Comet Tails and Visibility

[BobHegwood]

More information on the depletion of comet coma's can be found at
Harvard: http://adsabs.harvard.edu/abs/1995GeoRL..22..639M

As you know, I already believe that the coma will dissipate at a rate
similar to the tail. Just some more real scientific data here for those
who are interested.

Thanks, Brain-Dead

[BobHegwood]

In addition to the above, I've been in contact with Mr. Donald
Machholz... Perhaps you've HEARD of him?

Don replied to my inquiry concerning the coma dissipation as
follows:

Greetings Bob;

Yes, the tail and coma material dissipates from the comet nuclear region as the comet moves back into space.

Actually it is always dissipating from the nucleus, when the comet is closer to the sun the material dissipates faster then when the comet is further from the sun. As the comet moves further from the sun, less material leaves the nucleus while that which is already in the coma continues to dissipate, until you soon have almost no material around the nucleus.

I hope this helps. Take care

Don Machholz
Colfax, CA.

Don has been closely following comets (and discovering a few)
for YEARS, and his observations oughtta be of some value here
don'tcha think?

[Adirondack]

As the comet moves further from the sun, less material leaves the nucleus while that which is already in the coma continues to dissipate, until you soon have almost no material around the nucleus.

AFAIK, this is already the case when the comet leaves the orbit of Mars (approx. 1.5 - 2.0 AU).

Adirondack

[BobHegwood]

As the comet moves further from the sun, less material leaves the nucleus while that which is already in the coma continues to dissipate, until you soon have almost no material around the nucleus.

AFAIK, this is already the case when the comet leaves the orbit of Mars (approx. 1.5 - 2.0 AU).

Adirondack

Not the case Ulrich...

The tail disappears, but the coma stays present as ever. This is
true regardless of its distance from the Sun.

Thanks, Brain-Dead

[Adirondack]

Not the case Ulrich...

The tail disappears, but the coma stays present as ever. This is
true regardless of its distance from the Sun.

Yes, you are absolutely right, Bob.
So you see, YOU are smarter than me. Quod erat demonstrandum!

The tail disappears around 1.5 - 2.0 AU.

But doesn't the coma disapears around 4 - 5 AU?
That's what I read in the Brockhaus of Astronomy anyway.

Adirondack

[BobHegwood]

But doesn't the coma disapears around 4 - 5 AU?
That's what I read in the Brockhaus of Astronomy anyway.

Adirondack

I believe that it should, but in the current version of Celestia, Halley
is at 31 AU + from the Sun, and its coma is still there on my machine.

The problem is that - apparently - we do not have enough scientific
proof that the coma SHOULD disappear from the comet after 4-5 AU.

Do you have a reference we can look at? I tried searching for the
reference material you cited above, but didn't have much luck. Most
of the references I found required you to be a scientist in order to
login to see the reference.

Thanks, Bob

[Adirondack]

Do you have a reference we can look at?

Bob,

the "Brockhaus of Astronomy" is an encyclopedia (in Germany).
If it helps, I can scan the appropriate page and send it to
you with a translation.

Meanwhile you can take a look at the german wikipedia:
http://de.wikipedia.org/wiki/Koma_%28Astronomie%29#Koma
Just take a look at the first sentence:
"As soon as a comet crosses the orbit of Jupiter during
its approximation to the sun in a distance from approximately
5 AE, the comet gets a dish-shaped coma, which shows also
radiate-like structures in core proximity."


Adirondack