Video transcript of meeting

A Special General Meeting (SGM) was held before Astronomy Cafe commenced. After the SGM concluded, members heard a guest speaker and reports.

A Brief History of Galaxies: from the discovery of island universes to a clash of the Titans – Dr. Sara Ellison, UVic Astronomy professor

  • Our own Milky Way and other galaxies showing light and dust features
  • Deep field taken by JWST
    • FOV: a grain of sand held at arm’s length
    • thousands of galaxies in the image
  • History
    • Charles Messier – a 17th century comet hunter who listed 110 objects that are notcomets
    • Lord Ross used the 1.8m Leviathan telescope to sketch spiral galaxies
    • Shapely-Curtis debate in 1920 about the nature of nebulae
    • The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars: Sobel, Dava: 9780143111344: Books –
    • Henrietta Leavitt discovered the Type 1 Cepheid Variables, correlation between the brightness and variations in the luminosity
    • Leavitt’s discovery used by Edwin Hubble, who in 1923 settled the Shapely-Curtis debate. The Hubble Law related distance to velocity (red shift), the start of cosmology as we now know it.
    • Hubble Tuning Fork classifications of galaxies
    • Halton Arp studied Peculiar Galaxies – guide:
  • Early modelling of interacting galaxies
  • Video – current modelling of interacting galaxies
  • Toomre Sequence – showing different morphologies
  • Galaxies cluster in groups, which is how they grow mass
  • Stellar streams in the Triangulum Galaxy – research at Herzberg
  • Tidal streams in the Milky Way are remnants of small galaxies that have interacted in the past
  • How a galaxy merger transforms it – simulations predict:
    • Isolated disk
    • Small group
    • Gas funnels to the galaxy centre
    • Black hole accretion
    • Decay
    • Dead Elliptical
  • Sara’s research – Sara Ellison – University of Victoria
  • Q&A


  • Council meeting coming up – Tue 28th – AGM planning
  • Awards Nominations and nominees for Council – contact Reg Dunkley
  • AGM will be held online, tentatively on March 13th
  • Social dinner will also be held later – awards
  • SIGs

No Astro Cafe next week. Next Astro Cafe will be held on Feb 27th

Astronomy Cafe – Feb 13, 2023
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