Spectrum

by bluemagi

This spectrum looks as if it has a spike on the helium and hydrogen. I have had only one other galaxy with a spike of helium. How common is a helium spike?

Posted September 5, 2016 11:15 PM

by Budgieye moderator

SDSS says that only hot stars have ionized helium. So, 28,000 to 50,000 degrees K
http://skyserver.sdss.org/dr1/en/proj/advanced/spectraltypes/lines.asp

But galaxies are more than stars. There are emissions from black holes, and collisions between clouds of hydrogen. these temperatures can reach millions of degrees.

enter image description here

http://legacysurvey.org/viewer/jpeg-cutout/?ra=180.6878&dec=0.9954&zoom=16&layer=decals-dr2

enter image description here

http://skyservice.pha.jhu.edu/DR9/ImgCutout/getjpeg.aspx?ra=180.68800248&dec=0.99564014&scale=0.2&width=200&height=200&opt=G

enter image description here

z= 0.082 0.00001

Three of the big lines, with light blue extending from them, are artifacts, light from our atmosphere. Go to this link and explore sky flux.

http://dr12.sdss3.org/spectrumDetail?plateid=286&mjd=51999&fiber=332

Posted September 6, 2016 5:36 AM

by bluemagi

Thanks. Its interesting. The only thing I know is what you said, that it has to be really HOT for helium to appear on a spectrum.

Posted September 6, 2016 6:41 AM