Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Difference between 'Optical Spectral Type' and 'IR Spectral Type'?

  1. Feb 25, 2011 #1
    In the list of L and T dwarfs at 'dwarfarchives.org' (http://ldwarf.ipac.caltech.edu/archive/version5/viewlist.php?table=ltdwarf&format=html") there are two columns named 'spectral_type_opt' and 'spectral_type_ir'. I guess this comes from the type of instrument used in the measurements?

    If I'm correct, the Spectral Type indicates the surface temperature of stars. If so why would the optical and infrared spectra give two different measurements? Which one is more accurate? Since the visual spectra of L and T dwarfs are very faint, would the 'infrared spectral type' be more accurate?
    Last edited by a moderator: Apr 25, 2017
  2. jcsd
  3. Mar 2, 2011 #2


    User Avatar
    Science Advisor
    Gold Member

    The optical band, usually referred to as the V-band spectrum, is a small slice of the EM spectrum. The IR spectrum is much wider. Most objects in the universe are brighter in the IR spectrum - especially those with low V-band emissions.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Difference between 'Optical Spectral Type' and 'IR Spectral Type'?
  1. Spectral index (Replies: 1)

  2. Spectral Width (Replies: 1)