, Flat 4, 14/16 Canynge Road, Clifton, BRISTOL. BS8 3JX, England. (Urgent correspondence) Phone: (+44) (0)117 973 9963 E-Mail: JALAN @ AST.CAM.AC.UK CCD Advisor: Nick James, 11 Tavistock Road, CHELMSFORD, Essex. CM1 5JL, England. Phone: (+44) (0)1245 354366 E-mail: NDJ @ ASTRO1.DEMON.CO.UK or NICK.JAMES @ GMRC.GECM.COM Photographic Advisor: Michael Hendrie, Overbury, 33 Lexden Road, West Bergholt, COLCHESTER, Essex, CO6 3BX, England Phone: (+44) (0)1206 240021 Section news from the Director Dear Section member, reported in astronomical Stephen Laurie, Ron Livesey, magazines over the coming John Mackey, Glyn Marsh, Nick Needless to say I have been months. Martin, John McConnel, Hazel overwhelmed with observations McGee, Richard McKim, Haldun of comet Hale-Bopp! Despite The Keedy award for 1996 has Menali, Martin Mobberley, going through the details for been awarded to Gabriel Oksa of Stewart Moore, Bob Neville, reporting observations at the Starohajska, Slovakia. Gabriel Detlev Niechoy, Brian section meeting last year, has been studying at O'Halloran, Gabriel Oksa, Roy observers are still making Loughborough University on a Panther, Terry Platt, Tony mistakes in reporting their Royal Society post-doctoral Rickwood, John Rogers, Jonathan observations. This greatly fellowship, but has now returned Shanklin, Don Shirreff, James increases the workload for Guy home. He started observing Smith, John Smith, Peter Stanley, and myself as we have to correct comets for the Section in March Enrico Stomeo, David Storey, or replace the observations at a 1996 with the appearance of David Strange, Tony Tanti, later date. Some of the problems comet Hyakutake, and has quickly Christopher Taylor, Melvyn are listed in the observing section. developed into an experienced Taylor, Alex Vincent, Greme observer. Waddington, Richard Walters, Comet Hale-Bopp has certainly Peter Ward, James Weightman, been one of the most intensively Since the last newsletter Paul Yates, Joe Young and the observed comets in history and observations or contributions Mid Kent AS. section members have made the have been received from the following BAA members: most of the opportunity. I’ve Contents included a few of the many images received in the newsletter James Abott, Sally Beaumont, and more will be on display at the John Bingham, Graham Boots, Comet Section contacts 2 exhibition meeting. The Denis Buczynski, Robert Bullen, Section news 2 Astronomer magazine hopes to Peter Craven, Clive Curtis, Eric RAS meeting 3 bring out a supplement in the Dinham, Jean Dragesco, Len Spectroscopy 4 autumn which will document the Entwisle, John Fletcher, James comet’s apparition and at some Fraser, Mike Gainsford, Steven Fried comets ? 6 stage in the future a BAA Memoir Goldsmith, Massimo Giuntoli, Letters 6 will also appear. I haven’t David Graham, Werner Hasubick, Tales from the Past 7 documented the results of Michael Hendrie, Colin Henshaw, Review of observations 8 professional observations in great Guy Hurst, Nick James, Norman detail here as they will be Kiernan, James Lancashire, BAA COMET SECTION NEWSLETTER 1997 MAY 3 and also from: Jose Aguiar, classifications). Thanks to all of issue, section web page, or BAA Cornel Apetroaei, Alexandr you for your contributions. newsletter. Baransky, Sandro Baroni, John Bortle, Reinder Bouma, Mike Comets under observation were: Some BAA membership Cook, Tim Cooper, Matyas 22P/Kopff, 29P/Schwassmann- milestones reached over the past Csukas, Alfons Diepvens, Wachmann 1, 46P/Wirtanen, year include the Director (25 Maurizio Eltri, Stephen Getliffe, 81P/Wild 2, 118P/Shoemaker- years), David Frydman, Mike Guus Gilein, Bjoern Granslo, Levy 4, C/Hale-Bopp (1995 O1), Gainsford and Richard Miles (30 Roberto Haver, Lars Heen, C/Tabur (1996 Q1), years), Philip Vince (40 years) Andreas Kammerer, Heinz C/Hergenrother-Spahr (1996 R1) and Roy Panther (50 years). Kerner, Atilla Kosa-Kiss, Martin and C/Mueller (1997 D1). Congratulations to all. Lehky, Dee Levers, Romualdo Lourencon, Herman Mikuz, Some of the best material Finally if you do have any Antonio Milani, Sue Morley, John showing Hale-Bopp will be on comments on the newsletter, or O’Neill, Robert Oseman, Rok display at the Exhibition Meeting, requests for topics to be covered Palcic, Amanda Peters, Ernie so do come along and view it. I at the Section meeting do let me Richardson, Josep Rodriguez, hope to organise a section know. Clear skies, Virgil Scurtu, Oddleiv