It is currently Fri, 15-12-17, 11:54 GMT

All times are UTC




Post new topic Reply to topic  [ 6 posts ] 
Author Message
PostPosted: Sat, 03-07-10, 10:19 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4514
Location: Hamburg, Germany
Hi all,

it is known since not too long (mid 1990) that the core region of globular clusters tends to be populated with millisecond pulsars! The great globular cluster 47 Tucanae contains the highest number of radio pulsars currently known in any cluster , and about a third of the total number of known cluster pulsars. The known pulsar population in the core of 47 Tuc is VERY different from the pulsar population in the Galactic disk: all of the pulsars have periods less than 8ms, and 13 are members of binary systems. The coordinates, rotational parameters and timing solutions of the 47 Tuc pulsars are meanwhile known! That sounds exciting indeed...

++++++++++++++++++++++++++++++++
For my forthcoming Celestia.Sci release, I am currently working to create a beautiful rendering of these pulsars, including the measured sound patterns

A rotational period of T = 8ms corresponds to a well audible sound of frequency f = 1/T = 125 Hz!

To make such fundamental astrophysical phenomena audible constitutes for me a main reason for implementing a sound module into Celestia (.Sci). Of course, there are also accoustic phenomena of interest in planetary systems like Saturn or Jupiter...
++++++++++++++++++++++++++++++++

Here is a site that summarizes the available scientific information about the 23 known millisecond pulsars in 47 Tuc: http://www2.naic.edu/~pfreire/47Tuc/#Plots

along with some basic original publications:

http://adsabs.harvard.edu/abs/2003MNRAS.340.1359F
http://adsabs.harvard.edu/abs/2001MNRAS.326..901F

from which I took these illustrational plots:

Timings:
-------------
Image

Positions:
--------------
Image

Of course, there are more globular clusters in my Celestia.Sci data base that host known millisecond pulsars in their centers!

While my work is in progress, have a look at this video by Michael Kramer and Andrew Lyne, displaying the known pulsars in the center of 47 Tuc BOTH visually and accoustically. If your line is too slow, download the file. It's worth it!

++++++++++++++++++++++++++++++++++++++++++++++++++++
http://www.jb.man.ac.uk/~pulsar/Educati ... 2final.avi
++++++++++++++++++++++++++++++++++++++++++++++++++++

Or are you interested how the Crab pulsar sounds? Here it is:
http://www.celestialmatters.org/users/t ... s2/crab.au
Rotation frequency is about 30 times /sec

Here is a 'normal' pulsar PSR B0329+54, rotating about 1.40 times/sec
http://www.celestialmatters.org/users/t ... 2/B0329.au

There are more examples here: http://www.jb.man.ac.uk/~pulsar/Education/Sounds/

Enjoy,
Fridger


Last edited by t00fri on Sat, 03-07-10, 11:29 GMT, edited 1 time in total.

Top
 Profile  
 
PostPosted: Sat, 03-07-10, 10:52 GMT 
Offline
User avatar

Joined: Mon, 03-09-07, 23:01 GMT
Posts: 388
Location: Tuscany, Tyrrhenian Sea
t00fri wrote:

A rotational period of T = 8ms corresponds to a well audible sound of frequency f = 1/T = 125 Hz!



I think some guys with powerful subwoofers will insert Celestia.Sci into the dangerous softwares list for the masses (their next-door neighbours) :D


Top
 Profile  
 
PostPosted: Sun, 01-09-13, 18:56 GMT 
Offline
User avatar

Joined: Mon, 03-09-07, 23:01 GMT
Posts: 388
Location: Tuscany, Tyrrhenian Sea
Hi! The PDFs links above seems no longer available... :?
Nonetheless I've played a bit with the sound that such timings would get, at least for one pulsar, namely the E. I'm not sure whether the procedures below are correct just about for the lacking of further readings. Moreover, in the plots aren't specified the "decibels" (dB) between peaks, thus I've modelled the waveform through the "rule of thumb" of assuming 0 (zero) dB as the maximum visible peak within the relevant plot and then through the modelling of the remains waveforms against their spectrum until the visual matching. Nor their modulations, if any, has been taken into account, of course.
Anyhow, I followed two way:
1) by generating the suited 3 tones for the relevant timing (roughly, from the plot) and then edited and mixed down on the multitrack;

Attachment:
47Tuc-E-tone.png
47Tuc-E-tone.png [ 14.66 KiB | Viewed 4240 times ]

47Tuc-Pulsar-E (tone) FLAC

2) by generating several pink noise waveforms for the relevant timing and then applying a narrowest band-pass Chebychev filter to each one in order to yield only the peaks and the noise "armonics". Then the usual procedure of gain leveling and mixing down the tracks. In this case the sound is more "dirty".

