General commet questions!!

Hi

I would like to know..... what would be the definition of a commet's absolute magnitude (as apposed to its apparent magnatude).

Also I was wondering what do the different letters and numbers mean when each commet is named. eg. p, c, etc

P.S. thanks to TAS for Cosmos 2006 last weekend. Pitty I could only go on Friday. When would the next observing session be

Hi David

The letter 'C' stands for a long period comet. That is a comet who's orbital period is greater than 200 years. 'P' stands for short period comet which have orbits of less than 200 years. 73P SW3 is the 73 periodic comet known (short period Comet).

As for a comets magnitude. The M1 magnitude refers to the comets overall mag, that is the entire mag of the coma (head). M2 is the magnitude of the faint false nucleus at the comas centre.

I hope this helps..clear skies

Glad you came down David, it was nice to have a face to the name! Funny enough, a question similar to yours came up in the quiz!

By definition regarding Absolute Magnitude:
The Absolute Magnitude of any object is how bright it would actually be if placed at a distance of 10 persecs, or 32.6 light years, from Earth.

For example (one I used in a recent lecture) the apparent magnitude (as we see it) of 61 Cygnii is +5.2. With the mathematic formula:

mv - Mv = -5 + 5 log 10 (d)

(mv = apparent magnitude, Mv = Absolute magnitude)

the absolute magnitude of 61 Cygnii would be -2.32

Hope this is of some help to your query.

Seanie.

In addition...

COMETS: The absolute magnitude of a comet is the brightness it would exhibit if placed 1 AU from both the Earth and sun.

METEORS: The stellar magnitude any meteor would have if placed in the observers zenith at a height of 100 kms.

STARS: The apparent brightness a star would have if placed at a distance of 10 parsecs from the earth.

Dave

Ah, I didn't know there was a different uniform distance for comets Dave Mac, thanks for that!

Neither did I 'til I Googled it :oops:

Just shows you eh? I think asteroids fit into the Star/Celestial object category - well, I hope they do!

Cheers

Dave