Skilbrei, meeting in Cambridge during the Steinar Thorvaldsen, Alin Tolea, autumn, but this will depend on Jonathan Shanklin John Vetterlein, Seiichi Yoshida there being a breather from bright and Vittorio Zanotta (apologies comets! More details in the next for any omissions or miss- RAS Discussion Meeting on “Comet-Asteroid Connections” The media have an interest in of dormant comets as they would dead HTC (between 3000 and bombardment from space at the be embedded in a meteoroid 12,000). moment, but having watched stream and would soon be “Asteroid” on TV recently it is reactivated by collisions. Fabio Migliorini (Armagh) fairly clear that they don't have presented results of his study on much idea about what an asteroid Nathan Harris (Armagh) “Resonant Delivery of Asteroids is, or the links between asteroids disagreed with this in his paper on and Meteorites from the Main and comets. This meeting was “Inactive Comets Among the Belt” which is part of a European organised by Mark Bailey of Near-Earth Asteroids”. Plotting Community funded GAPTEC Armagh Observatory and Iwan the aphelion distance Q against project to investigate the NEO Williams of Queen Mary College, the perihelion distance q, allows impact hazard. This project has to London and was held at various groups of small bodies, be multinational in order to win Burlington House on March 14. such as main belt asteroids (MB), EC funding and will use ESO I’m not sure that the media would Trojan asteroids, Jupiter family telescopes etc. He showed many have been much wiser after the comets (JFC) and near-earth viewgraphs (often in far too small meeting, and although one or two objects (NEO) to be print) of simulations of resonant new ideas were presented, most distinguished. NEOs have q less scattering into earth crossing talks were repeats of presentations than 1.4 AU and most JFCs have orbits. Most end up in the sun at the ACM meeting last summer. Q greater than 4.2 AU. The after a few million years. He NEOs can be split into class 1 suggested that the cosmic ray ages David Hughes (Sheffield) kicked with Q greater than 4.2 AU (and of meteorites didn’t reflect off proceedings with a review of thus affected by Jupiter) and class transport time since the parent the ‘zoo’ of small solar system 2 with Q less than 4.2 AU. collision, but possibly the time bodies in a talk entitled Computer models suggest that it since the ‘grandfather’s’ collision. “Distinguishing between Comets is possible to produce JFCs from and Asteroids”. When the both the Oort cloud (OC) and the Neil McBride (Kent) spoke about cumulative number of bodies Kuiper belt (KB), but Halley type “Meteoroids: the Debris of larger than a certain size is plotted comets (HTC) only from the OC. Comets and Asteroids”. against the size, the slope of the They also suggest it is impossible Meteoroids can be observed from line is different for asteroids (~-2) to populate the class 2 region, the ground as meteors and as and comets (~-1.67). Several unless non-gravitational forces are impacts on spacecraft. We have a asteroidal families were formed included. Comets in this class good idea of the mass distribution by the collisional break-up of a include 2P/Encke, 111P/Helin- in the mean isotropic flux. parent; in the case of the Eos Roman-Crockett, 82P/Gehrels 3 However meteoroids also occur in family this would be around 300 and 107P/Wilson-Harrington, streams. The flux from these can km in diameter. Most asteroids which are all in some sense be calculated and it works out an were solid, and consisted of ‘strange’. The current population order of magnitude less than the several types, although a few of JFCs can be explained with an overall flux, which can be split might be re-aggregates after injection rate of about one per into helion/anthelion. north/south collisions. By contrast comets century and a dynamical lifetime toroidal and north/south apex were formed by accretion and for class 1 objects of around components. The Taurids do were low density irregular 10,000 years and 1500 years for contribute a significant amount to objects. He pointed out that there class 2 objects. He would expect the anthelion flux. Meteor radars seemed to be no small comets. around 100 dead JFCs to be still give a velocity distribution, but in He didn’t think much of the idea hanging around, but many more the past have missed a lot of fast BAA COMET SECTION NEWSLETTER 4 THE COMET’S TALE meteors (~60 kms-1).