Three questions for astronomers regarding Elenin

reply to post by jumpspace

Update:

Can someone please:

1) Explain to me how a 4km object generates a 33824km coma? (not answered)

2) Explain how an astronomer would mathematically determine the original 4km odd diameter of the nucleus? (Answered - between 48.367km and 108.153km it seems)

3) Explain what the colours are in the image and what the yellow colour means? (not anwered)

Cheers

JS

PS: I would have edited the OP but I can't

1. It was answered. Back on page 1 it was explained to you that you just cant use a blurry splodge on a photo to estimate the size of an object. It has to be resolved to do that. With clearly defined edges.
But dont take my word for it. Check for yourself. Do the same calculation as you did before, but with one of the bright stars in the image. Try it with a few estimates of distance, like 100 light years or so, and see for yourself the silly answers that arise from the method.

2. The answer of several tens of km in size is actually just a poor approximation.
I just stopped there on my previous answer because it was enough to prove to you that Elenin wasnt some super massive object like you first feared.
The more complex answer is that the table referred to is for asteroids, and probably assumes they are perfectly round, distinct horizon and uniformly reflective. Comets are different. They have a small solid core, and big diffuse cloud around them. So more exactly, the solid core of Elenin will be about 4km in size, but the cloud (dense near the comet, thinner further away) is many times larger. Making it appear bigger than it really is.
Look for photos of the Hartley 2 comet flyby as closeup example.

3. You'll have to ask the programmer who wrote the software.
To me, it just looks like the automated software puts a yellow circle around the comet where it decides thats where the edge is. Probably some parameters the user can tweak as well. You realise thats not the actual colour of the comet, right? Just some software.


But I've got a question for you.
Whats the issue with Elenin? I've seen it referred to several times on ATS. Who came up with the idea that this particular comet was somehow worthy of conspiracy theory attention, and why?

reply to post by jumpspace


haha, yeah true.. I can't offer anything with this thread. What you have done here is beyond my understanding of mathematics, and I respect that. So with everything that has been posted in this thread, what conclusions have you people come up with?

reply to post by alfa1

alfa1:

>1. It was answered.

No it wasn't.

The sizes I referred to in question number 1 were calculated by Leonid Elenin (the nucleus size of 4km) and Gustavo Muler (the coma size of 33 734km (from the OP)).

I simply asked HOW a 4km object generates a 33824km COMA. I'd recommend you re-read the first question.

>2. ...was enough to prove to you that Elenin wasnt some super massive object like you first feared.

I'm not really sure where you're coming from here alfa1. I actually thought it was around 4km but created this thread to settle the issue once and for all for everyone. Your assumption that I was in fear was 100% incorrect.

>The more complex answer is that the table referred to is for asteroids, and probably assumes they are perfectly round, distinct horizon and uniformly reflective. Comets are different.

Hmmm, then why did you refer me to that table alfa1? Now I'm even more intrigued.

>So more exactly, the solid core of Elenin will be about 4km in size

No disrespect alpha1 but I'd prefer to believe the calculations of the Department of Physics and Astronomy at the Stephen F. Austin State University, based on an absolute magnitude of 8.7. If you know of a reputable online source that disputes this, by all means, please direct me to that source.

>3. You'll have to ask the programmer who wrote the software.
OK, thanks. I thought it may be some "standard" that astronomers use.

>You realise thats not the actual colour of the comet, right?
Yes, I did realize that

>But I've got a question for you.
>Whats the issue with Elenin?

None whatsoever in my head.

>Who came up with the idea that this particular comet was somehow worthy of conspiracy theory attention, and why?

You tell me, I'm not particulalrly interested in wasting my time on that train of thought. I'm only interested in the facts.

BTW, that was 2 questions

Cheers

JS

reply to post by Redevilfan09

As I cannot update the OP, simply look at the Updates Redevilfan09.

Cheers

JS

reply to post by jumpspace


In the image, it says that the comet has a coma size of 33.734 kms. Are you sure you haven't misread what is written there? Because that looks like a dot too me. Not 33,734 kms.

Originally posted by Redevilfan09
reply to post by jumpspace

 

In the image, it says that the comet has a coma size of 33.734 kms. Are you sure you haven't misread what is written there? Because that looks like a dot too me. Not 33,734 kms.

Hi Redevilfan09

It's 33 734km.

Cheers

JS

Why is a large coma such a surprise? Comets can often have very large comas.

stereologist:

Originally posted by stereologist
Why is a large coma such a surprise?

Why do people ASSUME certain emotions?

First it was assumed I was in "fear" and now I'm apparently "surprised".

