Spectra of Stars: Reliable Data & Quantitative Analysis

[NihalRi]

I'm looking for reliable data of the spectra of different stars, anyone know any good resouces? Quantitative data would be best because I want to analyze it myself (not just find out something that was already on the site). Thanks in advance :)

 

[davenn]

I'm looking for reliable data of the spectra of different stars, anyone know any good resouces? Quantitative data would be best because I want to analyze it myself (not just find out something that was already on the site). Thanks in advance :)

did you actually try searching for data yourself ?

I typed spectra data for stars into google and got many good hits

 

[NihalRi]

i did, and i got synthesized data and files i could not open :?

 

[phyzguy]

The Sloan Digital Sky Survey SDSS has archived spectroscopic data on millions of stars and galaxies. You can plot the spectra, or download FITS files with the spectra for your own analysis. Here's how to use it:

Go to the site: http://mirror.sdss3.org . (don't use Internet Explorer, which has some issues with looking at this site). This site gives you access to a set of real astronomical data released in January 2011 by a team of astronomers. In the menu, go to "Spectra" and under that "Bulk Search." On the right side, enter the RA and Dec that you are interested in. One good one to start with is at coordinates 16.437201, -10.7071. Use a Tolerance of 2.0 arc seconds and click "Submit". Scroll down and under "Plot Spectrum" click "Plot". It will plot the spectrum, which is that of an A0 star with prominent H absorption lines.

There are a wealth of things you can do with this site.

 

[andrew s 1905]

i did, and i got synthesized data and files i could not open :?

To open spectra in FIT or FITS format you need specific software two free options are http://www.astrosurf.com/buil/isis/isis_en.htm and http://www.astrosurf.com/vdesnoux/. Hope this helps.

Andrew

 

[NihalRi]

The Sloan Digital Sky Survey SDSS has archived spectroscopic data on millions of stars and galaxies. You can plot the spectra, or download FITS files with the spectra for your own analysis. Here's how to use it:

Go to the site: http://mirror.sdss3.org . (don't use Internet Explorer, which has some issues with looking at this site). This site gives you access to a set of real astronomical data released in January 2011 by a team of astronomers. In the menu, go to "Spectra" and under that "Bulk Search." On the right side, enter the RA and Dec that you are interested in. One good one to start with is at coordinates 16.437201, -10.7071. Use a Tolerance of 2.0 arc seconds and click "Submit". Scroll down and under "Plot Spectrum" click "Plot". It will plot the spectrum, which is that of an A0 star with prominent H absorption lines.

There are a wealth of things you can do with this site.

Thank you that was really helpful, is there anywhere specific where you get the RA's and DEC's from?

 

[phyzguy]

Maybe an easier way to get started with the SDSS data is to go to this site:
http://skyserver.sdss.org/dr12/en/tools/chart/navi.aspx
This is an interactive viewer that allows you to scroll around and click on objects. If you click the box on the left that says "Objects with spectra", it will put a red box around the objects where spectra have been measured. If you click on one of those it will give you the information and show the spectrum.

On your question of how to find the coordinates for an object, there are many online tools. This site:
https://heasarc.gsfc.nasa.gov/cgi-bin/Tools/convcoord/convcoord.pl
allows you to enter the name of an object (for example "polaris"), and it will give you the coordinates.

 

[phyzguy]

Here's an interesting object that I happened upon while scrolling around and writing the last post. Go to the object at:
ra 133.03722
dec 11.43490
It is a quasar at a red shift of 2.26. The Lyman Alpha line, which at zero redshift is in the far ultraviolet at 1215 Angstroms, has been redshifted all the way into the visible at about 4000 Angstroms. We are seeing the light that left this object approximately 10 billion years ago. Cool!

 

[NihalRi]

Hi again, I've downloaded the fitz files from SDSS as you've recommended, and software that can open them, but all the data is in binary and I was just wondering is there an easy way of converting them? Or perhaps software that does that as well?

 

[phyzguy]

I just use Python and the pyfits module to interrogate and plot fits files. Below is some simple code to do this, and attached is the output of that code. If you want to learn how to extract and process data, Python is a great tool, and I encourage you to learn how to use it. There are many online tutorials.

import pyfits as pf
data = pf.getdata("~/Downloads/apStar-r5-2M08505976+1139222.fits")
plot(data[0])
show()

 

[NihalRi]

I just use Python and the pyfits module to interrogate and plot fits files. Below is some simple code to do this, and attached is the output of that code. If you want to learn how to extract and process data, Python is a great tool, and I encourage you to learn how to use it. There are many online tutorials.

import pyfits as pf
data = pf.getdata("~/Downloads/apStar-r5-2M08505976+1139222.fits")
plot(data[0])
show()

Thanks this was really helpful. I'm actually working on learning python but I'm still very new. At this frustrating part where I know what can be done but not how lol. :)