Sgr A* (galactic core)

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Cham M
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#1by Cham » 16.11.2008, 17:42

There's a page about the central core of the Milky Way, which shows a movie made with Celestia. They don't give Celestia's name on the page, and I was wondering about the data they're using. Is there a way to download the STC file they made ?

http://www.mpe.mpg.de/ir/GC/index.php
Last edited by Cham on 21.11.2008, 03:55, edited 1 time in total.
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Re: Celestia movie, there

#2by selden » 16.11.2008, 18:11

I'd suggest that you ask them.
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Re: Celestia movie, there

#3by t00fri » 16.11.2008, 20:19

After writing a (friendly) letter of complaint to the scientist (H. Steinle) responsible for the contents of the MPE Website, about the lack of citation of Celestia, I got right away an apology and the promise for immediate correction.

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Re: Celestia movie, there

#4by t00fri » 17.11.2008, 11:09

This morning I got another letter with the promise to immediately add the reference to Celestia in the Website of the

Max-Planck-Institut f?r extraterrestrische Physik (MPE)
- Infrared/Submillimeter Astronomy - Galactic Center Research


along with a formal apology on behalf of the whole Galactic Center Team of the MPE for the omission.

Fridger

They will add

This animation has been created using the free space simulation
<a href="http://www.celestiaproject.net/celestia/">Celestia.
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Cham M
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Re: Celestia movie, there

#5by Cham » 17.11.2008, 13:18

They added the reference. What about the data files ? I emailed the query, but didn't got any answer yet.
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Re: Celestia movie, there

#6by t00fri » 17.11.2008, 13:53

Cham wrote:They added the reference. What about the data files ? I emailed the query, but didn't got any answer yet.

I asked for the .stc file this morning and also gave them the reference of my analogous video (milky3.avi) that I did quite some time ago. The .stc file for all the many orbiting stars of my video is also available for download in my thread.

[That video (milky3.avi) might have to be downloaded before playing, since the resolution is pretty big]

http://forum.celestialmatters.org/viewtopic.php?t=210

I had devoted a whole thread at CelestialMatters quite some time ago to the interesting issue of a dense star cluster orbiting around the (supermassive black hole of the) galactic center (Sag A).

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Re: Celestia movie, there

#7by Cham » 20.11.2008, 18:05

Fridger,

did you got some news, about the data they're using (stc files...) ? I didn't received any response from my email query.

I would like to populate the galactic center with some real data (no fakes). Currently, it's pretty empty in there, in Celestia ! I defined a new black hole model at the galactic center (Sgr A*), but it's all lonely ! :cry:
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Re: Celestia movie, there

#8by t00fri » 20.11.2008, 18:28

Cham wrote:Fridger,

did you got some news, about the data they're using (stc files...) ? I didn't received any response from my email query.

I would like to populate the galactic center with some real data (no fakes). Currently, it's pretty empty in there, in Celestia ! I defined a new black hole model at the galactic center (Sgr A*), but it's all lonely ! :cry:

No, I didn't get an answer since my request for that .stc file. Apparently they confirmed over about 12 years of measurement that these innermost stars move on Keplerian orbits around the Sga A* black hole.

I recommend that .stc file of mine in the meantime ;-)

http://www.celestialmatters.org/users/t ... ns.stc.zip

It contains many more stars orbiting Sgr A*. Unfortunately, the orbits are from translating visualbins.stc rather than from 12 years of measurement ;-)

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Re: Celestia movie, there

#9by Cham » 20.11.2008, 18:44

t00fri wrote:I recommend that .stc file of mine in the meantime ;-)

I'm not interested in that file, since it's about fake stars (fictional).
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Re: Celestia movie, there

#10by t00fri » 20.11.2008, 18:48

Cham wrote:
t00fri wrote:I recommend that .stc file of mine in the meantime ;-)

I'm not interested in that file, since it's about fake stars (fictional).

An attitude that I thoroughly support :roll: :lol: :mrgreen:

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Re: Sgr A* (galactic core)

#11by Cham » 21.11.2008, 03:58

Here's a picture of my recent Sgr A* giant black hole that I placed at the center of the Milky Way. It needs its stars escort around him, though. I'm still waiting for the data from the previous web site. Click on the thumnail for a large version :
SgrA.jpg
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Re: Sgr A* (galactic core)

#12by ANDREA » 21.11.2008, 10:06

Cham wrote:Here's a picture of my recent Sgr A* giant black hole that I placed at the center of the Milky Way. It needs its stars escort around him, though. I'm still waiting for the data from the previous web site.
Martin, this project is very interesting and appreciated, I hope you'll obtain in a short time the ssc REAL data for the involved stars.
Cannot wait for the final result.
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Re: Sgr A* (galactic core)

#13by t00fri » 22.11.2008, 16:56

Martin,

The orbit data of the the stars within this arcsecond^3 region around the central black hole
have been published by a MPE group very recently! So what are you waiting for?

