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Emission in Ca II line of Binary star HD94853
Emission in Ca II line of Binary star HD94853
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Description: This is a real spectrum of the binary star HD94853. This shows Calcium emission in the Ca II K line. The dotted line is the synthetic spectrum fit, assuming no emission is present. Once again, there are two lines, one from each star in the binary pair, separated due to the Doppler effect.
Emission features in a star indicates it is rather young. It is caused by very hot gasses radiating in the upper, thin  chromosphere of the star. This particular star-pair are probably younger than our sun and about 10% heavier.

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Posted by: SlimJim at August 20, 2003, 12:20:22 PM

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Comments (21)

June 07, 2004, 02:47:03 AM

No, Rocket Scientist!
February 21, 2004, 10:27:59 PM
iamaboringperson wrote:
...and the Amiga relevance of this is??

And the Amiga relevance of you is?
October 02, 2003, 05:21:06 AM
You must be using the windows version of IDL. The verion I'm using on a Sun Sparc just has a command line without a GUI.

I used it on a Sun machine as well, and it did actually have a GUI thing, but I never used it. I didn't like it and I found it easier to code using pico.

Pretty neat someone else knows about IDL. I've not found any other folks outside my old job and the IDL/pwave newsgroup who have even heard of it. Next to FORTRAN, it's my favorite language.
September 25, 2003, 11:46:26 AM
Nice to be able to use your Amiga for PP-similar

However, personally, I overall much loathe the
concept of PP and similar presentations - they draw
too much attention away from the speaker (me) and
have everyone focus on the screen. PP is a powerful
tool, but it's way too easy to get lazy. Many, many,
many people use PP to display the points of what
they are currently talking about (often with very
distracting shades and animations). In my view, the
only time it's really warranted to use PP is for very
complex colour pictures or diagrams, and for small
Almost everything else is best done one at the
whiteboard and with only an occational
transparency. That's the only time you get a really
good connection to your audience.
September 18, 2003, 01:09:02 PM
(I almost fogot) for a bit of Amiga relevence, I did use my 'miggy for some postFX in my astrophysics report.  And when everyone was using powerpoint for presentations, guess what I was using!
September 18, 2003, 01:04:57 PM
I feel almost guilty about 'listerning' into your privite conversation  ;-)

I did a four year astrophysics course, so an astronomy section would be good.  For my final year project I used SPH modelling for accretion discs (mainly doing some work with magnetic propellers and plantary formation), I wanted to continue with it in a phD but couldn't find the funding  :-( , so I've turned trator and I'm now using SPH in the Engineering department.  :-D .

... so more astrophysics on Amiga.org!
September 18, 2003, 12:31:09 PM
Nerd :-)
August 22, 2003, 11:55:33 AM
...and the Amiga relevance of this is??

The fact that these spectra were conceived while people were
ogling my "AOS4 On Tour" poster on the wall. ;-)
I'll 'convert' some Astronomers yet!
August 21, 2003, 11:55:37 PM
...and the Amiga relevance of this is??
August 21, 2003, 06:47:01 PM
... Well, it helps to have access to one of the finest
observational sites in the world - The mountain of La
Silla in the Atacama Desert, Chile, at 2500m altitude ;-)
- but thanks for the praise at any rate!

P.S Maybe we should start up an Astronomy
section on Amiga.org for ourselves!

 :roflmao:  Yes perhaps we should!
August 21, 2003, 05:19:25 PM
Yeah, I really wanted to say congratulations to you. You have resolved the binary stars quite clearly in the other plot and I have no doubt you have worked out their period/mass etc. Most people think something like that is easy, but I can tell it can tell you it takes a lot of dedication, as one and a half thousand things can go wrong (bad weather, clouds, improperly calibrated instruments, the dreaded smearing effect of the atmosphere, traffic shaking the building, and well, lots more). Staying awake until 1am and then spending the next 3 hours grabbing results is not very pleasant. But its worth it when you get results like this.

Excellent stuff!

P.S Maybe we should start up an Astronomy section on Amiga.org for ourselves!
August 20, 2003, 06:33:13 PM
Interesting. I know about the detector strips over
planetary surfaces, just didn't know they were
referred to as "swaths".
I've not done all that much raw image processing - I
did a reduction of a set of CCD field images over the
Large Magellanic Clouds in order to be able to
apply point spread functions, but that's about it.
At any rate, these spectra I've posted are just two of
many of course, but I'm quite satisfied with the
results. Somehow I doubt there will be a "scientific
results" - section on Amiga.org anytime soon
though! :-D
August 20, 2003, 04:31:13 PM
You're right about idlde, I've just tried it. I think the Windows version I saw must be similar to that, but the icons and colours looked much better. To get a more interactive display you can use cursor,x,y to grab the mouse co-ords, so you could have a procedure that has displays the graph in a range, grab the mouse co-ords and then re-enter the procedure.