Attachment:
47Tuc-E-pink.png
47Tuc-E-pink.png [ 14.8 KiB | Viewed 4240 times ]

47Tuc-Pulsar-E (pink noise) FLAC

The two methods have different behaviour against the spectrum analizer, being the second resembling more visually the plot while the first act on more clean signal-to-noise ratio, isolating just the peaks from the floor.

Note that the spectrums are flipped respect to the plots because frequency = 1/time. The software used was Adobe Audition.


Top
 Profile  
 
PostPosted: Mon, 02-09-13, 9:26 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4514
Location: Hamburg, Germany
Massimo,

good you started playing again with the millisecond pulsars! That brings some momentum back to this nice subject. ;-)

Visually there is no special .Sci rendering of these millisecond pulsars available yet. Cham has experimented repeatedly with various nice pulsar renderings, but I want to use a somewhat different OpenGL & code-based technique. The pulsars in question typically sit in the centers of globulars which is nice, since people (users) could travel there and listen to electronic music ;-) . The good thing is that these central pulsars would be entered by means of a .dsc file and thus one can GOTO them as usual without further coding effort. Since they are located in the centers of globulars (like BH's in the centers of galaxies) , the sky view will be spectactular there.

No concise ideas yet about the required cross-platform sound engine, but I think a solution is not difficult. I suppose you had a look at the accoustic-visual video above that has been done by Michael Kramer and Andrew Lyne,

http://www.jb.man.ac.uk/~pulsar/Educati ... 2final.avi

Since there were several PDF links above, I was unable to locate the ones you claim missing. Anyway the links to the PDF versions of the scientific papers are still there and valid.

Fridger


Top
 Profile  
 
PostPosted: Mon, 02-09-13, 17:59 GMT 
Offline
User avatar

Joined: Mon, 03-09-07, 23:01 GMT
Posts: 388
Location: Tuscany, Tyrrhenian Sea
t00fri wrote:
No concise ideas yet about the required cross-platform sound engine, but I think a solution is not difficult.


For what I know, cross-platform API which are used to make audio software is JACK. It is used also in sound generators, which I suppose is the most suited form of achieving such pulsar impulses, since they could be hard coded instead of to play a waveform (weight!) all the time. here the list of audio softwares which uses JACK.


Top
 Profile  
 
PostPosted: Mon, 02-09-13, 21:44 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4514
Location: Hamburg, Germany
fenerit wrote:
t00fri wrote:
No concise ideas yet about the required cross-platform sound engine, but I think a solution is not difficult.


For what I know, cross-platform API which are used to make audio software is JACK. It is used also in sound generators, which I suppose is the most suited form of achieving such pulsar impulses, since they could be hard coded instead of to play a waveform (weight!) all the time. here the list of audio softwares which uses JACK.


I know JACK, the outstanding feature of which is its low latency. The code situation is, however, somewhat complex, since there is both JACK1 and JACK2. Only JACK2 sources are in C++ and support multi processors etc.

I think for various reasons our best option is really to explore the available multimedia features that are already integrated in our cross-platform Qt library! Notably the latest Qt 5.x branch has impressive new sound options.

Have a look at Qt Multimedia Overview

If you want to see more details, go on to the links at the bottom of that page

In Qt, the so-called AudioEngine acts as a central library for configuring all 3d audio content in an application. One may even set e.g. Doppler shifts, the speed of sound etc...

Notably, on the Qt Multimedia feature list is the possibility of playing 3D positional audio with QtAudioEngine. So, with a number of spacially separated "singing pulsars", this could lead to quite an amazing 3D "concert"... ;-)

Christophe (ElChristou) immediately referred to the gorgeous "Virtual Barber Shop" at YouTube when we discussed the issue earlier today ;-). On the QSoundLabs page there are many more 3D positional audio demo clips. Try e.g. the Jet Taking Off...

Using the Qt framework makes our sound (and video etc) not only automatically cross-platform, but also we don't need to attach a host of further service libraries, which can easily become a mess! Using Qt sound should give us the best possible guarantee of multimedia compatibility with the rest of the .Sci code. I am also thinking of course of a number of further multimedia features that I want to implement...

Despite this positive first impression of multimedia in Qt 5.x I am convinced that we'll still meet lots of little "devils" on the way until everything works as desired. Moreover, we'll have to try installing now the latest Qt 5.1 library along with the required recent compilers. As it seems the upgrade is all but trivial and will also cost plenty of time...

Anyway, getting into coding such a scenario, sounds like a lot of fun...

Fridger


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group