Have a look at the last few pages of:
http://arxiv.org/pdf/0810.4674v1

Cham wrote:I'm not interested in that file, since it's about fake stars (fictional).
With a little more interest in that file which I made to illustrate the way I generated a respective .stc file for this fictional toy model, you'd be able to transform these published S-star orbits in NO time into the right frame :mrgreen:

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Re: Sgr A* (galactic core)

#14by Cham » 22.11.2008, 17:08

t00fri wrote:Have a look at the last few pages of:
http://arxiv.org/pdf/0810.4674v1
...With a little more interest in that file, illustrating the way I generated a respective .stc file in my fictional case, you'd be able to transform these published S-star orbits in NO time into the right frame :mrgreen:

Ahaa ! Thanks Fridger, I wasn't aware of that paper. The table is there :
table.gif


However, I don't know how to convert the data into a proper STC file in the way you're sugesting, without doing it by hand one star at a time.

Since you already know how to do it "in NO time", why don't you do it ?
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Re: Sgr A* (galactic core)

#15by t00fri » 22.11.2008, 17:23

Cham wrote:Since you already know how to do it "in NO time", why don't you do it ?

I am NOT interested in making add-ons :lol:

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Re: Sgr A* (galactic core)

#16by Cham » 22.11.2008, 17:25

t00fri wrote:
Cham wrote:Since you already know how to do it "in NO time", why don't you do it ?

I am NOT interested in making add-ons :lol:

Well, okay then. No galactic core for all of us in Celestia. Too bad.
"Well! I've often seen a cat without a grin", thought Alice; "but a grin without a cat! It's the most curious thing I ever saw in all my life!"

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Re: Sgr A* (galactic core)

#17by t00fri » 22.11.2008, 17:36

Cham wrote:
t00fri wrote:
Cham wrote:Since you already know how to do it "in NO time", why don't you do it ?

I am NOT interested in making add-ons :lol:

Well, okay then. No galactic core for all of us in Celestia. Too bad.

It's an easy exercise, really. While I had the original idea of displaying orbiting stars around Sgr A*, as obvious from my video

http://forum.celestialmatters.org/viewt ... 10&start=0

you found that MPE site with some real S-star measurements.

So you got to work the NON-fictional part of the project out ;-) .

Clearly all people who are not so ambitious as to using REALLY measured orbits, can take recourse to my .stc file and can visualize the qualitative features very well!


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Re: Sgr A* (galactic core)

#18by Cham » 22.11.2008, 17:42

Fridger,

you said you're not interested in add-ons, but then why did you made a fictional addon in the first place ? You're contradicting yourself. :P

Since you found the real data (I just found the web site), YOU should do the STC file, especially since you already know how to do it in NO time (from your own words). :wink:
"Well! I've often seen a cat without a grin", thought Alice; "but a grin without a cat! It's the most curious thing I ever saw in all my life!"

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Re: Sgr A* (galactic core)

#19by t00fri » 22.11.2008, 19:10

Cham wrote:Fridger,

you said you're not interested in add-ons, but then why did you made a fictional addon in the first place ? You're contradicting yourself. :P

No, I am not at all contradicting myself. I merely considered my toy example to understand precisely how to parametrize orbits in remote galaxies using galactic coordinates and appropriate frame transformations via quaternions. That was the only reason.

I made several videos from the results and explained the procedure in various posts. But I would NEVER get involved with making and distributing add-ons therof. I think there are much better suited methods for displaying "cosmic structures" via appropriate classes in C++, as also Chris mentioned some time ago.
Here is his quote from the Dev list:
Chris wrote:* New DSO type: Structure
- For spiral arms, galactic clusters, superclusters, voids, etc.
- Undecided whether this needs to be in 1.6.0

Moreover, I am busy coding more important things for Celestia right before 1.6.0 will be released.

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Re: Sgr A* (galactic core)

#20by Cham » 24.11.2008, 03:20

TADAAAM ! 8O

Click the thumbnails for a larger view :
sgrA0.jpg

sgrA1.jpg


Pretty close encounter :
sgrA2.jpg


Thanks a lot to Grant for the data conversion. :D

The black hole has a mass of about 4 Million of solar masses. The accretion disk has a 100 au radius (as stated in most papers), and its jets are aligned with the Milky Way's axis.
"Well! I've often seen a cat without a grin", thought Alice; "but a grin without a cat! It's the most curious thing I ever saw in all my life!"


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