BAA / AAVSO Day 2: Novae & Supernovae for all

The word Novae generally refers to a “New Star,” or a “Guest Star” – An object that springs up in the sky quite suddenly as a new but non-permanent object. Today we give these non permanent sky features a dozen or more names: Supernovae (types I & II with all sorts of extra letters), Recurrent Novae, Cataclysmic Variables and more.

While observed and documented for about 2000 years, only for the last 100 years have we known that novae and supernovae are different objects, and that supernovae are stars blowing themselves to bits. Only in my lifetime have we known Novae are white dwarfs surrounded by accretion disks that periodically blow (some of) themselves to bits.

These dynamic objects change dramatically in brightness. For scale, human vision allows us to see objects from magnitude 0 (the brightest stars) to magnitude 6 (the things you only see in the middle of no where). With novae, stars often can increase in brightness by as much as 10 magnitudes in 24 hours. They don’t stay bright for long, however, and in the vastness of the sky it is easy to missing these pin prick flare ups.

To help try and find these things, in 1973 a Sky Patrol was started (although negatives weren’t even checked all the time). These images were used to examine pre-outburst appearances of objects and to search for every novae brighter then 8th magnitude. In 1976, visual searches for novae were added to photographic searches.

A “team plan” was designed, with small numbers of zones allocated to different observers around the globe – there was a very strong collaboration with the AAVSO, with different fields being assigned systematically on both sides of the Atlantic. Each clear night people went out, looked up, and watched for cosmic explosions. The biggest question was: can visual observers with binoculars find these new stars in fields rich with stars? For some it was an easy yes. With 10×50 binoculars it is possible to memorize a field down to 8th magnitude, and these observers were able to affectively find new objects. The biggest issue in these objects was the need for a solid master image to compare the sky against. No atlas exists that is entirely accurate, and only a photo can give a true view of the sky. This, photos (which could be used for master images) provided the needed check on observations.

Today, Guy Hurst is the Patrol Coordinator, and he organizes many observers searching many many sections of the sky. Hundreds of novae and supernovae have been discovered and data across the stars’ rises and falls, have been collected. This data helps us understand the way the outbursts evolve over time (like discovering how different woods burn in a camp fire).

This is interesting work, and new observers are always welcome to join. Interested in playing along? Email guy at tahq dot demon dot co dot uk.

2 Comments

  1. Daniel Fischer April 12, 2008 at 6:05 pm #

    Funny coincidence: Right while you were blogging on amateur nova discoveries a rather bright one in Cygnus was discovered by amateurs in Asia …

  2. Hubert April 13, 2008 at 5:46 am #

    Yes! A new nova in Cygnus! Because I wasn’t able to join the AAVSO/BAA meeting I was able to estimate the magnitude of the nova (now named V2491 Cyg)the next night.

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