American Association of Variable Star Observers AAVSO 100 Years of Support to the Amateur Scientific

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American Association of Variable Star Observers
(AAVSO) 100 Years of Support to the Amateur
Scientific Astronomy

• Chuck Pullen
• Coyote Hill Observatory
• Wilton, California
• cpullen_at_coyote-astronomy.org

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What well cover

• What are variable stars?
• Observing and archival programs
• How you can become involved

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Whats a variable star?

• All stars are variable
• Stars that change brightness in regular or
  irregular manner
• Caused by many astrophysical mechanisms, many
  still not well understood

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Astronomy and amateur science have a long
tradition

• Many amateurs have made significant
  contributions to astronomy.
• With equipment now available, capabilities now
  over lap.
• Fewer and fewer professional telescopes available.

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Variable stars are not new

• Initial discovery in late 1700s
• Topic of gentleman astronomers since the mid
  1800s
• Clear need for coordinated observations, with
  standard star sequences, identified in 1870s.
• AAVSO (1911) outgrowth of Harvard College
  Observatory Director Edward Pickering inititives.

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Types of Variable Stars

• Intrinsic Variables Pulsation
• Long Period Variables (Mira-like)
• Cepheids, RR Lyr, Delta Scuti
• Extrinsic
• Eclipsing Variables
• Eruptive Variables
• Novae, dwarf nova,
• Supernovae (Type 1 and II)
• Polars
• R CrB Stars
• Gamma Ray Bursts and other black hole caused
  variation in galactic nuclei

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Pulsating Variables

• Radial or multimodal pulsation
• Powered by various mechanisms.
• Pulsation period may occur on scales of minutes
  to months.
• Amount of brightness change 0.1 to 5 or more
  magnitudes.

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Pulsating Variables

• Primary distance indicators (Cepheids, RR Lyr)
  for galactic distance scale.
• Change periods due to interference between
  pulsation modes, mass loss, or mass gain.
• Period determinations and monitoring for long
  term change excellent data mining opportunity
  for amateur scientists.

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Eruptive Variables Things that go Bang! in the
night

• Exciting to watch!
• Routine eruptions Dwarf Novae
• Rare eruptions Novae
• Very Rare Supernovae
• Rarest of all GRB Afterglows

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How Novae Work

• White Dwarf and main sequence star binary system
• Hydrogen donated to the WD.
• High energy plasma physics laboratory in the
  accretion disk.
• Added mass reaches critical temperature and
  pressure.
• Boom!

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Supernovae

• Type I accretion and carbon detonation
• Type II collapse after end of hydrogen burning
• Type I have equal energy Now being used to
  extend distance ladder to high redshift

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Gamma Ray Bursts

• Caused by ?
• Most energetic events in universe
• Afterglow photometry critical to understanding.
• AAVSO / NASA have organized network

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Gamma Ray Bursts

• Very hot topic in astrophysics
• AAVSO recently contributed important early data
  for one of the closest GRBs ever detected.
• Excellent data quality compared to pros

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Eclipsing Binary Systems

• Orbital inclination nearly at line of sight
• Allow for mass determinations of both stars.
• Some change over just a couple of hours
• Period changes from mass transfer and other
  causes.

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So, what do we do?

• Monitor over 4,000 variable stars, in both
  hemispheres, of all kinds.
• Support specific observing requests from
  professionals
• Use a number of methods for light intensity
  measurement photometry (visual, CCD, PEP,
  photographic)
• Report and archive our observations over 11
  million observations on file.
• Evaluate data and make it available without
  charge to professional astronomers, amateurs,
  students anyone.

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Support Services of AAVSO

• Charts and standard star sequences
• Coordination of special observing campaigns
• Evaluation of data
• Archiving of data

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More help

• Learning guides
• Educational material
• Web Site
• Mentor program
• Journal
• Meetings and workshops
• Networking / discussion list

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Join Us!

• http//www.aavso.org