A swath is basically the width of the area covered by the satellite orthogonal to its direction of travel. So say a satellite travels in the x direction and the detector can rotate 3 degrees in the y axis. This 3 degrees might mean a length of 150km on the ground. (Use pythagorus and the height of the sat as one of the lengths). This is essentially the swath width. But the satellite is moving constantly so you don't end up with a perfect rectangle of the earth but a slightly warped one.

I'm studying Remote Sensing & Image Processing but its more for meteorology than astrophysics. A new satellite called Auro is (hopefully) being launched in Jan 2003. It has a limb sounding instrument that has a complicated retrieval algorithim. I'm producing statistics to say wether the retrieval will be accurate.
August 20, 2003, 04:12:04 PM
Actually, IDL for Linux has an IDE as well, you just start it
with 'idlde' instead of 'idl' (if I remember correctly). But I don't
need a better input environment - a shell is good enough for
that - I'd like a better display interface when displaying the
Anyway. If I remember correctly the Gallileo had a
malfunction so its primary antenna couldn't be extended
properly, right? T'was a shame, but at least they could get
some data through in the end. The data compression
development took some big leaps in those days. ;-)
By the way, what is a "swath", if I may ask?
What are you working on for your final report (I suppose
you mean final paper)?
August 20, 2003, 03:57:58 PM
Yeah, my spelling is terrible at the moment. It probably has a lot to do with the fact I'm writing my final report just now.

Anyway, the windows version of IDL is a world apart from the Linux one. It has an integrated debugger, IDE, variable trace and well, everything really. I think you download a trial version that lasts about 15 mins. You should check it out.

As for Gallileo, we did the work about 2 years ago. We had one nadir swath path over Jupiter so we didn't have to worry too much about the location of the swath. We had pixel counts at various wavelengths and the calibration info. I'm pretty sure it was a multi band spectrometer that had pretty fine resolution. I also remember most of the similiar channels were chucked away because Nasa could only recieve the data at 100bps. Nasa had arranged it with our uni to help process the data.
August 20, 2003, 03:25:00 PM
"Enthusiasm" ;-)
You reduced raw data from the Gallileo probe? Now that's cool work for an undergraduate!
August 20, 2003, 03:22:39 PM
I run IDL under Linux. Only a command line interface here
too. That's what I'm talking about ;-)
I have no problems writing commands, but I feel it would
help speed up things if I could get a somewhat more
interactive display - capable of zooming with a shortcut, for
example, or pan in the spectrum with the arrow keys.
set_xy,6670,6680,0.5,1.05 & plot,wtest-1.37,ftest*14.85 & oplot,wp,gfps,linestyle=1
(example from a non-normalized spectrum) ... is not
directly intuitive when you want to play around. Especially
as the command history is only 20 items long. Maybe
there are enhancements to get for the display system that I
didn't know about?
August 20, 2003, 01:36:43 PM
You must be using the windows version of IDL. The verion I'm using on a Sun Sparc just has a command line without a GUI. Still, I think thats one of the reasons why I love it so much.

Yes, my friend is creating a new stellar model. Apparently, one of the previous students had focused on the spectrum of one star and had found (they reasoned) some new forbidden lines. They know roughly the composition of the star, so Greg (my friend) is developing a new model based on this.

I can understand your enthusaism behind posting these plots.
When I was studying Astrophysics as an undergraduate, we got our hands on the raw data from the Galileo probe (the one that went to Jupiter). I remember being really excited when we saw  traces of compounds that (at the time) we thought couldn't exist in it's atmosphere.

[edit: can't spell enthusaism correctly!]
August 20, 2003, 12:47:24 PM
Yes,  it's IDL. It's very powerful, but I cannot say I'm overly
thrilled at the interface - it's cumbersome when having to
tweak small parameters at a time.
The synthetic fit is obtained using the Synthe
one-dimensional spectrum synthesis program. It uses the
ATLAS model by Kurucz at pretty much solar like input
conditions (the binary is a G1V system).
Is your pal creating a new stellar model for his PhD, or is he
using one? There is a lot of discussion these days about  
3D-modelling of atmospheres. It seems to predict certain
lines better. Is it something like that he's working on?
August 20, 2003, 12:36:54 PM
It looks like IDL was used to make this plot. I absolutely love this program, in fact I used it to create my avtar :-)  I'm waiting for it to be ported to the amiga. Anyway to your results, thats a great fit between predicted and actual flux. Whose star model are you using? My friend is actually creating one for his phd
August 20, 2003, 12:35:18 PM
For those not used to reading spectra, it's intensity of light on
the y-axis and wavelength in Åhmström (10Å=1nm) on the
x-axis. You might be used to thinking of a spectrum as a "band
of colours", and that is also correct. This "professional"
spectrum is simply looking at the spectral lines "from the side"
in a sense. If you were to look at this spectrum in the "normal"
way, representing intensity only with a colour rather than a  
numbered y-axis, it would be bluish dark, at the very edge
of ultraviolet.

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