Pulsars

Cham · Post #1by **Cham** » 17.01.2004, 15:24

I installed the PSR 1257 and M4 (with PSR B1620-26) addons from this page :

http://63.224.48.65/~rassilon/

These are really cool addons.

I want more pulsars. Is there a pulsar data base somewhere ?

Cormoran · Post #2by **Cormoran** » 22.02.2004, 15:39

I've been working on an add-on containing Pulsar data.

While the data has been gathered, it still needs filtering, plus I need to work out how to represent the Pulsars within Celestia.

With Rassilon's permission, I'd use his Pulsar model (credited in the readme of course

)

Would that be okay Rassilon?

Cheers,

Cormoran

Cham · Post #3by **Cham** » 22.02.2004, 18:47

How many pulsars will you add ?

Cormoran · Post #4by **Cormoran** » 22.02.2004, 19:16

After doing a quick filter for distance, I have data on 600+ pulsars.

A lot of them are quite far away while still being within the 16000 ly radius required by Celestia.

I may revisit the data source and make sure I'm grabbing the right stuff from it. I'm no expert on the subject, and would happily throw the data source at anyone who knows more about this than I do

Cormoran

Post #5by **selden** » 22.02.2004, 19:39

I probably shouldn't mention this, but...

Don't forget that the new CMOD model format can draw points in space. While their brightness doesn't (yet?) fall off with distance, it can be used to place points of light at arbitrary distances.

Now don't everyone go hog-wild designing galaxies full of stars and stuff like that...

Cham · Post #6by **Cham** » 22.02.2004, 19:47

"O my God, it's full of stars!"

Cormoran · Post #7by **Cormoran** » 03.03.2004, 12:16

Ladies and gents,

My first 'real-world' add-on is ready in its basic form!!

Using data taken from the following site:

http://www.atnf.csiro.au/research/pulsar/psrcat/

I have generated an STC file containing positional data on 630 Pulsars.

All are defined as Type "Q" within Celestia, with an absolute magnitude of 18.8 (I remember reading somewhere that this was fairly accurate... anyone got a better value?)

The file can be grabbed from:

http://homepage.ntlworld.com/jdchapman66/Pulsars.stc

Any input would be appreciated

Cormoran

Cormoran · Post #8by **Cormoran** » 03.03.2004, 12:21

Sorry, forgot to mention that the file just needs to be dropped into the Celestia Extras folder.

All pulsars within the file are prefixed with PSR, which should assist you in finding them

Regards,
Cormoran

Cham · Post #9by **Cham** » 03.03.2004, 15:46

This is absolutly great ! I'll try this file right away !

We'll have to add a mesh or something to make them all looking like pulsars.

Cormoran · Post #10by **Cormoran** » 03.03.2004, 16:04

I'm glad you like it, Cham.

I think it would be pretty cool to model Pulsars so that they look right, but I dislike the idea having to engulf the star object with another model.

I would have thought it was pretty simple to allow Stars to have a model assigned to them as opposed to the standard Sphere.

As a matter of fact, an oblateness setting might be good too, as I hear some stars are extremely oblate due to rapid rotation.

Anyways, enjoy

Cormoran

Cham · Post #11by **Cham** » 03.03.2004, 16:11

Oops, my post was double ! I edited this one. see the next.

Cham · Post #12by **Cham** » 03.03.2004, 16:12

I agree with you, and the pulsar models I've found don't have a glow, which is unrealistic.

Can we add an oblate setting to your pulsars ?

I tried your file. Appears to work nicely. Are the distances reliable ?

Cham · Post #13by **Cham** » 03.03.2004, 16:25

And what about rotation period ? They all rotate with a 1 sec period. Don't we know their true rotation period ? They are pulsars, after all.

Cormoran · Post #14by **Cormoran** » 03.03.2004, 18:58

Well, I DID say it was in its basic form

Okay, I'll dig up the rotation data if I can and add it.

Cormoran

Cham · Post #15by **Cham** » 03.03.2004, 19:02

Cool. That file may be a must have, especially if you can add some oblateness ! (but I can't see how). Is Celestia supporting star oblateness ?

Cormoran · Post #16by **Cormoran** » 03.03.2004, 19:46

I don't think celestia supports oblate stars.

I also can't find any way of setting the rotation period of a star in its stc file.

Shame really, as it took me about 3 minutes to find the extra data required :cry:

If anyone knows how to set the rotation period as above, please let me know

Cheers,

Cormoran

Cham · Post #17by **Cham** » 03.03.2004, 19:55

Maybe it's in a separate file ?

But why it's one second ? Other stars like our sun doesn't rotate with that period, so there's surelly a way.

Post #18by **selden** » 03.03.2004, 19:58

In order to minimize its size and maximize performance, Celestia's internal database of star information only includes location, spectral type and absolute visual magnitude. Everything else is calculated, including the radius and rotation speed. Obviously the results of the calculations are only going to be approximate, since they can't take into account things like a star's age. (Older stars rotate more slowly.) Maybe someday this can be improved...

Cham · Post #19by **Cham** » 03.03.2004, 20:02

Maybe it's stored in the stars.dat file.

Maybe the solution is to make a model of an oblate sphere, with a texture (?), just big enough to cover the star. I don't like much that solution, because when we moves around the star, the mesh sometimes change abruptly to a normal star. This is really a weakness in Celestia.

Celestia needs an update of its star definition.

Cham · Post #20by **Cham** » 03.03.2004, 20:05

Selden,

so the only solution is to make a generic model of a pulsar ?