Starburst and broadline?
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by
nyjtm
In SkyServer, in the spectrum chart, galaxies are sometimes labelled Starburst or Broadline. Could someone explain what those terms mean?
Posted
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by
Budgieye
moderator
Starburst refers to lots of blue in the spectrum. A galaxy that has lots of young blue stars has lots of blue in the spectrum. You get a hump in the blue area, at around 4000
Broadline
This image below is from http://www.astr.ua.edu/keel/agn/ by our own Dr Keel
Broadline usually refers to the hot area around the nucleus of a quasar. The hot hydrogen is getting pulled around in a whirlpool at high speed. If the quasar is almost edge-on, the speed of the hot hydrogen is greater as the hydrogen comes towards us, and less as the hot hydrogen goes away from us. The difference in speed has a Doppler effect, the frequency of the emission changes, and the emission peak of hot hydrogen gets messed up, making it broader.
Seyfert 1 quasar has a narrow peak at the right.
Seyfert 2 quasar (more edge-on)has a broad peak at the right
This illustration shows features of an active galactic nucleus (AGN). Credit: Aurore Simonnet, SSU NASA E/PO.
SDSS website: Quasar spectra http://www.sdss.org.uk/dr7/en/proj/challenges/quasars/
SDSS website: Redshift Gallery: Quasars http://classic.sdss.org/gallery/gal_zqso.html Excellent selection of quasar spectra from z=0.1 to 5.0
PAGE 2 Galaxy Redshift Chart http://talk.galaxyzoo.org/#/boards/BGZ0000007/discussions/DGZ0000ulp?page=2
PAGE 3 Spectra guide for SDSS images in Galaxy Zoo Talk http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef2ee3d5a77490c0001b6
PAGE 2 Galaxy Redshift Chart http://talk.galaxyzoo.org/#/boards/BGZ0000007/discussions/DGZ0000ulp?page=2PAGE 3 Spectra guide for SDSS images in Galaxy Zoo Talk http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef2ee3d5a77490c0001b6
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