If you're talking about about other people then I apologize for the assumption that you're talking about me. If you are talking about other people being surprized about the size then I recommend you start your own thread discussing the emotions that people feel when a new comet comes into our solar system.

Comets can often have very large comas.

It is well known fact that a comet can generate a coma bigger than the sun.

Regarding coma's, I'm not concerned about the size of Elenin's coma size, I am asking a simple question (the first one):

1) Explain to me HOW a 4km object generates a 33824km coma?

Cheers

JS

Originally posted by jumpspace
stereologist:

Originally posted by stereologist
Why is a large coma such a surprise?

Why do people ASSUME certain emotions?

First it was assumed I was in "fear" and now I'm apparently "surprised".

If you're talking about about other people then I apologize for the assumption that you're talking about me. If you are talking about other people being surprized about the size then I recommend you start your own thread discussing the emotions that people feel when a new comet comes into our solar system.

Comets can often have very large comas.

It is well known fact that a comet can generate a coma bigger than the sun.

Regarding coma's, I'm not concerned about the size of Elenin's coma size, I am asking a simple question (the first one):

1) Explain to me HOW a 4km object generates a 33824km coma?

Cheers

JS

edit on 7-4-2011 by jumpspace because: (no reason given)

Does the size matter?

Comet Holmes, a comet 3.4 km in diameter at its nucleus, gained a coma that glowed so brightly that it outshone the Sun, and one that was so large that, temporarily, Holmes' diameter was wider than the Sun's when taking said coma into consideration.

reply to post by jumpspace


I see. This is going to be a quibble fest. Here is what you wrote in the original post:

1) Explain to me how a 4km object generates a 33824km coma?

I asked why you even bothered to ask this question as if this needed to be asked. I used the word surprised and now you want to quibble over it. Fine. Go ahead and quibble. It's unbecoming to say the least.

The answer is simply outgassing.

Originally posted by stereologist
Why is a large coma such a surprise? Comets can often have very large comas.

Originally posted by stereologist
I asked why you even bothered to ask this question as if this needed to be asked. I used the word surprised and now you want to quibble over it. Fine. Go ahead and quibble. It's unbecoming to say the least.

stereologist:

Sorry but you are 100% WRONG. You DID NOT ask me why I even bothered to ask question 1. Why BS?

People who assume other peoples emotions and then start accusing them of "quibbling" either have some very serious issues or have an alternative agenda. Let me know which category you fit into and I'll try to accomodate your afflication.

Anyhow, if you were curious as to why I asked the question, why didn't you just ask me directly? It's not that hard really.

If you can't explain exactly HOW a 4km object generates a large coma then why are you even commenting on question 1? I asked 3 very simple direct questions and then you start asking me why I'm surprised about the size of the coma. Huh? Based on the following definition of quibbling, you're the one quibbling:

"To evade the truth or importance of an issue by raising trivial distinctions and objections."

One thing I have garnered from this thread is that Elenin isn't 4km odd in size. It's someone between 48km and 108km in size and this is based on _NASA_ information!!!

Is that the truth you are trying to evade by raising trivial matters?

Maybe I do see your afflication

It's simple really stereologist - read the question and if you don't know the answer, don't bother posting. We have another term we use often here in Australia - put up or shut up. If you need clariification or expansion of one of the questions then please, be my guest.

Cheers

JS

Originally posted by NyxOne
Does the size matter?

It seems to matter to a lot of people NyxOne, including yourself. If it didn't, you wouldn't ask the question.

I'm just trying to get to the facts without all the BS.

Factually, so far, Elenin's nucleus size is NOT 4km odd, it's between 48km and 108km...and this is using NASA's Albedo range.

Cheers

JS

reply to post by jumpspace

Sorry but you are 100% WRONG.

Wow you are a determined quibbler. Do you mind if I address you as The Quibbler from now on?

People who assume other peoples emotions

I did not assume other people's emotions, only the quibbler did that. That would be you who is determined to play a straw man argument. It's a whopping failure if you had not noticed.

If you can't explain exactly HOW a 4km object generates a large coma then why are you even commenting on question 1?

What do you want to now about outgassing? Are you claiming outgassing does not happen? Are you claiming that outgassing cannot eject material? Are you unaware of light pressure? Are you unaware of the effects of the solar wind? What is it that you seem to not understand?

"To evade the truth or importance of an issue by raising trivial distinctions and objections."

See your definition makes it evident that you brought up this false claim of people imposing emotions on you.

You might have done it:
1. because of some personal insecurity.
2. because you realize you asked a lackluster question.
3. because you love to quibble

I really don't care why you are a quibbler, but you need to move on.

One thing I have garnered from this thread is that Elenin isn't 4km odd in size. It's someone between 48km and 108km in size and this is based on _NASA_ information!!!

That is a falsehood. Why are you telling a lie. It is not NASA information. It is the application of a formula which does not appear to particularly relevant, but establishes a rough estimate.

Is that the truth you are trying to evade by raising trivial matters?

Are you actually quibbling to justify telling a lie? You certainly make it look that way.

So now why do you not understand radiation pressure , solar wind, and outgassing of comets?

reply to post by jumpspace

I'm just trying to get to the facts without all the BS.

Factually, so far, Elenin's nucleus size is NOT 4km odd, it's between 48km and 108km...and this is using NASA's Albedo range.

So if you tell a falsehood twice are you now a fibber? The formula being used is an estimator. It contains a great deal of uncertainty. You do realize that don't you? You also realize that the formula is not necessarily valid for the object in question?

Originally posted by jumpspace

Factually, so far, Elenin's nucleus size is NOT 4km odd, it's between 48km and 108km...and this is using NASA's Albedo range.

As has been explain before, you cant use a simple *Minor Planet* albedo table to get a size for a *Comet*.

As has been explained before, you will get a result larger than the actual solid mass of the comet due to outgassing making it appear larger than it is.

Update:

Can someone please:

1) Explain to me how a 4km object generates a 33824km coma?

This is called outgassing and was answered by stereologist. For the technically minded:

trs-new.jpl.nasa.gov...

2) Explain how an astronomer would mathematically determine the original 4km odd diameter of the nucleus?

The size of the nucleus is determined by the absolute magnitude and is calculated at 8.7; compliments to alfa1. The Minor Planet Center estimates the absolute magnitude to be 8.0, compliments of alfa1.

The size of the nucleus is further determined by the comet's albedo, compliments of various sources, some being:

neo.jpl.nasa.gov...
www.physics.sfasu.edu...

The "classical" albedo figure used to calculate the size of the nucleus for comets is 0.04, compliments of various sources, some being:

trs-new.jpl.nasa.gov...
neo.jpl.nasa.gov...
trs-new.jpl.nasa.gov...
onlinelibrary.wiley.com...

Elenin's estimated nucleus size is 120.919 km, based on an albedo of 0.04 and an absolute magnitude of 8.7 (see the four links above), compliments of:

Stephen F Austin State University (www.physics.sfasu.edu...).

There are still many variables for this calculation and, as such, the diamater of the nucleus could be smaller or larger than indicated above.

If someone has a more accurate way of calculating the size of Elenin's nucleus using fewer estimates then please, be my guest

3) Explain what the colours are in the image and what the yellow colour means?

The colours are related to whatever imaging process the astronomer uses.

Cheers

JS

Originally posted by alfa1

Originally posted by jumpspace

Factually, so far, Elenin's nucleus size is NOT 4km odd, it's between 48km and 108km...and this is using NASA's Albedo range.

As has been explain before, you cant use a simple *Minor Planet* albedo table to get a size for a *Comet*.

As has been explained before, you will get a result larger than the actual solid mass of the comet due to outgassing making it appear larger than it is.

I totally agree with Alfa1 and would like to add that as the comet approaches the Sun, its apparent diameter will increase as it out-gasses.

The albedo of the coma is different to the albedo of the core and so its absolute magnitude could also be expected to change over time.

Originally posted by chr0naut

Originally posted by alfa1

Originally posted by jumpspace

Factually, so far, Elenin's nucleus size is NOT 4km odd, it's between 48km and 108km...and this is using NASA's Albedo range.

As has been explain before, you cant use a simple *Minor Planet* albedo table to get a size for a *Comet*.

As has been explained before, you will get a result larger than the actual solid mass of the comet due to outgassing making it appear larger than it is.

I totally agree with Alfa1 and would like to add that as the comet approaches the Sun, its apparent diameter will increase as it out-gasses.

The albedo of the coma is different to the albedo of the core and so its absolute magnitude could also be expected to change over time.

edit on 11/4/2011 by chr0naut because: (no reason given)

Hi chr0naut

Yes, the albedo may change either way, however at this point in time we have no other alternative to estimate the nucleus size, as Leonid Elenin did when he first discovered the comet. As such, I would prefer to use a "classical" comet albedo of 0.04 and this is what NASA and others also use:

trs-new.jpl.nasa.gov...
neo.jpl.nasa.gov...
trs-new.jpl.nasa.gov...
onlinelibrary.wiley.com...



Cheers

JS